eProsima Fast DDS Documentation
eProsima Fast DDS is a C++ implementation of the DDS (Data Distribution Service) Specification, a protocol defined by the Object Management Group (OMG). The eProsima Fast DDS library provides both an Application Programming Interface (API) and a communication protocol that deploy a Data-Centric Publisher-Subscriber (DCPS) model, with the purpose of establishing efficient and reliable information distribution among Real-Time Systems. eProsima Fast DDS is predictable, scalable, flexible, and efficient in resource handling. For meeting these requirements, it makes use of typed interfaces and hinges on a many-to-many distributed network paradigm that neatly allows separation of the publisher and subscriber sides of the communication. eProsima Fast DDS comprises:
The DDS API implementation.
Fast DDS-Gen, a generation tool for bridging typed interfaces with the middleware implementation.
The underlying RTPS wire protocol implementation.
For all the above, eProsima Fast DDS has been chosen as the default middleware supported by the Robot Operating System 2 (ROS 2) in every long term (LTS) releases and most of the non-LTS releases.
DDS API¶
The communication model adopted by DDS is a many-to-many unidirectional data exchange where the applications that produce the data publish it to the local caches of subscribers belonging to applications that consume the data. The information flow is regulated by Quality of Service (QoS) policies established between the entities in charge of the data exchange.
As a data-centric model, DDS builds on the concept of a “global data space” accessible to all interested applications. Applications that want to contribute information declare their intent to become publishers, whereas applications that want to access portions of the data space declare their intent to become subscribers. Each time a publisher posts new data into this space, the middleware propagates the information to all interested subscribers.
The communication happens across domains, i. e. isolated abstract planes that link all the distributed applications able to communicate with each other. Only entities belonging to a same domain can interact, and the matching between entities subscribing to data and entities publishing them is mediated by topics. Topics are unambiguous identifiers that associate a name, which is unique in the domain, to a data type and a set of attached data-specific QoS.
DDS entities are modeled either as classes or typed interfaces. The latter imply a more efficient resource handling as knowledge of the data type prior to the execution allows allocating memory in advance rather than dynamically.
Conceptual diagram of how information flows within DDS domains. Only entities belonging to the same domain can discover each other through matching topics, and consequently exchange data between publishers and subscribers.¶
Fast DDS-Gen¶
Relying on interfaces implies the need for a generation tool that translates type descriptions into appropriate implementations that fill the gap between the interfaces and the middleware. This task is carried out by a dedicated generation tool, Fast DDS-Gen, a Java application that generates source code using the data types defined in an Interface Definition Language (IDL) file.
RTPS Wire Protocol¶
The protocol used by eProsima Fast DDS to exchange messages over standard networks is the Real-Time Publish-Subscribe protocol (RTPS), an interoperability wire protocol for DDS defined and maintained by the OMG consortium. This protocol provides publisher-subscriber communications over transports such as TCP/UDP/IP, and guarantees compatibility among different DDS implementations.
Given its publish-subscribe roots and its specification designed for meeting the same requirements addressed by the DDS application domain, the RTPS protocol maps to many DDS concepts and is therefore a natural choice for DDS implementations. All the RTPS core entities are associated with an RTPS domain, which represents an isolated communication plane where endpoints match. The entities specified in the RTPS protocol are in one-to-one correspondence with the DDS entities, thus allowing the communication to occur.
Main Features¶
Two API Layers. eProsima Fast DDS comprises a high-level DDS compliant layer focused on usability and a lower-level RTPS compliant layer that provides finer access to the RTPS protocol.
Real-Time behaviour. eProsima Fast DDS can be configured to offer real-time features, guaranteeing responses within specified time constrains.
Built-in Discovery Server. eProsima Fast DDS is based on the dynamical discovery of existing publishers and subscribers, and performs this task continuously without the need to contacting or setting any servers. However, a Client-Server discovery as well as other discovery paradigms can also be configured.
Sync and Async publication modes. eProsima Fast DDS supports both synchronous and asynchronous data publication.
Best effort and reliable communication. eProsima Fast DDS supports an optional reliable communication paradigm over Best Effort communications protocols such as UDP. Furthermore, another way of setting a reliable communication is to use our TCP transport.
Transport layers. eProsima Fast DDS implements an architecture of pluggable transports. The current version implements five transports: UDPv4, UDPv6, TCPv4, TCPv6 and SHM (shared memory).
Security. eProsima Fast DDS can be configured to provide secure communications. For this purpose, it implements pluggable security at three levels: authentication of remote participants, access control of entities and encryption of data.
Statistics Module. eProsima Fast DDS can be configured to gather and provide information about the data being exchanged by the user application.
Flow controllers. We support user-configurable flow controllers, that can be used to limit the amount of data to be sent under certain conditions.
Plug-and-play Connectivity. New applications and services are automatically discovered, and can join and leave the network at any time without the need for reconfiguration.
Scalability and Flexibility. DDS builds on the concept of a global data space. The middleware is in charge of propagating the information between publishers and subscribers. This guarantees that the distributed network is adaptable to reconfigurations and scalable to a large number of entities.
Application Portability. The DDS specification includes a platform specific mapping to IDL, allowing an application using DDS to switch among DDS implementations with only a re-compile.
Extensibility. eProsima Fast DDS allows the protocol to be extended and enhanced with new services without breaking backwards compatibility and interoperability.
Configurability and Modularity. eProsima Fast DDS provides an intuitive way to be configured, either through code or XML profiles. Modularity allows simple devices to implement a subset of the protocol and still participate in the network.
High performance. eProsima Fast DDS uses a static low-level serialization library, Fast CDR, a C++ library that serializes according to the standard CDR serialization mechanism defined in the RTPS Specification (see the Data Encapsulation chapter as a reference).
Easy to use. The project comes with an out-of-the-box example, the DDSHelloWorld (see Getting Started) that puts into communication a publisher and a subscriber, showcasing how eProsima Fast DDS is deployed. Additionally, the interactive demo ShapesDemo is available for the user to dive into the DDS world. The DDS and the RTPS layers are thoroughly explained in the DDS Layer and RTPS Layer sections.
Low resources consumption. eProsima Fast DDS:
Allows to preallocate resources, to minimize dynamic resource allocation.
Avoids the use of unbounded resources.
Minimizes the need to copy data.
Multi-platform. The OS dependencies are treated as pluggable modules. Users may easily implement platform modules using the eProsima Fast DDS library on their target platforms. By default, the project can run over Linux, Windows and MacOS.
Free and Open Source. The Fast DDS library, the underneath RTPS library, the generator tool, the internal dependencies (such as eProsima Fast CDR) and the external ones (such as the foonathan library) are free and open source.
Dependencies and compatibilities¶
eProsima Fast DDS is continuously evolving and improving. This means that the different software products that are part of the Fast DDS ecosystem are evolving and improving together with Fast DDS.
Fast DDS has some library dependencies, e.g. the previously mentioned Fast CDR for data serialization, or OpenSSL for secure communications. Depending on different platform support levels, it has also different build dependencies.
Finally, there are some other eProsima products that use Fast DDS as a middleware, such as Micro XRCE-DDS, DDS Router and Fast DDS python wrapper. Those that are strongly attached to each Fast DDS supported version are described in this product compatibility table.
Contacts and Commercial support¶
Find more about us at eProsima’s webpage.
Support available at:
Email: support@eprosima.com
Phone: +34 91 804 34 48
Contributing to the documentation¶
Fast DDS-Docs is an open source project, and as such all contributions, both in the form of feedback and content generation, are most welcomed. To make such contributions, please refer to the Contribution Guidelines hosted in our GitHub repository.
Structure of the documentation¶
This documentation is organized into the sections below.
eProsima Fast DDS Documentation
eProsima Fast DDS is a C++ implementation of the DDS (Data Distribution Service) Specification, a protocol defined by the Object Management Group (OMG). The eProsima Fast DDS library provides both an Application Programming Interface (API) and a communication protocol that deploy a Data-Centric Publisher-Subscriber (DCPS) model, with the purpose of establishing efficient and reliable information distribution among Real-Time Systems. eProsima Fast DDS is predictable, scalable, flexible, and efficient in resource handling. For meeting these requirements, it makes use of typed interfaces and hinges on a many-to-many distributed network paradigm that neatly allows separation of the publisher and subscriber sides of the communication. eProsima Fast DDS comprises:
The DDS API implementation.
Fast DDS-Gen, a generation tool for bridging typed interfaces with the middleware implementation.
The underlying RTPS wire protocol implementation.
For all the above, eProsima Fast DDS has been chosen as the default middleware supported by the Robot Operating System 2 (ROS 2) in every long term (LTS) releases and most of the non-LTS releases.
DDS API¶
The communication model adopted by DDS is a many-to-many unidirectional data exchange where the applications that produce the data publish it to the local caches of subscribers belonging to applications that consume the data. The information flow is regulated by Quality of Service (QoS) policies established between the entities in charge of the data exchange.
As a data-centric model, DDS builds on the concept of a “global data space” accessible to all interested applications. Applications that want to contribute information declare their intent to become publishers, whereas applications that want to access portions of the data space declare their intent to become subscribers. Each time a publisher posts new data into this space, the middleware propagates the information to all interested subscribers.
The communication happens across domains, i. e. isolated abstract planes that link all the distributed applications able to communicate with each other. Only entities belonging to a same domain can interact, and the matching between entities subscribing to data and entities publishing them is mediated by topics. Topics are unambiguous identifiers that associate a name, which is unique in the domain, to a data type and a set of attached data-specific QoS.
DDS entities are modeled either as classes or typed interfaces. The latter imply a more efficient resource handling as knowledge of the data type prior to the execution allows allocating memory in advance rather than dynamically.
Conceptual diagram of how information flows within DDS domains. Only entities belonging to the same domain can discover each other through matching topics, and consequently exchange data between publishers and subscribers.¶
Fast DDS-Gen¶
Relying on interfaces implies the need for a generation tool that translates type descriptions into appropriate implementations that fill the gap between the interfaces and the middleware. This task is carried out by a dedicated generation tool, Fast DDS-Gen, a Java application that generates source code using the data types defined in an Interface Definition Language (IDL) file.
RTPS Wire Protocol¶
The protocol used by eProsima Fast DDS to exchange messages over standard networks is the Real-Time Publish-Subscribe protocol (RTPS), an interoperability wire protocol for DDS defined and maintained by the OMG consortium. This protocol provides publisher-subscriber communications over transports such as TCP/UDP/IP, and guarantees compatibility among different DDS implementations.
Given its publish-subscribe roots and its specification designed for meeting the same requirements addressed by the DDS application domain, the RTPS protocol maps to many DDS concepts and is therefore a natural choice for DDS implementations. All the RTPS core entities are associated with an RTPS domain, which represents an isolated communication plane where endpoints match. The entities specified in the RTPS protocol are in one-to-one correspondence with the DDS entities, thus allowing the communication to occur.
Main Features¶
Two API Layers. eProsima Fast DDS comprises a high-level DDS compliant layer focused on usability and a lower-level RTPS compliant layer that provides finer access to the RTPS protocol.
Real-Time behaviour. eProsima Fast DDS can be configured to offer real-time features, guaranteeing responses within specified time constrains.
Built-in Discovery Server. eProsima Fast DDS is based on the dynamical discovery of existing publishers and subscribers, and performs this task continuously without the need to contacting or setting any servers. However, a Client-Server discovery as well as other discovery paradigms can also be configured.
Sync and Async publication modes. eProsima Fast DDS supports both synchronous and asynchronous data publication.
Best effort and reliable communication. eProsima Fast DDS supports an optional reliable communication paradigm over Best Effort communications protocols such as UDP. Furthermore, another way of setting a reliable communication is to use our TCP transport.
Transport layers. eProsima Fast DDS implements an architecture of pluggable transports. The current version implements five transports: UDPv4, UDPv6, TCPv4, TCPv6 and SHM (shared memory).
Security. eProsima Fast DDS can be configured to provide secure communications. For this purpose, it implements pluggable security at three levels: authentication of remote participants, access control of entities and encryption of data.
Statistics Module. eProsima Fast DDS can be configured to gather and provide information about the data being exchanged by the user application.
Flow controllers. We support user-configurable flow controllers, that can be used to limit the amount of data to be sent under certain conditions.
Plug-and-play Connectivity. New applications and services are automatically discovered, and can join and leave the network at any time without the need for reconfiguration.
Scalability and Flexibility. DDS builds on the concept of a global data space. The middleware is in charge of propagating the information between publishers and subscribers. This guarantees that the distributed network is adaptable to reconfigurations and scalable to a large number of entities.
Application Portability. The DDS specification includes a platform specific mapping to IDL, allowing an application using DDS to switch among DDS implementations with only a re-compile.
Extensibility. eProsima Fast DDS allows the protocol to be extended and enhanced with new services without breaking backwards compatibility and interoperability.
Configurability and Modularity. eProsima Fast DDS provides an intuitive way to be configured, either through code or XML profiles. Modularity allows simple devices to implement a subset of the protocol and still participate in the network.
High performance. eProsima Fast DDS uses a static low-level serialization library, Fast CDR, a C++ library that serializes according to the standard CDR serialization mechanism defined in the RTPS Specification (see the Data Encapsulation chapter as a reference).
Easy to use. The project comes with an out-of-the-box example, the DDSHelloWorld (see Getting Started) that puts into communication a publisher and a subscriber, showcasing how eProsima Fast DDS is deployed. Additionally, the interactive demo ShapesDemo is available for the user to dive into the DDS world. The DDS and the RTPS layers are thoroughly explained in the DDS Layer and RTPS Layer sections.
Low resources consumption. eProsima Fast DDS:
Allows to preallocate resources, to minimize dynamic resource allocation.
Avoids the use of unbounded resources.
Minimizes the need to copy data.
Multi-platform. The OS dependencies are treated as pluggable modules. Users may easily implement platform modules using the eProsima Fast DDS library on their target platforms. By default, the project can run over Linux, Windows and MacOS.
Free and Open Source. The Fast DDS library, the underneath RTPS library, the generator tool, the internal dependencies (such as eProsima Fast CDR) and the external ones (such as the foonathan library) are free and open source.
Dependencies and compatibilities¶
eProsima Fast DDS is continuously evolving and improving. This means that the different software products that are part of the Fast DDS ecosystem are evolving and improving together with Fast DDS.
Fast DDS has some library dependencies, e.g. the previously mentioned Fast CDR for data serialization, or OpenSSL for secure communications. Depending on different platform support levels, it has also different build dependencies.
Finally, there are some other eProsima products that use Fast DDS as a middleware, such as Micro XRCE-DDS, DDS Router and Fast DDS python wrapper. Those that are strongly attached to each Fast DDS supported version are described in this product compatibility table.
Contacts and Commercial support¶
Find more about us at eProsima’s webpage.
Support available at:
Email: support@eprosima.com
Phone: +34 91 804 34 48
Contributing to the documentation¶
Fast DDS-Docs is an open source project, and as such all contributions, both in the form of feedback and content generation, are most welcomed. To make such contributions, please refer to the Contribution Guidelines hosted in our GitHub repository.
Structure of the documentation¶
This documentation is organized into the sections below.
Linux installation from binaries¶
The instructions for installing eProsima Fast DDS in a Linux environment from binaries are provided in this page.
Install¶
The latest release of eProsima Fast DDS for Linux is available at the eProsima website
Downloads tab.
Once downloaded, extract the contents in your preferred directory.
Then, to install eProsima Fast DDS and all its dependencies in the system, execute
the install.sh script with administrative privileges:
cd <extraction_directory>
sudo ./install.sh
Note
By default, eProsima Fast DDS does not compile tests. To activate them, please refer to the Linux installation from sources page.
To use the xml validation tool, please refer to the Linux installation from sources page.
Contents¶
The src folder contains the following packages:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library for data serialization according to the CDR standard (Section 10.2.1.2 OMG CDR).fastdds, the core library of eProsima Fast DDS library.fastddsgen, a Java application that generates source code using the data types defined in an IDL file.
See also
For further information about Fast DDS dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Dependencies and compatibilities section.
In case any of these components is unwanted, it can be simply renamed or removed from the src
directory.
Run an application¶
When running an instance of an application using eProsima Fast DDS, it must be linked with the library where the
packages have been installed, /usr/local/lib/. There are two possibilities:
Prepare the environment locally by typing in the console used for running the eProsima Fast DDS instance the command:
export LD_LIBRARY_PATH=/usr/local/lib/
Add it permanently to the
PATHby executing:echo 'export LD_LIBRARY_PATH=/usr/local/lib/' >> ~/.bashrc
Including Fast-DDS in a CMake project¶
The installer deploys CMake config files that simplify to incorporate Fast-DDS to any CMake project via the find_package CMake API.
By setting the CMake variable BUILD_SHARED_LIBS is possible to choose the desired linkage (dynamic or static library) in the CMake generator stage. If the variable is missing build process will default to static linking.
For example in order to build the examples dynamically linked to Fast-DDS do:
$ cmake -Bbuildexample -DBUILD_SHARED_LIBS=ON . $ cmake --build buildexample --target install
Uninstall¶
To uninstall all installed components, execute the uninstall.sh script (with administrative privileges):
cd <extraction_directory>
sudo ./uninstall.sh
Warning
If any of the other components were already installed in some other way in the system, they will be removed as well. To avoid it, edit the script before executing it.
Windows installation from binaries¶
The instructions for installing eProsima Fast DDS in a Windows environment from binaries are provided in this page. It is organized as follows:
First of all, the Requirements detailed below need to be met.
Requirements¶
The installation of eProsima Fast DDS in a Windows environment from binaries requires the following tools to be installed in the system:
Visual Studio¶
Visual Studio is required to
have a C++ compiler in the system. For this purpose, make sure to check the
Desktop development with C++ option during the Visual Studio installation process.
If Visual Studio is already installed but the Visual C++ Redistributable packages are not,
open Visual Studio and go to Tools -> Get Tools and Features and in the Workloads tab enable
Desktop development with C++. Finally, click Modify at the bottom right.
Install¶
The latest release of eProsima Fast DDS for Windows is available at the company website downloads page. Once downloaded, execute the installer and follow the instructions, choosing the preferred Visual Studio version and architecture when prompted.
Note
By default, eProsima Fast DDS does not compile tests. To activate them, please refer to the Windows installation from sources page.
To use the xml validation tool, please refer to the Windows installation from sources page.
Contents¶
By default, the installation will download all the available packages, namely:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.fastdds, the core library of eProsima Fast DDS library.fastddsgen, a Java application that generates source code using the data types defined in an IDL file.
See also
For further information about Fast DDS dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Dependencies and compatibilities section.
Environment variables¶
eProsima Fast DDS requires the following environment variable setup in order to function properly:
FASTDDSHOME: Root folder where eProsima Fast DDS is installed.Additions to the
PATH: The location of eProsima Fast DDS scripts and libraries should be appended to thePATH.
These variables are set automatically by checking the corresponding box during the installation process.
Including Fast-DDS in a CMake project¶
The installer deploys CMake config files that simplify to incorporate Fast-DDS to any CMake project via the find_package CMake API.
Shared and static libraries are provided by the installer. The user can select which one will be used in the CMake project using next mechanisms.
Through CMake package components when calling find_package().
find_package(fastdds shared) # Load shared library target find_package(fastdds static) # Load static library target
Through the custom CMake variable fastdds_SHARED_LIBS.
cmake -Dfastdds_SHARED_LIBS=ON .. # Load shared library target cmake -Dfastdds_SHARED_LIBS=OFF .. # Load static library target
Through the built-in CMake variable BUILD_SHARED_LIBS.
cmake -DBUILD_SHARED_LIBS=ON .. # Load shared library target cmake -DBUILD_SHARED_LIBS=OFF .. # Load static library target
In case no previous mechanism is used, CMake will try to load static library target. If it fails then CMake will try to load shared library target.
For example in order to build the examples dynamically linked to Fast-DDS do:
> cmake -Bbuildexample -DBUILD_SHARED_LIBS=ON . > cmake --build buildexample --target install
Linux installation from sources¶
The instructions for installing the Fast DDS library, the Fast DDS Python bindings and the Fast DDS-Gen generation tool from sources are provided in this page. It is organized as follows:
Fast DDS library installation¶
This section describes the instructions for installing eProsima Fast DDS in a Linux environment from sources. The following packages will be installed:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.fastdds, the core library of eProsima Fast DDS library.
First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.
Requirements¶
The installation of eProsima Fast DDS in a Linux environment from sources requires the following tools to be installed in the system:
CMake, g++, pip3, wget and git¶
These packages provide the tools required to install eProsima Fast DDS and its dependencies from command line. Install CMake, g++, pip3, wget and git using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:
sudo apt install cmake g++ python3-pip wget git
Dependencies¶
eProsima Fast DDS has the following dependencies, when installed from sources in a Linux environment:
Gtest [optional]
XML validation tool [optional]
See also
For further information about this Fast DDS version dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Library dependencies section.
Asio and TinyXML2 libraries¶
Asio is a cross-platform C++ library for network and low-level I/O programming, which provides a consistent asynchronous model. TinyXML2 is a simple, small and efficient C++ XML parser. Install these libraries using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:
sudo apt install libasio-dev libtinyxml2-dev
OpenSSL¶
OpenSSL is a robust toolkit for the TLS and SSL protocols and a general-purpose cryptography library. Install OpenSSL using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:
sudo apt install libssl-dev
Libp11 and SoftHSM libraries¶
Libp11 provides PKCS#11 support for OpenSSL. This is an optional dependency, that is needed only when eprosima Fast DDS is used with security and PKCS#11 URIs.
Install libp11 using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:
sudo apt install libp11-dev
SoftHSM is a software implementation of an HSM (Hardware Security Module). If eProsima Fast DDS tests are activated and libp11 is installed on the system, SoftHSM is additionally required to run tests of PKCS#11 features.
Install SoftHSM using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:
sudo apt install softhsm2
Note that the softhsm2 package creates a new group called softhsm. In order to grant access to the HSM module a user must belong to this group.
sudo usermod -a -G softhsm <user>
OpenSSL access HSM and other hardware devices through its engine functionality. In order to set up a new engine the OpenSSL configuration files (usually /etc/ssl/openssl.cnf) must be updated specifying the libp11 and hardware module (here SoftHSM) dynamic libraries location.
This configuration step can be avoided using p11kit which allows OpenSSL to find PKCS#11 devices on runtime without static configuration. This kit is often available through the Linux distribution package manager. On Ubuntu, for example:
sudo apt install libengine-pkcs11-openssl
Once installed, to check p11kit is able to find the SoftHSM module use:
p11-kit list-modules
In order to check if OpenSSL is able to access PKCS#11 engine use:
openssl engine pkcs11 -t
Gtest¶
GTest is a unit testing library for C++. By default, eProsima Fast DDS does not compile tests. It is possible to activate them with the opportune CMake configuration options when calling colcon or CMake. For more details, please refer to the CMake options section. Also add the Gtest repository into the workspace directory.
git clone --branch release-1.11.0 https://github.com/google/googletest src/googletest-distribution
XML validation tool¶
XML validation is a new command introduced to validate the XML profiles against an XSD schema through Fast DDS CLI. That ensures the proper characterization of the entities using the xml profiles.
For more details, please refer to the xml section.
Install the xmlschema dependency to be able to use this optional tool.
Colcon installation¶
colcon is a command line tool based on CMake aimed at building sets of software packages. This section explains how to use it to compile eProsima Fast DDS and its dependencies.
Install the ROS 2 development tools (colcon and vcstool) by executing the following command:
pip3 install -U colcon-common-extensions vcstool
Note
Mind that under non-root users,
pip3may install pythoncolconandvcsexecutables in$HOME/.local/bin, for instance when running with--user. To be able to run these applications, make sure thatpip3binary installation directory is in your$PATH($HOME/.local/binis normally introduced while login on an interactive non-root shell).Create a
Fast-DDSdirectory and download the repos file that will be used to install eProsima Fast DDS and its dependencies:mkdir ~/Fast-DDS cd ~/Fast-DDS wget https://raw.githubusercontent.com/eProsima/Fast-DDS/master/fastdds.repos mkdir src vcs import src < fastdds.repos
Build the packages:
colcon build
Note
Being based on CMake, it is possible to pass CMake configuration options to the colcon build command.
For more information on the specific syntax, please refer to the
CMake specific arguments
page of the colcon manual.
Run an application¶
When running an instance of an application using eProsima Fast DDS, the colcon overlay built in the
dedicated Fast-DDS directory must be sourced.
There are two possibilities:
Every time a new shell is opened, prepare the environment locally by typing the command:
source ~/Fast-DDS/install/setup.bash
Add the sourcing of the colcon overlay permanently to the
PATH, by typing the following:echo 'source ~/Fast-DDS/install/setup.bash' >> ~/.bashrc
CMake installation¶
This section explains how to compile eProsima Fast DDS with CMake, either locally or globally.
Local installation¶
Create a
Fast-DDSdirectory where to download and build eProsima Fast DDS and its dependencies:mkdir ~/Fast-DDSClone the following dependencies and compile them using CMake.
-
cd ~/Fast-DDS git clone https://github.com/eProsima/foonathan_memory_vendor.git mkdir foonathan_memory_vendor/build cd foonathan_memory_vendor/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install -DBUILD_SHARED_LIBS=ON cmake --build . --target install
-
cd ~/Fast-DDS git clone https://github.com/eProsima/Fast-CDR.git mkdir Fast-CDR/build cd Fast-CDR/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install cmake --build . --target install
-
Once all dependencies are installed, install eProsima Fast DDS:
cd ~/Fast-DDS git clone https://github.com/eProsima/Fast-DDS.git mkdir Fast-DDS/build cd Fast-DDS/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install cmake --build . --target install
Note
By default, eProsima Fast DDS does not compile tests. However, they can be activated by downloading and installing Gtest.
Global installation¶
To install eProsima Fast DDS system-wide instead of locally, remove all the flags that
appear in the configuration steps of Fast-CDR and Fast-DDS, and change the first in the
configuration step of foonathan_memory_vendor to the following:
-DCMAKE_INSTALL_PREFIX=/usr/local/ -DBUILD_SHARED_LIBS=ON
Note
Installation on system directories may need of permissions.
Maybe permissions have to be granted through sudo.
sudo cmake --build . --target install
Run an application¶
When running an instance of an application using eProsima Fast DDS, it must be linked with the library where the
packages have been installed, which in the case of system-wide installation is: /usr/local/lib/ (if local
installation is used, adjust for the correct directory).
There are two possibilities:
Prepare the environment locally by typing the command:
export LD_LIBRARY_PATH=/usr/local/lib/
Add it permanently it to the
PATH, by typing:echo 'export LD_LIBRARY_PATH=/usr/local/lib/' >> ~/.bashrc
Fast DDS Python bindings installation¶
This section provides the instructions for installing Fast DDS Python bindings in a Linux environment from sources. Fast DDS Python bindings is an extension of Fast DDS which provides access to the Fast DDS API through Python. Therefore, its installation is an extension of the installation of Fast DDS.
Fast DDS Python bindings source code consists on several .i files which will be processed by SWIG. Then C++ files (for connecting C++ and Python) and Python files (Python module for Fast DDS) will be generated.
First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.
Requirements¶
The installation of Fast DDS Python bindings in a Linux environment from sources requires the following tools to be installed in the system:
SWIG¶
SWIG is a development tool that allows connecting programs written in C/C++ with a variety of other programming languages, among them Python. SWIG 4.0 is required in order to build Fast DDS Python bindings.
Note
More recent SWIG releases are not yet supported. Please, ensure to be using SWIG 4.0.
SWIG can be installed directly from the package manager of the appropriate Linux distribution. For Ubuntu, please run:
sudo apt install swig
Dependencies¶
Fast DDS Python bindings has the following dependencies, when installed from sources in a Linux environment:
Colcon installation¶
colcon is a command line tool based on CMake aimed at building sets of software packages. This section explains how to use it to compile Fast DDS Python bindings and its dependencies.
Install the ROS 2 development tools (colcon and vcstool) by executing the following command:
pip3 install -U colcon-common-extensions vcstool
Note
If this fails due to an Environment Error, add the
--userflag to thepip3installation command.Create a
Fast-DDS-pythondirectory and download the repos file that will be used to install Fast DDS Python bindings and its dependencies:mkdir ~/Fast-DDS-python cd ~/Fast-DDS-python wget https://raw.githubusercontent.com/eProsima/Fast-DDS-python/main/fastdds_python.repos mkdir src vcs import src < fastdds_python.repos
Build the packages:
colcon build
Note
Being based on CMake, it is possible to pass CMake configuration options to the colcon build command.
For more information on the specific syntax, please refer to the
CMake specific arguments
page of the colcon manual.
Run an application¶
When running an instance of an application using Fast DDS Python bindings, the colcon overlay built in the
dedicated Fast-DDS-python directory must be sourced.
There are two possibilities:
Every time a new shell is opened, prepare the environment locally by typing the command:
source ~/Fast-DDS-python/install/setup.bash
Add the sourcing of the colcon overlay permanently to the
PATH, by typing the following:echo 'source ~/Fast-DDS-python/install/setup.bash' >> ~/.bashrc
CMake installation¶
This section explains how to compile Fast DDS Python bindings with CMake, either locally or globally.
Local installation¶
Create a
Fast-DDS-pythondirectory where to download and build Fast DDS Python bindings and its dependencies:mkdir ~/Fast-DDS-pythonClone the following dependencies and compile them using CMake.
-
cd ~/Fast-DDS-python git clone https://github.com/eProsima/foonathan_memory_vendor.git mkdir foonathan_memory_vendor/build cd foonathan_memory_vendor/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS-python/install -DBUILD_SHARED_LIBS=ON cmake --build . --target install
-
cd ~/Fast-DDS-python git clone https://github.com/eProsima/Fast-CDR.git mkdir Fast-CDR/build cd Fast-CDR/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS-python/install cmake --build . --target install
-
cd ~/Fast-DDS-python git clone https://github.com/eProsima/Fast-DDS.git mkdir Fast-DDS/build cd Fast-DDS/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS-python/install cmake --build . --target install
-
Once all dependencies are installed, install Fast DDS Python bindings:
cd ~/Fast-DDS-python git clone https://github.com/eProsima/Fast-DDS-python.git mkdir -p Fast-DDS-python/fastdds_python/build cd Fast-DDS-python/fastdds_python/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS-python/install cmake --build . --target install
Global installation¶
To install Fast DDS Python bindings system-wide instead of locally, remove all the flags that
appear in the configuration steps of Fast-CDR, Fast-DDS and Fast-DDS-python, and change the
first in the configuration step of foonathan_memory_vendor to the following:
-DCMAKE_INSTALL_PREFIX=/usr/local/ -DBUILD_SHARED_LIBS=ON
Note
Installation on system directories may need of permissions.
Maybe permissions have to be granted through sudo.
sudo cmake --build . --target install
Run an application¶
When running an instance of an application using Fast DDS Python bindings, it must be linked with the library where
the packages have been installed, which in the case of system-wide installation is: /usr/local/lib/ (if local
installation is used, adjust for the correct directory).
There are two possibilities:
Prepare the environment locally by typing the command:
export LD_LIBRARY_PATH=/usr/local/lib/
Add it permanently it to the
PATH, by typing:echo 'export LD_LIBRARY_PATH=/usr/local/lib/' >> ~/.bashrc
Fast DDS-Gen installation¶
This section provides the instructions for installing Fast DDS-Gen in a Linux environment from sources. Fast DDS-Gen is a Java application that generates source code using the data types defined in an IDL file. Please refer to Introduction for more information.
Requirements¶
Fast DDS-Gen is built using Gradle. Gradle is an open-source build automation tool which requires a Java version to be executed (see Gradle-Java compatibility matrix).
Important
Even though earlier versions of Gradle support Java 8, Fast DDS-Gen stopped supporting Java versions previous to Java 11 since release v2.4.0.
Important
Fast DDS-Gen introduced support for Gradle 7 in release v2.2.0. Gradle 8 is not yet supported.
See also
For further information about Fast DDS-Gen product related versions, please refer to the Library dependencies section.
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. There are several versions of Java available. For instance, to install Java 11 JDK, run the following command:
sudo apt install openjdk-11-jdk
Note
Fast DDS-Gen supports Java versions from 11 to 19.
Compiling Fast DDS-Gen¶
In order to compile Fast DDS-Gen, an executable script is included in the repository which will download Gradle temporarily for the compilation step. Please, follow the steps below to build Fast DDS-Gen:
Note
If Fast DDS has already been installed following Colcon installation, skip cloning Fast DDS-Gen’s
repository, as it can already be found under the src directory within the colcon workspace.
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
./gradlew assemble
Note
In case that a supported Gradle version is already installed in the system, Fast DDS-Gen can also be built running directly:
gradle assemble
Contents¶
The Fast-DDS-Gen folder contains the following packages:
share/fastddsgen, where the generated Java application is.scripts, containing some user friendly scripts.Note
To make these scripts accessible from any shell session and directory, add the
scriptsfolder path to thePATHenvironment variable.
Windows installation from sources¶
The instructions for installing both the Fast DDS library and the Fast DDS-Gen generation tool from sources are provided in this page. It is organized as follows:
Fast DDS library installation¶
This section provides the instructions for installing eProsima Fast DDS in a Windows environment from sources. The following packages will be installed:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.fastdds, the core library of eProsima Fast DDS library.
First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.
Requirements¶
The installation of eProsima Fast DDS in a Windows environment from sources requires the following tools to be installed in the system:
Gtest [optional]
XML validation tool [optional]
Visual Studio¶
Visual Studio is required to have a C++ compiler in the system.
For this purpose, make sure to check the Desktop development with C++ option during the Visual Studio
installation process.
If Visual Studio is already installed but the Visual C++ Redistributable packages are not,
open Visual Studio and go to Tools -> Get Tools and Features and in the Workloads tab enable
Desktop development with C++.
Finally, click Modify at the bottom right.
Chocolatey¶
Chocolatey is a Windows package manager. It is needed to install some of eProsima Fast DDS’s dependencies. Download and install it directly from the website.
CMake, pip3, wget and git¶
These packages provide the tools required to install eProsima Fast DDS and its dependencies from command line.
Download and install CMake, pip3, wget and git by following the instructions detailed in the respective
websites.
Once installed, add the path to the executables to the PATH from the
Edit the system environment variables control panel.
Gtest¶
GTest is a unit testing library for C++. By default, eProsima Fast DDS does not compile tests. It is possible to activate them with the opportune CMake configuration options when calling colcon or CMake. For more details, please refer to the CMake options section. Also add the Gtest repository into the workspace directory.
git clone --branch release-1.11.0 https://github.com/google/googletest src/googletest-distribution
and add next argument to the colcon call
colcon build --cmake-args -Dgtest_force_shared_crt=ON
XML validation tool¶
XML validation is a new command introduced to validate the XML profiles against an XSD schema through Fast DDS CLI. That ensures the proper characterization of the entities using the xml profiles.
For more details, please refer to the xml section.
Install the xmlschema dependency to be able to use this optional tool.
Dependencies¶
eProsima Fast RTPS has the following dependencies, when installed from sources in a Windows environment:
See also
For further information about this Fast DDS version dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Library dependencies section.
Asio and TinyXML2 libraries¶
Asio is a cross-platform C++ library for network and low-level I/O programming, which provides a consistent asynchronous model. TinyXML2 is a simple, small and efficient C++ XML parser. They can be downloaded directly from the links below:
After downloading these packages, open an administrative shell with PowerShell and execute the following command:
choco install -y -s <PATH_TO_DOWNLOADS> asio tinyxml2
where <PATH_TO_DOWNLOADS> is the folder into which the packages have been downloaded.
OpenSSL¶
OpenSSL is a robust toolkit for the TLS and SSL protocols and a general-purpose cryptography library. Install it by running the following command inside an administrative shell with PowerShell:
choco install -y openssl
Libp11 and SoftHSM libraries¶
Libp11 provides PKCS#11 support for OpenSSL. This is an optional dependency, that is needed only when eprosima Fast DDS is used with security and PKCS#11 URIs.
Download the latest libp11 version for Windows from this repository and follow the installation instructions
SoftHSM is a software implementation of an HSM (Hardware Security Module). If eProsima Fast DDS tests are activated and libp11 is installed on the system, SoftHSM is additionally required to run tests of PKCS#11 features.
Download the SoftHSM for Windows installer from this repository. Execute the installer and follow the installation instructions.
OpenSSL access HSM and other hardware devices through its engine functionality. In order to set up a new engine the OpenSSL configuration files must be updated specifying the libp11 and hardware module (here SoftHSM) dynamic libraries location.
OpenSSL on Windows references its default configuration file through the OPENSSL_CONF environment variable. By default OpenSSL installs two identical default configuration files:
C:\Program Files\OpenSSL-Win64\bin\cnf\openssl.cnf mimics the Linux distributions one.
C:\Program Files\OpenSSL-Win64\bin\openssl.cfg kept for backward compatibility.
Neither of them are loaded by default. In order to direct OpenSSL to load one of them or any other we must set the variable:
cmd> set OPENSSL_CONF=C:\Program Files\OpenSSL-Win64\bin\cnf\openssl.cnf
powershell> $Env:OPENSSL_CONF="C:\Program Files\OpenSSL-Win64\bin\cnf\openssl.cnf"
Once we have hinted OpenSSL the configuration file to use we must modify it to set up the new PKCS#11 engine following the OpenSSL guidelines replacing the binaries path with the proper ones. For example, before any section in the configuration file we introduce:
openssl_conf = openssl_init
at the end of the file we include the engine devoted sections. Note to use POSIX path separator instead of the windows one.
[openssl_init]
engines = engine_section
[engine_section]
pkcs11 = pkcs11_section
[pkcs11_section]
engine_id = pkcs11
dynamic_path = C:/Program Files/libp11/src/pkcs11.dll
MODULE_PATH = C:/Program Files (x86)/SoftHSM2/lib/softhsm2-x64.dll
init = 0
A proper set up can be verified using OpenSSL command line tool:
openssl engine pkcs11 -t
Colcon installation¶
colcon is a command line tool based on CMake aimed at building sets of software packages. This section explains how to use it to compile eProsima Fast DDS and its dependencies.
Important
Run colcon within a Visual Studio prompt. To do so, launch a Developer Command Prompt from the search engine.
Install the ROS 2 development tools (colcon and vcstool) by executing the following command:
pip3 install -U colcon-common-extensions vcstool
and add the path to the
vcsexecutable to thePATHfrom the Edit the system environment variables control panel.Note
If this fails due to an Environment Error, add the
--userflag to thepip3installation command.Create a
Fast-DDSdirectory and download the repos file that will be used to install eProsima Fast DDS and its dependencies:mkdir ~\Fast-DDS cd ~\Fast-DDS wget https://raw.githubusercontent.com/eProsima/Fast-DDS/master/fastdds.repos -output fastdds.repos mkdir src vcs import src --input fastdds.repos
Finally, use colcon to compile all software:
colcon build
Note
Being based on CMake, it is possible to pass the CMake configuration options to the colcon build command.
For more information on the specific syntax, please refer to the
CMake specific arguments
page of the colcon manual.
Run an application¶
When running an instance of an application using eProsima Fast DDS, the colcon overlay built in the
dedicated Fast-DDS directory must be sourced.
There are two possibilities:
Every time a new shell is opened, prepare the environment locally by typing the command:
setup.bat
Add the sourcing of the colcon overlay permanently, by opening the Edit the system environment variables control panel, and adding
~/Fast-DDS/install/setup.batto thePATH.
CMake installation¶
This section explains how to compile eProsima Fast DDS with CMake, either locally or globally.
Local installation¶
Open a command prompt, and create a
Fast-DDSdirectory where to download and build eProsima Fast DDS and its dependencies:mkdir %USERPROFILE%\Fast-DDS
Clone the following dependencies and compile them using CMake.
Fast DDS depends on Foonathan memory. To ease the dependency management, eProsima provides a vendor package Foonathan memory vendor, which downloads and builds a specific revision of Foonathan memory if the library is not found in the system.
cd %USERPROFILE%\Fast-DDS git clone https://github.com/eProsima/foonathan_memory_vendor.git cd foonathan_memory_vendor mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS/install .. cmake --build . --target install
-
cd %USERPROFILE%\Fast-DDS git clone https://github.com/eProsima/Fast-CDR.git cd Fast-CDR mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS/install .. cmake --build . --target install
Once all dependencies are installed, install eProsima Fast DDS:
cd %USERPROFILE%\Fast-DDS git clone https://github.com/eProsima/Fast-DDS.git cd Fast-DDS mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS/install .. cmake --build . --target install
Global installation¶
To install eProsima Fast DDS system-wide instead of locally, remove the CMAKE_INSTALL_PREFIX flags that
appear in the configuration steps of Fast-CDR and Fast-DDS.
Note
By default, eProsima Fast DDS does not compile tests. However, they can be activated by downloading and installing Gtest.
Run an application¶
When running an instance of an application using eProsima Fast DDS, it must be linked with the library where the
packages have been installed.
This can be done by opening the Edit system environment variables control panel and adding to the PATH the
Fast DDS and Fast CDR installation directories:
Fast DDS: C:\Program Files\fastdds
Fast CDR: C:\Program Files\fastcdr
Fast DDS Python bindings installation¶
This section provides the instructions for installing Fast DDS Python bindings in a Windows environment from sources. Fast DDS Python bindings is an extension of Fast DDS which provides access to the Fast DDS API through Python. Therefore, its installation is an extension of the installation of Fast DDS.
Fast DDS Python bindings source code consists on several .i files which will be processed by SWIG. Then C++ files (for connecting C++ and Python) and Python files (Python module for Fast DDS) will be generated.
First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.
Requirements¶
The installation of Fast DDS Python bindings in a Windows environment from sources requires the following tools to be installed in the system:
SWIG¶
SWIG is a development tool that allows connecting programs written in C/C++ with a variety of other programming languages, among them Python. SWIG 4.0 is required in order to build Fast DDS Python bindings.
Note
More recent SWIG releases are not yet supported. Please, ensure to be using SWIG 4.0.
Dependencies¶
Fast DDS Python bindings has the following dependencies, when installed from sources in a Windows environment:
Colcon installation¶
colcon is a command line tool based on CMake aimed at building sets of software packages. This section explains how to use it to compile Fast DDS Python bindings and its dependencies.
Important
Run colcon within a Visual Studio prompt. To do so, launch a Developer Command Prompt from the search engine.
Install the ROS 2 development tools (colcon and vcstool) by executing the following command:
pip3 install -U colcon-common-extensions vcstool
and add the path to the
vcsexecutable to thePATHfrom the Edit the system environment variables control panel.Note
If this fails due to an Environment Error, add the
--userflag to thepip3installation command.Create a
Fast-DDS-pythondirectory and download the repos file that will be used to install Fast DDS Python bindings and its dependencies:mkdir ~\Fast-DDS-python cd ~\Fast-DDS-python wget https://raw.githubusercontent.com/eProsima/Fast-DDS-python/main/fastdds_python.repos mkdir src vcs import src --input fastdds_python.repos
Build the packages:
colcon build
Note
Being based on CMake, it is possible to pass CMake configuration options to the colcon build command.
For more information on the specific syntax, please refer to the
CMake specific arguments
page of the colcon manual.
Run an application¶
When running an instance of an application using Fast DDS Python bindings, the colcon overlay built in the
dedicated Fast-DDS-python directory must be sourced.
There are two possibilities:
Every time a new shell is opened, prepare the environment locally by typing the command:
setup.bat
Add the sourcing of the colcon overlay permanently, by opening the Edit the system environment variables control panel, and adding
~/Fast-DDS/install/setup.batto thePATH.
CMake installation¶
This section explains how to compile Fast DDS Python bindings with CMake, either locally or globally.
Local installation¶
Open a command prompt, and create a
Fast-DDS-pythondirectory where to download and build Fast DDS Python bindings and its dependencies:mkdir %USERPROFILE%\Fast-DDS-python
Clone the following dependencies and compile them using CMake.
Fast DDS depends on Foonathan memory. To ease the dependency management, eProsima provides a vendor package Foonathan memory vendor, which downloads and builds a specific revision of Foonathan memory if the library is not found in the system.
cd %USERPROFILE%\Fast-DDS-python git clone https://github.com/eProsima/foonathan_memory_vendor.git cd foonathan_memory_vendor mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS-python/install .. cmake --build . --target install
-
cd %USERPROFILE%\Fast-DDS-python git clone https://github.com/eProsima/Fast-CDR.git cd Fast-CDR mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS-python/install .. cmake --build . --target install
-
cd %USERPROFILE%\Fast-DDS-python git clone https://github.com/eProsima/Fast-DDS.git cd Fast-DDS mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS-python/install .. cmake --build . --target install
Once all dependencies are installed, install Fast DDS Python bindings:
cd ~/Fast-DDS-python git clone https://github.com/eProsima/Fast-DDS-python.git cd Fast-DDS-python mkdir build && cd build cmake -DCMAKE_INSTALL_PREFIX=%USERPROFILE%/Fast-DDS-python/install .. cmake --build . --target install
Global installation¶
To install Fast DDS Python bindings system-wide instead of locally, remove all the flags that
appear in the configuration steps of Fast-CDR, Fast-DDS and Fast-DDS-python, and change the
first in the configuration step of foonathan_memory_vendor to the following:
-DCMAKE_INSTALL_PREFIX=/usr/local/ -DBUILD_SHARED_LIBS=ON
Note
Installation on system directories may need of permissions.
Maybe permissions have to be granted through sudo.
sudo cmake --build . --target install
Run an application¶
When running an instance of an application using Fast DDS Python bindings, it must be linked with the library where
the packages have been installed.
This can be done by opening the Edit system environment variables control panel and adding to the PATH the
Fast DDS python, Fast CDR and Fast DDS installation directories:
Fast DDS python: C:\Program Files\fastdds_python
Fast DDS: C:\Program Files\fastdds
Fast CDR: C:\Program Files\fastcdr
Fast DDS-Gen installation¶
This section outlines the instructions for installing Fast DDS-Gen in a Windows environment from sources. Fast DDS-Gen is a Java application that generates source code using the data types defined in an IDL file. Please refer to Introduction for more information.
Requirements¶
Fast DDS-Gen is built using Gradle. Gradle is an open-source build automation tool which requires a Java version to be executed (see Gradle-Java compatibility matrix).
Important
Even though earlier versions of Gradle support Java 8, Fast DDS-Gen stopped supporting Java versions previous to Java 11 since release v2.4.0.
Important
Fast DDS-Gen introduced support for Gradle 7 in release v2.2.0. Gradle 8 is not yet supported.
See also
For further information about Fast DDS-Gen product related versions, please refer to the Library dependencies section.
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. Download and install it following the steps given in the Oracle website.
Note
Fast DDS-Gen supports Java versions from 11 to 19.
Compiling Fast DDS-Gen¶
In order to compile Fast DDS-Gen, an executable script is included in the repository which will download Gradle temporarily for the compilation step. Please, follow the steps below to build Fast DDS-Gen:
Note
If Fast DDS has already been installed following Colcon installation, skip cloning Fast DDS-Gen’s
repository, as it can already be found under the src directory within the colcon workspace.
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
gradlew.bat assemble
Note
In case that a supported Gradle version is already installed in the system, Fast DDS-Gen can also be built running directly:
gradle assemble
Contents¶
The Fast-DDS-Gen folder contains the following packages:
share/fastddsgen, where the generated Java application is.scripts, containing some user friendly scripts.Note
To make these scripts accessible from any directory, add the
scriptsfolder path to thePATHenvironment variable.
Mac OS installation from sources¶
The instructions for installing both the Fast DDS library and the Fast DDS-Gen generation tool from sources are provided in this page. It is organized as follows:
Fast DDS library installation¶
This section describes the instructions for installing eProsima Fast DDS in a Mac OS environment from sources. The following packages will be installed:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.fastdds, the core library of eProsima Fast DDS library.
First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon) or the CMake) installation instructions.
Requirements¶
The installation of eProsima Fast DDS in a MacOS environment from sources requires the following tools to be installed in the system:
Gtest [optional]
XML validation tool [optional]
Homebrew¶
Homebrew is a macOS package manager, it is needed to install some of eProsima Fast DDS’s dependencies. To install it open a terminal window and run the following command.
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
Xcode Command Line Tools¶
The Xcode command line tools package is separate from Xcode and allows for command line development in mac. The previous step should have installed Xcode CLI, to check the correct installation run the following command:
gcc --version
CMake, g++, pip3, wget and git¶
These packages provide the tools required to install eProsima Fast DDS and its dependencies from command line. Install CMake, pip3 and wget using the Homebrew package manager:
brew install cmake python3 wget
Gtest¶
GTest is a unit testing library for C++. By default, eProsima Fast DDS does not compile tests. It is possible to activate them with the opportune CMake configuration options when calling colcon or CMake. For more details, please refer to the CMake options section. Also add the Gtest repository into the workspace directory.
git clone --branch release-1.11.0 https://github.com/google/googletest src/googletest-distribution
XML validation tool¶
XML validation is a new command introduced to validate the XML profiles against an XSD schema through Fast DDS CLI. That ensures the proper characterization of the entities using the xml profiles.
For more details, please refer to the xml section.
Install the xmlschema dependency to be able to use this optional tool.
Dependencies¶
eProsima Fast DDS has the following dependencies, when installed from binaries in a Linux environment:
See also
For further information about this Fast DDS version dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Library dependencies section.
Asio and TinyXML2 libraries¶
Asio is a cross-platform C++ library for network and low-level I/O programming, which provides a consistent asynchronous model. TinyXML2 is a simple, small and efficient C++ XML parser. Install these libraries using Homebrew:
brew install asio tinyxml2
Colcon installation¶
colcon is a command line tool based on CMake aimed at building sets of software packages. This section explains how to use it to compile eProsima Fast DDS and its dependencies.
Install the ROS 2 development tools (colcon and vcstool) by executing the following command:
pip3 install -U colcon-common-extensions vcstool
Create a
Fast-DDSdirectory and download the repos file that will be used to install eProsima Fast DDS and its dependencies:mkdir ~/Fast-DDS cd ~/Fast-DDS wget https://raw.githubusercontent.com/eProsima/Fast-DDS/master/fastdds.repos mkdir src vcs import src < fastdds.repos
Build the packages:
colcon build
Note
The --cmake-args option allows to pass the CMake configuration options to the colcon build command.
In Mac OS the location of OpenSSL is not found automatically and therefore has to be passed explicitly:
--cmake-args -DOPENSSL_ROOT_DIR=/usr/local/opt/openssl -DOPENSSL_LIBRARIES=/usr/local/opt/openssl/lib.
This is only required when building with Security.
For more information on the specific syntax, please refer to the CMake specific arguments page of the colcon
manual.
Run an application¶
When running an instance of an application using eProsima Fast DDS, the colcon overlay built in the
dedicated Fast-DDS directory must be sourced.
There are two possibilities:
Every time a new shell is opened, prepare the environment locally by typing the command:
source ~/Fast-DDS/install/setup.bash
Add the sourcing of the colcon overlay permanently to the
PATH, by typing the following:touch ~/.bash_profile echo 'source ~/Fast-DDS/install/setup.bash' >> ~/.bash_profile
CMake installation¶
This section explains how to compile eProsima Fast DDS with CMake, either locally or globally.
Local installation¶
Create a
Fast-DDSdirectory where to download and build eProsima Fast DDS and its dependencies:mkdir ~/Fast-DDSClone the following dependencies and compile them using CMake.
-
cd ~/Fast-DDS git clone https://github.com/eProsima/foonathan_memory_vendor.git mkdir foonathan_memory_vendor/build cd foonathan_memory_vendor/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install -DBUILD_SHARED_LIBS=ON sudo cmake --build . --target install
-
cd ~/Fast-DDS git clone https://github.com/eProsima/Fast-CDR.git mkdir Fast-CDR/build cd Fast-CDR/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install sudo cmake --build . --target install
-
Once all dependencies are installed, install eProsima Fast DDS:
cd ~/Fast-DDS git clone https://github.com/eProsima/Fast-DDS.git mkdir Fast-DDS/build cd Fast-DDS/build cmake .. -DCMAKE_INSTALL_PREFIX=~/Fast-DDS/install -DCMAKE_PREFIX_PATH=~/Fast-DDS/install sudo cmake --build . --target install
Note
By default, eProsima Fast DDS does not compile tests. However, they can be activated by downloading and installing Gtest.
Global installation¶
To install eProsima Fast DDS system-wide instead of locally, remove all the flags that
appear in the configuration steps of Fast-CDR and Fast-DDS, and change the first in the
configuration step of foonathan_memory_vendor to the following:
-DCMAKE_INSTALL_PREFIX=/usr/local/ -DBUILD_SHARED_LIBS=ON
Run an application¶
When running an instance of an application using eProsima Fast DDS, it must be linked with the library where the
packages have been installed, which in the case of system-wide installation is: /usr/local/lib/ (if local
installation is used, adjust for the correct directory).
There are two possibilities:
Prepare the environment locally by typing the command:
export LD_LIBRARY_PATH=/usr/local/lib/
Add it permanently it to the
PATH, by typing:touch ~/.bash_profile echo 'export LD_LIBRARY_PATH=/usr/local/lib/' >> ~/.bash_profile
Fast DDS-Gen installation¶
This section provides the instructions for installing Fast DDS-Gen in a Mac OS environment from sources. Fast DDS-Gen is a Java application that generates source code using the data types defined in an IDL file. Please refer to Introduction for more information.
Requirements¶
Fast DDS-Gen is built using Gradle. Gradle is an open-source build automation tool which requires a Java version to be executed (see Gradle-Java compatibility matrix).
Important
Even though earlier versions of Gradle support Java 8, Fast DDS-Gen stopped supporting Java versions previous to Java 11 since release v2.4.0.
Important
Fast DDS-Gen introduced support for Gradle 7 in release v2.2.0. Gradle 8 is not yet supported.
See also
For further information about Fast DDS-Gen product related versions, please refer to the Library dependencies section.
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. Download and install it following the steps given in the Oracle website.
Note
Fast DDS-Gen supports Java versions from 11 to 19.
Compiling Fast DDS-Gen¶
In order to compile Fast DDS-Gen, an executable script is included in the repository which will download Gradle temporarily for the compilation step. Please, follow the steps below to build Fast DDS-Gen:
Note
If Fast DDS has already been installed following Colcon installation, skip cloning Fast DDS-Gen’s
repository, as it can already be found under the src directory within the colcon workspace.
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
./gradlew assemble
Note
In case that a supported Gradle version is already installed in the system, Fast DDS-Gen can also be built running directly:
gradle assemble
Contents¶
The Fast-DDS-Gen folder contains the following packages:
share/fastddsgen, where the generated Java application is.scripts, containing some user friendly scripts.Note
To make these scripts accessible from any shell session and directory, add the
scriptsfolder path to thePATHenvironment variable using the method described above.
QNX 7.1 installation from sources¶
The instructions for installing Fast DDS library and running examples and tests on QNX 7.1 are provided in this page. It is organized as follows:
Fast DDS library installation¶
This section provides the instructions for installing eProsima Fast DDS for QNX 7.1 in a Ubuntu environment from sources. The following packages will be installed:
foonathan_memory_vendor, an STL compatible C++ memory allocator library.fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.fastdds, the core library of eProsima Fast DDS library.
See also
For further information about Fast DDS library dependencies, as well as for the corresponding versions of other related products, please refer to the Fast DDS Library dependencies section.
The Requirements detailed below needs to be met first.
Requirements¶
Users must be in a Ubuntu environment to cross-compile for QNX 7.1. It is recommended that users use Ubuntu 20.04. The installation of eProsima Fast DDS in a Ubuntu environment from sources requires the following tools to be installed in the system:
QNX SDP 7.1¶
QNX SDP 7.1 is required to be installed in the user’s Ubuntu environment. QNX SDP is QNX’s Software Development Platform which contains tools and files which are needed to cross-compile for QNX.
For the purpose of these instructions, QNX SDP 7.1 is assumed to be installed at ~/qnx710. If this is not the case, please adjust the paths accordingly.
See also
For further information about Fast DDS build system dependencies regarding QNX 7.1, please refer to the Fast DDS Build system dependencies section.
CMake, pip3, git, dos2unix, and automake¶
These packages provide the tools required to install eProsima Fast DDS and its dependencies from command line.
sudo apt install cmake python3-pip git dos2unix automake
Build and Installation¶
Open a terminal and clone eProsima Fast DDS:
git clone https://github.com/eProsima/Fast-DDS.git && cd Fast-DDS WORKSPACE=$PWD
Initialize git submodules for Asio, Fast-CDR and TinyXML2 and apply QNX patches to them:
Note
OpenSSL is already installed in the QNX SDP 7.1.
cd $WORKSPACE # Initialize git submodules git submodule update --init $WORKSPACE/thirdparty/asio/ $WORKSPACE/thirdparty/fastcdr $WORKSPACE/thirdparty/tinyxml2/ # Apply QNX patch to Asio. cd $WORKSPACE/thirdparty/asio git apply $WORKSPACE/build_qnx/qnx_patches/asio_qnx.patch # Apply QNX patch to Fast-CDR. cd $WORKSPACE/thirdparty/fastcdr git apply $WORKSPACE/build_qnx/qnx_patches/fastcdr_qnx.patch # Apply QNX patch to TinyXML2. # TinyXML2's CMakeLists.txt has CRLF, so use unix2dos to convert the patch to CRLF. cd $WORKSPACE/thirdparty/tinyxml2 unix2dos $WORKSPACE/build_qnx/qnx_patches/tinyxml2_qnx.patch git apply $WORKSPACE/build_qnx/qnx_patches/tinyxml2_qnx.patch
Get foonathan_memory_vendor:
cd $WORKSPACE git clone https://github.com/eProsima/foonathan_memory_vendor.git
Optional: clone GoogleTest and apply QNX patch to it:
Note
GoogleTest is required for building Fast-DDS tests.
cd $WORKSPACE git clone https://github.com/google/googletest.git && cd googletest git checkout v1.13.0 git apply $WORKSPACE/build_qnx/qnx_patches/googletest_qnx.patch
Source the QNX environment script:
source ~/qnx710/qnxsdp-env.sh
Build and install Fast-DDS and its dependencies:
Note
To build examples, set COMPILE_EXAMPLES to ON in $WORKSPACE/build_qnx/common.mk.To build tests, set EPROSIMA_BUILD_TESTS to ON in $WORKSPACE/build_qnx/common.mk.Note
All libraries will be installed to $(QNX_TARGET)/$(CPUVARDIR)/usr/lib.All examples will be installed to $(QNX_TARGET)/$(CPUVARDIR)/usr/examples.All tests will be installed to $(QNX_TARGET)/$(CPUVARDIR)/usr/bin/Fast-DDS_test.QNX_TARGET is where the QNX SDP 7.1 installation’s target folder is.If QNX SDP 7.1 is installed at ~/qnx710, the QNX_TARGET will be at ~/qnx710/target/qnx7.CPUVARDIR is a directory for a specific target architecture e.g. aarch64le and x86_64.For example, libraries compiled for an aarch64 target will be at ~/qnx710/target/qnx7/aarch64le/usr/lib assuming QNX SDP 7.1 is installed at ~/qnx710.cd $WORKSPACE/build_qnx make install -j 4
Run Examples and Tests on a QNX 7.1 Target¶
Move Libraries, Examples, and Tests to the QNX Target¶
Move the built libraries to the QNX target:
The following steps assume that $(QNX_TARGET) is ~/qnx710/target/qnx7 and that $(CPUVARDIR) is aarch64le. Adjust the values if this is not the case.
# Move Fast-CDR library to the QNX target scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libfastcdr.so* root@<target-ip-address>:/usr/lib # Move Fast-DDS library to the QNX target scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libfastdds.so* root@<target-ip-address>:/usr/lib # Move Foonathan Memory library to the QNX target scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libfoonathan_memory* root@<target-ip-address>:/usr/lib # Move TinyXML2 library to the QNX target scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libtinyxml2.so* root@<target-ip-address>:/usr/lib # Move GoogleTest library to the QNX target scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libgtest* root@<target-ip-address>:/usr/lib scp ~/qnx710/target/qnx7/aarch64le/usr/lib/libgmock* root@<target-ip-address>:/usr/lib
Move examples and tests to the QNX target:
# Move Fast-CDR library to the QNX target scp -r ~/qnx710/target/qnx7/aarch64le/usr/examples root@<target-ip-address>:/var # Move Fast-DDS library to the QNX target scp -r ~/qnx710/target/qnx7/aarch64le/usr/bin/Fast-DDS_test root@<target-ip-address>:/var
Run DDSHelloWorldExample¶
Open a terminal and run a subscriber:
# ssh into the QNX target ssh root@<target-ip-address> # Run a subscriber /var/examples/cpp/dds/HelloWorldExample/bin/DDSHelloWorldExample subscriber
Open another terminal and run a publisher:
# ssh into the QNX target ssh root@<target-ip-address> # Run a publisher /var/examples/cpp/dds/HelloWorldExample/bin/DDSHelloWorldExample publisher
The following output will be shown in the subscriber terminal:
Starting Subscriber running. Please press enter to stop the Subscriber Subscriber matched. Message HelloWorld 1 RECEIVED Message HelloWorld 2 RECEIVED Message HelloWorld 3 RECEIVED Message HelloWorld 4 RECEIVED Message HelloWorld 5 RECEIVED Message HelloWorld 6 RECEIVED Message HelloWorld 7 RECEIVED Message HelloWorld 8 RECEIVED Message HelloWorld 9 RECEIVED Message HelloWorld 10 RECEIVED Subscriber unmatched.
The following output will be shown for the publisher:
Starting Publisher running 10 samples. Publisher matched. Message: HelloWorld with index: 1 SENT Message: HelloWorld with index: 2 SENT Message: HelloWorld with index: 3 SENT Message: HelloWorld with index: 4 SENT Message: HelloWorld with index: 5 SENT Message: HelloWorld with index: 6 SENT Message: HelloWorld with index: 7 SENT Message: HelloWorld with index: 8 SENT Message: HelloWorld with index: 9 SENT Message: HelloWorld with index: 10 SENT
Run a Test¶
Because test binaries compiled for QNX cannot be run on Ubuntu, test binaries must be run on a target which is running QNX.
# ssh into the QNX target ssh root@<target-ip-address> # Run a test cd /var/Fast-DDS_test/unittest/dds/core/entity ./EntityTests
The following test output for EntityTests will be shown:
[==========] Running 5 tests from 1 test suite. [----------] Global test environment set-up. [----------] 5 tests from EntityTests [ RUN ] EntityTests.entity_constructor [ OK ] EntityTests.entity_constructor (0 ms) [ RUN ] EntityTests.entity_enable [ OK ] EntityTests.entity_enable (0 ms) [ RUN ] EntityTests.entity_get_instance_handle [ OK ] EntityTests.entity_get_instance_handle (0 ms) [ RUN ] EntityTests.entity_equal_operator [ OK ] EntityTests.entity_equal_operator (0 ms) [ RUN ] EntityTests.get_statuscondition [ OK ] EntityTests.get_statuscondition (0 ms) [----------] 5 tests from EntityTests (0 ms total) [----------] Global test environment tear-down [==========] 5 tests from 1 test suite ran. (0 ms total) [ PASSED ] 5 tests.
CMake options¶
eProsima Fast DDS provides numerous CMake options for changing the behavior and configuration of Fast DDS. These options allow the user to enable/disable certain Fast DDS settings by defining these options to ON/OFF at the CMake execution. This section is structured as follows: first, the CMake options for the general configuration of Fast DDS are described; then, the options related to the third party libraries are presented; finally, the possible options for the building of Fast DDS tests are defined.
General options¶
The Fast DDS CMake options for configuring general settings are shown below, together with their description and dependency on other options.
Option |
Description |
Possible values |
Default |
|---|---|---|---|
|
Creates a build for Windows binary installers. Specifically it adds to the list of
|
|
|
|
Activates internal Fast DDS builds.
It is set to
|
|
|
|
Builds internal libraries as shared libraries, i.e. cause |
|
|
|
Activates the Fast DDS security module. Please refer to Security for more |
|
|
|
Disables Transport Layer Security (TLS) Support. Please refer to TLS over TCP |
|
|
|
Adds Shared Memory transport (SHM) to the default transports.
Please refer to |
|
|
|
Enables the Fast DDS Statistics module. Please refer to Statistics Module for |
|
|
|
Builds the Fast DDS examples. It is set to |
|
|
|
Installs the Fast DDS examples, i.e. adds the Fast DDS examples to the list of |
|
|
|
Uses doxygen to create the Fast DDS API reference documentation. It is set to |
|
|
|
Downloads Fast DDS documentation from Read the Docs media servers. The |
|
|
|
Enables a strict real-time behaviour. Please refer to the Real-Time Use Case for |
|
|
|
Builds the SQLITE3 Plugin, which enables the |
|
|
|
When |
|
|
|
When
Fast-DDS requires the use of |
|
|
|
Adds run-time instrumentation to the code. Supported options are:
|
|
|
Log options¶
Fast DDS uses its own configurable Log module with different verbosity levels. Please, refer to Logging section for more information.
This module can be configured using Fast DDS CMake arguments regarding the following options.
Option |
Description |
Possible values |
Default |
|---|---|---|---|
|
Selects the default log consumer for the logging module. |
|
|
|
Deactivates Info Log level. |
|
|
|
Enables Info Log level even on non |
|
|
|
Deactivates Warning Log level. |
|
|
|
Deactivates Error Log level. |
|
|
|
Activates compilation of log messages |
|
|
|
Enable old log macros |
|
|
Third-party libraries options¶
Fast DDS relies on the eProsima FastCDR library for serialization
mechanisms.
Moreover, Fast DDS requires two external dependencies for its proper operation: Asio and TinyXML2.
Asio is a cross-platform C++ library for network and low-level I/O programming, while TinyXML2 parses the XML profile
files, so Fast DDS can use them (see XML profiles).
These three libraries (eProsima FastCDR, Asio and TinyXML2) can be installed by the user, or downloaded on the
Fast DDS build.
In the latter case, they are referred to as Fast DDS internal third-party libraries.
This can be done by setting either THIRDPARTY or EPROSIMA_BUILD to ON.
These libraries can also be configured using Fast DDS CMake options.
Option |
Description |
Possible values |
Default |
|---|---|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
android-ifaddrs is an implementation of |
|
|
|
Unless they are otherwise specified, sets value of all third-party |
|
|
|
Activates the update of all third-party git submodules. |
|
|
Note
ANDROID is a CMake environment variable that is set to 1 if the target system
(CMAKE_SYSTEM_NAME) is Android.
Test options¶
eProsima Fast DDS comes with a full set of tests for continuous integration. The types of tests are: unit tests, black-box tests, performance tests, profiling tests, and XTypes tests. The building and execution of these tests is specified by the Fast DDS CMake options shown in the table below.
Option |
Description |
Possible values |
Default |
|---|---|---|---|
|
Enables the building of black-box tests for the verification of DDS communications |
|
|
|
Enables the building of example tests for the verification of the Fast DDS examples |
|
|
|
Activates the building of performance tests, except for the video test, which requires |
|
|
|
Activates the building of profiling tests using Valgrind. |
|
|
|
Activates the building of black-box, unit, xtypes, RTPS communication and |
|
|
|
If |
|
|
|
Disables UDPv6 tests. |
|
|
|
Android cross-compilation only. Marks the tests for installation on the |
|
|
|
Android cross-compilation only. Path on the Android device/emulator to |
|
|
Getting Started¶
This section defines the concepts of DDS and RTPS. It also provides a step-by-step tutorial on how to write a simple Fast DDS (formerly Fast RTPS) publish/subscribe application.
What is DDS?¶
The Data Distribution Service (DDS) is a data-centric communication protocol used for distributed software application communications. It describes the communications Application Programming Interfaces (APIs) and Communication Semantics that enable communication between data providers and data consumers.
Since it is a Data-Centric Publish Subscribe (DCPS) model, three key application entities are defined in its implementation: publication entities, which define the information-generating objects and their properties; subscription entities, which define the information-consuming objects and their properties; and configuration entities that define the types of information that are transmitted as topics, and create the publisher and subscriber with its Quality of Service (QoS) properties, ensuring the correct performance of the above entities.
DDS uses QoS to define the behavioral characteristics of DDS Entities. QoS are comprised of individual QoS policies (objects of type deriving from QoSPolicy). These are described in Policy.
The DCPS conceptual model¶
In the DCPS model, four basic elements are defined for the development of a system of communicating applications.
Publisher. It is the DCPS entity in charge of the creation and configuration of the DataWriters it implements. The DataWriter is the entity in charge of the actual publication of the messages. Each one will have an assigned Topic under which the messages are published. See Publisher for further details.
Subscriber. It is the DCPS Entity in charge of receiving the data published under the topics to which it subscribes. It serves one or more DataReader objects, which are responsible for communicating the availability of new data to the application. See Subscriber for further details.
Topic. It is the entity that binds publications and subscriptions. It is unique within a DDS domain. Through the TopicDescription, it allows the uniformity of data types of publications and subscriptions. See Topic for further details.
Domain. This is the concept used to link all publishers and subscribers, belonging to one or more applications, which exchange data under different topics. These individual applications that participate in a domain are called DomainParticipant. The DDS Domain is identified by a domain ID. The DomainParticipant defines the domain ID to specify the DDS domain to which it belongs. Two DomainParticipants with different IDs are not aware of each other’s presence in the network. Hence, several communication channels can be created. This is applied in scenarios where several DDS applications are involved, with their respective DomainParticipants communicating with each other, but these applications must not interfere. The DomainParticipant acts as a container for other DCPS Entities, acts as a factory for Publisher, Subscriber and Topic Entities, and provides administrative services in the domain. See Domain for further details.
These elements are shown in the figure below.
DCPS model entities in the DDS Domain.¶
What is RTPS?¶
The Real-Time Publish Subscribe (RTPS) protocol, developed to support DDS applications, is a publication-subscription communication middleware over best-effort transports such as UDP/IP. Furthermore, Fast DDS provides support for TCP and Shared Memory (SHM) transports.
It is designed to support both unicast and multicast communications.
At the top of RTPS, inherited from DDS, the Domain can be found, which defines a separate plane of communication. Several domains can coexist at the same time independently. A domain contains any number of RTPSParticipants, that is, elements capable of sending and receiving data. To do this, the RTPSParticipants use their Endpoints:
RTPSWriter: Endpoint able to send data.
RTPSReader: Endpoint able to receive data.
A RTPSParticipant can have any number of writer and reader endpoints.
RTPS high-level architecture¶
Communication revolves around Topics, which define and label the data being exchanged. The topics do not belong to a specific participant. The participant, through the RTPSWriters, makes changes in the data published under a topic, and through the RTPSReaders receives the data associated with the topics to which it subscribes. The communication unit is called Change, which represents an update in the data that is written under a Topic. RTPSReaders/RTPSWriters register these changes on their History, a data structure that serves as a cache for recent changes.
In the default configuration of eProsima Fast DDS, when you publish a change through a RTPSWriter endpoint, the following steps happen behind the scenes:
The change is added to the RTPSWriter’s history cache.
The RTPSWriter sends the change to any RTPSReaders it knows about.
After receiving data, RTPSReaders update their history cache with the new change.
However, Fast DDS supports numerous configurations that allow you to change the behavior of RTPSWriters/RTPSReaders. A modification in the default configuration of the RTPS entities implies a change in the data exchange flow between RTPSWriters and RTPSReaders. Moreover, by choosing Quality of Service (QoS) policies, you can affect how these history caches are managed in several ways, but the communication loop remains the same. You can continue reading section RTPS Layer to learn more about the implementation of the RTPS protocol in Fast DDS.
Writing a simple C++ publisher and subscriber application¶
This section details how to create a simple Fast DDS application with a publisher and a subscriber using C++ API step by step. It is also possible to self-generate a similar example to the one implemented in this section by using the eProsima Fast DDS-Gen tool. This additional approach is explained in Building a publish/subscribe application.
Background¶
DDS is a data-centric communications middleware that implements the DCPS model. This model is based on the development of a publisher, a data generating element; and a subscriber, a data consuming element. These entities communicate by means of the topic, an element that binds both DDS entities. Publishers generate information under a topic and subscribers subscribe to this same topic to receive information.
Prerequisites¶
First of all, you need to follow the steps outlined in the Installation Manual for the installation of eProsima Fast DDS and all its dependencies. You also need to have completed the steps outlined in the Installation Manual for the installation of the eProsima Fast DDS-Gen tool. Moreover, all the commands provided in this tutorial are outlined for a Linux environment.
Create the application workspace¶
The application workspace will have the following structure at the end of the project.
Files build/DDSHelloWorldPublisher and build/DDSHelloWorldSubscriber are the Publisher application and
Subscriber application respectively.
.
└── workspace_DDSHelloWorld
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── DDSHelloWorldPublisher
│ ├── DDSHelloWorldSubscriber
│ └── Makefile
├── CMakeLists.txt
└── src
├── HelloWorld.hpp
├── HelloWorld.idl
├── HelloWorldCdrAux.hpp
├── HelloWorldCdrAux.ipp
├── HelloWorldPublisher.cpp
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
├── HelloWorldSubscriber.cpp
├── HelloWorldTypeObjectSupport.cxx
└── HelloWorldTypeObjectSupport.hpp
Let’s create the directory tree first.
mkdir workspace_DDSHelloWorld && cd workspace_DDSHelloWorld
mkdir src build
Import linked libraries and its dependencies¶
The DDS application requires the Fast DDS and Fast CDR libraries. Depending on the installation procedure followed the process of making these libraries available for our DDS application will be slightly different.
Installation from binaries and manual installation¶
If we have followed the installation from binaries or the manual installation, these libraries are already accessible from the workspace. On Linux, the header files can be found in directories /usr/include/fastdds/ and /usr/include/fastcdr/ for Fast DDS and Fast CDR respectively. The compiled libraries of both can be found in the directory /usr/lib/.
Colcon installation¶
From a Colcon installation there are several ways to import the libraries. If the libraries need to be available just for the current session, run the following command.
source <path/to/Fast-DDS/workspace>/install/setup.bash
They can be made accessible from any session by adding the Fast DDS installation directory to your $PATH
variable in the shell configuration files for the current user running the following command.
echo 'source <path/to/Fast-DDS/workspace>/install/setup.bash' >> ~/.bashrc
This will set up the environment after each of this user’s logins.
Configure the CMake project¶
We will use the CMake tool to manage the building of the project. With your preferred text editor, create a new file called CMakeLists.txt and copy and paste the following code snippet. Save this file in the root directory of your workspace. If you have followed these steps, it should be workspace_DDSHelloWorld.
cmake_minimum_required(VERSION 3.20)
project(DDSHelloWorld)
# Find requirements
if(NOT fastcdr_FOUND)
find_package(fastcdr 2 REQUIRED)
endif()
if(NOT fastdds_FOUND)
find_package(fastdds 3 REQUIRED)
endif()
# Set C++11
include(CheckCXXCompilerFlag)
if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANG OR
CMAKE_CXX_COMPILER_ID MATCHES "Clang")
check_cxx_compiler_flag(-std=c++11 SUPPORTS_CXX11)
if(SUPPORTS_CXX11)
add_compile_options(-std=c++11)
else()
message(FATAL_ERROR "Compiler doesn't support C++11")
endif()
endif()
message(STATUS "Configuring HelloWorld publisher/subscriber example...")
file(GLOB DDS_HELLOWORLD_SOURCES_CXX "src/*.cxx")
In each section we will complete this file to include the specific generated files.
Build the topic data type¶
eProsima Fast DDS-Gen is a Java application that generates source code using the data types defined in an Interface Description Language (IDL) file. This application can do two different things:
Generate C++ definitions for your custom topic.
Generate a functional example that uses your topic data.
It will be the former that will be followed in this tutorial. To see an example of application of the latter you can check this other example. See Introduction for further details. For this project, we will use the Fast DDS-Gen application to define the data type of the messages that will be sent by the publishers and received by the subscribers.
In the workspace directory, execute the following commands:
cd src && touch HelloWorld.idl
This creates the HelloWorld.idl file in the src directory. Open the file in a text editor and copy and paste the following snippet of code.
struct HelloWorld
{
unsigned long index;
string message;
};
By doing this we have defined the HelloWorld data type, which has two elements: an index of type uint32_t
and a message of type std::string.
All that remains is to generate the source code that implements this data type in C++11.
To do this, run the following command from the src directory.
<path/to/Fast DDS-Gen>/scripts/fastddsgen HelloWorld.idl
This must have generated the following files:
HelloWorld.hpp: HelloWorld type definition.
HelloWorldPubSubTypes.cxx: Interface used by Fast DDS to support HelloWorld type.
HelloWorldPubSubTypes.h: Header file for HelloWorldPubSubTypes.cxx.
HelloWorldCdrAux.ipp: Serialization and Deserialization code for the HelloWorld type.
HelloWorldCdrAux.hpp: Header file for HelloWorldCdrAux.ipp.
HelloWorldTypeObjectSupport.cxx: TypeObject representation registration code.
HelloWorldTypeObjectSupport.hpp: Header file for HelloWorldTypeObjectSupport.cxx.
CMakeLists.txt¶
Include the following code snippet at the end of the CMakeList.txt file you created earlier. This includes the files we have just created.
target_link_libraries(DDSHelloWorldPublisher fastdds fastcdr)
Write the Fast DDS publisher¶
From the src directory in the workspace, run the following command to download the HelloWorldPublisher.cpp file.
wget -O HelloWorldPublisher.cpp \
https://raw.githubusercontent.com/eProsima/Fast-RTPS-docs/master/code/Examples/C++/DDSHelloWorld/src/HelloWorldPublisher.cpp
This is the C++ source code for the publisher application. It is going to send 10 publications under the topic HelloWorldTopic.
1// Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15/**
16 * @file HelloWorldPublisher.cpp
17 *
18 */
19
20#include "HelloWorldPubSubTypes.h"
21
22#include <chrono>
23#include <thread>
24
25#include <fastdds/dds/domain/DomainParticipant.hpp>
26#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
27#include <fastdds/dds/publisher/DataWriter.hpp>
28#include <fastdds/dds/publisher/DataWriterListener.hpp>
29#include <fastdds/dds/publisher/Publisher.hpp>
30#include <fastdds/dds/topic/TypeSupport.hpp>
31
32using namespace eprosima::fastdds::dds;
33
34class HelloWorldPublisher
35{
36private:
37
38 HelloWorld hello_;
39
40 DomainParticipant* participant_;
41
42 Publisher* publisher_;
43
44 Topic* topic_;
45
46 DataWriter* writer_;
47
48 TypeSupport type_;
49
50 class PubListener : public DataWriterListener
51 {
52 public:
53
54 PubListener()
55 : matched_(0)
56 {
57 }
58
59 ~PubListener() override
60 {
61 }
62
63 void on_publication_matched(
64 DataWriter*,
65 const PublicationMatchedStatus& info) override
66 {
67 if (info.current_count_change == 1)
68 {
69 matched_ = info.total_count;
70 std::cout << "Publisher matched." << std::endl;
71 }
72 else if (info.current_count_change == -1)
73 {
74 matched_ = info.total_count;
75 std::cout << "Publisher unmatched." << std::endl;
76 }
77 else
78 {
79 std::cout << info.current_count_change
80 << " is not a valid value for PublicationMatchedStatus current count change." << std::endl;
81 }
82 }
83
84 std::atomic_int matched_;
85
86 } listener_;
87
88public:
89
90 HelloWorldPublisher()
91 : participant_(nullptr)
92 , publisher_(nullptr)
93 , topic_(nullptr)
94 , writer_(nullptr)
95 , type_(new HelloWorldPubSubType())
96 {
97 }
98
99 virtual ~HelloWorldPublisher()
100 {
101 if (writer_ != nullptr)
102 {
103 publisher_->delete_datawriter(writer_);
104 }
105 if (publisher_ != nullptr)
106 {
107 participant_->delete_publisher(publisher_);
108 }
109 if (topic_ != nullptr)
110 {
111 participant_->delete_topic(topic_);
112 }
113 DomainParticipantFactory::get_instance()->delete_participant(participant_);
114 }
115
116 //!Initialize the publisher
117 bool init()
118 {
119 hello_.index(0);
120 hello_.message("HelloWorld");
121
122 DomainParticipantQos participantQos;
123 participantQos.name("Participant_publisher");
124 participant_ = DomainParticipantFactory::get_instance()->create_participant(0, participantQos);
125
126 if (participant_ == nullptr)
127 {
128 return false;
129 }
130
131 // Register the Type
132 type_.register_type(participant_);
133
134 // Create the publications Topic
135 topic_ = participant_->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
136
137 if (topic_ == nullptr)
138 {
139 return false;
140 }
141
142 // Create the Publisher
143 publisher_ = participant_->create_publisher(PUBLISHER_QOS_DEFAULT, nullptr);
144
145 if (publisher_ == nullptr)
146 {
147 return false;
148 }
149
150 // Create the DataWriter
151 writer_ = publisher_->create_datawriter(topic_, DATAWRITER_QOS_DEFAULT, &listener_);
152
153 if (writer_ == nullptr)
154 {
155 return false;
156 }
157 return true;
158 }
159
160 //!Send a publication
161 bool publish()
162 {
163 if (listener_.matched_ > 0)
164 {
165 hello_.index(hello_.index() + 1);
166 writer_->write(&hello_);
167 return true;
168 }
169 return false;
170 }
171
172 //!Run the Publisher
173 void run(
174 uint32_t samples)
175 {
176 uint32_t samples_sent = 0;
177 while (samples_sent < samples)
178 {
179 if (publish())
180 {
181 samples_sent++;
182 std::cout << "Message: " << hello_.message() << " with index: " << hello_.index()
183 << " SENT" << std::endl;
184 }
185 std::this_thread::sleep_for(std::chrono::milliseconds(1000));
186 }
187 }
188};
189
190int main(
191 int argc,
192 char** argv)
193{
194 std::cout << "Starting publisher." << std::endl;
195 uint32_t samples = 10;
196
197 HelloWorldPublisher* mypub = new HelloWorldPublisher();
198 if(mypub->init())
199 {
200 mypub->run(samples);
201 }
202
203 delete mypub;
204 return 0;
205}
Examining the code¶
At the beginning of the file we have a Doxygen style comment block with the @file field that tells us the name of
the file.
/**
* @file HelloWorldPublisher.cpp
*
*/
Below are the includes of the C++ headers. The first one includes the HelloWorldPubSubTypes.h file with the serialization and deserialization functions of the data type that we have defined in the previous section.
#include "HelloWorldPubSubTypes.h"
The next block includes the C++ header files that allow the use of the Fast DDS API.
DomainParticipantFactory. Allows for the creation and destruction of DomainParticipant objects.DomainParticipant. Acts as a container for all other Entity objects and as a factory for the Publisher, Subscriber, and Topic objects.TypeSupport. Provides the participant with the functions to serialize, deserialize and get the key of a specific data type.Publisher. It is the object responsible for the creation of DataWriters.DataWriter. Allows the application to set the value of the data to be published under a given Topic.DataWriterListener. Allows the redefinition of the functions of the DataWriterListener.
#include <chrono>
#include <thread>
#include <fastdds/dds/domain/DomainParticipant.hpp>
#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/publisher/DataWriter.hpp>
#include <fastdds/dds/publisher/DataWriterListener.hpp>
#include <fastdds/dds/publisher/Publisher.hpp>
#include <fastdds/dds/topic/TypeSupport.hpp>
Next, we define the namespace that contains the eProsima Fast DDS classes and functions that we are going to use in our application.
using namespace eprosima::fastdds::dds;
The next line creates the HelloWorldPublisher class that implements a publisher.
class HelloWorldPublisher
Continuing with the private data members of the class, the hello_ data member is defined as an object of the
HelloWorld class that defines the data type
we created with the IDL file.
Next, the private data members corresponding to the participant, publisher, topic, DataWriter and data type are
defined.
The type_ object of the TypeSupport class is the object that will be used to register the topic data type
in the DomainParticipant.
private:
HelloWorld hello_;
DomainParticipant* participant_;
Publisher* publisher_;
Topic* topic_;
DataWriter* writer_;
TypeSupport type_;
Then, the PubListener class is defined by inheriting from the DataWriterListener class.
This class overrides the default DataWriter listener callbacks, which allows the execution of routines in case of an
event.
The overridden callback on_publication_matched()
allows the definition of a series of actions when a new DataReader
is detected listening to the topic under which the DataWriter is publishing.
The info.current_count_change() detects these changes of DataReaders that are matched to the
DataWriter.
This is a member in the MatchedStatus structure that allows tracking changes in the status of subscriptions.
Finally, the listener_ object of the class is defined as an instance of PubListener.
class PubListener : public DataWriterListener
{
public:
PubListener()
: matched_(0)
{
}
~PubListener() override
{
}
void on_publication_matched(
DataWriter*,
const PublicationMatchedStatus& info) override
{
if (info.current_count_change == 1)
{
matched_ = info.total_count;
std::cout << "Publisher matched." << std::endl;
}
else if (info.current_count_change == -1)
{
matched_ = info.total_count;
std::cout << "Publisher unmatched." << std::endl;
}
else
{
std::cout << info.current_count_change
<< " is not a valid value for PublicationMatchedStatus current count change." << std::endl;
}
}
std::atomic_int matched_;
} listener_;
The public constructor and destructor of the HelloWorldPublisher class are defined below.
The constructor initializes the private data members of the class to nullptr, with the exception of the TypeSupport
object, that is initialized as an instance of the HelloWorldPubSubType class.
The class destructor removes these data members and thus cleans the system memory.
HelloWorldPublisher()
: participant_(nullptr)
, publisher_(nullptr)
, topic_(nullptr)
, writer_(nullptr)
, type_(new HelloWorldPubSubType())
{
}
virtual ~HelloWorldPublisher()
{
if (writer_ != nullptr)
{
publisher_->delete_datawriter(writer_);
}
if (publisher_ != nullptr)
{
participant_->delete_publisher(publisher_);
}
if (topic_ != nullptr)
{
participant_->delete_topic(topic_);
}
DomainParticipantFactory::get_instance()->delete_participant(participant_);
}
Continuing with the public member functions of the HelloWorldPublisher class, the next snippet of code defines
the public publisher’s initialization member function.
This function performs several actions:
Initializes the content of the HelloWorld type
hello_structure members.Assigns a name to the participant through the QoS of the DomainParticipant.
Uses the
DomainParticipantFactoryto create the participant.Registers the data type defined in the IDL.
Creates the topic for the publications.
Creates the publisher.
Creates the DataWriter with the listener previously created.
As you can see, the QoS configuration for all entities, except for the participant’s name, is the default configuration
(PARTICIPANT_QOS_DEFAULT, PUBLISHER_QOS_DEFAULT, TOPIC_QOS_DEFAULT, DATAWRITER_QOS_DEFAULT).
The default value of the QoS of each DDS Entity can be checked in the
DDS standard.
//!Initialize the publisher
bool init()
{
hello_.index(0);
hello_.message("HelloWorld");
DomainParticipantQos participantQos;
participantQos.name("Participant_publisher");
participant_ = DomainParticipantFactory::get_instance()->create_participant(0, participantQos);
if (participant_ == nullptr)
{
return false;
}
// Register the Type
type_.register_type(participant_);
// Create the publications Topic
topic_ = participant_->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
if (topic_ == nullptr)
{
return false;
}
// Create the Publisher
publisher_ = participant_->create_publisher(PUBLISHER_QOS_DEFAULT, nullptr);
if (publisher_ == nullptr)
{
return false;
}
// Create the DataWriter
writer_ = publisher_->create_datawriter(topic_, DATAWRITER_QOS_DEFAULT, &listener_);
if (writer_ == nullptr)
{
return false;
}
return true;
}
To make the publication, the public member function publish() is implemented.
In the DataWriter’s listener callback which states that the DataWriter has matched with a DataReader
that listens to the publication topic, the data member matched_ is updated. It contains the number of DataReaders
discovered.
Therefore, when the first DataReader has been discovered, the application starts to publish.
This is simply the writing of a change by the DataWriter object.
//!Send a publication
bool publish()
{
if (listener_.matched_ > 0)
{
hello_.index(hello_.index() + 1);
writer_->write(&hello_);
return true;
}
return false;
}
The public run function executes the action of publishing a given number of times, waiting for 1 second between publications.
//!Run the Publisher
void run(
uint32_t samples)
{
uint32_t samples_sent = 0;
while (samples_sent < samples)
{
if (publish())
{
samples_sent++;
std::cout << "Message: " << hello_.message() << " with index: " << hello_.index()
<< " SENT" << std::endl;
}
std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}
}
Finally, the HelloWorldPublisher is initialized and run in main.
int main(
int argc,
char** argv)
{
std::cout << "Starting publisher." << std::endl;
uint32_t samples = 10;
HelloWorldPublisher* mypub = new HelloWorldPublisher();
if(mypub->init())
{
mypub->run(samples);
}
delete mypub;
return 0;
}
CMakeLists.txt¶
Include at the end of the CMakeList.txt file you created earlier the following code snippet. This adds all the source files needed to build the executable, and links the executable and the library together.
add_executable(DDSHelloWorldPublisher src/HelloWorldPublisher.cpp ${DDS_HELLOWORLD_SOURCES_CXX})
target_link_libraries(DDSHelloWorldPublisher fastdds fastcdr)
At this point the project is ready for building, compiling and running the publisher application. From the build directory in the workspace, run the following commands.
cmake ..
cmake --build .
./DDSHelloWorldPublisher
Write the Fast DDS subscriber¶
From the src directory in the workspace, execute the following command to download the HelloWorldSubscriber.cpp file.
wget -O HelloWorldSubscriber.cpp \
https://raw.githubusercontent.com/eProsima/Fast-RTPS-docs/master/code/Examples/C++/DDSHelloWorld/src/HelloWorldSubscriber.cpp
This is the C++ source code for the subscriber application. The application runs a subscriber until it receives 10 samples under the topic HelloWorldTopic. At this point the subscriber stops.
1// Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15/**
16 * @file HelloWorldSubscriber.cpp
17 *
18 */
19
20#include "HelloWorldPubSubTypes.h"
21
22#include <chrono>
23#include <thread>
24
25#include <fastdds/dds/domain/DomainParticipant.hpp>
26#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
27#include <fastdds/dds/subscriber/DataReader.hpp>
28#include <fastdds/dds/subscriber/DataReaderListener.hpp>
29#include <fastdds/dds/subscriber/qos/DataReaderQos.hpp>
30#include <fastdds/dds/subscriber/SampleInfo.hpp>
31#include <fastdds/dds/subscriber/Subscriber.hpp>
32#include <fastdds/dds/topic/TypeSupport.hpp>
33
34using namespace eprosima::fastdds::dds;
35
36class HelloWorldSubscriber
37{
38private:
39
40 DomainParticipant* participant_;
41
42 Subscriber* subscriber_;
43
44 DataReader* reader_;
45
46 Topic* topic_;
47
48 TypeSupport type_;
49
50 class SubListener : public DataReaderListener
51 {
52 public:
53
54 SubListener()
55 : samples_(0)
56 {
57 }
58
59 ~SubListener() override
60 {
61 }
62
63 void on_subscription_matched(
64 DataReader*,
65 const SubscriptionMatchedStatus& info) override
66 {
67 if (info.current_count_change == 1)
68 {
69 std::cout << "Subscriber matched." << std::endl;
70 }
71 else if (info.current_count_change == -1)
72 {
73 std::cout << "Subscriber unmatched." << std::endl;
74 }
75 else
76 {
77 std::cout << info.current_count_change
78 << " is not a valid value for SubscriptionMatchedStatus current count change" << std::endl;
79 }
80 }
81
82 void on_data_available(
83 DataReader* reader) override
84 {
85 SampleInfo info;
86 if (reader->take_next_sample(&hello_, &info) == eprosima::fastdds::dds::RETCODE_OK)
87 {
88 if (info.valid_data)
89 {
90 samples_++;
91 std::cout << "Message: " << hello_.message() << " with index: " << hello_.index()
92 << " RECEIVED." << std::endl;
93 }
94 }
95 }
96
97 HelloWorld hello_;
98
99 std::atomic_int samples_;
100
101 }
102 listener_;
103
104public:
105
106 HelloWorldSubscriber()
107 : participant_(nullptr)
108 , subscriber_(nullptr)
109 , topic_(nullptr)
110 , reader_(nullptr)
111 , type_(new HelloWorldPubSubType())
112 {
113 }
114
115 virtual ~HelloWorldSubscriber()
116 {
117 if (reader_ != nullptr)
118 {
119 subscriber_->delete_datareader(reader_);
120 }
121 if (topic_ != nullptr)
122 {
123 participant_->delete_topic(topic_);
124 }
125 if (subscriber_ != nullptr)
126 {
127 participant_->delete_subscriber(subscriber_);
128 }
129 DomainParticipantFactory::get_instance()->delete_participant(participant_);
130 }
131
132 //!Initialize the subscriber
133 bool init()
134 {
135 DomainParticipantQos participantQos;
136 participantQos.name("Participant_subscriber");
137 participant_ = DomainParticipantFactory::get_instance()->create_participant(0, participantQos);
138
139 if (participant_ == nullptr)
140 {
141 return false;
142 }
143
144 // Register the Type
145 type_.register_type(participant_);
146
147 // Create the subscriptions Topic
148 topic_ = participant_->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
149
150 if (topic_ == nullptr)
151 {
152 return false;
153 }
154
155 // Create the Subscriber
156 subscriber_ = participant_->create_subscriber(SUBSCRIBER_QOS_DEFAULT, nullptr);
157
158 if (subscriber_ == nullptr)
159 {
160 return false;
161 }
162
163 // Create the DataReader
164 reader_ = subscriber_->create_datareader(topic_, DATAREADER_QOS_DEFAULT, &listener_);
165
166 if (reader_ == nullptr)
167 {
168 return false;
169 }
170
171 return true;
172 }
173
174 //!Run the Subscriber
175 void run(
176 uint32_t samples)
177 {
178 while (listener_.samples_ < samples)
179 {
180 std::this_thread::sleep_for(std::chrono::milliseconds(100));
181 }
182 }
183
184};
185
186int main(
187 int argc,
188 char** argv)
189{
190 std::cout << "Starting subscriber." << std::endl;
191 uint32_t samples = 10;
192
193 HelloWorldSubscriber* mysub = new HelloWorldSubscriber();
194 if (mysub->init())
195 {
196 mysub->run(samples);
197 }
198
199 delete mysub;
200 return 0;
201}
Examining the code¶
Since the source code of both the publisher and subscriber applications is mostly identical, this document will focus on the main differences between them, omitting the parts of the code that have already been explained.
Following the same structure as in the publisher explanation, the first step is the includes of the C++ header files. In these, the files that include the publisher class are replaced by the subscriber class and the data writer class by the data reader class.
Subscriber. It is the object responsible for the creation and configuration of DataReaders.DataReader. It is the object responsible for the actual reception of the data. It registers in the application the topic (TopicDescription) that identifies the data to be read and accesses the data received by the subscriber.DataReaderListener. This is the listener assigned to the data reader.DataReaderQoS. Structure that defines the QoS of the DataReader.SampleInfo. It is the information that accompanies each sample that is ‘read’ or ‘taken’.
#include <fastdds/dds/domain/DomainParticipant.hpp>
#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/subscriber/DataReader.hpp>
#include <fastdds/dds/subscriber/DataReaderListener.hpp>
#include <fastdds/dds/subscriber/qos/DataReaderQos.hpp>
#include <fastdds/dds/subscriber/SampleInfo.hpp>
#include <fastdds/dds/subscriber/Subscriber.hpp>
#include <fastdds/dds/topic/TypeSupport.hpp>
The next line defines the HelloWorldSubscriber class that implements a subscriber.
class HelloWorldSubscriber
Starting with the private data members of the class, it is worth mentioning the implementation of the data reader
listener.
The private data members of the class will be the participant, the subscriber, the topic, the data reader, and the
data type.
As it was the case with the data writer, the listener implements the callbacks to be executed in case an event
occurs.
The first overridden callback of the SubListener is the on_subscription_matched(), which is the
analog of the on_publication_matched() callback of the DataWriter.
void on_subscription_matched(
DataReader*,
const SubscriptionMatchedStatus& info) override
{
if (info.current_count_change == 1)
{
std::cout << "Subscriber matched." << std::endl;
}
else if (info.current_count_change == -1)
{
std::cout << "Subscriber unmatched." << std::endl;
}
else
{
std::cout << info.current_count_change
<< " is not a valid value for SubscriptionMatchedStatus current count change" << std::endl;
}
}
The second overridden callback is on_data_available().
In this, the next received sample that the data reader can access is taken and processed to display its content.
It is here that the object of the SampleInfo class is defined, which determines whether a sample has already
been read or taken.
Each time a sample is read, the counter of samples received is increased.
void on_data_available(
DataReader* reader) override
{
SampleInfo info;
if (reader->take_next_sample(&hello_, &info) == eprosima::fastdds::dds::RETCODE_OK)
{
if (info.valid_data)
{
samples_++;
std::cout << "Message: " << hello_.message() << " with index: " << hello_.index()
<< " RECEIVED." << std::endl;
}
}
}
The public constructor and destructor of the class is defined below.
HelloWorldSubscriber()
: participant_(nullptr)
, subscriber_(nullptr)
, topic_(nullptr)
, reader_(nullptr)
, type_(new HelloWorldPubSubType())
{
}
virtual ~HelloWorldSubscriber()
{
if (reader_ != nullptr)
{
subscriber_->delete_datareader(reader_);
}
if (topic_ != nullptr)
{
participant_->delete_topic(topic_);
}
if (subscriber_ != nullptr)
{
participant_->delete_subscriber(subscriber_);
}
DomainParticipantFactory::get_instance()->delete_participant(participant_);
Next comes the subscriber initialization public member function.
This is the same as the initialization public member function defined for the HelloWorldPublisher.
The QoS configuration for all entities, except for the participant’s name, is the default QoS
(PARTICIPANT_QOS_DEFAULT, SUBSCRIBER_QOS_DEFAULT, TOPIC_QOS_DEFAULT, DATAREADER_QOS_DEFAULT).
The default value of the QoS of each DDS Entity can be checked in the
DDS standard.
//!Initialize the subscriber
bool init()
{
DomainParticipantQos participantQos;
participantQos.name("Participant_subscriber");
participant_ = DomainParticipantFactory::get_instance()->create_participant(0, participantQos);
if (participant_ == nullptr)
{
return false;
}
// Register the Type
type_.register_type(participant_);
// Create the subscriptions Topic
topic_ = participant_->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
if (topic_ == nullptr)
{
return false;
}
// Create the Subscriber
subscriber_ = participant_->create_subscriber(SUBSCRIBER_QOS_DEFAULT, nullptr);
if (subscriber_ == nullptr)
{
return false;
}
// Create the DataReader
reader_ = subscriber_->create_datareader(topic_, DATAREADER_QOS_DEFAULT, &listener_);
if (reader_ == nullptr)
{
return false;
}
return true;
The public member function run() ensures that the subscriber runs until all the samples have been received.
This member function implements an active wait of the subscriber, with a 100ms sleep interval to ease the CPU.
//!Run the Subscriber
void run(
uint32_t samples)
{
while (listener_.samples_ < samples)
{
std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
Finally, the participant that implements a subscriber is initialized and run in main.
};
int main(
int argc,
char** argv)
{
std::cout << "Starting subscriber." << std::endl;
uint32_t samples = 10;
HelloWorldSubscriber* mysub = new HelloWorldSubscriber();
if (mysub->init())
{
mysub->run(samples);
}
delete mysub;
CMakeLists.txt¶
Include at the end of the CMakeList.txt file you created earlier the following code snippet. This adds all the source files needed to build the executable, and links the executable and the library together.
add_executable(DDSHelloWorldSubscriber src/HelloWorldSubscriber.cpp ${DDS_HELLOWORLD_SOURCES_CXX})
target_link_libraries(DDSHelloWorldSubscriber fastdds fastcdr)
At this point the project is ready for building, compiling and running the subscriber application. From the build directory in the workspace, run the following commands.
cmake ..
cmake --build .
./DDSHelloWorldSubscriber
Putting all together¶
Finally, from the build directory, run the publisher and subscriber applications from two terminals.
./DDSHelloWorldPublisher
./DDSHelloWorldSubscriber
Summary¶
In this tutorial you have built a publisher and a subscriber DDS application. You have also learned how to build the CMake file for source code compilation, and how to include and use the Fast DDS and Fast CDR libraries in your project.
Writing a simple Python publisher and subscriber application¶
This section details how to create a simple Fast DDS application with a publisher and a subscriber using Python API step by step.
Background¶
DDS is a data-centric communications middleware that implements the DCPS model. This model is based on the development of a publisher, a data generating element; and a subscriber, a data consuming element. These entities communicate by means of the topic, an element that binds both DDS entities. Publishers generate information under a topic and subscribers subscribe to this same topic to receive information.
Prerequisites¶
First of all, you need to follow the steps outlined in the Installation Manual for the installation of eProsima Fast DDS and all its dependencies. You also need to have completed the steps outlined in the Installation Manual for the installation of the eProsima Fast DDS-Gen tool. Moreover, all the commands provided in this tutorial are outlined for a Linux environment.
Create the application workspace¶
The application workspace will have the following structure at the end of the project.
Files HelloWorldPublisher.py and HelloWorldSubscriber.py are the Publisher application and
Subscriber application respectively.
.
├── CMakeCache.txt
├── CMakeFiles
├── CMakeLists.txt
├── HelloWorld.hpp
├── HelloWorld.i
├── HelloWorld.idl
├── HelloWorld.py
├── HelloWorldCdrAux.hpp
├── HelloWorldCdrAux.ipp
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
├── HelloWorldPubSubTypes.i
├── HelloWorldPublisher.py
├── HelloWorldSubscriber.py
├── HelloWorldTypeObjectSupport.cxx
├── HelloWorldTypeObjectSupport.hpp
├── Makefile
├── _HelloWorldWrapper.so
├── cmake_install.cmake
└── libHelloWorld.so
Let’s create the directory tree first.
mkdir workspace_HelloWorld && cd workspace_HelloWorld
Import linked libraries and its dependencies¶
The DDS application requires the Fast DDS, Fast CDR and Fast DDS Python bindings libraries. Depending on the installation procedure followed the process of making these libraries available for our DDS application will be slightly different.
Colcon installation¶
From a Colcon installation there are several ways to import the libraries. If the libraries need to be available just for the current session, run the following command.
source <path/to/Fast-DDS-python/workspace>/install/setup.bash
They can be made accessible from any session by adding the Fast DDS installation directory to your $PATH
variable in the shell configuration files for the current user running the following command.
echo 'source <path/to/Fast-DDS-python/workspace>/install/setup.bash' >> ~/.bashrc
This will set up the environment after each of this user’s logins.
Build the topic data type¶
eProsima Fast DDS-Gen is a Java application that generates source code using the data types defined in an Interface Description Language (IDL) file. This application can do two different things:
Generate C++ definitions for your custom topic.
Generate SWIG interface files to generate the Python bindings for your custom topic.
For this project, we will use the Fast DDS-Gen application to define the data type of the messages that will be sent by the publishers and received by the subscribers.
In the workspace directory, execute the following commands:
touch HelloWorld.idl
This creates the HelloWorld.idl file. Open the file in a text editor and copy and paste the following snippet of code.
struct HelloWorld
{
unsigned long index;
string message;
};
By doing this we have defined the HelloWorld data type, which has two elements: an index of type uint32_t
and a message of type std::string.
All that remains is to generate the source code that implements this data type in C++11 and the
SWIG interface files for the Python bindings.
To do this, run the following command.
<path/to/Fast DDS-Gen>/scripts/fastddsgen -python HelloWorld.idl
This must have generated the following files:
HelloWorld.hpp: HelloWorld C++ type definition.
HelloWorld.i: SWIG interface file for HelloWorld C++ type definition.
HelloWorldPubSubTypes.cxx: C++ interface used by Fast DDS to support HelloWorld type.
HelloWorldPubSubTypes.h: C++ header file for HelloWorldPubSubTypes.cxx.
HelloWorldPubSubTypes.i: SWIG interface file for C++ Serialization and Deserialization code.
HelloWorldCdrAux.ipp: C++ serialization and deserialization code for the HelloWorld type.
HelloWorldCdrAux.hpp: C++ header file for HelloWorldCdrAux.ipp.
HelloWorldTypeObjectSupport.cxx: TypeObject representation registration code.
HelloWorldTypeObjectSupport.hpp: Header file for HelloWorldTypeObjectSupport.cxx.
CMakeLists.txt: CMake file to generate C++ source code and Python module from the SWIG interface files, compile and generate C++ libraries.
After that, the python bindings can be generated by running the following command.
cmake .
make
This must have generated the python binding:
HelloWorld.py: Python module to be imported by your Python example.
CMakeLists.txt¶
At this point the project is ready for building, compiling and generating Python bindings for this data type. From the workspace, run the following commands.
cmake .
make
Write the Fast DDS publisher¶
From the workspace, run the following command to download the HelloWorldPublisher.py file.
wget -O HelloWorldPublisher.py \
https://raw.githubusercontent.com/eProsima/Fast-RTPS-docs/master/code/Examples/Python/HelloWorld/HelloWorldPublisher.py
This is the Python source code for the publisher application. It is going to send 10 publications under the topic HelloWorldTopic.
1# Copyright 2022 Proyectos y Sistemas de Mantenimiento SL (eProsima).
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14"""
15HelloWorld Publisher
16"""
17from threading import Condition
18import time
19
20import fastdds
21import HelloWorld
22
23DESCRIPTION = """HelloWorld Publisher example for Fast DDS python bindings"""
24USAGE = ('python3 HelloWorldPublisher.py')
25
26class WriterListener (fastdds.DataWriterListener) :
27 def __init__(self, writer) :
28 self._writer = writer
29 super().__init__()
30
31
32 def on_publication_matched(self, datawriter, info) :
33 if (0 < info.current_count_change) :
34 print ("Publisher matched subscriber {}".format(info.last_subscription_handle))
35 self._writer._cvDiscovery.acquire()
36 self._writer._matched_reader += 1
37 self._writer._cvDiscovery.notify()
38 self._writer._cvDiscovery.release()
39 else :
40 print ("Publisher unmatched subscriber {}".format(info.last_subscription_handle))
41 self._writer._cvDiscovery.acquire()
42 self._writer._matched_reader -= 1
43 self._writer._cvDiscovery.notify()
44 self._writer._cvDiscovery.release()
45
46
47class Writer:
48
49
50 def __init__(self):
51 self._matched_reader = 0
52 self._cvDiscovery = Condition()
53 self.index = 0
54
55 factory = fastdds.DomainParticipantFactory.get_instance()
56 self.participant_qos = fastdds.DomainParticipantQos()
57 factory.get_default_participant_qos(self.participant_qos)
58 self.participant = factory.create_participant(0, self.participant_qos)
59
60 self.topic_data_type = HelloWorld.HelloWorldPubSubType()
61 self.topic_data_type.setName("HelloWorld")
62 self.type_support = fastdds.TypeSupport(self.topic_data_type)
63 self.participant.register_type(self.type_support)
64
65 self.topic_qos = fastdds.TopicQos()
66 self.participant.get_default_topic_qos(self.topic_qos)
67 self.topic = self.participant.create_topic("HelloWorldTopic", self.topic_data_type.getName(), self.topic_qos)
68
69 self.publisher_qos = fastdds.PublisherQos()
70 self.participant.get_default_publisher_qos(self.publisher_qos)
71 self.publisher = self.participant.create_publisher(self.publisher_qos)
72
73 self.listener = WriterListener(self)
74 self.writer_qos = fastdds.DataWriterQos()
75 self.publisher.get_default_datawriter_qos(self.writer_qos)
76 self.writer = self.publisher.create_datawriter(self.topic, self.writer_qos, self.listener)
77
78
79 def write(self):
80 data = HelloWorld.HelloWorld()
81 data.message("Hello World")
82 data.index(self.index)
83 self.writer.write(data)
84 print("Sending {message} : {index}".format(message=data.message(), index=data.index()))
85 self.index = self.index + 1
86
87
88 def wait_discovery(self) :
89 self._cvDiscovery.acquire()
90 print ("Writer is waiting discovery...")
91 self._cvDiscovery.wait_for(lambda : self._matched_reader != 0)
92 self._cvDiscovery.release()
93 print("Writer discovery finished...")
94
95
96 def run(self):
97 self.wait_discovery()
98 for x in range(10) :
99 time.sleep(1)
100 self.write()
101 self.delete()
102
103
104 def delete(self):
105 factory = fastdds.DomainParticipantFactory.get_instance()
106 self.participant.delete_contained_entities()
107 factory.delete_participant(self.participant)
108
109
110if __name__ == '__main__':
111 print('Starting publisher.')
112 writer = Writer()
113 writer.run()
114 exit()
Examining the code¶
At the beginning of the file we import the Fast DDS Python bindings.
import fastdds
and also the Python module generated by Fast-DDS-Gen as described in Build the topic data type section.
import HelloWorld
Then, the WriterListener class is defined by inheriting from the DataWriterListener class.
This class overrides the default DataWriter listener callbacks, which allows the execution of routines in case of an
event.
The overridden callback on_publication_matched()
allows the definition of a series of actions when a new DataReader
is detected listening to the topic under which the DataWriter is publishing.
The info.current_count_change() detects these changes of DataReaders that are matched to the
DataWriter.
This is a member in the MatchedStatus structure that allows tracking changes in the status of
subscriptions.
class WriterListener (fastdds.DataWriterListener) :
def __init__(self, writer) :
self._writer = writer
super().__init__()
def on_publication_matched(self, datawriter, info) :
if (0 < info.current_count_change) :
print ("Publisher matched subscriber {}".format(info.last_subscription_handle))
self._writer._cvDiscovery.acquire()
self._writer._matched_reader += 1
self._writer._cvDiscovery.notify()
self._writer._cvDiscovery.release()
else :
print ("Publisher unmatched subscriber {}".format(info.last_subscription_handle))
self._writer._cvDiscovery.acquire()
self._writer._matched_reader -= 1
self._writer._cvDiscovery.notify()
self._writer._cvDiscovery.release()
The next block creates the Writer class that implements a publisher.
class Writer:
The publisher’s initialization member function of the Writer class are defined below.
This function performs several actions:
Uses the
DomainParticipantFactoryto create the participant.Registers the data type defined in the IDL.
Creates the topic for the publications.
Creates the publisher.
Creates the DataWriter with the listener previously created.
def __init__(self):
self._matched_reader = 0
self._cvDiscovery = Condition()
self.index = 0
factory = fastdds.DomainParticipantFactory.get_instance()
self.participant_qos = fastdds.DomainParticipantQos()
factory.get_default_participant_qos(self.participant_qos)
self.participant = factory.create_participant(0, self.participant_qos)
self.topic_data_type = HelloWorld.HelloWorldPubSubType()
self.topic_data_type.setName("HelloWorld")
self.type_support = fastdds.TypeSupport(self.topic_data_type)
self.participant.register_type(self.type_support)
self.topic_qos = fastdds.TopicQos()
self.participant.get_default_topic_qos(self.topic_qos)
self.topic = self.participant.create_topic("HelloWorldTopic", self.topic_data_type.getName(), self.topic_qos)
self.publisher_qos = fastdds.PublisherQos()
self.participant.get_default_publisher_qos(self.publisher_qos)
self.publisher = self.participant.create_publisher(self.publisher_qos)
self.listener = WriterListener(self)
self.writer_qos = fastdds.DataWriterQos()
self.publisher.get_default_datawriter_qos(self.writer_qos)
self.writer = self.publisher.create_datawriter(self.topic, self.writer_qos, self.listener)
To make the publication, the public member function write() is implemented.
This is simply the writing of a change by the DataWriter object.
def write(self):
data = HelloWorld.HelloWorld()
data.message("Hello World")
data.index(self.index)
self.writer.write(data)
print("Sending {message} : {index}".format(message=data.message(), index=data.index()))
self.index = self.index + 1
To detect when a DataReader has matched, the public member function wait_discovery() is implemented.
In the DataWriter’s listener callback which states that the DataWriter has matched with a DataReader
that listens to the publication topic, the data member _matched_reader is updated.
It contains the number of DataReaders discovered.
Therefore, when the first DataReader has been discovered, the application starts to publish.
def wait_discovery(self) :
self._cvDiscovery.acquire()
print ("Writer is waiting discovery...")
self._cvDiscovery.wait_for(lambda : self._matched_reader != 0)
self._cvDiscovery.release()
print("Writer discovery finished...")
The public run function waits until a DataReader is discovered and executes the action of publishing 10 samples.
def run(self):
self.wait_discovery()
for x in range(10) :
time.sleep(1)
self.write()
self.delete()
Finally, the Writer is initialized and run in main.
if __name__ == '__main__':
print('Starting publisher.')
writer = Writer()
writer.run()
exit()
Write the Fast DDS subscriber¶
From the workspace, run the following command to download the HelloWorldSubscriber.py file.
wget -O HelloWorldSubscriber.py \
https://raw.githubusercontent.com/eProsima/Fast-RTPS-docs/master/code/Examples/Python/HelloWorld/HelloWorldSubscriber.py
This is the Python source code for the subscriber application. The application runs a subscriber until the user press Ctrl+C receiving samples under the topic HelloWorldTopic.
1# Copyright 2022 Proyectos y Sistemas de Mantenimiento SL (eProsima).
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14"""
15HelloWorld Subscriber
16"""
17import signal
18
19import fastdds
20import HelloWorld
21
22DESCRIPTION = """HelloWorld Subscriber example for Fast DDS python bindings"""
23USAGE = ('python3 HelloWorldSubscriber.py')
24
25# To capture ctrl+C
26def signal_handler(sig, frame):
27 print('Interrupted!')
28
29class ReaderListener(fastdds.DataReaderListener):
30
31
32 def __init__(self):
33 super().__init__()
34
35
36 def on_subscription_matched(self, datareader, info) :
37 if (0 < info.current_count_change) :
38 print ("Subscriber matched publisher {}".format(info.last_publication_handle))
39 else :
40 print ("Subscriber unmatched publisher {}".format(info.last_publication_handle))
41
42
43 def on_data_available(self, reader):
44 info = fastdds.SampleInfo()
45 data = HelloWorld.HelloWorld()
46 reader.take_next_sample(data, info)
47
48 print("Received {message} : {index}".format(message=data.message(), index=data.index()))
49
50
51class Reader:
52
53
54 def __init__(self):
55 factory = fastdds.DomainParticipantFactory.get_instance()
56 self.participant_qos = fastdds.DomainParticipantQos()
57 factory.get_default_participant_qos(self.participant_qos)
58 self.participant = factory.create_participant(0, self.participant_qos)
59
60 self.topic_data_type = HelloWorld.HelloWorldPubSubType()
61 self.topic_data_type.setName("HelloWorld")
62 self.type_support = fastdds.TypeSupport(self.topic_data_type)
63 self.participant.register_type(self.type_support)
64
65 self.topic_qos = fastdds.TopicQos()
66 self.participant.get_default_topic_qos(self.topic_qos)
67 self.topic = self.participant.create_topic("HelloWorldTopic", self.topic_data_type.getName(), self.topic_qos)
68
69 self.subscriber_qos = fastdds.SubscriberQos()
70 self.participant.get_default_subscriber_qos(self.subscriber_qos)
71 self.subscriber = self.participant.create_subscriber(self.subscriber_qos)
72
73 self.listener = ReaderListener()
74 self.reader_qos = fastdds.DataReaderQos()
75 self.subscriber.get_default_datareader_qos(self.reader_qos)
76 self.reader = self.subscriber.create_datareader(self.topic, self.reader_qos, self.listener)
77
78
79 def delete(self):
80 factory = fastdds.DomainParticipantFactory.get_instance()
81 self.participant.delete_contained_entities()
82 factory.delete_participant(self.participant)
83
84
85 def run(self):
86 signal.signal(signal.SIGINT, signal_handler)
87 print('Press Ctrl+C to stop')
88 signal.pause()
89 self.delete()
90
91
92if __name__ == '__main__':
93 print('Creating subscriber.')
94 reader = Reader()
95 reader.run()
96 exit()
Examining the code¶
Since the source code of both the publisher and subscriber applications is mostly identical, this document will focus on the main differences between them, omitting the parts of the code that have already been explained.
Following the same structure as in the publisher explanation, the first step is the implementation of the data reader
listener.
The first overridden callback of the ReaderListener is the on_subscription_matched(),
which is the analog of the on_publication_matched() callback of the DataWriter.
def on_subscription_matched(self, datareader, info) :
if (0 < info.current_count_change) :
print ("Subscriber matched publisher {}".format(info.last_publication_handle))
else :
print ("Subscriber unmatched publisher {}".format(info.last_publication_handle))
The second overridden callback is on_data_available().
In this, the next received sample that the data reader can access is taken and processed to display its content.
It is here that the object of the SampleInfo class is defined, which determines whether a sample has
already been read or taken.
def on_data_available(self, reader):
info = fastdds.SampleInfo()
data = HelloWorld.HelloWorld()
reader.take_next_sample(data, info)
The next line defines the Reader class that implements a subscriber.
class Reader:
Next comes the subscriber initialization public member function.
This is the same as the initialization public member function defined for the Writer.
def __init__(self):
factory = fastdds.DomainParticipantFactory.get_instance()
self.participant_qos = fastdds.DomainParticipantQos()
factory.get_default_participant_qos(self.participant_qos)
self.participant = factory.create_participant(0, self.participant_qos)
self.topic_data_type = HelloWorld.HelloWorldPubSubType()
self.topic_data_type.setName("HelloWorld")
self.type_support = fastdds.TypeSupport(self.topic_data_type)
self.participant.register_type(self.type_support)
self.topic_qos = fastdds.TopicQos()
self.participant.get_default_topic_qos(self.topic_qos)
self.topic = self.participant.create_topic("HelloWorldTopic", self.topic_data_type.getName(), self.topic_qos)
self.subscriber_qos = fastdds.SubscriberQos()
self.participant.get_default_subscriber_qos(self.subscriber_qos)
self.subscriber = self.participant.create_subscriber(self.subscriber_qos)
self.listener = ReaderListener()
self.reader_qos = fastdds.DataReaderQos()
self.subscriber.get_default_datareader_qos(self.reader_qos)
self.reader = self.subscriber.create_datareader(self.topic, self.reader_qos, self.listener)
The public member function run() ensures that the subscriber runs until the user press Ctrl+C.
def run(self):
signal.signal(signal.SIGINT, signal_handler)
print('Press Ctrl+C to stop')
signal.pause()
self.delete()
Finally, the participant that implements a subscriber is initialized and run in main.
if __name__ == '__main__':
print('Creating subscriber.')
reader = Reader()
reader.run()
exit()
Putting all together¶
Finally, from the build directory, run the publisher and subscriber applications from two terminals.
python3 HelloWorldPublisher.py
python3 HelloWorldSubscriber.py
Summary¶
In this tutorial you have built a Python publisher and a subscriber DDS application. You have also learned how to generate from an IDL file the specific Python module for your Topic data type.
See also
Check Fast DDS dependencies, libraries, and related packages in the Dependencies and compatibilities section.
Library Overview¶
Fast DDS (formerly Fast RTPS) is an efficient and high-performance implementation of the DDS specification, a data-centric communications middleware (DCPS) for distributed application software. This section reviews the architecture, operation and key features of Fast DDS.
Architecture¶
The architecture of Fast DDS is shown in the figure below, where a layer model with the following different environments can be seen.
Application layer. The user application that makes use of the Fast DDS API for the implementation of communications in distributed systems.
Fast DDS layer. Robust implementation of the DDS communications middleware. It allows the deployment of one or more DDS domains in which DomainParticipants within the same domain exchange messages by publishing/subscribing under a domain topic.
RTPS layer. Implementation of the Real-Time Publish-Subscribe (RTPS) protocol for interoperability with DDS applications. This layer acts an abstraction layer of the transport layer.
Transport Layer. Fast DDS can be used over various transport protocols such as unreliable transport protocols (UDP), reliable transport protocols (TCP), or shared memory transport protocols (SHM).
Fast DDS layer model architecture¶
DDS Layer¶
Several key elements for communication are defined in the DDS layer of Fast DDS. The user will create these elements in their application, thus incorporating DDS application elements and creating a data-centric communication system. Fast DDS, following the DDS specification, defines these elements involved in communication as Entities. A DDS Entity is any object that supports Quality of Service configuration (QoS), and that implements a listener.
QoS. The mechanism by which the behavior of each of the entities is defined.
Listener. The mechanism by which the entities are notified of the possible events that arise during the application’s execution.
Below are listed the DDS Entities together with their description and functionality. For a more detailed explanation of each entity, their QoS, and their listeners, please refer to DDS Layer section.
Domain. A positive integer which identifies the DDS domain. Each DomainParticipant will have an assigned DDS domain, so that DomainParticipants in the same domain can communicate, as well as isolate communications between DDS domains. This value must be given by the application developer when creating the DomainParticipants.
DomainParticipant. Object containing other DDS entities such as publishers, subscribers, topics and multitopics. It is the entity that allows the creation of the previous entities it contains, as well as the configuration of their behavior.
Publisher. The Publisher publishes data under a topic using a DataWriter, which writes the data to the transport. It is the entity that creates and configures the DataWriter entities it contains, and may contain one or more of them.
DataWriter. It is the entity in charge of publishing messages. The user must provide a Topic when creating this entity which will be the Topic under which the data will be published. Publication is done by writing the data-objects as a change in the DataWriterHistory.
DataWriterHistory. This is a list of changes to the data-objects. When the DataWriter proceeds to publish data under a specific Topic, it actually creates a change in this data. It is this change that is registered in the History. These changes are then sent to the DataReader that subscribes to that specific topic.
Subscriber. The Subscriber subscribes to a topic using a DataReader, which reads the data from the transport. It is the entity that creates and configures the DataReader entities it contains, and may contain one or more DataReader entities.
DataReader. It is the entity that subscribes to the topics for the reception of publications. The user must provide a subscription Topic when creating this entity. A DataReader receives the messages as changes in its HistoryDataReader.
DataReaderHistory. It contains the changes in the data-objects that the DataReader receives as a result of subscribing to a certain Topic.
Topic. Entity that binds Publishers’ DataWriters with Subscribers’ DataReaders.
RTPS layer¶
As mentioned above, the RTPS protocol in Fast DDS allows the abstraction of DDS application entities from the transport layer. According to the graph shown above, the RTPS layer has four main Entities.
RTPSDomain. It is the extension of the DDS domain to the RTPS protocol.
RTPSParticipant. Entity containing other RTPS entities. It allows the configuration and creation of the entities it contains.
RTPSWriter. The source of the messages. It reads the changes written in the DataWriterHistory and transmits them to all the RTPSReaders to which it has previously matched.
RTPSReader. Receiving entity of the messages. It writes the changes reported by the RTPSWriter into the DataReaderHistory.
For a more detailed explanation of each entity, their attributes, and their listeners, please refer to RTPS Layer section.
Transport layer¶
Fast DDS supports the implementation of applications over various transport protocols. Those are UDPv4, UDPv6, TCPv4, TCPv6 and Shared Memory Transport (SHM). By default, a DomainParticipant implements a UDPv4 and a SHM transport protocol. The configuration of all supported transport protocols is detailed in the Transport Layer section.
Programming and execution model¶
Fast DDS is concurrent and event-based. The following explains the multithreading model that governs the operation of Fast DDS as well as the possible events.
Concurrency and multithreading¶
Fast DDS implements a concurrent multithreading system. Each DomainParticipant spawns a set of threads to take care of background tasks such as logging, message reception, and asynchronous communication. This should not impact the way you use the library, i.e. the Fast DDS API is thread safe, so you can fearlessly call any methods on the same DomainParticipant from different threads. However, this multithreading implementation must be taken into account when external functions access to resources that are modified by threads running internally in the library. An example of this is the modified resources in the entity listener callbacks.
The complete set of threads spawned by Fast DDS is shown below. Transport related threads (marked as UDP, TCP and SHM types) are only created when the appropriate Transport is used.
Name |
Type |
Cardinality |
OS thread name |
Description |
|---|---|---|---|---|
Event |
General |
One per DomainParticipant |
|
Processes periodic and triggered time events. |
Discovery Server Event |
General |
One per DomainParticipant |
|
Synchronizes access to the Discovery Server |
Asynchronous Writer |
General |
One per enabled asynchronous |
|
Manages asynchronous writes.
Even for synchronous writers, some forms of |
Datasharing Listener |
General |
One per |
|
Listener thread that processes messages |
Reception |
UDP |
One per port |
|
Listener thread that processes incoming |
Reception |
TCP |
One per TCP connection |
|
Listener thread that processes incoming |
Accept |
TCP |
One per TCP transport |
|
Thread that processes incoming TCP connection requests. |
Keep Alive |
TCP |
One per TCP transport |
|
Keep alive thread for TCP connections. |
Reception |
SHM |
One per port |
|
Listener thread that processes incoming |
Logging |
SHM |
One per port |
|
Stores and dumps transferred packets to a file. |
Watchdog |
SHM |
One |
|
Monitors health of open shared memory |
General Logging |
Log |
One |
|
Accumulates and writes to the appropriate |
Security Logging |
Log |
One per |
|
Accumulates and writes security log entries. |
Watchdog |
Filewatch |
One |
|
Tracks the status of the watched file for |
Callback |
Filewatch |
One |
|
Runs the registered callback when the |
Reception |
TypeLookup Service |
Two per DomainParticipant |
|
Runs when remote endpoint discovery information has been received |
Some of these threads are only spawned when certain conditions are met:
Datasharing listener thread is created only when Datasharing is in use.
Discovery Server Event thread is only created when the DomainParticipant is configured as a Discovery Server SERVER.
TCP keep alive thread requires the keep alive period to be configured to a value greater than zero.
Security logging and Shared Memory packet logging threads both require certain configuration options to be enabled.
Filewatch threads are only spawned if the FASTDDS_ENVIRONMENT_FILE is in use.
Regarding transport threads, Fast DDS by default uses both a UDP and a Shared Memory transport. Port configuration can be configured to suit the specific needs of the deployment, but the default configuration is to always use a metatraffic port and a unicast user traffic port. This applies both to UDP and Shared Memory since TCP does not support multicast. More information can be found at the Default Listening Locators page.
Fast DDS offers the possibility of configuring certain attributes of the threads it creates by means of the ThreadSettings.
Event-driven architecture¶
There is a time-event system that enables Fast DDS to respond to certain conditions, as well as schedule periodic
operations.
Few of them are visible to the user since most are related to DDS and RTPS metadata.
However, the user can define in their application periodic time-events by inheriting from the TimedEvent
class.
Functionalities¶
Fast DDS has some added features that can be implemented and configured by the user in their application. These are outlined below.
Discovery Protocols¶
The discovery protocols define the mechanisms by which DataWriters publishing under a given Topic, and DataReaders subscribing to that same Topic are matched, so that they can start sharing data. This applies at any point in the communication process. Fast DDS provides the following discovery mechanisms:
Simple Discovery. This is the default discovery mechanism, which is defined in the RTPS standard and provides compatibility with other DDS implementations. Here the DomainParticipants are discovered individually at an early stage to subsequently match the DataWriter and DataReader they implement.
Discovery Server. This discovery mechanism uses a centralized discovery architecture, where servers act as hubs for meta traffic discovery.
Static Discovery. This implements the discovery of DomainParticipants to each other but it is possible to skip the discovery of the entities contained in each DomainParticipant (DataReader/DataWriter) if these entities are known in advance by the remote DomainParticipants.
Manual Discovery. This mechanism is only compatible with the RTPS layer. It allows the user to manually match and unmatch RTPSParticipants, RTPSWriters, and RTPSReaders using whatever external meta-information channel of its choice.
The detailed explanation and configuration of all the discovery protocols implemented in Fast DDS can be seen in the Discovery section.
Security¶
Fast DDS can be configured to provide secure communications by implementing pluggable security at three levels:
Authentication of remote DomainParticipants. The DDS:Auth:PKI-DH plugin provides authentication using a trusted Certificate Authority (CA) and ECDSA Digital Signature Algorithms to perform the mutual authentication. It also establishes a shared secret using Elliptic Curve Diffie-Hellman (ECDH) Key Agreement protocol.
Access control of entities. The DDS:Access:Permissions plugin provides access control to DomainParticipants at the DDS Domain and Topic level.
Encryption of data. The DDS:Crypto:AES-GCM-GMAC plugin provides authenticated encryption using Advanced Encryption Standard (AES) in Galois Counter Mode (AES-GCM).
More information about security configuration in Fast DDS is available in the Security section.
Logging¶
Fast DDS provides an extensible Logging system.
Log class is the entry point of the Logging system.
It exposes three macro definitions to ease its usage:
EPROSIMA_LOG_INFO, EPROSIMA_LOG_WARNING and EPROSIMA_LOG_ERROR.
Moreover, it allows the definition of new categories, in addition to those already available
(INFO_MSG, WARN_MSG and ERROR_MSG).
It provides filtering by category using regular expressions, as well as control of the verbosity of the Logging system.
Details of the possible Logging system configurations can be found in the Logging section.
XML profiles configuration¶
Fast DDS offers the possibility to make changes in its default settings by using XML profile configuration files. Thus, the behavior of the DDS Entities can be modified without the need for the user to implement any program source code or re-build an existing application.
The user has XML tags for each of the API functionalities.
Therefore, it is possible to build and configure DomainParticipant profiles through the <participant> tag, or
the DataWriter and DataReader profiles with the <data_writer> and <data_reader> tags respectively.
For a better understanding of how to write and use these XML profiles configuration files you can continue reading the XML profiles section.
Environment variables¶
Environment variables are those variables that are defined outside the scope of the program, through operating system functionalities. Fast DDS relies on environment variables so that the user can easily customize the default settings of DDS applications. Please, refer to the Environment variables section for a complete list and description of the environment variables affecting Fast DDS.
DDS Layer¶
eProsima Fast DDS exposes two different APIs to interact with the communication service at different levels. The main API is the Data Distribution Service (DDS) Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API, or DDS DCPS PIM for short, which is defined by the Data Distribution Service (DDS) version 1.4 specification, to which Fast DDS complies. This section is devoted to explain the main characteristics and modes-of-use of this API under Fast DDS, providing an in depth explanation of the five modules into which it is divided:
Core: It defines the abstract classes and interfaces that are refined by the other modules. It also provides the Quality of Service (QoS) definitions, as well as support for the notification-based interaction style with the middleware.
Domain: It contains the
DomainParticipantclass that acts as an entry-point of the Service, as well as a factory for many of the classes. TheDomainParticipantalso acts as a container for the other objects that make up the Service.Publisher: It describes the classes used on the publication side, including
PublisherandDataWriterclasses, as well as thePublisherListenerandDataWriterListenerinterfaces.Subscriber: It describes the classes used on the subscription side, including
SubscriberandDataReaderclasses, as well as theSubscriberListenerandDataReaderListenerinterfaces.Topic: It describes the classes used to define communication topics and data types, including
TopicandTopicDescriptionclasses, as well asTypeSupport, and theTopicListenerinterface.
Core¶
This module defines the infrastructure classes and types that will be used by the other ones. It contains the definition of Entity class, QoS policies, and Statuses.
Entity: An Entity is a DDS communication object that has a Status and can be configured with Policies.
Policy: Each of the configuration objects that govern the behavior of an Entity.
Status: Each of the objects associated with an Entity, whose values represent the communication status of that Entity.
Entity¶
Entity is the abstract base class for all the DDS entities, meaning an object that supports QoS policies,
a listener, and statuses.
Types of Entities¶
DomainParticipant: This entity is the entry-point of the Service and acts as a factory for Publishers, Subscribers, and Topics. See DomainParticipant for further details.
Publisher: It acts as a factory that can create any number of DataWriters. See Publisher for further details.
Subscriber: It acts as a factory that can create any number of DataReaders. See Subscriber for further details.
Topic: This entity fits between the publication and subscription entities and acts as a channel. See Topic for further details.
DataWriter: Is the object responsible for the data distribution. See DataWriter for further details.
DataReader: Is the object used to access the received data. See DataReader for further details.
The following figure shows the hierarchy between all DDS entities:
Common Entity Characteristics¶
All entity types share some characteristics that are common to the concept of an entity. Those are:
Entity Identifier¶
Each entity is identified by a unique ID, which is shared between the DDS entity and its corresponding RTPS entity
if it exists.
That ID is stored on an Instance Handle object declared on Entity base class, which can be accessed using the getter
function get_instance_handle().
QoS policy¶
The behavior of each entity can be configured with a set of configuration policies.
For each entity type, there is a corresponding Quality of Service (QoS) class that groups all the policies that affect
said entity type.
Users can create instances of these QoS classes, modify the contained policies to their needs,
and use them to configure the entities, either during their creation or at a later time with the set_qos()
function that every entity exposes (DomainParticipant::set_qos(), Publisher::set_qos(),
Subscriber::set_qos(), Topic::set_qos(), DataWriter::set_qos(), DataReader::set_qos()).
See Policy for a list of the available policies and their description.
The QoS classes and the policies they contain are explained in the documentation for each entity type.
Listener¶
A listener is an object with functions that an entity will call in response to events. Therefore, the listener acts as an asynchronous notification system that allows the entity to notify the application about the Status changes in the entity.
All entity types define an abstract listener interface, which contains the callback functions that the entity will
trigger to communicate the Status changes to the application.
Users can implement their own listeners inheriting from these interfaces and implementing the callbacks that
are needed on their application.
Then they can link these listeners to each entity, either during their creation or at a later time with the
set_listener() function that every entity exposes
(DomainParticipant::set_listener(), Publisher::set_listener(),
Subscriber::set_listener(), Topic::set_listener(), DataWriter::set_listener(),
DataReader::set_listener()).
The listener interfaces that each entity type and their callbacks are explained in the documentation
for each entity type.
When an event occurs it is handled by the lowest level entity with a listener that is non-null
and has the corresponding callback enabled in its StatusMask.
Higher level listeners inherit from the lower level ones as shown in the following
diagram:
Listeners inheritance diagram.¶
Note
The on_data_on_readers() callback intercepts messages before
on_data_available().
This implies that if DomainParticipantListener is enabled, users should take into account that by default
the listener uses StatusMask::all().
As the callback entity hierarchy is kept, the on_data_on_readers() is going to be called
in this case.
If an application wants to use on_data_available() instead, the corresponding bit of
StatusMask should be disabled.
Important
Using StatusMask::none() when creating the Entity only disables the DDS standard callbacks:
on_sample_rejected()on_liveliness_changed()on_requested_deadline_missed()on_requested_incompatible_qos()on_data_available()on_subscription_matched()on_sample_lost()on_offered_incompatible_qos()on_offered_deadline_missed()on_liveliness_lost()on_publication_matched()on_inconsistent_topic()on_data_on_readers()
Any callback specific to Fast DDS is always enabled:
on_participant_discovery()onParticipantAuthentication()on_data_reader_discovery()on_data_writer_discovery()on_unacknowledged_sample_removed()
Warning
Only one thread is created to listen for every listener implemented, so it is encouraged to keep listener functions simple, leaving the process of such information to the proper class.
Warning
Do not create or delete any Entity within the scope of a Listener member function, since it could lead to an undefined behavior. It is recommended instead to use the Listener class as an information channel and the upper Entity class to encapsulate such behaviour.
Status¶
Each entity is associated with a set of status objects whose values represent the communication status of that entity. The changes on these status values are the ones that trigger the invocation of the appropriate Listener callback to asynchronously inform the application. See Status for a list of all the status objects and a description of their content. There you can also find which status applies to which entity type.
StatusCondition¶
Every entity owns a StatusCondition that will be notified whenever its enabled statuses change. The StatusCondition provides the link between an Entity and a Wait-set. See section Conditions and Wait-sets for more information.
Enabling Entities¶
All the entities can be created either enabled or not enabled. By default, the factories are configured to create the entities enabled, but it can be changed using the EntityFactoryQosPolicy on enabled factories. A disabled factory creates disabled entities regardless of its QoS. A disabled entity has its operations limited to the following ones:
Set/Get the entity QoS Policy.
Set/Get the entity Listener.
Create/Delete subentities.
Get the Status of the entity, even if they will not change.
Lookup operations.
Any other function called in this state will return NOT_ENABLED.
Policy¶
The Quality of Service (QoS) is used to specify the behavior of the Service, allowing the user to define how each entity will behave. To increase the flexibility of the system, the QoS is decomposed in several QoS Policies that can be configured independently. However, there may be cases where several policies conflict. Those conflicts are notified to the user through the ReturnCodes that the QoS setter functions returns.
Each Qos Policy has a unique ID defined in the QosPolicyId_t enumerator.
This ID is used in some Status instances to identify the specific Qos Policy
to which the Status refers.
There are QoS Policies that are immutable, which means that only can be specified either at the entity creation or before calling the enable operation.
Each DDS Entity has a specific set of QoS Policies that can be a mix of Standard QoS Policies, XTypes Extensions and eProsima Extensions.
Standard QoS Policies¶
This section explains each of the DDS standard QoS Policies:
DeadlineQosPolicy¶
This QoS policy raises an alarm when the frequency of new samples falls below a certain threshold.
It is useful for cases where data is expected to be updated periodically (see DeadlineQosPolicy).
On the publishing side, the deadline defines the maximum period in which the application is expected to supply a new sample. On the subscribing side, it defines the maximum period in which new samples should be received.
For Topics with keys, this QoS is applied by key. Suppose that the positions of some vehicles have to be published periodically. In that case, it is possible to set the ID of the vehicle as the key of the data type and the deadline QoS to the desired publication period.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It can be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
To maintain the compatibility between DeadlineQosPolicy in DataReaders and DataWriters, the offered deadline period (configured on the DataWriter) must be less than or equal to the requested deadline period (configured on the DataReader), otherwise, the entities are considered to be incompatible.
The DeadlineQosPolicy must be set consistently with the TimeBasedFilterQosPolicy, which means that the deadline period must be higher or equal to the minimum separation.
DeadlineQosPolicy deadline;
//The DeadlineQosPolicy is default constructed with an infinite period.
//Change the period to 1 second
deadline.period.seconds = 1;
deadline.period.nanosec = 0;
<data_writer profile_name="writer_xml_conf_deadline_profile">
<qos>
<deadline>
<period>
<sec>1</sec>
</period>
</deadline>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_deadline_profile">
<qos>
<deadline>
<period>
<sec>1</sec>
</period>
</deadline>
</qos>
</data_reader>
DestinationOrderQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
Multiple DataWriters can send messages in the same Topic using the same key, and on the DataReader side all those
messages are stored within the same instance of data (see DestinationOrderQosPolicy).
This QoS policy controls the criteria used to determine the logical order of those messages.
The behavior of the system depends on the value of the DestinationOrderQosPolicyKind.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It cannot be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are two possible values (see DestinationOrderQosPolicyKind):
BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS: This indicates that the data is ordered based on the reception time at each DataReader, which means that the last received value should be the one kept. This option may cause that each DataReader ends up with a different final value, since the DataReaders may receive the data at different times.BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS: This indicates that the data is ordered based on the DataWriter timestamp at the time the message is sent. This option guarantees the consistency of the final value.
Both options depend on the values of the OwnershipQosPolicy and OwnershipStrengthQosPolicy, meaning that if the Ownership is set to EXCLUSIVE and the last value came from a DataWriter with low ownership strength, it will be discarded.
To maintain the compatibility between DestinationOrderQosPolicy in DataReaders and DataWriters when they have different kind values, the DataWriter kind must be higher or equal to the DataReader kind. And the order between the different kinds is:
BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS < BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS
Table with the possible combinations:
DataWriter kind |
DataReader kind |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
DurabilityQosPolicy¶
A DataWriter can send messages throughout a Topic even if there are no DataReaders on the network.
Moreover, a DataReader that joins to the Topic after some data has been written could be interested in accessing
that information (see DurabilityQosPolicy).
The DurabilityQoSPolicy defines how the system will behave regarding those samples that existed on the Topic before the DataReader joins. The behavior of the system depends on the value of the DurabilityQosPolicyKind.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It cannot be changed on enabled entities.
Important
In order to receive past samples in the DataReader, besides setting this Qos Policy, it is required that the
ReliabilityQosPolicy is set to RELIABLE_RELIABILITY_QOS.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are four possible values (see DurabilityQosPolicyKind):
VOLATILE_DURABILITY_QOS: Past samples are ignored and a joining DataReader receives samples generated after the moment it matches.TRANSIENT_LOCAL_DURABILITY_QOS: When a new DataReader joins, its History is filled with past samples.TRANSIENT_DURABILITY_QOS: When a new DataReader joins, its History is filled with past samples, which are stored on persistent storage (see Persistence Service).PERSISTENT_DURABILITY_QOS: (Not Implemented): All the samples are stored on a permanent storage, so that they can outlive a system session.
To maintain the compatibility between DurabilityQosPolicy in DataReaders and DataWriters when they have different kind values, the DataWriter kind must be higher or equal to the DataReader kind. And the order between the different kinds is:
VOLATILE_DURABILITY_QOS < TRANSIENT_LOCAL_DURABILITY_QOS < TRANSIENT_DURABILITY_QOS <
PERSISTENT_DURABILITY_QOS
Table with the possible combinations:
DataWriter kind |
DataReader kind |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
DurabilityQosPolicy durability;
//The DurabilityQosPolicy is default constructed with kind = VOLATILE_DURABILITY_QOS
//Change the kind to TRANSIENT_LOCAL_DURABILITY_QOS
durability.kind = TRANSIENT_LOCAL_DURABILITY_QOS;
<data_writer profile_name="writer_xml_conf_durability_profile">
<qos>
<durability>
<kind>TRANSIENT_LOCAL</kind>
</durability>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_durability_profile">
<qos>
<durability>
<kind>VOLATILE</kind>
</durability>
</qos>
</data_reader>
DurabilityServiceQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This QoS Policy is used to configure the HistoryQosPolicy and ResourceLimitsQosPolicy of the fictitious
DataReader and DataWriter used when the DurabilityQosPolicy kind is set to TRANSIENT_DURABILITY_QOS or
PERSISTENT_DURABILITY_QOS (see DurabilityServiceQosPolicy).
Those entities are used to simulate the persistent storage. The fictitious DataReader reads the data written on the Topic and stores it, so that if the user DataWriter does not have the information requested by the user DataReaders, the fictitious DataWriter takes care of sending that information.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
|
|
1 |
|
|
-1 (Length Unlimited) |
|
|
-1 (Length Unlimited) |
|
|
-1 (Length Unlimited) |
service_cleanup_delay: It controls when the service can remove all the information regarding a data instance. That information is kept until all the following conditions are met:The instance has been explicitly disposed and its InstanceState becomes
NOT_ALIVE_DISPOSED_INSTANCE_STATE.There is not any alive DataWriter writing the instance, which means that all existing writers either unregister the instance or lose their liveliness.
A time interval longer than the one established on the
service_cleanup_delayhas elapsed since the moment the service detected that the two previous conditions were met.
history_kind: Controls the kind of the HistoryQosPolicy associated with the Durability Service fictitious entities.history_depth: Controls the depth of the HistoryQosPolicy associated with the Durability Service fictitious entities.max_samples: Controls the maximum number of samples of the ResourceLimitsQosPolicy associated with the Durability Service fictitious entities. This value must be higher than the maximum number of samples per instance.max_instances: Controls the maximum number of instances of the ResourceLimitsQosPolicy associated with the Durability Service fictitious entities.max_samples_per_instance: Controls the maximum number of samples within an instance of the ResourceLimitsQosPolicy associated with the Durability Service fictitious entities. This value must be lower than the maximum number of samples.
Note
This QoS Policy concerns to Topic and DataWriter entities.
It cannot be changed on enabled entities.
EntityFactoryQosPolicy¶
This QoS Policy controls the behavior of an Entity when it acts as a factory for other entities.
By default, all the entities are created enabled, but if you change the value of the autoenable_created_entities
to false, the new entities will be created disabled (see EntityFactoryQosPolicy).
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to DomainParticipantFactory (as factory for DomainParticipant), DomainParticipant
(as factory for
Publisher, Subscriber and Topic), Publisher (as factory for DataWriter) and Subscriber (as factory for
DataReader).
It can be changed on enabled entities, but it only affects those entities created after the change.
EntityFactoryQosPolicy entity_factory;
//The EntityFactoryQosPolicy is default constructed with autoenable_created_entities = true
//Change it to false
entity_factory.autoenable_created_entities = false;
This QoS Policy cannot be configured using XML for the moment.
GroupDataQosPolicy¶
Allows the application to attach additional information to created Publishers or Subscribers.
This data is common to all DataWriters/DataReaders belonging to the Publisher/Subscriber and it is propagated by
means of the built-in topics (see GroupDataQosPolicy).
This QoS Policy can be used in combination with DataWriter and DataReader listeners to implement a matching policy similar to the PartitionQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
collection |
std::vector< |
Empty vector |
Note
This QoS Policy concerns to Publisher and Subscriber entities.
It can be changed on enabled entities.
GroupDataQosPolicy group_data;
//The GroupDataQosPolicy is default constructed with an empty collection
//Collection is a private member so you need to use getters and setters to access
//Add data to the collection
std::vector<eprosima::fastrtps::rtps::octet> vec;
vec = group_data.data_vec(); // Getter function
//Add two new octets to group data vector
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
val = 10;
vec.push_back(val);
group_data.data_vec(vec); //Setter function
<data_writer profile_name="writer_xml_conf_groupdata_profile">
<qos>
<groupData>
<value>3.a</value>
</groupData>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_groupdata_profile">
<qos>
<groupData>
<value>3.a</value>
</groupData>
</qos>
</data_reader>
HistoryQosPolicy¶
This QoS Policy controls the behavior of the system when the value of an instance changes one or more times before it can be successfully communicated to the existing DataReader entities.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
1 |
kind: Controls if the service should deliver only the most recent values, all the intermediate values or do something in between. See HistoryQosPolicyKind for further details.depth: Establishes the maximum number of samples that must be kept on the history. It only has effect if the kind is set toKEEP_LAST_HISTORY_QOSand it needs to be consistent with the ResourceLimitsQosPolicy, which means that its value must be lower or equal to max_samples_per_instance.
Note
This QoS Policy concerns to Topic, DataWriter and DataReader entities.
It cannot be changed on enabled entities.
There are two possible values (see HistoryQosPolicyKind):
KEEP_LAST_HISTORY_QOS: The service will only attempt to keep the most recent values of the instance and discard the older ones. The maximum number of samples to keep and deliver is defined by the depth of the HistoryQosPolicy, which needs to be consistent with the ResourceLimitsQosPolicy settings. If the limit defined by depth is reached, the system will discard the oldest sample to make room for a new one.KEEP_ALL_HISTORY_QOS: The service will attempt to keep all the values of the instance until it can be delivered to all the existing Subscribers. If this option is selected, the depth will not have any effect, so the history is only limited by the values set in ResourceLimitsQosPolicy.
The HistoryQos must be set consistently with the ResourceLimitsQosPolicy, but also other QoS as DurabilityQosPolicy and ReliabilityQosPolicy, so there are several cases to take into account:
The
depthis only considered if thekindis set toKEEP_LAST_HISTORY_QOS.The
depthmust be consistent with the ResourceLimitsQosPolicy settings, which means that thedepthmust be lower or equal than the ResourceLimitsQosPolicy’smax_samples_per_instance. Also,max_samplesmust be equal or higher than the product ofmax_samples_per_instancetimesmax_instances.The
depthcannot be lower or equal than zero. If an unlimited depth is required, please consider usingkindasKEEP_ALL_HISTORY_QOS.Setting the
kindasKEEP_ALL_HISTORY_QOSentails that limits are set by the ResourceLimitsQosPolicy limits (max_samples_per_instanceprior thanmax_samples).In the case of the ReliabilityQosPolicy
ReliabilityQosPolicyKindbeing set toRELIABLE_RELIABILITY_QOSand the HistoryQosPolicykindbeing set toKEEP_ALL_HISTORY_QOS, when the resource limits are reached, the behavior of the service is depends on the DurabilityQosPolicy:If the DurabilityQosPolicy
kindis configured asVOLATILE_DURABILITY_QOS, the DataWriterwrite()call will discard the oldest sample in the history. Note that the removed sample may belong to different instances than the newly written one.If the DurabilityQosPolicy
kindis configured asTRANSIENT_LOCAL_DURABILITY_QOSorTRANSIENT_DURABILITY_QOS, the DataWriterwrite()call will be blocked until the history has space for the new sample.
HistoryQosPolicy history;
//The HistoryQosPolicy is default constructed with kind = KEEP_LAST and depth = 1.
//Change the depth to 20
history.depth = 20;
//You can also change the kind to KEEP_ALL but after that the depth will not have effect.
history.kind = KEEP_ALL_HISTORY_QOS;
<topic>
<historyQos>
<kind>KEEP_LAST</kind> <!-- string -->
<depth>20</depth> <!-- uint32 -->
</historyQos>
</topic>
LatencyBudgetQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This QoS Policy specifies the maximum acceptable delay from the time the data is
written until the data is inserted on the DataReader History and notified of the fact.
That delay by default is set to 0 in order to optimize the internal operations (see LatencyBudgetQosPolicy).
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to Topic, DataWriter and DataReader entities.
It can be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
To maintain the compatibility between LatencyBudgetQosPolicy in DataReaders and DataWriters, the DataWriter duration must be lower or equal to the DataReader duration.
LifespanQosPolicy¶
Each data sample written by a DataWriter has an associated expiration time beyond which the data is removed from the
DataWriter and DataReader history as well as from the transient and persistent information caches
(see LifespanQosPolicy).
By default, the duration is infinite, which means that there is not a maximum duration for the validity of the samples written by the DataWriter.
The expiration time is computed by adding the duration to the source timestamp, which can be calculated automatically
if write() member function is called or supplied by the application by means of
write_w_timestamp() member function.
The DataReader is allowed to use the reception timestamp instead of the source timestamp.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It can be changed on enabled entities.
LifespanQosPolicy lifespan;
//The LifespanQosPolicy is default constructed with duration set to infinite.
//Change the duration to 5 s
lifespan.duration = {5, 0};
<data_writer profile_name="writer_xml_conf_lifespan_profile">
<qos>
<lifespan>
<duration>
<sec>5</sec>
</duration>
</lifespan>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_lifespan_profile">
<qos>
<lifespan>
<duration>
<sec>5</sec>
</duration>
</lifespan>
</qos>
</data_reader>
LivelinessQosPolicy¶
This QoS Policy controls the mechanism used by the service to ensure that a particular entity on the network is still
alive.
There are different settings that allow distinguishing between applications where data is updated periodically and
applications where data is changed sporadically.
It also allows customizing the application regarding the kind of failures that should be detected by the liveliness
mechanism (see LivelinessQosPolicy).
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
|
|
|
kind: This data member establishes if the service needs to assert the liveliness automatically or if it needs to wait until the liveliness is asserted by the publishing side. See LivelinessQosPolicyKind for further details.lease_duration: Amount of time to wait since the last time the DataWriter asserts its liveliness to consider that it is no longer alive.announcement_period: Amount of time between consecutive liveliness messages sent by the DataWriter. This data member only takes effect if the kind isAUTOMATIC_LIVELINESS_QOSorMANUAL_BY_PARTICIPANT_LIVELINESS_QOSand needs to be lower than thelease_duration.
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It cannot be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are three possible values (see LivelinessQosPolicyKind):
AUTOMATIC_LIVELINESS_QOS: The service takes the responsibility for renewing the leases at the required rates, as long as the local process where the participant is running and the link connecting it to remote participants exists, the entities within the remote participant will be considered alive. This kind is suitable for applications that only need to detect whether a remote application is still running.The two Manual modes require that the application on the publishing side asserts the liveliness periodically before the lease_duration timer expires. Publishing any new data value implicitly asserts the DataWriter’s liveliness, but it can be done explicitly by calling the assert_liveliness member function.
MANUAL_BY_PARTICIPANT_LIVELINESS_QOS: If one of the entities in the publishing side asserts its liveliness, the service deduces that all other entities within the same DomainParticipant are also alive.MANUAL_BY_TOPIC_LIVELINESS_QOS: This mode is more restrictive and requires that at least one instance within the DataWriter is asserted to consider that the DataWriter is alive.
To maintain the compatibility between LivelinessQosPolicy in DataReaders and DataWriters, the DataWriter kind must be higher or equal to the DataReader kind. And the order between the different kinds is:
|AUTOMATIC_LIVELINESS_QOS-api| < |MANUAL_BY_PARTICIPANT_LIVELINESS_QOS-api| < |MANUAL_BY_TOPIC_LIVELINESS_QOS-api|
Table with the possible combinations:
DataWriter kind |
DataReader kind |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
Additionally, the lease_duration of the DataWriter must not be greater than
the lease_duration of the DataReader.
LivelinessQosPolicy liveliness;
//The LivelinessQosPolicy is default constructed with kind = AUTOMATIC
//Change the kind to MANUAL_BY_PARTICIPANT
liveliness.kind = MANUAL_BY_PARTICIPANT_LIVELINESS_QOS;
//The LivelinessQosPolicy is default constructed with lease_duration set to infinite
//Change the lease_duration to 1 second
liveliness.lease_duration = {1, 0};
//The LivelinessQosPolicy is default constructed with announcement_period set to infinite
//Change the announcement_period to 1 ms
liveliness.announcement_period = {0, 1000000};
<data_writer profile_name="writer_xml_conf_liveliness_profile">
<qos>
<liveliness>
<announcement_period>
<nanosec>1000000</nanosec>
</announcement_period>
<lease_duration>
<sec>1</sec>
</lease_duration>
<kind>AUTOMATIC</kind>
</liveliness>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_liveliness_profile">
<qos>
<liveliness>
<lease_duration>
<sec>1</sec>
</lease_duration>
<kind>AUTOMATIC</kind>
</liveliness>
</qos>
</data_reader>
OwnershipQosPolicy¶
This QoS Policy specifies whether it is allowed for multiple DataWriters to update the same instance of data, and if
so, how these modifications should be arbitrated (see OwnershipQosPolicy).
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It cannot be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are two possible values (see OwnershipQosPolicyKind):
SHARED_OWNERSHIP_QOS: This option indicates that the service does not enforce unique ownership for each instance. In this case, multiple DataWriters are allowed to update the same data instance and all the updates are made available to the existing DataReaders. Those updates are also subject to the TimeBasedFilterQosPolicy or HistoryQosPolicy settings, so they can be filtered.EXCLUSIVE_OWNERSHIP_QOS: This option indicates that each instance can only be updated by one DataWriter, meaning that at any point in time a single DataWriter owns each instance and is the only one whose modifications will be visible for the existing DataReaders. The owner can be changed dynamically according to the highest strength between the alive DataWriters, which has not violated the deadline contract concerning the data instances. That strength can be changed using the OwnershipStrengthQosPolicy. In case two DataWriters have the same strength value, the DataWriter with a lower GUID value would be the owner of the topic.
To maintain the compatibility between OwnershipQosPolicy in DataReaders and DataWriters, the DataWriter kind must be equal to the DataReader kind.
Table with the possible combinations:
DataWriter kind |
DataReader kind |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
No |
|
|
Yes |
OwnershipQosPolicy ownership;
//The OwnershipQosPolicy is default constructed with kind = SHARED.
//Change the kind to EXCLUSIVE
ownership.kind = EXCLUSIVE_OWNERSHIP_QOS;
<data_writer profile_name="writer_xml_conf_ownership_profile">
<qos>
<ownership>
<kind>EXCLUSIVE</kind>
</ownership>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_ownership_profile">
<qos>
<ownership>
<kind>EXCLUSIVE</kind>
</ownership>
</qos>
</data_reader>
OwnershipStrengthQosPolicy¶
This QoS Policy specifies the value of the strength used to arbitrate among multiple DataWriters that attempt to
modify the same data instance. It is only applicable if the OwnershipQosPolicy kind is set to
EXCLUSIVE_OWNERSHIP_QOS.
See OwnershipStrengthQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
Note
This QoS Policy concerns to DataWriter entities.
It can be changed on enabled entities.
OwnershipStrengthQosPolicy ownership_strength;
//The OwnershipStrengthQosPolicy is default constructed with value 0
//Change the strength to 10
ownership_strength.value = 10;
<data_writer profile_name="writer_xml_conf_ownership_strength_profile">
<qos>
<ownershipStrength>
<value>10</value>
</ownershipStrength>
</qos>
</data_writer>
PartitionQosPolicy¶
This Qos Policy allows the introduction of a logical partition inside the physical partition introduced by a domain.
For a DataReader to see the changes made by a DataWriter, not only the Topic must match, but also they have to share
at least one logical partition (see PartitionQosPolicy).
The empty string is also considered as a valid partition and it matches with other partition names using the same rules of string matching and regular-expression matching used for any other partition name.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 (Length Unlimited) |
|
|
Empty List |
max_size: Maximum size for the list of partition names.names: List of partition names.
Note
This QoS Policy concerns to Publisher and Subscriber entities.
Partitions can also be explicitly defined at the endpoint level to override this configuration. Information
to do so can be found here.
It can be changed on enabled Publishers and Subscribers.
PartitionQosPolicy partitions;
//The PartitionsQosPolicy is default constructed with max_size = 0.
//Max_size is a private member so you need to use getters and setters to access
//Change the max_size to 20
partitions.set_max_size(20); //Setter function
//The PartitionsQosPolicy is default constructed with an empty list of partitions
//Partitions is a private member so you need to use getters and setters to access
//Add new partitions
std::vector<std::string> part = partitions.names(); //Getter function
part.push_back("part1");
part.push_back("part2");
partitions.names(part); //Setter function
<data_writer profile_name="pub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</data_writer>
<data_reader profile_name="sub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</data_reader>
PresentationQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This QoS Policy specifies how the samples representing changes to data instances are presented to the subscribing
application.
It controls the extent to which changes to data instances can be made dependent on each other, as well as the kind
of dependencies that can be propagated and maintained.
See PresentationQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
|
|
|
access_scope: Determines the largest scope spanning the entities for which the order and coherency can be preserved. See PresentationQosPolicyAccessScopeKind for further details.coherent_access: Controls whether the service will preserve grouping of changes made on the publishing side, such that they are received as a unit on the subscribing side.ordered_access: Controls whether the service supports the ability of the subscriber to see changes in the same order as they occurred on the publishing side.
Note
This QoS Policy concerns to Publisher and Subscriber entities.
It cannot be changed on enabled entities.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are three possible values, which have different behaviors depending on the values of coherent_access and
ordered_access variables (see PresentationQosPolicyAccessScopeKind):
INSTANCE_PRESENTATION_QOS: The changes to a data instance do not need to be coherent nor ordered with respect to the changes to any other instance, which means that the order and coherent changes apply to each instance separately.Enabling the coherent_access, in this case, has no effect on how the subscriber can access the data as the scope is limited to each instance, changes to separate instances are considered independent and thus cannot be grouped by a coherent change.
Enabling the ordered_access, in this case, only affects to the changes within the same instance. Therefore, the changes made to two instances are not necessarily seen in the order they occur even if the same application thread and DataWriter made them.
TOPIC_PRESENTATION_QOS: The scope spans to all the instances within the same DataWriter.Enabling the coherent_access makes that the grouping made with changes within the same DataWriter will be available as coherent with respect to other changes to instances in that DataWriter, but will not be grouped with changes made to instances belonging to different DataWriters.
Enabling the ordered_access means that the changes made by a single DataWriter are made available to the subscribers in the same order that they occur, but the changes made to instances through different DataWriters are not necessarily seen in order.
GROUP_PRESENTATION_QOS: The scope spans to all the instances belonging to DataWriters within the same Publisher.Enabling the coherent_access, means that the coherent changes made to instances through DataWriters attached to a common Publisher are made available as a unit to remote subscribers.
Enabling the ordered_access with this scope makes that the changes done by any of the DataWriters attached to the same Publisher are made available to the subscribers in the same order they occur.
To maintain the compatibility between PresentationQosPolicy in DataReaders and DataWriters, the Publisher
access_scope must be higher or equal to the Subscriber access_scope.
And the order between the different access scopes is:
|INSTANCE_PRESENTATION_QOS-api| < |TOPIC_PRESENTATION_QOS-api| < |GROUP_PRESENTATION_QOS-api|
Table with the possible combinations:
Publisher scope |
Subscriber scope |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
Additionally, the coherent_access and ordered_access of the Subscriber can only be enabled if they are also enabled on the Publisher.
ReaderDataLifecycleQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This QoS Policy specifies the behavior of the DataReader with respect to the lifecycle of the data instances it
manages, that is, the instances that have been received and for which the DataReader maintains some internal resources.
The DataReader maintains the samples that have not been taken by the application, subject to the constraints imposed by
HistoryQosPolicy and ResourceLimitsQosPolicy.
See ReaderDataLifecycleQosPolicy.
Under normal circumstances, the DataReader can only reclaim the resources associated with data instances if there are no writers and all the samples have been taken. But this fact can cause problems if the application does not take those samples as the service will prevent the DataReader from reclaiming the resources and they will remain in the DataReader indefinitely. This QoS exist to avoid that situation.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
autopurge_no_writer_samples_delay: Defines the maximum duration the DataReader must retain the information regarding an instance once itsinstance_statebecomesNOT_ALIVE_NO_WRITERS_INSTANCE_STATE. After this time elapses, the DataReader purges all the internal information of the instance, including the untaken samples that will be lost.autopurge_disposed_samples_delay: Defines the maximum duration the DataReader must retain the information regarding an instance once itsinstance_statebecomesNOT_ALIVE_DISPOSED_INSTANCE_STATE. After this time elapses, the DataReader purges all the samples for the instance.
Note
This QoS Policy concerns to DataReader entities.
It can be changed on enabled entities.
ReliabilityQosPolicy¶
This QoS Policy indicates the level of reliability offered and requested by the service.
See ReliabilityQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
100 ms |
kind: Specifies the behavior of the service regarding delivery of the samples. See ReliabilityQosPolicyKind for further details.max_blocking_time: Configures the maximum duration that the write operation can be blocked.
Note
This QoS Policy concerns to Topic, DataWriter and DataReader entities.
It cannot be changed on enabled entities.
Important
Setting this QoS Policy to BEST_EFFORT_RELIABILITY_QOS affects to the DurabilityQosPolicy, making the
endpoints behave as VOLATILE_DURABILITY_QOS.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
There are two possible values ():
BEST_EFFORT_RELIABILITY_QOS: It indicates that it is acceptable not to retransmit the missing samples, so the messages are sent without waiting for an arrival confirmation. Presumably new values for the samples are generated often enough that it is not necessary to re-send any sample. However, the data samples sent by the same DataWriter will be stored in the DataReader history in the same order they occur. In other words, even if the DataReader misses some data samples, an older value will never overwrite a newer value.RELIABLE_RELIABILITY_QOS: It indicates that the service will attempt to deliver all samples of the DataWriter’s history expecting an arrival confirmation from the DataReader. The data samples sent by the same DataWriter cannot be made available to the DataReader if there are previous samples that have not been received yet. The service will retransmit the lost data samples in order to reconstruct a correct snapshot of the DataWriter history before it is accessible by the DataReader.This option may block the write operation, hence the
max_blocking_timeis set that will unblock it once the time expires. But if themax_blocking_timeexpires before the data is sent, the write operation will return an error.
To maintain the compatibility between ReliabilityQosPolicy in DataReaders and DataWriters, the DataWriter kind must be higher or equal to the DataReader kind. And the order between the different kinds is:
|BEST_EFFORT_RELIABILITY_QOS-api| < |RELIABLE_RELIABILITY_QOS-api|
Table with the possible combinations:
DataWriter kind |
DataReader kind |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
ReliabilityQosPolicy reliability;
//The ReliabilityQosPolicy is default constructed with kind = BEST_EFFORT
//Change the kind to RELIABLE
reliability.kind = RELIABLE_RELIABILITY_QOS;
//The ReliabilityQosPolicy is default constructed with max_blocking_time = 100ms
//Change the max_blocking_time to 1s
reliability.max_blocking_time = {1, 0};
<data_writer profile_name="writer_xml_conf_reliability_profile">
<qos>
<reliability>
<kind>RELIABLE</kind>
<max_blocking_time>
<sec>1</sec>
</max_blocking_time>
</reliability>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_reliability_profile">
<qos>
<reliability>
<kind>BEST_EFFORT</kind>
</reliability>
</qos>
</data_reader>
ResourceLimitsQosPolicy¶
This QoS Policy controls the resources that the service can use in order to meet the requirements imposed by the
application and other QoS Policies.
See ResourceLimitsQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
5000 |
|
|
10 |
|
|
400 |
|
|
100 |
|
|
1 |
max_samples: Controls the maximum number of samples that the DataWriter or DataReader can manage across all the instances associated with it. In other words, it represents the maximum samples that the middleware can store for a DataReader or DataWriter. Value less or equal to 0 means infinite resources.max_instances: Controls the maximum number of instances that a DataWriter or DataReader can manage. Value less or equal to 0 means infinite resources.max_samples_per_instance: Controls the maximum number of samples within an instance that the DataWriter or DataReader can manage. Value less or equal to 0 means infinite resources.allocated_samples: States the number of samples that will be allocated on initialization.extra_samples: States the number of extra samples that will be allocated on the pool, so the maximum number of samples on the pool will bemax_samplesplusextra_samples. These extra samples act as a reservoir of samples even when the history is full.
Note
This QoS Policy concerns to Topic, DataWriter and DataReader entities.
It cannot be changed on enabled entities.
To maintain the consistency within the ResourceLimitsQosPolicy, the values of the data members must follow the next conditions:
The value of
max_samplesmust be higher or equal to the value ofmax_samples_per_instance.The value established for the HistoryQosPolicy
depthmust be lower or equal to the value stated formax_samples_per_instance.
ResourceLimitsQosPolicy resource_limits;
//The ResourceLimitsQosPolicy is default constructed with max_samples = 5000
//Change max_samples to 200
resource_limits.max_samples = 200;
//The ResourceLimitsQosPolicy is default constructed with max_instances = 10
//Change max_instances to 20
resource_limits.max_instances = 20;
//The ResourceLimitsQosPolicy is default constructed with max_samples_per_instance = 400
//Change max_samples_per_instance to 100 as it must be lower than max_samples
resource_limits.max_samples_per_instance = 100;
//The ResourceLimitsQosPolicy is default constructed with allocated_samples = 100
//Change allocated_samples to 50
resource_limits.allocated_samples = 50;
<data_writer profile_name="writer_xml_conf_resource_limits_profile">
<topic>
<resourceLimitsQos>
<max_samples>200</max_samples>
<max_instances>20</max_instances>
<max_samples_per_instance>100</max_samples_per_instance>
<allocated_samples>50</allocated_samples>
</resourceLimitsQos>
</topic>
</data_writer>
<data_reader profile_name="reader_xml_conf_resource_limits_profile">
<topic>
<resourceLimitsQos>
<max_samples>200</max_samples>
<max_instances>20</max_instances>
<max_samples_per_instance>100</max_samples_per_instance>
<allocated_samples>50</allocated_samples>
</resourceLimitsQos>
</topic>
</data_reader>
TimeBasedFilterQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
Filter that allows a DataReader to specify that it is interested only in a subset of the values of the data.
This filter states that the DataReader does not want to receive more than one value each
minimum_separation, regardless of how fast the changes occur.
See TimeBasedFilterQosPolicy.
The minimum_separation must be lower than the DeadlineQosPolicy
period.
By default, the minimum_separation is zero, which means that the DataReader is
potentially interested in all the values.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to DataReader entities.
It can be changed on enabled entities.
TopicDataQosPolicy¶
Allows the application to attach additional information to a created Topic so that when it is discovered by a remote
application, it can access the data and use it.
See TopicDataQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
collection |
std::vector< |
Empty vector |
Note
This QoS Policy concerns to Topic entities.
It can be changed even if it is already created.
//The TopicDataQosPolicy is default constructed with an empty vector.
TopicDataQosPolicy topic_data;
std::vector<eprosima::fastrtps::rtps::octet> vec;
vec = topic_data.data_vec(); // Getter Function
//Add two new octets to topic data vector
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
val = 10;
vec.push_back(val);
topic_data.data_vec(vec); //Setter Function
<data_writer profile_name="writer_xml_conf_topicdata_profile">
<qos>
<topicData>
<value>3.a</value>
</topicData>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_topicdata_profile">
<qos>
<topicData>
<value>3.a</value>
</topicData>
</qos>
</data_reader>
TransportPriorityQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
The purpose of this QoS Policy is to allow the service to take advantage of those transports capable of sending
messages with different priorities. It establishes the priority of the underlying transport used to send the data.
See TransportPriorityQosPolicy
You can choose any value within the 32-bit range for the priority. The higher the value, the higher the priority.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
Note
This QoS Policy concerns to Topic and DataWriter entities.
It can be changed on enabled entities.
UserDataQosPolicy¶
Allows the application to attach additional information to the Entity object so that when the entity is discovered
the remote application can access the data and use it.
For example, it can be used to attach the security credentials to authenticate the source from the remote application.
See UserDataQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
collection |
std::vector< |
Empty vector |
Note
This QoS Policy concerns to all DDS entities.
It can be changed on enabled entities.
//The TopicDataQosPolicy is default constructed with an empty vector.
UserDataQosPolicy user_data;
std::vector<eprosima::fastrtps::rtps::octet> vec;
vec = user_data.data_vec(); // Getter Function
//Add two new octets to user data vector
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
val = 10;
vec.push_back(val);
user_data.data_vec(vec); //Setter Function
<participant profile_name="participant_xml_conf_userdata_profile">
<rtps>
<userData>
<value>3.a</value>
</userData>
</rtps>
</participant>
<data_writer profile_name="writer_xml_conf_userdata_profile">
<qos>
<userData>
<value>3.a</value>
</userData>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_userdata_profile">
<qos>
<userData>
<value>3.a</value>
</userData>
</qos>
</data_reader>
WriterDataLifecycleQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This QoS Policy specifies the behavior of the DataWriter with respect to the lifecycle of the data instances it manages , that is, the instance that has been either explicitly registered with the DataWriter using the register operations or implicitly by directly writing data.
The autodispose_unregistered_instances
controls whether a DataWriter will automatically dispose an instance each time
it is unregistered. Even if it is disabled, the application can still get the same result if it uses the dispose
operation before unregistering the instance.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
Note
This QoS Policy concerns to DataWriter entities.
It can be changed on enabled entities.
eProsima Extensions¶
The eProsima QoS Policies extensions are those that allow changing the values of the RTPS layer configurable settings.
DataSharingQosPolicy¶
This additional QoS allows configuring the data-sharing delivery communication between a writer and a reader. Please, see Data-sharing delivery for a description of the data-sharing delivery functionality.
List of QoS Policy data members:
Data Member |
Type |
Accessor |
Default Value |
|---|---|---|---|
Data-sharing kind |
|
|
|
Shared memory directory |
|
|
Empty string |
Maximum domain number |
|
|
0 (unlimited) |
Data-sharing domain IDs |
|
|
Empty |
Data-sharing listener thread settings |
|
Data-sharing kind: Specifies the behavior of data-sharing delivery. See DataSharingKind for a description of possible values and their effect.
Shared memory directory: The directory that will be used for the memory-mapped files. If none is configured, then the system default directory will be used.
Maximum domain number: Establishes the maximum number of data-sharing domain IDs in the local or remote endpoints. Domain IDs are exchanged between data-sharing delivery compatible endpoints. If this value is lower that the size of the list for any remote endpoint, the matching may fail. A value of zero represents unlimited number of IDs.
Data sharing domain IDs: The list of data-sharing domain IDs configured for the current DataWriter or DataReader. If no ID is provided, the system will create a unique one for the current machine.
Data-sharing listener thread settings: The ThreadSettings for the data-sharing thread dedicated to listening for incoming traffic.
Note
This QoS Policy concerns to DataWriter and DataReader entities.
It cannot be changed on enabled entities.
There are three possible values (see DataSharingKind):
OFF: The data-sharing delivery is disabled. No communication will be performed using data-sharing delivery functionality.ON: The data-sharing delivery is manually enabled. An error will occur if the current topic is not compatible with data-sharing delivery. Communication with remote entities that share at least one data-sharing domain ID will be done using data-sharing delivery functionality.AUTO: data-sharing delivery will be activated if the current topic is compatible with data-sharing, and deactivated if not.
In order to set the data-sharing delivery configuration, one of the following helper member functions must be used. There is one for each DataSharingKind flavor:
Function |
Resulting DataSharingKind |
Shared memory directory |
Data sharing domain IDs |
|---|---|---|---|
|
|
Optional |
Optional |
|
|
Mandatory |
Optional |
|
|
N/A |
N/A |
Instead of defining the data-sharing domain IDs on these helper functions,
you can add them later with the add_domain_id() function.
Beware that adding a new domain ID counts as modifying the QosPolicy,
so it must be done before the entity is enabled.
DataSharingQosPolicy datasharing;
// Configure the DataSharing as AUTO with two user-defined IDs
std::vector<uint16_t> ids;
ids.push_back(0x1234);
ids.push_back(0xABCD);
datasharing.automatic(ids);
// Alternatively, configure with no IDs and add them afterwards
datasharing.automatic();
datasharing.add_domain_id(uint16_t(0x1234));
datasharing.add_domain_id(uint16_t(0xABCD));
// Or you can leave the IDs empty and the system will create one for you
// unique for the current machine
datasharing.automatic();
// [OPTIONAL] ThreadSettings for listening thread
datasharing.data_sharing_listener_thread(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="writer_profile_qos_datasharing">
<qos>
<data_sharing>
<kind>AUTOMATIC</kind>
<domain_ids>
<domainId>123</domainId>
<domainId>098</domainId>
</domain_ids>
</data_sharing>
</qos>
</data_writer>
<data_reader profile_name="reader_profile_qos_datasharing">
<qos>
<data_sharing>
<kind>AUTOMATIC</kind>
<domain_ids>
<domainId>123</domainId>
<domainId>098</domainId>
</domain_ids>
<data_sharing_listener_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</data_sharing_listener_thread>
</data_sharing>
</qos>
</data_reader>
</profiles>
<dds>
DisablePositiveACKsQosPolicy¶
This additional QoS allows reducing network traffic when strict reliable communication is not required and bandwidth is
limited.
It consists in changing the default behavior by which positive acks are sent from readers to writers.
Instead, only negative acks will be sent when a reader is missing a sample, but writers will keep data for an adjustable
time before considering it as acknowledged.
See DisablePositiveACKsQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
enabled: Specifies if the QoS is enabled or not. If it is true means that the positive acks are disabled and the DataReader only sends negative acks. Otherwise, both positive and negative acks are sent.duration: State the duration that the DataWriters keep the data before considering it as acknowledged. This value does not apply to DataReaders.
Note
This QoS Policy concerns to DataWriter and DataReader entities.
The enabled Data Member cannot be modified on enabled entities.
Thus, this feature must be set up during initialization.
Only the duration Data Member can be modified at runtime.
Warning
For DataWriters and DataReaders to match, they must follow the compatibility rule. See Compatibility Rule for further details.
To maintain the compatibility between DisablePositiveACKsQosPolicy in DataReaders and DataWriters, the DataReader cannot have this QoS enabled if the DataWriter have it disabled.
Table with the possible combinations:
DataWriter enabled value |
DataReader enabled value |
Compatibility |
|---|---|---|
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
DisablePositiveACKsQosPolicy disable_acks;
//The DisablePositiveACKsQosPolicy is default constructed with enabled = false
//Change enabled to true
disable_acks.enabled = true;
//The DisablePositiveACKsQosPolicy is default constructed with infinite duration
//Change the duration to 1 second
disable_acks.duration = {1, 0};
<data_writer profile_name="writer_xml_conf_disable_positive_acks_profile">
<qos>
<disablePositiveAcks>
<enabled>true</enabled>
<duration>
<sec>1</sec>
</duration>
</disablePositiveAcks>
</qos>
</data_writer>
<data_reader profile_name="reader_xml_conf_disable_positive_acks_profile">
<qos>
<disablePositiveAcks>
<enabled>true</enabled>
</disablePositiveAcks>
</qos>
</data_reader>
FlowControllersQos¶
This QoS configures the list of flow controllers of a participant, so they can later be used on
its DataWriters.
It is a vector of shared pointers to FlowControllerDescriptor, which has the following fields:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
FIFO_SCHED_POLICY-api| |
|
|
0 (i.e. infinite) |
|
|
100 |
|
Please refer to Flow Controllers section for more information.
Note
This QoS Policy concerns to DomainParticipant entities.
It cannot be changed on enabled entities.
ParticipantResourceLimitsQos¶
This QoS configures allocation limits and the use of physical memory for internal resources.
See ParticipantResourceLimitsQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
locators: Defines the limits for collections of remote locators.participants: Specifies the allocation behavior and limits for collections dependent on the total number of participants.readers: Specifies the allocation behavior and limits for collections dependent on the total number of readers per participant.writers: Specifies the allocation behavior and limits for collections dependent on the total number of writers per participant.send_buffers: Defines the allocation behavior and limits for the send buffer manager.data_limits: States the limits for variable-length data.content_filter: States the limits for content-filter discovery information.
Note
This QoS Policy concerns to DomainParticipant entities.
It cannot be changed on enabled entities.
This structure holds the limits for the remote locators’ collections.
See RemoteLocatorsAllocationAttributes.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
4 |
|
|
1 |
max_unicast_locators: This member controls the maximum number of unicast locators to keep for each discovered remote entity. It is recommended to use the highest number of local addresses found on all the systems belonging to the same domain.max_multicast_locators: This member controls the maximum number of multicast locators to keep for each discovered remote entity. The default value is usually enough, as it does not make sense to add more than one multicast locator per entity.
This structure holds the limits of a resource limited collection, as well as the allocation configuration, which can be fixed size or dynamic size.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
|
|
|
|
|
1 (dynamic size), 0 (fixed size) |
initial: Indicates the number of elements to preallocate in the collection.maximum: Specifies the maximum number of elements allowed in the collection.increment: States the number of items to add when the reserved capacity limit is reached. This member has a different default value depending on the allocation configuration chosen.
This structure holds the limits for the allocations of the send buffers.
See SendBuffersAllocationAttributes.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
|
|
|
preallocated_number: This member controls the initial number of send buffers to be allocated. The default value will perform an initial guess of the number of buffers required, based on the number of threads from which a send operation could be started.dynamic: This member controls how the buffer manager behaves when a send buffer is not available. When true, a new buffer will be created. Otherwise, it will wait for a buffer to be returned.
This structure holds the limits for variable-length data.
See VariableLengthDataLimits.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
|
|
0 |
|
|
0 |
max_properties: Defines the maximum size, in octets, of the properties data in the local or remote participant.max_user_data: Establishes the maximum size, in octets, of the user data in the local or remote participant.max_partitions: States the maximum size, in octets, of the partitions data in the local or remote participant.
This structure holds the limits for content-filter related discovery information.
See ContentFilterProperty::AllocationConfiguration.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
|
|
expression_initial_size: Preallocated size of the filter expression.expression_parameters: Allocation configuration for the list of expression parameters.
ParticipantResourceLimitsQos participant_limits;
//Set the maximum size of participant resource limits collection to 3 and it allocation configuration to fixed size
participant_limits.participants = eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(
3u);
//Set the maximum size of reader's resource limits collection to 2 and its allocation configuration to fixed size
participant_limits.readers = eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(2u);
//Set the maximum size of writer's resource limits collection to 1 and its allocation configuration to fixed size
participant_limits.writers = eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
//Set the maximum size of the partition data to 256
participant_limits.data_limits.max_partitions = 256u;
//Set the maximum size of the user data to 256
participant_limits.data_limits.max_user_data = 256u;
//Set the maximum size of the properties data to 512
participant_limits.data_limits.max_properties = 512u;
//Set the preallocated filter expression size to 512
participant_limits.content_filter.expression_initial_size = 512u;
//Set the maximum number of expression parameters to 4 and its allocation configuration to fixed size
participant_limits.content_filter.expression_parameters =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(4u);
<!--
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
-->
<participant profile_name="participant_alloc_qos_example">
<rtps>
<allocation>
<!-- We know we have 3 participants on the domain -->
<total_participants>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</total_participants>
<!-- We know we have at most 2 readers on each participant -->
<total_readers>
<initial>2</initial>
<maximum>2</maximum>
<increment>0</increment>
</total_readers>
<!-- We know we have at most 1 writer on each participant -->
<total_writers>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</total_writers>
<max_partitions>256</max_partitions>
<max_user_data>256</max_user_data>
<max_properties>512</max_properties>
<!-- content_filter cannot be configured using XML (yet) -->
</allocation>
</rtps>
</participant>
PropertyPolicyQos¶
This additional QoS Policy (PropertyPolicyQos) stores name/value pairs that can be used to configure certain
DDS settings that cannot be configured directly using an standard QoS Policy.
For the complete list of settings that can be configured with this QoS Policy, please refer to PropertyPolicyQos Options.
This QoS also allows to add custom user properties that could be sent to the external entities.
This could be done by setting as true the propagate value of the Property.
PropertyPolicyQos property_policy;
//Add new property for the Auth:PKI-DH plugin
property_policy.properties().emplace_back("dds.sec.auth.plugin", "builtin.PKI-DH");
//Add new property for the Access:Permissions plugin
property_policy.properties().emplace_back(eprosima::fastrtps::rtps::Property("dds.sec.access.plugin",
"builtin.Access-Permissions"));
//Add new user custom property to send to external Participants
property_policy.properties().emplace_back("Custom Property Name", "Custom value", true);
<participant profile_name="secure_participant_conf_all_plugin_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate Auth:PKI-DH plugin -->
<property>
<name>dds.sec.auth.plugin</name>
<value>builtin.PKI-DH</value>
</property>
<!-- Activate Access:Permissions plugin -->
<property>
<name>dds.sec.access.plugin</name>
<value>builtin.Access-Permissions</value>
</property>
<!-- User Custom Property to send externally -->
<property>
<name>Custom Property Name</name>
<value>Custom value</value>
<propagate>true</propagate>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
PublishModeQosPolicy¶
This QoS Policy configures how the DataWriter sends the data.
See PublishModeQosPolicy.
It also configures the name of the flow controller to use when asynchronous publishing is used. It should be the name of a flow controller registered on the creation of the DomainParticipant. See FlowControllersQos.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
Note
This QoS Policy concerns to DataWriter entities.
It cannot be changed on enabled entities.
There are two possible values (see PublishModeQosPolicyKind):
SYNCHRONOUS_PUBLISH_MODE: The data is sent in the context of the user thread that calls the write operation.ASYNCHRONOUS_PUBLISH_MODE: An internal thread takes the responsibility of sending the data asynchronously. The write operation returns before the data is actually sent.
PublishModeQosPolicy publish_mode;
//The PublishModeQosPolicy is default constructed with kind = SYNCHRONOUS
//Change the kind to ASYNCHRONOUS
publish_mode.kind = ASYNCHRONOUS_PUBLISH_MODE;
<data_writer profile_name="writer_profile_qos_publishmode">
<qos>
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
</qos>
</data_writer>
ReaderResourceLimitsQos¶
This QoS Policy states the limits for the matched DataWriters’ resource limited collections based on the maximum
number of DataWriters that are going to match with the DataReader.
See ReaderResourceLimitsQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
Note
This QoS Policy concerns to DataReader entities.
It cannot be changed on enabled entities.
ReaderResourceLimitsQos reader_limits;
//Set the maximum size for writer matched resource limits collection to 1 and its allocation configuration to fixed size
reader_limits.matched_publisher_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
<data_reader profile_name="alloc_qos_example_sub">
<!-- we know we will only have one matching publisher -->
<matchedPublishersAllocation>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</matchedPublishersAllocation>
</data_reader>
RTPSEndpointQos¶
This QoS Policy configures the aspects of an RTPS endpoint, such as the list of locators, the identifiers, and the
history memory policy.
See RTPSEndpointQos.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
Empty List |
|
|
Empty List |
|
|
Empty List |
|
|
Empty |
|
|
false |
|
|
-1 |
|
|
-1 |
|
|
unicast_locator_list: Defines the list of unicast locators associated to the DDS Entity. DataReaders and DataWriters inherit the list of unicast locators set in the DomainParticipant, but it can be changed by means of this QoS.multicast_locator_list: Stores the list of multicast locators associated to the DDS Entity. By default, DataReaders and DataWriters do not use any multicast locator, but it can be changed by means of this QoS.remote_locator_list: States the list of remote locators associated to the DDS Entity.external_unicast_locators: Defines the External Locators to announce for the communication with this DDS Entity.ignore_non_matching_locators: Defines whether to ignore locators received on announcements from other DDS entities when they don’t match with any of the locators announced by this DDS Entity.user_defined_id: Establishes the unique identifier used for StaticEndpointDiscovery.entity_id: The user can specify the identifier for the endpoint.history_memory_policy: Indicates the way the memory is managed in terms of dealing with the CacheChanges.
Note
This QoS Policy concerns to DataWriter and DataReader entities.
It cannot be changed on enabled entities.
There are four possible values (see MemoryManagementPolicy):
PREALLOCATED_MEMORY_MODE: This option sets the size to the maximum of each data type. It produces the largest memory footprint but the smallest allocation count.PREALLOCATED_WITH_REALLOC_MEMORY_MODE: This option set the size to the default for each data type and it requires reallocation when a bigger message arrives. It produces a lower memory footprint at the expense of increasing the allocation count.DYNAMIC_RESERVE_MEMORY_MODE: This option allocates the size dynamically at the time of message arrival. It produces the least memory footprint but the highest allocation count.DYNAMIC_REUSABLE_MEMORY_MODE: This option is similar toDYNAMIC_RESERVE_MEMORY_MODE, but the allocated memory is reused for future messages.
RTPSEndpointQos endpoint;
//Add new unicast locator with port 7800
eprosima::fastrtps::rtps::Locator_t new_unicast_locator;
new_unicast_locator.port = 7800;
endpoint.unicast_locator_list.push_back(new_unicast_locator);
//Add new multicast locator with IP 239.255.0.4 and port 7900
eprosima::fastrtps::rtps::Locator_t new_multicast_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(new_multicast_locator, "239.255.0.4");
new_multicast_locator.port = 7900;
endpoint.multicast_locator_list.push_back(new_multicast_locator);
// Add an external locator with IP 100.100.100.10, port 12345, mask 24, externality 1, and cost 0
eprosima::fastdds::rtps::LocatorWithMask external_locator;
external_locator.kind = LOCATOR_KIND_UDPv4;
external_locator.port = 12345;
external_locator.mask(24);
endpoint.external_unicast_locators[1][0].push_back(external_locator);
// Drop non matching locators
endpoint.ignore_non_matching_locators = true;
//Set 3 as user defined id
endpoint.user_defined_id = 3;
//Set 4 as entity id
endpoint.entity_id = 4;
//The RTPSEndpointQos is default constructed with history_memory_policy = PREALLOCATED
//Change the history_memory_policy to DYNAMIC_RESERVE
endpoint.history_memory_policy = eprosima::fastrtps::rtps::DYNAMIC_RESERVE_MEMORY_MODE;
<data_writer profile_name="writer_xml_conf_unicast_locators_profile">
<userDefinedID>3</userDefinedID>
<entityID>2</entityID> <!-- Int16 -->
<unicastLocatorList>
<locator>
<udpv4>
<port>7800</port>
</udpv4>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<locator>
<udpv4>
<address>239.255.0.4</address>
<port>7900</port>
</udpv4>
</locator>
</multicastLocatorList>
<external_unicast_locators>
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>12345</port>
</udpv4>
</external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<!-- The history memory policy is changed to DYNAMIC_RESERVE -->
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
</data_writer>
<data_reader profile_name="reader_xml_conf_unicast_locators_profile">
<userDefinedID>5</userDefinedID>
<entityID>4</entityID> <!-- Int16 -->
<unicastLocatorList>
<locator>
<udpv4>
<port>7800</port>
</udpv4>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<locator>
<udpv4>
<address>239.255.0.4</address>
<port>7900</port>
</udpv4>
</locator>
</multicastLocatorList>
<external_unicast_locators>
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>12345</port>
</udpv4>
</external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<historyMemoryPolicy>PREALLOCATED_WITH_REALLOC</historyMemoryPolicy>
</data_reader>
RTPSReliableReaderQos¶
This RTPS QoS Policy allows the configuration of several RTPS reliable reader’s aspects.
See RTPSReliableReaderQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
|
|
times: Defines the duration of the RTPSReader events. See ReaderTimes for further details.disable_positive_ACKs: Configures the settings to disable the positive acks. See DisablePositiveACKsQosPolicy for further details.
Note
This QoS Policy concerns to DataReader entities.
Only the duration Data Member of the DisablePositiveACKsQosPolicy and the times
Data Member can be modified on enabled entities.
This structure defines the times associated with the Reliable Readers’ events.
See ReaderTimes.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
70 ms |
|
|
5 ms |
initialAcknackDelay: Defines the duration of the initial acknack delay.heartbeatResponseDelay: Establishes the duration of the delay applied when a heartbeat message is received.
RTPSReliableReaderQos reliable_reader_qos;
//The RTPSReliableReaderQos is default constructed with initialAcknackDelay = 70 ms
//Change the initialAcknackDelay to 70 nanoseconds
reliable_reader_qos.times.initialAcknackDelay = {0, 70};
//The RTPSReliableWriterQos is default constructed with heartbeatResponseDelay = 5 ms
//Change the heartbeatResponseDelay to 5 nanoseconds
reliable_reader_qos.times.heartbeatResponseDelay = {0, 5};
//You can also change the DisablePositiveACKsQosPolicy. For further details see DisablePositiveACKsQosPolicy section.
reliable_reader_qos.disable_positive_ACKs.enabled = true;
<data_reader profile_name="sub_profile_name">
<times> <!-- readerTimesType -->
<initialAcknackDelay> <!-- DURATION -->
<nanosec>70</nanosec>
</initialAcknackDelay>
<heartbeatResponseDelay> <!-- DURATION -->
<nanosec>5</nanosec>
</heartbeatResponseDelay>
</times>
<!--You can also change the values of DisablePositiveACKsQosPolicy.-->
<!--See DisablePositiveACKsQosPolicy section for further details-->
</data_reader>
RTPSReliableWriterQos¶
This RTPS QoS Policy allows the configuration of several RTPS reliable writer’s aspects.
See RTPSReliableWriterQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
times: Defines the duration of the RTPSWriter events. See WriterTimes for further details.disable_positive_acks: Configures the settings to disable the positive acks. See DisablePositiveACKsQosPolicy for further details.disable_heartbeat_piggyback: Configures the settings to disable the heartbeat piggyback mechanism. See DisableHeartbeatPiggyback for further details.
Note
This QoS Policy concerns to DataWriter entities.
Only the duration Data Member of the DisablePositiveACKsQosPolicy and the times
Data Member can be modified on enabled entities.
This structure defines the times associated with the Reliable Writers’ events.
List of structure members:
Member Name |
Type |
Default Value |
|---|---|---|
|
|
12ms |
|
|
3s |
|
|
5ms |
|
|
0s |
initialHeartbeatDelay: Defines duration of the initial heartbeat delay.heartbeatPeriod: Specifies the interval between periodic heartbeats.nackResponseDelay: Establishes the duration of the delay applied to the response of an ACKNACK message.nackSupressionDuration: The RTPSWriter ignores the nack messages received after sending the data until the duration time elapses.
Besides sending heartbeats periodically using the heartbeatPeriod (see WriterTimes), reliable
DataWriters also use a mechanism to append a heartbeat submessage in the same message where data is being delivered to
the DataReaders.
This mechanism acts in specific situations where the reliable communication state must be up to date to maintain
optimal communication:
When the DataWriter sends as many bytes to the socket as the length of the socket buffer, a heartbeat submessage is appended after the last data.
When the DataWriter’s history is full, the DataWriter starts to append heartbeat submessages after each data.
This mechanism can be disabled using this policy.
RTPSReliableWriterQos reliable_writer_qos;
//The RTPSReliableWriterQos is default constructed with initialHeartbeatDelay = 12 ms
//Change the initialHeartbeatDelay to 20 nanoseconds
reliable_writer_qos.times.initialHeartbeatDelay = {0, 20};
//The RTPSReliableWriterQos is default constructed with heartbeatPeriod = 3 s
//Change the heartbeatPeriod to 5 seconds
reliable_writer_qos.times.heartbeatPeriod = {5, 0};
//The RTPSReliableWriterQos is default constructed with nackResponseDelay = 5 ms
//Change the nackResponseDelay to 10 nanoseconds
reliable_writer_qos.times.nackResponseDelay = {0, 10};
//The RTPSReliableWriterQos is default constructed with nackSupressionDuration = 0 s
//Change the nackSupressionDuration to 20 nanoseconds
reliable_writer_qos.times.nackSupressionDuration = {0, 20};
//You can also change the DisablePositiveACKsQosPolicy. For further details see DisablePositiveACKsQosPolicy section.
reliable_writer_qos.disable_positive_acks.enabled = true;
//The RTPSReliableWriterQos is default constructed with disable_heartbeat_piggyback = false
//Disable the heartbeat piggyback mechanism.
reliable_writer_qos.disable_heartbeat_piggyback = true;
<data_writer profile_name="pub_profile_name">
<times> <!-- writerTimesType -->
<initialHeartbeatDelay> <!-- DURATION -->
<nanosec>20</nanosec>
</initialHeartbeatDelay>
<heartbeatPeriod> <!-- DURATION -->
<sec>5</sec>
</heartbeatPeriod>
<nackResponseDelay> <!-- DURATION -->
<nanosec>10</nanosec>
</nackResponseDelay>
<nackSupressionDuration> <!-- DURATION -->
<nanosec>20</nanosec>
</nackSupressionDuration>
</times>
<!--You can also change the values of DisablePositiveACKsQosPolicy.-->
<!--See DisablePositiveACKsQosPolicy section for further details-->
<qos>
<!--Disable heartbeat piggyback mechanism.-->
<disable_heartbeat_piggyback>true</disable_heartbeat_piggyback>
</qos>
</data_writer>
ThreadSettings¶
This structure is part of other QoS policies, and allows controlling some OS settings for the threads created. The default values will leave the default OS settings on the created threads. Changing these values may require special permissions.
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
-1 |
|
|
-2^31 |
|
|
0 |
|
|
-1 |
scheduling_policy: Configures the scheduling policy used for the thread. This value is platform specific and it is used as-is to configure the specific platform thread. It is ignored on Windows platforms.priority: Configures the thread’s priority. This value is platform specific and it is used as-is to configure the specific platform thread.affinity: On some systems (Windows, Linux), this is a bit mask for setting the threads affinity to each core individually. On MacOS, this sets the affinity tag for the thread, and the OS tries to share the L2 cache between threads with the same affinity. This value is platform specific and it is used as-is to configure the specific platform thread.stack_size: Configures the thread’s stack size in bytes. This value is platform specific and it is used as-is to configure the specific platform thread.
ThreadSettings thread_settings;
thread_settings.scheduling_policy = 2;
thread_settings.priority = 10;
thread_settings.affinity = 4;
thread_settings.stack_size = 2000;
<thread_settings>
<scheduling_policy>2</scheduling_policy>
<priority>10</priority>
<affinity>4</affinity>
<stack_size>2000</stack_size>
</thread_settings>
TransportConfigQos¶
This QoS Policy allows the configuration of the transport layer settings.
See TransportConfigQos.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
Empty vector |
|
|
|
|
|
0 |
|
|
0 |
|
user_transports: This data member defines the list of transports to use alongside or in place of builtins.use_builtin_transports: It controls whether the built-in transport layer is enabled or disabled. If it is set to false, the default UDPv4 implementation is disabled.send_socket_buffer_size: By default, Fast DDS creates socket buffers using the system default size. This data member allows to change the send socket buffer size used to send data.listen_socket_buffer_size: The listen socket buffer size is also created with the system default size, but it can be changed using this data member.builtin_transports_reception_threads(): The ThreadSettings for the reception threads of the builtin transports.
Note
This QoS Policy concerns to DomainParticipant entities.
It cannot be changed on enabled entities.
This structure is the base for the data type used to define transport configuration.
List of structure members:
Member Name |
Type |
|---|---|
|
|
|
|
maxMessageSize: This member sets the maximum size in bytes of the transport’s message buffer.maxInitialPeersRange: This member states the maximum number of guessed initial peers to try to connect.
TransportConfigQos transport;
// Add new transport to the list of user transports
std::shared_ptr<eprosima::fastdds::rtps::UDPv4TransportDescriptor> descriptor =
std::make_shared<eprosima::fastdds::rtps::UDPv4TransportDescriptor>();
descriptor->sendBufferSize = 9126;
descriptor->receiveBufferSize = 9126;
transport.user_transports.push_back(descriptor);
// Set use_builtin_transports to false
transport.use_builtin_transports = false;
// [OPTIONAL] Set ThreadSettings for the builtin transports reception threads
transport.builtin_transports_reception_threads_ = eprosima::fastdds::rtps::ThreadSettings{2, 2, 2, 2};
<transport_descriptors>
<transport_descriptor>
<transport_id>my_transport</transport_id>
<type>UDPv4</type>
<sendBufferSize>9216</sendBufferSize>
<receiveBufferSize>9216</receiveBufferSize>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="my_transport">
<rtps>
<userTransports>
<transport_id>my_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
</rtps>
</participant>
Note
TransportConfigQos can also be configured modifying the builtin
transports configuration by selecting one of the available builtin transports options.
See Managing the Builtin Transports or setup_transports().
TypeConsistencyQos¶
This QoS Policy allows the configuration of the XTypes extension QoS on the DataReader.
See TypeConsistencyQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
|
|
type_consistency: It states the rules for the data types compatibility. See TypeConsistencyEnforcementQosPolicy for further details.representation: It specifies the data representations valid for the entities. See DataRepresentationQosPolicy for further details.
Note
This QoS Policy concerns to DataReader entities.
It cannot be changed on enabled entities.
TypeConsistencyQos consistency_qos;
//You can change the DataRepresentationQosPolicy. For further details see DataRepresentationQosPolicySection section.
consistency_qos.representation.m_value.push_back(DataRepresentationId_t::XCDR2_DATA_REPRESENTATION);
//You can change the TypeConsistencyEnforcementQosPolicy. For further details see TypeConsistencyEnforcementQosPolicy section.
consistency_qos.type_consistency.m_kind = TypeConsistencyKind::ALLOW_TYPE_COERCION;
This QoS Policy cannot be configured using XML for the moment.
WireProtocolConfigQos¶
This QoS Policy allows the configuration of the wire protocol.
See WireProtocolConfigQos.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
0 |
|
|
-1 |
|
|
|
|
|
|
|
|
Empty List |
|
|
Empty List |
|
|
Empty |
|
|
false |
prefix: This data member allows the user to set manually the GUID prefix.participant_id: It sets the participant identifier. By default, it will be automatically generated by the Domain.builtin: This data member allows the configuration of the built-in parameters.port: This data member allows the configuration of the port parameters and gains related to the RTPS protocol (Well Known Ports).default_unicast_locator_list: States the default list of unicast locators to be used for any endpoint defined inside the RTPSParticipant in the case that it was defined without unicast locators. This list should include at least one locator.default_multicast_locator_list: Stores the default list of multicast locators to be used for any endpoint defined inside the RTPSParticipant in the case that it was defined without multicast locators. This list is usually left empty.default_external_unicast_locators: Defines the External Locators to be used for any endpoint defined inside the participant in the case that it was defined without unicast locators.ignore_non_matching_locators: Defines whether to ignore locators received on announcements from other DDS participants when they don’t match with any of the locators announced by this DDS participant.
Note
This QoS Policy concerns to DomainParticipant entities.
Important
The only mutable field on enabled entities is m_DiscoveryServers, which is contained in
discovery_config within builtin (see
Modifying remote servers list at run time).
WireProtocolConfigQos wire_protocol;
//Set the guid prefix
std::istringstream("72.61.73.70.66.61.72.6d.74.65.73.74") >> wire_protocol.prefix;
//Configure Builtin Attributes
wire_protocol.builtin.discovery_config.discoveryProtocol =
eprosima::fastrtps::rtps::DiscoveryProtocol_t::SERVER;
//Add locator to unicast list
eprosima::fastrtps::rtps::Locator_t server_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(server_locator, "192.168.10.57");
server_locator.port = 56542;
wire_protocol.builtin.metatrafficUnicastLocatorList.push_back(server_locator);
// Add a metatraffic external locator with IP 100.100.100.10, port 34567, mask 24, externality 1, and cost 0
eprosima::fastdds::rtps::LocatorWithMask meta_external_locator;
meta_external_locator.kind = LOCATOR_KIND_UDPv4;
meta_external_locator.port = 34567;
meta_external_locator.mask(24);
wire_protocol.builtin.metatraffic_external_unicast_locators[1][0].push_back(meta_external_locator);
//Add locator to default unicast locator list
eprosima::fastrtps::rtps::Locator_t unicast_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(unicast_locator, 192, 168, 1, 41);
unicast_locator.port = 7400;
wire_protocol.default_unicast_locator_list.push_back(unicast_locator);
//Add locator to default multicast locator list
eprosima::fastrtps::rtps::Locator_t multicast_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(multicast_locator, 192, 168, 1, 41);
multicast_locator.port = 7400;
wire_protocol.default_multicast_locator_list.push_back(multicast_locator);
// Add a default external locator with IP 100.100.100.10, port 23456, mask 24, externality 1, and cost 0
eprosima::fastdds::rtps::LocatorWithMask external_locator;
external_locator.kind = LOCATOR_KIND_UDPv4;
external_locator.port = 23456;
external_locator.mask(24);
wire_protocol.default_external_unicast_locators[1][0].push_back(external_locator);
// Drop non matching locators
wire_protocol.ignore_non_matching_locators = true;
<participant profile_name="UDP SERVER WP" is_default_profile="true">
<rtps>
<prefix>72.61.73.70.66.61.72.6d.74.65.73.74</prefix>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<metatraffic_external_unicast_locators>
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>34567</port>
</udpv4>
</metatraffic_external_unicast_locators>
</builtin>
<defaultUnicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
</defaultUnicastLocatorList>
<defaultMulticastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
</defaultMulticastLocatorList>
<default_external_unicast_locators>
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>23456</port>
</udpv4>
</default_external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
</rtps>
</participant>
WriterResourceLimitsQos¶
This QoS Policy states the limits for the matched DataReaders’ resource limited collections based on the maximum
number of DataReaders that are going to match with the DataWriter.
See WriterResourceLimitsQos.
List of QoS Policy data members:
Data Member Name |
Type |
|---|---|
|
|
|
Note
This QoS Policy concerns to DataWriter entities.
It cannot be changed on enabled entities.
WriterResourceLimitsQos writer_limits;
//Set the maximum size for reader matched resource limits collection to 3 and its allocation configuration to fixed size
writer_limits.matched_subscriber_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
// Set the maximum number of writer side content filters to 1 and its allocation configuration to fixed size
writer_limits.reader_filters_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
<data_writer profile_name="alloc_qos_example_pub_for_topic_1">
<!-- we know we will have three matching subscribers -->
<matchedSubscribersAllocation>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
<!-- reader_filters_allocation cannot be configured using XML (yet) -->
</data_writer>
XTypes Extensions¶
This section explain those QoS Policy extensions defined in the XTypes Specification:
DataRepresentationQosPolicy¶
This XTypes QoS Policy states which data representations will be used by the DataWriters and DataReaders.
The DataWriters offer a single data representation that will be used to communicate with the matched DataReaders.
The DataReaders can request one or more data representations and in order to have communication with the DataWriter,
the offered data representation needs to be contained within the DataReader request.
See DataRepresentationQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
std::vector<DataRepresentationId> |
Empty vector |
Note
This QoS Policy concerns to Topic, DataReader and DataWriter entities.
It cannot be changed on enabled entities.
There are three possible values (see DataRepresentationId):
XCDR_DATA_REPRESENTATION: This option corresponds to the first version of the Extended CDR Representation encoding.XML_DATA_REPRESENTATION: This option corresponds to the XML Data Representation.XCDR2_DATA_REPRESENTATION: This option corresponds to the second version of the Extended CDR Representation encoding.
DataRepresentationQosPolicy data_representation;
//Add XCDR v1 data representation to the list of valid representations
data_representation.m_value.push_back(DataRepresentationId_t::XCDR_DATA_REPRESENTATION);
//Add XML data representation to the list of valid representations
data_representation.m_value.push_back(DataRepresentationId_t::XML_DATA_REPRESENTATION);
This QoS Policy cannot be configured using XML for the moment.
TypeConsistencyEnforcementQosPolicy¶
Warning
This QoS Policy will be implemented in future releases.
This XTypes QoS Policy extension defines the rules for determining whether the data type used in the
DataWriter is consistent with the one used in the DataReader.
See TypeConsistencyEnforcementQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
m_kind: It determines whether the type in the DataWriter type must be equal to the type in the DataReader or not. See TypeConsistencyKind for further details.m_ignore_sequence_bounds: This data member controls whether the sequence bounds are taken into account for type assignability or not. If its value is true, the sequences maximum lengths are not considered, which means that a sequence T2 with length L2 would be assignable to a sequence T1 with length L1, even if L2 is greater than L1. But if it is false, L1 must be higher or equal to L2 to consider the sequences as assignable.m_ignore_string_bounds: It controls whether the string bounds are considered for type assignation or not. If its value is true, the strings maximum lengths are not considered, which means that a string S2 with length L2 would be assignable to a string S1 with length L1, even if L2 is greater than L1. But if it is false, L1 must be higher or equal to L2 to consider the strings as assignable.m_ignore_member_names: This boolean controls whether the member names are taken into consideration for type assignability or not. If it is true, apart from the member ID, the member names are considered as part of assignability, which means that the members with the same ID must also have the same name. But if the value is false, the member names are ignored.m_prevent_type_widening: This data member controls whether the type widening is allowed or not. If it is false, the type widening is permitted, but if true, a wider type cannot be assignable to a narrower type.m_force_type_validation: It controls if the service needs the type information to complete the matching between a DataWriter and a DataReader. If it is enabled, it must have the Complete Type Information, otherwise it is not necessary.
Note
This QoS Policy concerns to DataReader entities.
It cannot be changed on enabled entities.
There are two possible values:
DISALLOW_TYPE_COERCION: The DataWriter and the DataReader must support the same data type in order to communicate.ALLOW_TYPE_COERCION: The DataWriter and the DataReader do not need to support the same data type in order to communicate as long as the DataReader’s type is assignable from the DataWriter’s type.
TypeConsistencyEnforcementQosPolicy type_enforcement;
//The TypeConsistencyEnforcementQosPolicy is default constructed with kind = ALLOW_TYPE_COERCION
//Change the kind to DISALLOW_TYPE_COERCION
type_enforcement.m_kind = TypeConsistencyKind::DISALLOW_TYPE_COERCION;
//Configures the system to ignore the sequence sizes in assignations
type_enforcement.m_ignore_sequence_bounds = true;
//Configures the system to ignore the string sizes in assignations
type_enforcement.m_ignore_string_bounds = true;
//Configures the system to ignore the member names. Members with same ID could have different names
type_enforcement.m_ignore_member_names = true;
//Configures the system to allow type widening
type_enforcement.m_prevent_type_widening = false;
//Configures the system to not use the complete Type Information in entities match process
type_enforcement.m_force_type_validation = false;
This QoS Policy cannot be configured using XML for the moment.
Status¶
Each Entity is associated with a set of Status objects whose values represent
the communication status of that Entity.
Changes on the status values occur due to communication events related to each of the entities,
e.g., when new data arrives, a new participant is discovered, or a remote endpoint is lost.
The status is decomposed into several status objects, each concerning a different aspect of the communication,
so that each of these status objects can vary independently of the others.
Changes on a status object trigger the corresponding Listener callbacks
that allow the Entity to inform the application about the event.
For a given status object with name fooStatus, the entity listener interface defines a callback
function on_foo() that will be called when the status changes.
Beware that some statuses have data members that are reset every time the corresponding listener is called.
The only exception to this rule is when the entity has no listener attached, so the callback cannot be called.
See the documentation of each status for details.
Conditions and Wait-sets provide the application with an alternative mechanism to make it aware of changes on status objects, by means of a StatusCondition. The advantage of this mechanism is that the application can wait for changes on several entities at the same time. It will also help the determinism of your system, as the notification is not processed on an internal thread, as it is done when using listeners.
The entities expose functions to access the value of its statuses.
For a given status with name fooStatus, the entity exposes a member function get_foo() to
access the data in its fooStatus.
The only exceptions are DataOnReaders and DataAvailable.
These getter functions return a read-only struct where all data members are public and accessible to the application.
Beware that some statuses have data members that are reset every time the getter function is called by the application.
See the documentation of each status for details.
The following subsections describe each of the status objects, their data members, and to which
Entity type they concern.
The next table offers a quick reference as well as the corresponding bit for each status in the StatusMask.
Status Name |
Entity |
Listener callback |
Accessor |
Bit |
|---|---|---|---|---|
|
|
0 |
||
|
|
1 |
||
|
|
2 |
||
|
|
5 |
||
|
|
6 |
||
|
|
7 |
||
|
|
8 |
||
|
N/A |
9 |
||
|
N/A |
10 |
||
|
|
11 |
||
|
|
12 |
||
|
|
13 |
||
|
|
14 |
InconsistentTopicStatus¶
This status changes every time an inconsistent remote Topic is discovered,
that is, one with the same name but different characteristics than the current Topic.
See InconsistentTopicStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
total_count: Total cumulative count of inconsistent Topics discovered since the creation of the current Topic.total_count_change: The change intotal_countsince the last timeon_inconsistent_topic()was called or the status was read.
Warning
Currently this status is not supported and will be implemented in future releases.
As a result, trying to access this status will return NOT_SUPPORTED
and the corresponding listener will never be called.
DataOnReaders¶
This status becomes active every time there is new data available for the application on any
DataReader belonging to the current Subscriber.
There is no getter function to access this status, as it does not keep track of any information related to the
data itself.
Its only purpose is to trigger the on_data_on_readers() callback on the listener attached to the
DataReader.
DataAvailable¶
This status becomes active every time there is new data available for the application on the
DataReader.
There is no getter function to access this status, as it does not keep track of any information related to the
data itself.
Its only purpose is to trigger the on_data_available() callback on the listener attached to the
DataReader.
LivelinessChangedStatus¶
This status changes every time the liveliness status of a matched DataWriter has changed.
Either because a DataWriter that was inactive has become active or the other way around.
See LivelinessChangedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
|
|
alive_count: Total number of currently active DataWriters. This count increases every time a newly matched DataWriter asserts its liveliness or a DataWriter that was considered not alive reasserts its liveliness. It decreases every time an active DataWriter becomes not alive, either because it failed to asserts its liveliness or because it was deleted for any reason.not_alive_count: Total number of matched DataWriters that are currently considered not alive. This count increases every time an active DataWriter becomes not alive because it fails to assert its liveliness. It decreases every time a DataWriter that was considered not alive reasserts its liveliness. Normal matching and unmatching of DataWriters does not affect this count.alive_count_change: The change inalive_countsince the last timeon_liveliness_changed()was called or the status was read. It can have positive or negative values.not_alive_count_change: The change innot_alive_countsince the last timeon_liveliness_changed()was called or the status was read. It can have positive or negative values.last_publication_handle: Handle to the last DataWriter whose liveliness status was changed. If no liveliness has ever changed, it will have valuec_InstanceHandle_Unknown.
RequestedDeadlineMissedStatus¶
This status changes every time the DataReader does not receive
data within the deadline period configured on its DataReaderQos.
See RequestedDeadlineMissedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
total_count: Total cumulative count of missed deadlines for any instance read by the current DataReader. As the deadline period applies to each instance of the Topic independently, the count will will be incremented by one for each instance for which data was not received in the deadline period.total_count_change: The change intotal_countsince the last timeon_requested_deadline_missed()was called or the status was read. It can only have zero or positive values.last_instance_handle: Handle to the last instance that missed the deadline. If no deadline was ever missed, it will have valuec_InstanceHandle_Unknown.
RequestedIncompatibleQosStatus¶
This status changes every time the DataReader finds a
DataWriter that matches the Topic and has
a common partition, but with a QoS configuration incompatible with the one defined on the
DataReader.
See RequestedIncompatibleQosStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
total_count: Total cumulative count of DataWriters found matching the Topic and with a common partition, but with a QoS configuration that is incompatible with the one defined on the DataReader.total_count_change: The change intotal_countsince the last timeon_requested_incompatible_qos()was called or the status was read. It can only have zero or positive values.last_policy_id: The policy ID of one of the policies that was found to be incompatible with the current DataReader. If more than one policy happens to be incompatible, only one of them will be reported in this member.policies: A collection that holds, for each policy, the total number of times that the policy was found to be incompatible with the one offered by a remote DataWriter that matched the Topic and with a common partition. See QosPolicyCountSeq and QosPolicyCount for more information the information that is stored for each policy.
QosPolicyCountSeq¶
Holds a QosPolicyCount for each Policy,
indexed by its QosPolicyId_t. Therefore, the Qos Policy with ID N will be at position N in the sequence.
See QosPolicyCountSeq.
DataReader* data_reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
// Get how many times ReliabilityQosPolicy was not compatible with a remote writer
RequestedIncompatibleQosStatus status;
data_reader->get_requested_incompatible_qos_status(status);
uint32_t incompatible_reliability_count = status.policies[RELIABILITY_QOS_POLICY_ID].count;
QosPolicyCount¶
This structure holds a counter for a policy.
See QosPolicyCount.
List of data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
policy_id: The ID of the policy.count: The counter value for the policy.
SampleLostStatus¶
This status changes every time a new data sample is lost and will never be received.
See SampleLostStatus.
There are two different criteria for considering a sample as lost depending on the reliability():
When using
BEST_EFFORT_RELIABILITY_QOS, a not yet received sample is considered lost whenever a sample with a greater sequence number is received.When using
RELIABLE_RELIABILITY_QOS, a not yet received sample is considered lost whenever theDataWriterinforms, through an RTPSHEARTBEATsubmessage, that the sample is not available anymore.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
total_count: Total cumulative count of lost samples under the Topic of the current DataReader.total_count_change: The change intotal_countsince the last timeon_sample_lost()was called or the status was read. It can only be positive or zero.
SampleRejectedStatus¶
This status changes every time an incoming data sample is rejected by the DataReader.
The reason for the rejection is defined by SampleRejectedStatusKind.
For further information see SampleRejectedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
total_count: Total cumulative count of rejected samples under the Topic of the current DataReader.total_count_change: The change intotal_countsince the last timeon_sample_rejected()was called or the status was read. It can only be positive or zero.last_reason: The reason for rejecting the last rejected sample. If no sample was ever rejected, it will have valueNOT_REJECTED. See SampleRejectedStatusKind for further details.last_instance_handle: Handle to the last instance whose sample was rejected. If no sample was ever rejected, it will have valuec_InstanceHandle_Unknown.
SampleRejectedStatusKind¶
In Fast DDS, samples can be rejected due to resource limit reasons. However, the fact that the samples are rejected does not imply that they are lost, i.e. a rejected sample may be accepted in the future.
SampleRejectedStatusKind specifies the reason of the rejection:
NOT_REJECTEDspecifies that the samples were not rejected.REJECTED_BY_SAMPLES_LIMITspecifies that the samples were rejected because there were not enough resources to stored them. This can happen even when there are free resources if those resources must be guaranteed to be available for other samples. This situation, which arises in the RTPS layer, occurs when there are yet to be received samples with lower sequence number and there is not enough resources for all of them (becausemax_sampleshas been reached).REJECTED_BY_INSTANCES_LIMITspecifies that the samples were rejected because there were not enough resources to allocate the samples’ instances. This situation, which arises in the DDS layer, more precisely in the in theDataReader’s history, occurs when the sample corresponds to a new instance for which the middleware should reserve resources but the history’s number of instances has already reachedmax_instances.REJECTED_BY_SAMPLES_PER_INSTANCE_LIMITspecifies that the samples were rejected because there were not enough resources within their instance to stored them. This situation, which arises in the DDS layer, more precisely in theDataReader’s history, occurs when theDataReaderis configured withKEEP_ALL_HISTORY_QOSand the instance’s number of samples has reachedmax_samples_per_instance.
SubscriptionMatchedStatus¶
This status changes every time the DataReader finds a DataWriter
that matches the Topic and has a common partition and a compatible QoS,
or has ceased to be matched with a DataWriter that was previously considered to be matched.
See SubscriptionMatchedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
|
|
total_count: Total cumulative count of remote DataWriters that have been discovered publishing on the same Topic and has a common partition and a compatible QoS. They may not all be matched at the moment.total_count_change: The change intotal_countsince the last timeon_subscription_matched()was called or the status was read. It can only have zero or positive values.current_count: The number of remote DataWriters currently matched to the DataReader.current_count_change: The change incurrent_countsince the last timeon_subscription_matched()was called or the status was read. It can have positive or negative values.last_publication_handle: Handle to the last DataWriter that matched the DataReader. If no matching ever happened, it will have valuec_InstanceHandle_Unknown.
LivelinessLostStatus¶
This status changes every time the DataWriter failed to assert its liveliness
during the period configured on its DataWriterQos.
This means that matched DataReader entities will consider the
DataWriter as no longer alive.
See LivelinessLostStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
total_count: Total cumulative count of times that the DataWriter failed to assert its liveliness during the period configured on its DataWriterQos, becoming considered not alive. This count does not change when the DataWriter is already considered not alive and simply remains not alive for another liveliness period.total_count_change: The change intotal_countsince the last timeon_liveliness_lost()was called or the status was read. It can only have zero or positive values.
OfferedDeadlineMissedStatus¶
This status changes every time the DataWriter fails to provide
data within the deadline period configured on its DataWriterQos.
See OfferedDeadlineMissedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
total_count: Total cumulative count of missed deadlines for any instance written by the current DataWriter. As the deadline period applies to each instance of the Topic independently, the count will will be incremented by one for each instance for which data was not sent in the deadline period.total_count_change: The change intotal_countsince the last timeon_offered_deadline_missed()was called or the status was read. It can only have zero or positive values.last_instance_handle: Handle to the last instance that missed the deadline. If no deadline was ever missed, it will have valuec_InstanceHandle_Unknown.
OfferedIncompatibleQosStatus¶
This status changes every time the DataWriter finds a
DataReader that matches the Topic and has
a common partition, but with a QoS configuration that is incompatible with the one defined on the
DataWriter.
See OfferedIncompatibleQosStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
total_count: Total cumulative count of DataReaders found matching the Topic and with a common partition, but with a QoS configuration that is incompatible with the one defined on the DataWriter.total_count_change: The change intotal_countsince the last timeon_offered_incompatible_qos()was called or the status was read. It can only have zero or positive values.last_policy_id: The policy ID of one of the policies that was found to be incompatible with the current DataWriter. If more than one policy happens to be incompatible, only one of them will be reported in this member.policies: A collection that holds, for each policy, the total number of times that the policy was found to be incompatible with the one requested by a remote DataReader that matched the Topic and with a common partition. See QosPolicyCountSeq and QosPolicyCount for more information the information that is stored for each policy.
PublicationMatchedStatus¶
This status changes every time the DataWriter finds a DataReader
that matches the Topic and has a common partition and a compatible QoS,
or has ceased to be matched with a DataReader that was previously considered to be matched.
See PublicationMatchedStatus.
List of status data members:
Data Member Name |
Type |
|---|---|
|
|
|
|
|
|
|
|
|
|
total_count: Total cumulative count of remote DataReaders that have been discovered publishing on the same Topic and has a common partition and a compatible QoS. They may not all be matched at the moment.total_count_change: The change intotal_countsince the last timeon_publication_matched()was called or the status was read. It can only have zero or positive values.current_count: The number of remote DataReaders currently matched to the DataWriter.current_count_change: The change incurrent_countsince the last timeon_publication_matched()was called or the status was read. It can have positive or negative values.last_subscription_handle: Handle to the last DataReader that matched the DataWriter. If no matching ever happened, it will have valuec_InstanceHandle_Unknown.
Conditions and Wait-sets¶
Conditions (in conjunction with wait-sets) provide an alternative mechanism to allow the middleware to notify communication status changes (including arrival of data) to the application.
This mechanism is wait-based. Its general use pattern is as follows:
The application indicates which relevant information it wants to get, by means of Condition objects (GuardCondition, StatusCondition, or ReadCondition) and attaching them to a Wait-set via the
attach_condition()call.It then waits on that Wait-set via the
wait()call until the trigger value of one or several Condition objects become true.It then uses the result of the
wait()(i.e., the list of Condition objects with trigger_value == true) to actually get the information by calling:get_status_changes(), then checking if any of the changes is relevant using theStatusMask::is_active()method on the result and finally calling get_<communication_status> on the relevant Entity, when the condition is a StatusCondition and the status changes refer to plain communication status. Refer to Status for additional information on the different statuses that can be queried.get_status_changes()and thenSubscriber::get_datareaders()on the relevant Subscriber, when the condition is a StatusCondition and the status changes refer to DataOnReaders.get_status_changes()and thenDataReader::read()/DataReader::take()on the relevant DataReader, when the condition is a StatusCondition and the status changes refer to DataAvailable.Directly
DataReader::read_w_condition()/DataReader::take_w_condition()on the DataReader with the Condition as a parameter, when it is a ReadCondition
When a Condition is no longer relevant it can be detached from a Wait-set via the
detach_condition()call.
The first step is usually done in an initialization phase, while the others are put in the application main loop.
class ApplicationJob
{
WaitSet wait_set_;
GuardCondition terminate_condition_;
std::thread thread_;
void main_loop()
{
// Main loop is repeated until the terminate condition is triggered
while (false == terminate_condition_.get_trigger_value())
{
// Wait for any of the conditions to be triggered
ReturnCode_t ret_code;
ConditionSeq triggered_conditions;
ret_code = wait_set_.wait(triggered_conditions, eprosima::fastrtps::c_TimeInfinite);
if (RETCODE_OK != ret_code)
{
// ... handle error
continue;
}
// Process triggered conditions
for (Condition* cond : triggered_conditions)
{
StatusCondition* status_cond = dynamic_cast<StatusCondition*>(cond);
if (nullptr != status_cond)
{
Entity* entity = status_cond->get_entity();
StatusMask changed_statuses = entity->get_status_changes();
// Process status. Liveliness changed and data available are depicted as an example
if (changed_statuses.is_active(StatusMask::liveliness_changed()))
{
std::cout << "Liveliness changed reported for entity " <<
entity->get_instance_handle() <<
std::endl;
}
if (changed_statuses.is_active(StatusMask::data_available()))
{
std::cout << "Data avilable on reader " << entity->get_instance_handle() << std::endl;
FooSeq data_seq;
SampleInfoSeq info_seq;
DataReader* reader = static_cast<DataReader*>(entity);
// Process all the samples until no one is returned
while (RETCODE_OK == reader->take(data_seq, info_seq,
LENGTH_UNLIMITED, ANY_SAMPLE_STATE,
ANY_VIEW_STATE, ANY_INSTANCE_STATE))
{
// Both info_seq.length() and data_seq.length() will have the number of samples returned
for (FooSeq::size_type n = 0; n < info_seq.length(); ++n)
{
// Only samples with valid data should be accessed
if (info_seq[n].valid_data &&
reader->is_sample_valid(&data_seq[n], &info_seq[n]))
{
// Process sample on data_seq[n]
}
}
// must return the loaned sequences when done processing
reader->return_loan(data_seq, info_seq);
}
}
}
}
}
}
public:
ApplicationJob(
const std::vector<DataReader*>& readers,
const std::vector<DataWriter*>& writers)
{
// Add a GuardCondition, so we can signal the processing thread to stop
wait_set_.attach_condition(terminate_condition_);
// Add the status condition of every reader and writer
for (DataReader* reader : readers)
{
wait_set_.attach_condition(reader->get_statuscondition());
}
for (DataWriter* writer : writers)
{
wait_set_.attach_condition(writer->get_statuscondition());
}
thread_ = std::thread(&ApplicationJob::main_loop, this);
}
~ApplicationJob()
{
// Signal the GuardCondition to force the WaitSet to wake up
terminate_condition_.set_trigger_value(true);
// Wait for the thread to finish
thread_.join();
}
};
// Application initialization
ReturnCode_t ret_code;
std::vector<DataReader*> application_readers;
std::vector<DataWriter*> application_writers;
// Create the participant, topics, readers, and writers.
ret_code = create_dds_application(application_readers, application_writers);
if (RETCODE_OK != ret_code)
{
// ... handle error
return;
}
{
ApplicationJob main_loop_thread(application_readers, application_writers);
// ... wait for application termination signaling (signal handler, user input, etc)
// ... Destructor of ApplicationJob takes care of stopping the processing thread
}
// Destroy readers, writers, topics, and participant
destroy_dds_application();
Calling the wait() operation on the Wait-set will block the calling thread
if the trigger value of all the conditions attached to it are false.
The thread will wake up, and the wait() operation will return RETCODE_OK, whenever the trigger value of any
of the attached conditions becomes true.
GuardCondition¶
A condition for which the trigger value is completely controlled by the application via its
set_trigger_value() operation.
StatusCondition¶
A condition that triggers whenever there are changes on the communication statuses of an Entity.
The sensitivity of the StatusCondition to a particular communication status is controlled by the
list of enabled_statuses set on the condition by means of the set_enabled_statuses() operation.
ReadCondition¶
A condition that triggers whenever the DataReader that created it contains at least a sample with SampleState, ViewState, and InstanceState matching those of the ReadCondition.
The fact that the trigger value of a ReadCondition is dependent on the presence of samples on the
associated DataReader implies that a single take operation can potentially change the trigger value
of several ReadCondition conditions.
For example, if all samples are taken, any ReadCondition associated with the DataReader that were
triggered before, will see their trigger value changed to false.
Note that this does not guarantee that WaitSet objects that were separately attached to those
conditions will not be woken up.
Once we have trigger_value == true on a condition, it may wake up the attached Wait-set.
The condition transitioning to trigger_value == false does not necessarily ‘unwakeup’ the Wait-set,
as ‘unwakening’ may not be possible in general.
The consequence is that an application blocked on a Wait-set may return from the wait with a list
of conditions, some of which are no longer triggered.
This also may be the consequence of user actions.
A user manually calling set_trigger_value() could potentially trigger the same behavior.
This is unavoidable if multiple threads are concurrently waiting on separate Wait-set objects and
taking data associated with the same DataReader entity.
To elaborate further, consider the following example: A ReadCondition that has a sample_state_mask = {NOT_READ} will have trigger_value == true whenever a new sample arrives and will transition to false as soon as all the newly-arrived samples are either read (so their status changes to READ) or taken (so they are no longer managed by the DataReader). However, if the same ReadCondition had a sample_state_mask = {READ, NOT_READ}, then the trigger_value would only become false once all the newly-arrived samples are taken (it is not sufficient to read them as that would only change the SampleState to READ which overlaps the mask on the ReadCondition).
Domain¶
A domain represents a separate communication plane. It creates a logical separation among the Entities that share a common communication infrastructure. Conceptually, it can be seen as a virtual network linking all applications running on the same domain and isolating them from applications running on different domains. This way, several independent distributed applications can coexist in the same physical network without interfering, or even being aware of each other.
Every domain has a unique identifier, called domainId, that is implemented as a uint32 value.
Applications that share this domainId belong to the same domain and will be able to communicate.
For an application to be added to a domain, it must create an instance of DomainParticipant with the appropriate domainId. Instances of DomainParticipant are created through the DomainParticipantFactory singleton.
Partitions introduce another entity isolation level within the domain. While DomainParticipant will be able to communicate with each other if they are in the same domain, it is still possible to isolate their Publishers and Subscribers assigning them to different Partitions.
Domain class diagram¶
DomainParticipant¶
A DomainParticipant is the entry point of the application to a domain. Every DomainParticipant is linked to a single domain from its creation, and contains all the Entities related to that domain. It also acts as a factory for Publisher, Subscriber and Topic.
The behavior of the DomainParticipant can be modified with the QoS values
specified on DomainParticipantQos.
The QoS values can be set at the creation of the DomainParticipant,
or modified later with DomainParticipant::set_qos() member function.
As an Entity, DomainParticipant accepts a DomainParticipantListener that will be notified of status changes on the DomainParticipant instance.
DomainParticipantQos¶
DomainParticipantQos controls the behavior of the DomainParticipant.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
Yes |
|
|
Yes |
|
|
No |
|
|
No |
|
|
No* |
|
|
No |
|
|
No |
|
|
No |
|
|
No |
|
|
No |
|
|
No |
|
|
No |
Important
The only mutable field in WireProtocolConfigQos is m_DiscoveryServers, which is contained in
discovery_config within builtin (see
Modifying remote servers list at run time).
Important
Upon the call to create_participant(), if Fast DDS is compiled with statistics support
(enabled by default, see CMake options), the internal DomainParticipantQos may differ from the input
DomainParticipantQos (see Statistics Module Settings).
This entails that applications willing to further modify the DomainParticipantQos after
DomainParticipant creation should:
Retrieve the internal
DomainParticipantQosby the means ofDomainParticipant::get_qos().Perform the desired modifications.
Update the
DomainParticipantQosby the means ofDomainParticipant::set_qos().
Refer to the detailed description of each QosPolicy class for more information about their usage and default values.
The QoS value of a previously created DomainParticipant can be modified using the
DomainParticipant::set_qos() member function.
Trying to modify an immutable QosPolicy on an already enabled DomainParticipant
will result on an error.
In such case, no changes will be applied and the DomainParticipant will keep its
previous DomainParticipantQos.
// Create a DomainParticipant with default DomainParticipantQos
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DomainParticipantQos qos = participant->get_qos();
// Modify QoS attributes
qos.entity_factory().autoenable_created_entities = false;
// Assign the new Qos to the object
participant->set_qos(qos);
Default DomainParticipantQos¶
The default DomainParticipantQos refers to the value returned by the
get_default_participant_qos() member function on the
DomainParticipantFactory singleton.
The special value PARTICIPANT_QOS_DEFAULT can be used as QoS argument on
create_participant()
or DomainParticipant::set_qos() member functions to indicate that the current default
DomainParticipantQos should be used.
When the system starts, the default DomainParticipantQos is equivalent to the default constructed
value DomainParticipantQos().
The default DomainParticipantQos can be modified at any time using the
set_default_participant_qos()
member function on the DomainParticipantFactory singleton.
Modifying the default DomainParticipantQos will not affect already existing
DomainParticipant instances.
// Get the current QoS or create a new one from scratch
DomainParticipantQos qos_type1 = DomainParticipantFactory::get_instance()->get_default_participant_qos();
// Modify QoS attributes
// (...)
// Set as the new default TopicQos
if (DomainParticipantFactory::get_instance()->set_default_participant_qos(qos_type1) !=
RETCODE_OK)
{
// Error
return;
}
// Create a DomainParticipant with the new default DomainParticipantQos.
DomainParticipant* participant_with_qos_type1 =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DomainParticipantQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default TopicQos
if (DomainParticipantFactory::get_instance()->set_default_participant_qos(qos_type2) !=
RETCODE_OK)
{
// Error
return;
}
// Create a Topic with the new default TopicQos.
DomainParticipant* participant_with_qos_type2 =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant_with_qos_type2)
{
// Error
return;
}
// Resetting the default DomainParticipantQos to the original default constructed values
if (DomainParticipantFactory::get_instance()->set_default_participant_qos(PARTICIPANT_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (DomainParticipantFactory::get_instance()->set_default_participant_qos(DomainParticipantQos())
!= RETCODE_OK)
{
// Error
return;
}
set_default_participant_qos()
member function also accepts the value PARTICIPANT_QOS_DEFAULT
as input argument.
This will reset the current default DomainParticipantQos to the default constructed value
DomainParticipantQos().
// Create a custom DomainParticipantQos
DomainParticipantQos custom_qos;
// Modify QoS attributes
// (...)
// Create a DomainParticipant with a custom DomainParticipantQos
DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(0, custom_qos);
if (nullptr == participant)
{
// Error
return;
}
// Set the QoS on the participant to the default
if (participant->set_qos(PARTICIPANT_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (participant->set_qos(DomainParticipantFactory::get_instance()->get_default_participant_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value PARTICIPANT_QOS_DEFAULT has different meaning depending on where it is used:
On
create_participant()andDomainParticipant::set_qos()it refers to the default DomainParticipantQos as returned byget_default_participant_qos().On
set_default_participant_qos()it refers to the default constructedDomainParticipantQos().
DomainParticipantListener¶
DomainParticipantListener is an abstract class defining the callbacks that will be triggered
in response to state changes on the DomainParticipant.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
DomainParticipantListener inherits from TopicListener,
PublisherListener, and SubscriberListener.
Therefore, it has the ability to react to every kind of event that is
reported to any of its attached Entities.
Since events are always notified to the most specific Entity Listener that can handle the event,
callbacks that DomainParticipantListener inherits from other Listeners will only be called
if no other Entity was able to handle the event,
either because it has no Listener attached,
or because the callback is disabled by the StatusMask on the Entity.
Additionally, DomainParticipantListener adds the following non-standard callbacks:
on_participant_discovery(): A new DomainParticipant is discovered in the same domain, a previously known DomainParticipant has been removed, or some DomainParticipant has changed its QoS. This method provides an overload with an additional boolean output parameter so a discovery callback can tell the middleware if a newly discovered participant has to be ignored via the use of theignore_participant(). This overload should be used when there is a need to ignore participants inside the discovery callback, since callingignore_participant()inside the listener might deadlock. If both callbacks are implemented, the discovery callback with theshould_be_ignoredboolean flag takes precedence. The second discovery callback is only executed if the discovered DomainParticipant is not ignored in the first callback (should_be_ignoredparameter returnsfalse).
on_data_reader_discovery(): A new DataReader is discovered in the same domain, a previously known DataReader has been removed, or some DataReader has changed its QoS.
on_data_writer_discovery(): A new DataWriter is discovered in the same domain, a previously known DataWriter has been removed, or some DataWriter has changed its QoS.
onParticipantAuthentication(): Informs about the result of the authentication process of a remote DomainParticipant (either on failure or success).
Important
For more information about callbacks and its hierarchy, please refer to Listener.
class CustomDomainParticipantListener : public DomainParticipantListener
{
public:
CustomDomainParticipantListener()
: DomainParticipantListener()
{
}
virtual ~CustomDomainParticipantListener()
{
}
void on_participant_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ParticipantDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DISCOVERED_PARTICIPANT)
{
std::cout << "New participant discovered" << std::endl;
// The following line can be modified to evaluate whether the discovered participant should be ignored
// (usually based on fields present in the discovery information)
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered participant
}
}
else if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::REMOVED_PARTICIPANT ||
info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DROPPED_PARTICIPANT)
{
std::cout << "Participant lost" << std::endl;
}
}
#if HAVE_SECURITY
void onParticipantAuthentication(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ParticipantAuthenticationInfo&& info) override
{
if (info.status == eprosima::fastrtps::rtps::ParticipantAuthenticationInfo::AUTHORIZED_PARTICIPANT)
{
std::cout << "A participant was authorized" << std::endl;
}
else if (info.status == eprosima::fastrtps::rtps::ParticipantAuthenticationInfo::UNAUTHORIZED_PARTICIPANT)
{
std::cout << "A participant failed authorization" << std::endl;
}
}
#endif // if HAVE_SECURITY
void on_data_reader_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ReaderDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
if (info.status == eprosima::fastrtps::rtps::ReaderDiscoveryInfo::DISCOVERED_READER)
{
std::cout << "New datareader discovered" << std::endl;
// The following line can be modified to evaluate whether the discovered datareader should be ignored
// (usually based on fields present in the discovery information)
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered datareader
}
}
else if (info.status == eprosima::fastrtps::rtps::ReaderDiscoveryInfo::REMOVED_READER)
{
std::cout << "Datareader lost" << std::endl;
}
}
void on_data_writer_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::WriterDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
if (info.status == eprosima::fastrtps::rtps::WriterDiscoveryInfo::DISCOVERED_WRITER)
{
std::cout << "New datawriter discovered" << std::endl;
// The following line can be modified to evaluate whether the discovered datawriter should be ignored
// (usually based on fields present in the discovery information)
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered datawriter
}
}
else if (info.status == eprosima::fastrtps::rtps::WriterDiscoveryInfo::REMOVED_WRITER)
{
std::cout << "Datawriter lost" << std::endl;
}
}
};
DomainParticipantFactory¶
The sole purpose of this class is to allow the creation and destruction of DomainParticipant objects.
DomainParticipantFactory itself has no factory, it is a singleton object that can be accessed
through the get_instance() static member function on the DomainParticipantFactory
class.
The behavior of the DomainParticipantFactory can be modified with the QoS values
specified on DomainParticipantFactoryQos.
Since the DomainParticipantFactory is a singleton, its QoS can only be modified with the
DomainParticipantFactory::set_qos() member function.
DomainParticipantFactory does not accept any Listener, since it is not an Entity.
DomainParticipantFactoryQos¶
DomainParticipantFactoryQos controls the behavior of the DomainParticipantFactory.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
Yes |
|
|
No |
|
|
No |
Since the DomainParticipantFactory is a singleton, its QoS can only be modified with the
DomainParticipantFactory::set_qos() member function.
DomainParticipantFactoryQos qos;
// Setting autoenable_created_entities to true makes the created DomainParticipants
// to be enabled upon creation
qos.entity_factory().autoenable_created_entities = true;
if (DomainParticipantFactory::get_instance()->set_qos(qos) != RETCODE_OK)
{
// Error
return;
}
// Create a DomainParticipant with the new DomainParticipantFactoryQos.
// The returned DomainParticipant is already enabled
DomainParticipant* enabled_participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == enabled_participant)
{
// Error
return;
}
// Setting autoenable_created_entities to false makes the created DomainParticipants
// to be disabled upon creation
qos.entity_factory().autoenable_created_entities = false;
if (DomainParticipantFactory::get_instance()->set_qos(qos) != RETCODE_OK)
{
// Error
return;
}
// Create a DomainParticipant with the new DomainParticipantFactoryQos.
// The returned DomainParticipant is disabled and will need to be enabled explicitly
DomainParticipant* disabled_participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == disabled_participant)
{
// Error
return;
}
Loading profiles from an XML file¶
To create Entities based on XML profiles, the file containing such profiles must be loaded first.
If the profile is described in one of the default loaded files, it will be automatically available on initialization.
Otherwise, load_XML_profiles_file() member function can be used to load the profiles in
the XML.
See section XML profiles for more information regarding XML profile format and automatic loading.
Once loaded, the name of the profiles can be used to create Entities that will have QoS settings according to the profile specifications.
// Load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Profiles can now be used to create Entities
DomainParticipant* participant_with_profile =
DomainParticipantFactory::get_instance()->create_participant_with_profile(0, "participant_profile");
if (nullptr == participant_with_profile)
{
// Error
return;
}
Creating a DomainParticipant¶
Creation of a DomainParticipant is done with the create_participant()
member function on the
DomainParticipantFactory singleton, that acts as a factory for the DomainParticipant.
Mandatory arguments are:
The
DomainIdthat identifies the domain where the DomainParticipant will be created.The DomainParticipantQos describing the behavior of the DomainParticipant. If the provided value is
TOPIC_QOS_DEFAULT, the value of the DomainParticipantQos is used.
Optional arguments are:
A Listener derived from DomainParticipantListener, implementing the callbacks that will be triggered in response to events and state changes on the DomainParticipant. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DomainParticipantListener. By default all events are enabled.
Warning
Following the DDSI-RTPS V2.2 standard (Section 9.6.1.1), the default ports are calculated depending on the
DomainId, as it is explained in section Well Known Ports.
Thus, it is encouraged to use DomainId lower than 200
(over DomainId 233 default port assign will fail consistently).
create_participant()
will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DomainParticipant with default DomainParticipantQos and no Listener
// The value PARTICIPANT_QOS_DEFAULT is used to denote the default QoS.
DomainParticipant* participant_with_default_attributes =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant_with_default_attributes)
{
// Error
return;
}
// A custom DomainParticipantQos can be provided to the creation method
DomainParticipantQos custom_qos;
// Modify QoS attributes
// (...)
DomainParticipant* participant_with_custom_qos =
DomainParticipantFactory::get_instance()->create_participant(0, custom_qos);
if (nullptr == participant_with_custom_qos)
{
// Error
return;
}
// Create a DomainParticipant with default QoS and a custom Listener.
// CustomDomainParticipantListener inherits from DomainParticipantListener.
// The value PARTICIPANT_QOS_DEFAULT is used to denote the default QoS.
CustomDomainParticipantListener custom_listener;
DomainParticipant* participant_with_default_qos_and_custom_listener =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT,
&custom_listener);
if (nullptr == participant_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a DomainParticipant¶
Instead of using a DomainParticipantQos, the name of a profile
can be used to create a DomainParticipant with the create_participant_with_profile()
member function on the DomainParticipantFactory singleton.
Mandatory arguments are:
The
DomainIdthat identifies the domain where the DomainParticipant will be created. Do not useDomainIdhigher than 200 (see Creating a DomainParticipant).The name of the profile to be applied to the DomainParticipant.
Optional arguments are:
A Listener derived from DomainParticipantListener, implementing the callbacks that will be triggered in response to events and state changes on the DomainParticipant. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DomainParticipantListener. By default all events are enabled.
create_participant_with_profile() will return a null pointer if there was an error during
the operation, e.g if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DomainParticipant using a profile and no Listener
DomainParticipant* participant_with_profile =
DomainParticipantFactory::get_instance()->create_participant_with_profile(0, "participant_profile");
if (nullptr == participant_with_profile)
{
// Error
return;
}
// Create a DomainParticipant using a profile and a custom Listener.
// CustomDomainParticipantListener inherits from DomainParticipantListener.
CustomDomainParticipantListener custom_listener;
DomainParticipant* participant_with_profile_and_custom_listener =
DomainParticipantFactory::get_instance()->create_participant_with_profile(0, "participant_profile",
&custom_listener);
if (nullptr == participant_with_profile_and_custom_listener)
{
// Error
return;
}
Default profile DomainParticipant creation¶
If there is a profile already exported in the environment (please refer to XML profiles for related
information), creating a DomainParticipant with the
create_participant_with_default_profile() member function on the
DomainParticipantFactory singleton would use that settings to configure the participant.
If the profile has not been exported, the DomainParticipant will be created with the default values per
DomainParticipantQos, and 0 as DomainId.
Optional arguments are:
A Listener derived from DomainParticipantListener, implementing the callbacks that will be triggered in response to events and state changes on the DomainParticipant. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DomainParticipantListener. By default all events are enabled.
create_participant_with_default_profile() will return a null pointer if there was an
error during the operation.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See XML profiles.
// Create a DomainParticipant using the environment profile and no Listener
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant_with_default_profile();
if (nullptr == participant)
{
// Error
return;
}
// Create a DomainParticipant using the environment profile and a custom Listener.
// CustomDomainParticipantListener inherits from DomainParticipantListener.
CustomDomainParticipantListener custom_listener;
DomainParticipant* participant_with_custom_listener =
DomainParticipantFactory::get_instance()->create_participant_with_default_profile(
&custom_listener, StatusMask::none());
if (nullptr == participant_with_custom_listener)
{
// Error
return;
}
Deleting a DomainParticipant¶
A DomainParticipant can be deleted with the delete_participant() member function on the
DomainParticipantFactory singleton.
Note
A DomainParticipant can only be deleted if all Entities belonging to the participant
(Publisher, Subscriber or Topic) have already been deleted.
Otherwise, the function will issue an error and the DomainParticipant will not be deleted.
This can be performed by using the delete_contained_entities() member function of the
DomainParticipant.
// Create a DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Use the DomainParticipant to communicate
// (...)
// Delete entities created by the DomainParticipant
if (participant->delete_contained_entities() != RETCODE_OK)
{
// DomainParticipant failed to delete the entities it created.
return;
}
// Delete the DomainParticipant
if (DomainParticipantFactory::get_instance()->delete_participant(participant) != RETCODE_OK)
{
// Error
return;
}
Partitions¶
Partitions introduce a logical entity isolation level concept inside the physical isolation induced by a Domain. They represent another level to separate Publishers and Subscribers beyond Domain and Topic. For a Publisher to communicate with a Subscriber, they have to belong at least to one common partition. In this sense, partitions represent a light mechanism to provide data separation among endpoints:
Unlike Domain and Topic, Partitions can be changed dynamically during the life cycle of the endpoint with little cost. Specifically, no new threads are launched, no new memory is allocated, and the change history is not affected. Beware that modifying the Partition membership of endpoints will trigger the announcement of the new QoS configuration, and as a result, new endpoint matching may occur, depending on the new Partition configuration. Changes on the memory allocation and running threads may occur due to the matching of remote endpoints.
Unlike Domain and Topic, an endpoint can belong to several Partitions at the same time. For certain data to be shared over different Topics, there must be a different Publisher for each Topic, each of them sharing its own history of changes. On the other hand, a single Publisher can share the same data over different Partitions using a single topic data change, thus reducing network overload.
The Partition membership of an endpoint can be configured on the PartitionQosPolicy data member of the PublisherQos or SubscriberQos objects. This member holds a list of Partition name strings. If no Partition is defined for an entity, it will be automatically included in the default nameless Partition. Therefore, a Publisher and a Subscriber that specify no Partition will still be able to communicate through the default nameless Partition.
Warning
Partitions are linked to the endpoint and not to the changes. This means that the endpoint history is oblivious to modifications in the Partitions. For example, if a Publisher switches Partitions and afterwards needs to resend some older change again, it will deliver it to the new Partition set, regardless of which Partitions were defined when the change was created. This means that a late joiner Subscriber may receive changes that were created when another set of Partitions was active.
Wildcards in Partitions¶
Partition name entries can have wildcards following the naming conventions defined by the
POSIX fnmatch API (1003.2-1992 section B.6).
Entries with wildcards can match several names, allowing an endpoint to easily be included in several Partitions.
Two Partition names with wildcards will match if either of them matches the other one according to fnmatch.
That is, the matching is checked both ways.
For example, consider the following configuration:
A Publisher with Partition
part*A Subscriber with Partition
partition*
Even though partition* does not match part*, these Publisher and Subscriber
will communicate between them because part* matches partition*.
Note that a Partition with name * will match any other partition except the default Partition.
Full example¶
Given a system with the following Partition configuration:
Participant_1 |
Pub_11 |
{“Partition_1”, “Partition_2”} |
Pub_12 |
{“*”} |
|
Participant_2 |
Pub_21 |
{} |
Pub_22 |
{“Partition*”} |
|
Participant_3 |
Subs_31 |
{“Partition_1”} |
Subs_32 |
{“Partition_2”} |
|
Subs_33 |
{“Partition_3”} |
|
Subs_34 |
{} |
The endpoints will finally match the Partitions depicted on the following table.
Note that Pub_12 does not match the default Partition.
Participant_1 |
Participant_2 |
Participant_3 |
||||||
Pub_11 |
Pub_12 |
Pub_21 |
Pub_22 |
Subs_31 |
Subs_32 |
Subs_33 |
Subs_34 |
|
Partition_1 |
✓ |
✓ |
✕ |
✓ |
✓ |
✕ |
✕ |
✕ |
Partition_2 |
✓ |
✓ |
✕ |
✓ |
✕ |
✓ |
✕ |
✕ |
Partition_3 |
✕ |
✓ |
✕ |
✓ |
✕ |
✕ |
✓ |
✕ |
{default} |
✕ |
✕ |
✓ |
✕ |
✕ |
✕ |
✕ |
✓ |
The following table provides the communication matrix for the given example:
Participant_1 |
Participant_2 |
||||
Pub_11 |
Pub_12 |
Pub_21 |
Pub_22 |
||
Participant_3 |
Subs_31 |
✓ |
✓ |
✕ |
✓ |
Subs_32 |
✓ |
✓ |
✕ |
✓ |
|
Subs_33 |
✕ |
✓ |
✕ |
✓ |
|
Subs_34 |
✕ |
✕ |
✓ |
✕ |
|
The following piece of code shows the set of parameters needed for the use case depicted in this example.
C++ |
PublisherQos pub_11_qos;
pub_11_qos.partition().push_back("Partition_1");
pub_11_qos.partition().push_back("Partition_2");
PublisherQos pub_12_qos;
pub_12_qos.partition().push_back("*");
PublisherQos pub_21_qos;
//No partitions defined for pub_21
PublisherQos pub_22_qos;
pub_22_qos.partition().push_back("Partition*");
SubscriberQos subs_31_qos;
subs_31_qos.partition().push_back("Partition_1");
SubscriberQos subs_32_qos;
subs_32_qos.partition().push_back("Partition_2");
SubscriberQos subs_33_qos;
subs_33_qos.partition().push_back("Partition_3");
SubscriberQos subs_34_qos;
//No partitions defined for subs_34
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="pub_11">
<qos>
<partition>
<names>
<name>Partition_1</name>
<name>Partition_2</name>
</names>
</partition>
</qos>
</data_writer>
<data_writer profile_name="pub_12">
<qos>
<partition>
<names>
<name>*</name>
</names>
</partition>
</qos>
</data_writer>
<data_writer profile_name="pub_22">
<qos>
<partition>
<names>
<name>Partition*</name>
</names>
</partition>
</qos>
</data_writer>
<data_reader profile_name="subs_31">
<qos>
<partition>
<names>
<name>Partition_1</name>
</names>
</partition>
</qos>
</data_reader>
<data_reader profile_name="subs_32">
<qos>
<partition>
<names>
<name>Partition_2</name>
</names>
</partition>
</qos>
</data_reader>
<data_reader profile_name="subs_33">
<qos>
<partition>
<names>
<name>Partition_3</name>
</names>
</partition>
</qos>
</data_reader>
</profiles>
|
Publisher¶
A publication is defined by the association of a DataWriter to a Publisher. To start publishing the values of a data instance, the application creates a new DataWriter in a Publisher. This DataWriter will be bound to the Topic that describes the data type that is being transmitted. Remote subscriptions that match with this Topic will be able to receive the data value updates from the DataWriter.
Publisher¶
The Publisher acts on behalf of one or several DataWriter objects that belong to it. It serves as a container that allows grouping different DataWriter objects under a common configuration given by the PublisherQos of the Publisher.
DataWriter objects that belong to the same Publisher do not have any other relation among each other beyond the PublisherQos of the Publisher and act independently otherwise. Specifically, a Publisher can host DataWriter objects for different Topics and data types.
PublisherQos¶
PublisherQos controls the behavior of the Publisher.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
Refer to the detailed description of each QosPolicy class for more information about their usage and
default values.
The QoS value of a previously created Publisher can be modified using the
Publisher::set_qos() member function.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Publisher with default PublisherQos
Publisher* publisher =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
PublisherQos qos = publisher->get_qos();
// Modify QoS attributes
// (...)
// Assign the new Qos to the object
publisher->set_qos(qos);
Default PublisherQos¶
The default PublisherQos refers to the value returned by the
get_default_publisher_qos() member function on the DomainParticipant instance.
The special value PUBLISHER_QOS_DEFAULT can be used as QoS argument on
create_publisher() or Publisher::set_qos() member functions to indicate that the current
default PublisherQos should be used.
When the system starts, the default PublisherQos is equivalent to the default constructed
value PublisherQos().
The default PublisherQos can be modified at any time using the
set_default_publisher_qos() member function on the DomainParticipant instance.
Modifying the default PublisherQos will not affect already existing
Publisher instances.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
PublisherQos qos_type1 = participant->get_default_publisher_qos();
// Modify QoS attributes
// (...)
// Set as the new default PublisherQos
if (participant->set_default_publisher_qos(qos_type1) != RETCODE_OK)
{
// Error
return;
}
// Create a Publisher with the new default PublisherQos.
Publisher* publisher_with_qos_type1 =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
PublisherQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default PublisherQos
if (participant->set_default_publisher_qos(qos_type2) != RETCODE_OK)
{
// Error
return;
}
// Create a Publisher with the new default PublisherQos.
Publisher* publisher_with_qos_type2 =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher_with_qos_type2)
{
// Error
return;
}
// Resetting the default PublisherQos to the original default constructed values
if (participant->set_default_publisher_qos(PUBLISHER_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_publisher_qos(PublisherQos())
!= RETCODE_OK)
{
// Error
return;
}
set_default_publisher_qos() member function also accepts the special value
PUBLISHER_QOS_DEFAULT as input argument.
This will reset the current default PublisherQos to default constructed
value PublisherQos().
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a custom PublisherQos
PublisherQos custom_qos;
// Modify QoS attributes
// (...)
// Create a publisher with a custom PublisherQos
Publisher* publisher = participant->create_publisher(custom_qos);
if (nullptr == publisher)
{
// Error
return;
}
// Set the QoS on the publisher to the default
if (publisher->set_qos(PUBLISHER_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (publisher->set_qos(participant->get_default_publisher_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value PUBLISHER_QOS_DEFAULT has different meaning depending on where it is used:
On
create_publisher()andPublisher::set_qos()it refers to the default PublisherQos. as returned byget_default_publisher_qos().On
set_default_publisher_qos()it refers to the default constructedPublisherQos().
PublisherListener¶
PublisherListener is an abstract class defining the callbacks that will be triggered
in response to state changes on the Publisher.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
PublisherListener inherits from DataWriterListener.
Therefore, it has the ability to react to all events that are reported to the
DataWriter.
Since events are always notified to the most specific Entity Listener that can handle the event,
callbacks that PublisherListener inherits from DataWriterListener
will only be called if the triggering DataWriter has
no Listener attached,
or if the callback is disabled by the StatusMask on the DataWriter.
PublisherListener does not add any new callback.
Please, refer to the DataWriterListener for the list of inherited callbacks
and override examples.
Creating a Publisher¶
A Publisher always belongs to a DomainParticipant.
Creation of a Publisher is done with the create_publisher() member function on the
DomainParticipant instance, that acts as a factory for the Publisher.
Mandatory arguments are:
The PublisherQos describing the behavior of the Publisher. If the provided value is
PUBLISHER_QOS_DEFAULT, the value of the Default PublisherQos is used.
Optional arguments are:
A Listener derived from PublisherListener, implementing the callbacks that will be triggered in response to events and state changes on the Publisher. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the PublisherListener. By default all events are enabled.
create_publisher() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Publisher with default PublisherQos and no Listener
// The value PUBLISHER_QOS_DEFAULT is used to denote the default QoS.
Publisher* publisher_with_default_qos =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher_with_default_qos)
{
// Error
return;
}
// A custom PublisherQos can be provided to the creation method
PublisherQos custom_qos;
// Modify QoS attributes
// (...)
Publisher* publisher_with_custom_qos =
participant->create_publisher(custom_qos);
if (nullptr == publisher_with_custom_qos)
{
// Error
return;
}
// Create a Publisher with default QoS and a custom Listener.
// CustomPublisherListener inherits from PublisherListener.
// The value PUBLISHER_QOS_DEFAULT is used to denote the default QoS.
CustomPublisherListener custom_listener;
Publisher* publisher_with_default_qos_and_custom_listener =
participant->create_publisher(PUBLISHER_QOS_DEFAULT, &custom_listener);
if (nullptr == publisher_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a Publisher¶
Instead of using a PublisherQos, the name of a profile
can be used to create a Publisher with the create_publisher_with_profile()
member function on the DomainParticipant instance.
Mandatory arguments are:
A string with the name that identifies the Publisher.
Optional arguments are:
A Listener derived from PublisherListener, implementing the callbacks that will be triggered in response to events and state changes on the Publisher. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the PublisherListener. By default all events are enabled.
create_publisher_with_profile() will return a null pointer if there was an error during the
operation, e.g. if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Publisher using a profile and no Listener
Publisher* publisher_with_profile =
participant->create_publisher_with_profile("publisher_profile");
if (nullptr == publisher_with_profile)
{
// Error
return;
}
// Create a Publisher using a profile and a custom Listener.
// CustomPublisherListener inherits from PublisherListener.
CustomPublisherListener custom_listener;
Publisher* publisher_with_profile_and_custom_listener =
participant->create_publisher_with_profile("publisher_profile", &custom_listener);
if (nullptr == publisher_with_profile_and_custom_listener)
{
// Error
return;
}
Deleting a Publisher¶
A Publisher can be deleted with the delete_publisher() member function on the
DomainParticipant instance where the Publisher was created.
Note
A Publisher can only be deleted if all Entities belonging to the Publisher
(DataWriters) have already been deleted.
Otherwise, the function will issue an error and the Publisher will not be deleted.
This can be performed by using the delete_contained_entities() member function of the
Publisher.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Publisher
Publisher* publisher =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher)
{
// Error
return;
}
// Use the Publisher to communicate
// (...)
// Delete the entities the Publisher created.
if (publisher->delete_contained_entities() != RETCODE_OK)
{
// Publisher failed to delete the entities it created.
return;
}
// Delete the Publisher
if (participant->delete_publisher(publisher) != RETCODE_OK)
{
// Error
return;
}
DataWriter¶
A DataWriter is attached to exactly one Publisher that acts as a factory for it.
Additionally, each DataWriter is bound to a single Topic since its creation.
This Topic must exist prior to the creation of the DataWriter,
and must be bound to the data type that the DataWriter wants to publish.
The effect of creating a new DataWriter in a Publisher for a specific Topic is to initiate a new publication with the name and data type described by the Topic.
Once the DataWriter is created, the application can inform of changes in the data value using the
write() member function on the DataWriter.
These changes will be transmitted to all subscriptions matched with this publication.
DataWriterQos¶
DataWriterQos controls the behavior of the DataWriter.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
No (*) |
|
|
No |
|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
No |
|
|
No |
|
|
Yes (*) |
|
|
No |
|
|
No |
|
|
No |
The following non-consolidated property-assigned QoS apply to DataWriters:
Property name |
Non-consolidated QoS |
|---|---|
fastdds.push_mode |
|
partitions |
Refer to the detailed description of each QosPolicy class for more information about their usage and
default values.
Note
Reliability kind (whether the publication is reliable or best effort) is not mutable.
However, the max_blocking_time data member of ReliabilityQosPolicy can be modified any time.
Note
Not all data members of RTPSReliableWriterQos are mutable, please refer to RTPSReliableWriterQos for more information.
The QoS value of a previously created DataWriter can be modified using the
DataWriter::set_qos() member function.
// Create a DataWriter with default DataWriterQos
DataWriter* data_writer =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DataWriterQos qos = data_writer->get_qos();
// Modify QoS attributes
// (...)
// Assign the new Qos to the object
data_writer->set_qos(qos);
Default DataWriterQos¶
The default DataWriterQos refers to the value returned by the
get_default_datawriter_qos() member function on the Publisher instance.
The special value DATAWRITER_QOS_DEFAULT can be used as QoS argument on create_datawriter()
or DataWriter::set_qos() member functions to indicate that the current default
DataWriterQos should be used.
When the system starts, the default DataWriterQos is equivalent to the default constructed
value DataWriterQos().
The default DataWriterQos can be modified at any time using the
set_default_datawriter_qos() member function on the Publisher instance.
Modifying the default DataWriterQos will not affect already existing
DataWriter instances.
// Get the current QoS or create a new one from scratch
DataWriterQos qos_type1 = publisher->get_default_datawriter_qos();
// Modify QoS attributes
// (...)
// Set as the new default DataWriterQos
if (publisher->set_default_datawriter_qos(qos_type1) != RETCODE_OK)
{
// Error
return;
}
// Create a DataWriter with the new default DataWriterQos.
DataWriter* data_writer_with_qos_type1 =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DataWriterQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default DataWriterQos
if (publisher->set_default_datawriter_qos(qos_type2) != RETCODE_OK)
{
// Error
return;
}
// Create a DataWriter with the new default DataWriterQos.
DataWriter* data_writer_with_qos_type2 =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer_with_qos_type2)
{
// Error
return;
}
// Resetting the default DataWriterQos to the original default constructed values
if (publisher->set_default_datawriter_qos(DATAWRITER_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (publisher->set_default_datawriter_qos(DataWriterQos())
!= RETCODE_OK)
{
// Error
return;
}
set_default_datawriter_qos() member function also accepts the special value DATAWRITER_QOS_DEFAULT
as input argument.
This will reset the current default DataWriterQos to default constructed
value DataWriterQos().
// Create a custom DataWriterQos
DataWriterQos custom_qos;
// Modify QoS attributes
// (...)
// Create a DataWriter with a custom DataWriterQos
DataWriter* data_writer = publisher->create_datawriter(topic, custom_qos);
if (nullptr == data_writer)
{
// Error
return;
}
// Set the QoS on the DataWriter to the default
if (data_writer->set_qos(DATAWRITER_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (data_writer->set_qos(publisher->get_default_datawriter_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value DATAWRITER_QOS_DEFAULT has different meaning depending on where it is used:
On
create_datawriter()andDataWriter::set_qos()it refers to the default DataWriterQos as returned byget_default_datawriter_qos().On
set_default_datawriter_qos()it refers to the default constructedDataWriterQos().
DataWriterListener¶
DataWriterListener is an abstract class defining the callbacks that will be triggered
in response to state changes on the DataWriter.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
DataWriterListener defines the following callbacks:
on_publication_matched(): The DataWriter has found a DataReader that matches the Topic and has a common partition and a compatible QoS, or has ceased to be matched with a DataReader that was previously considered to be matched.on_offered_deadline_missed(): The DataWriter failed to provide data within the deadline period configured on its DataWriterQos. It will be called for each deadline period and data instance for which the DataWriter failed to provide data.on_offered_incompatible_qos(): The DataWriter has found a DataReader that matches the Topic and has a common partition, but with a requested QoS that is incompatible with the one defined on the DataWriter.on_liveliness_lost(): The DataWriter did not respect the liveliness configuration on its DataWriterQos, and therefore, DataReader entities will consider the DataWriter as no longer active.on_unacknowledged_sample_removed(): The Datawriter has removed a sample that has not been acknowledged by every matched DataReader.
on_unacknowledged_sample_removed callback¶
on_unacknowledged_sample_removed() non-standard callback notifies the user when a sample has
been removed without being sent/received by the matched DataReaders.
This could happen in constrained networks or if the publication throughput is too demanding.
This callback can be used to detect these situations so the publishing application can apply some solution to ease this
issue like reducing the publication rate.
The criteria to consider that a sample has been removed without being acknowledged depends on the ReliabilityQosPolicy:
BEST_EFFORT_RELIABILITY_QOSDataWriters will notify that a sample has been removed while unacknowledged if the sample has not been sent through the transport.RELIABLE_RELIABILITY_QOSDataWriters consider samples to have been removed unacknowledged if not every matched DataReader has confirmed its reception by sending the corresponding meta-trafficACKmessage. Consequently, a sample that is notified as removed unacknowledged might be received by one or more DataReaders, but not by every matched one, or at least, theACKmessage has not been received at the moment of sample removal. A race condition is inevitable in this case, because when the sample is removed, theACKfrom some matched DataReader is missing, but that means that it might have been lost in the transmission or that the message is still coming through and it will be received after the sample removal. Thus, this criteria may include false positives, but from the user’s point of view, it is more meaningful to know when the sample has not been acknowledged by every matched DataReader even if some samples are erroneously notified.
A specific case must be considered for reliable DataWriters with DisablePositiveACKsQosPolicy enabled.
This policy disables the sending of positive ACK messages, unless the sample has been lost in which case the matched
DataReader notifies the loss with a negative NACK message.
If no NACK has been received in the time defined in the QoS policy, the sample is considered to be received.
Again, this is prone to race conditions because the NACK message might be on its way or have been lost in the
network.
For this specific case, where ACK messages are not going to be received, the reliable DataWriter uses the same
criteria as the best effort DataWriter.
class CustomDataWriterListener : public DataWriterListener
{
public:
CustomDataWriterListener()
: DataWriterListener()
{
}
virtual ~CustomDataWriterListener()
{
}
void on_publication_matched(
DataWriter* writer,
const PublicationMatchedStatus& info) override
{
static_cast<void>(writer);
if (info.current_count_change == 1)
{
std::cout << "Matched a remote Subscriber for one of our Topics" << std::endl;
}
else if (info.current_count_change == -1)
{
std::cout << "Unmatched a remote Subscriber" << std::endl;
}
}
void on_offered_deadline_missed(
DataWriter* writer,
const OfferedDeadlineMissedStatus& status) override
{
static_cast<void>(writer);
static_cast<void>(status);
std::cout << "Some data could not be delivered on time" << std::endl;
}
void on_offered_incompatible_qos(
DataWriter* writer,
const OfferedIncompatibleQosStatus& status) override
{
std::cout << "Found a remote Topic with incompatible QoS (QoS ID: " << status.last_policy_id <<
")" << std::endl;
}
void on_liveliness_lost(
DataWriter* writer,
const LivelinessLostStatus& status) override
{
static_cast<void>(writer);
static_cast<void>(status);
std::cout << "Liveliness lost. Matched Subscribers will consider us offline" << std::endl;
}
void on_unacknowledged_sample_removed(
DataWriter* writer,
const InstanceHandle_t& instance) override
{
static_cast<void>(writer);
static_cast<void>(instance);
std::cout << "Sample removed unacknowledged" << std::endl;
}
};
Creating a DataWriter¶
A DataWriter always belongs to a Publisher.
Creation of a DataWriter is done with the create_datawriter() member function on the
Publisher instance, that acts as a factory for the DataWriter.
Mandatory arguments are:
A Topic bound to the data type that will be transmitted.
The DataWriterQos describing the behavior of the DataWriter. If the provided value is
DATAWRITER_QOS_DEFAULT, the value of the Default DataWriterQos is used.
Optional arguments are:
A Listener derived from DataWriterListener, implementing the callbacks that will be triggered in response to events and state changes on the DataWriter. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DataWriterListener. By default all events are enabled.
create_datawriter() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DataWriter with default DataWriterQos and no Listener
// The value DATAWRITER_QOS_DEFAULT is used to denote the default QoS.
DataWriter* data_writer_with_default_qos =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer_with_default_qos)
{
// Error
return;
}
// A custom DataWriterQos can be provided to the creation method
DataWriterQos custom_qos;
// Modify QoS attributes
// (...)
DataWriter* data_writer_with_custom_qos =
publisher->create_datawriter(topic, custom_qos);
if (nullptr == data_writer_with_custom_qos)
{
// Error
return;
}
// Create a DataWriter with default QoS and a custom Listener.
// CustomDataWriterListener inherits from DataWriterListener.
// The value DATAWRITER_QOS_DEFAULT is used to denote the default QoS.
CustomDataWriterListener custom_listener;
DataWriter* data_writer_with_default_qos_and_custom_listener =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT, &custom_listener);
if (nullptr == data_writer_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a DataWriter¶
Instead of using a DataWriterQos, the name of a profile
can be used to create a DataWriter with the create_datawriter_with_profile()
member function on the Publisher instance.
Mandatory arguments are:
A Topic bound to the data type that will be transmitted.
A string with the name that identifies the DataWriter.
Optional arguments are:
A Listener derived from DataWriterListener, implementing the callbacks that will be triggered in response to events and state changes on the DataWriter. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DataWriterListener. By default all events are enabled.
create_datawriter_with_profile() will return a null pointer if there was an error during the
operation, e.g. if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DataWriter using a profile and no Listener
DataWriter* data_writer_with_profile =
publisher->create_datawriter_with_profile(topic, "data_writer_profile");
if (nullptr == data_writer_with_profile)
{
// Error
return;
}
// Create a DataWriter using a profile and a custom Listener.
// CustomDataWriterListener inherits from DataWriterListener.
CustomDataWriterListener custom_listener;
DataWriter* data_writer_with_profile_and_custom_listener =
publisher->create_datawriter_with_profile(topic, "data_writer_profile", &custom_listener);
if (nullptr == data_writer_with_profile_and_custom_listener)
{
// Error
return;
}
Creating a DataWriter with a custom PayloadPool¶
A custom PayloadPool can be passed as an argument during the creation of a DataWriter. This allows for customizing the management of the information exchanged between DataWriters and DataReaders. The same configuration can be set in the opposite endpoint.
// A DataWriterQos must be provided to the creation method
DataWriterQos qos;
// Create PayloadPool
std::shared_ptr<eprosima::fastrtps::rtps::IPayloadPool> payload_pool =
std::dynamic_pointer_cast<eprosima::fastrtps::rtps::IPayloadPool>(std::make_shared<CustomPayloadPool>());
DataWriter* data_writer = publisher->create_datawriter(topic, qos, nullptr, StatusMask::all(), payload_pool);
if (nullptr == data_writer)
{
// Error
return;
}
This configuration can be performed also in the RTPS layer. The customization example applies both layers.
Deleting a DataWriter¶
A DataWriter can be deleted with the delete_datawriter() member function on the
Publisher instance where the DataWriter was created.
// Create a DataWriter
DataWriter* data_writer =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer)
{
// Error
return;
}
// Use the DataWriter to communicate
// (...)
// Delete the DataWriter
if (publisher->delete_datawriter(data_writer) != RETCODE_OK)
{
// Error
return;
}
Publishing data¶
The user informs of a change in the value of a data instance with the write() member function on the
DataWriter. This change will then be communicated to every
DataReader matched with the DataWriter.
As a side effect, this operation asserts liveliness on the DataWriter itself,
the Publisher and the DomainParticipant.
The function takes two arguments:
A pointer to the data instance with the new values.
The handler to the instance.
An empty (i.e., default constructed InstanceHandle_t) instance handler can be used for the argument handle.
This indicates that the identity of the instance should be automatically deduced from the key of the
instance data.
Alternatively, the member function write() is overloaded to take only the pointer to the data instance,
which will always deduced the identity from the key of the instance data.
If the handle is not empty, then it must correspond to the value obtained with the getKey() of the
TypeSupport instance.
Otherwise the write function will fail with RETCODE_PRECONDITION_NOT_MET.
// Register the data type in the DomainParticipant.
TypeSupport custom_type_support(new CustomDataType());
custom_type_support.register_type(participant, custom_type_support.get_type_name());
// Create a Topic with the registered type.
Topic* custom_topic =
participant->create_topic("topic_name", custom_type_support.get_type_name(), TOPIC_QOS_DEFAULT);
if (nullptr == custom_topic)
{
// Error
return;
}
// Create a DataWriter
DataWriter* data_writer =
publisher->create_datawriter(custom_topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer)
{
// Error
return;
}
// Get a data instance
void* data = custom_type_support->createData();
// Fill the data values
// (...)
// Publish the new value, deduce the instance handle
if (data_writer->write(data, eprosima::fastrtps::rtps::InstanceHandle_t()) != RETCODE_OK)
{
// Error
return;
}
// The data instance can be reused to publish new values,
// but delete it at the end to avoid leaks
custom_type_support->deleteData(data);
Blocking of the write operation¶
If the reliability kind is set to RELIABLE on the DataWriterQos,
the write() operation may block.
Specifically, if the limits specified in the configured resource limits have been reached, the
write() operation will block waiting for space to become available.
Under these circumstances, the reliability max_blocking_time configures the maximum time
the write operation may block waiting.
If max_blocking_time elapses before the DataWriter is able to store
the modification without exceeding the limits, the write operation will fail and return TIMEOUT.
Borrowing a data buffer¶
When the user calls write() with a new sample value,
the data is copied from the given sample to the DataWriter’s memory.
For large data types this copy can consume significant time and memory resources.
Instead, the DataWriter can loan a sample from its memory to the user,
and the user can fill this sample with the required values.
When write() is called with such a loaned sample,
the DataWriter does not copy its contents, as it already owns the buffer.
To use loaned data samples in publications, perform the following steps:
Get a reference to a loaned sample using
loan_sample().Use the reference to build the data sample.
Write the sample using
write().
Once write() has been called with a loaned sample,
the loan is considered returned, and it is not safe to make any
changes on the contents of the sample.
If function loan_sample() is called but the sample is never written,
the loan must be returned to the DataWriter using discard_loan().
Otherwise the DataWriter may run out of samples.
// Borrow a data instance
void* data = nullptr;
if (RETCODE_OK == data_writer->loan_sample(data))
{
bool error = false;
// Fill the data values
// (...)
if (error)
{
// Return the loan without publishing
data_writer->discard_loan(data);
return;
}
// Publish the new value
if (data_writer->write(data, eprosima::fastrtps::rtps::InstanceHandle_t()) != RETCODE_OK)
{
// Error
return;
}
}
// The data instance can be reused to publish new values,
// but delete it at the end to avoid leaks
custom_type_support->deleteData(data);
Subscriber¶
A subscription is defined by the association of a DataReader to a Subscriber. To start receiving updates of a publication, the application creates a new DataReader in a Subscriber. This DataReader will be bound to the Topic that describes the data type that is going to be received. The DataReader will then start receiving data value updates from remote publications that match this Topic.
When the Subscriber receives data, it informs the application that new data is available. Then, the application can use the DataReader to get the received data.
Subscriber class diagram¶
Subscriber¶
The Subscriber acts on behalf of one or several DataReader objects
that belong to it.
It serves as a container that allows grouping different DataReader objects under
a common configuration given by the SubscriberQos of the Subscriber.
DataReader objects that belong to the same Subscriber
do not have any other relation among each other beyond the SubscriberQos of the Subscriber
and act independently otherwise.
Specifically, a Subscriber can host DataReader objects
for different topics and data types.
SubscriberQos¶
SubscriberQos controls the behavior of the Subscriber.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
Refer to the detailed description of each QosPolicy class for more information about their usage and
default values.
The QoS value of a previously created Subscriber can be modified using the
Subscriber::set_qos() member function.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Subscriber with default SubscriberQos
Subscriber* subscriber =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
SubscriberQos qos = subscriber->get_qos();
// Modify QoS attributes
qos.entity_factory().autoenable_created_entities = false;
// Assign the new Qos to the object
subscriber->set_qos(qos);
Default SubscriberQos¶
The default SubscriberQos refers to the value returned by the
get_default_subscriber_qos() member function
on the DomainParticipant instance.
The special value SUBSCRIBER_QOS_DEFAULT can be used as QoS argument on
create_subscriber() or Subscriber::set_qos()
member functions to indicate that the current default SubscriberQos
should be used.
When the system starts, the default SubscriberQos is equivalent to the default constructed
value SubscriberQos().
The default SubscriberQos can be modified at any time using the
set_default_subscriber_qos() member function on the
DomainParticipant instance.
Modifying the default SubscriberQos will not affect already existing
Subscriber instances.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
SubscriberQos qos_type1 = participant->get_default_subscriber_qos();
// Modify QoS attributes
// (...)
// Set as the new default SubscriberQos
if (participant->set_default_subscriber_qos(qos_type1) != RETCODE_OK)
{
// Error
return;
}
// Create a Subscriber with the new default SubscriberQos.
Subscriber* subscriber_with_qos_type1 =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
SubscriberQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default SubscriberQos
if (participant->set_default_subscriber_qos(qos_type2) != RETCODE_OK)
{
// Error
return;
}
// Create a Subscriber with the new default SubscriberQos.
Subscriber* subscriber_with_qos_type2 =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber_with_qos_type2)
{
// Error
return;
}
// Resetting the default SubscriberQos to the original default constructed values
if (participant->set_default_subscriber_qos(SUBSCRIBER_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_subscriber_qos(SubscriberQos())
!= RETCODE_OK)
{
// Error
return;
}
set_default_subscriber_qos() member function also accepts
the special value SUBSCRIBER_QOS_DEFAULT as input argument.
This will reset the current default SubscriberQos to default constructed
value SubscriberQos().
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a custom SubscriberQos
SubscriberQos custom_qos;
// Modify QoS attributes
// (...)
// Create a subscriber with a custom SubscriberQos
Subscriber* subscriber = participant->create_subscriber(custom_qos);
if (nullptr == subscriber)
{
// Error
return;
}
// Set the QoS on the subscriber to the default
if (subscriber->set_qos(SUBSCRIBER_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (subscriber->set_qos(participant->get_default_subscriber_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value SUBSCRIBER_QOS_DEFAULT has different meaning depending on where it is used:
On
create_subscriber()andSubscriber::set_qos()it refers to the default SubscriberQos as returned byget_default_subscriber_qos().On
set_default_subscriber_qos()it refers to the default constructedSubscriberQos().
SubscriberListener¶
SubscriberListener is an abstract class defining the
callbacks that will be triggered in response to state changes on the
Subscriber.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
SubscriberListener inherits from DataReaderListener.
Therefore, it has the ability to react to all events that are reported to the
DataReader.
Since events are always notified to the most specific Entity Listener that can handle the event,
callbacks that SubscriberListener inherits from
DataReaderListener will only be called if the triggering DataReader has no Listener attached,
or if the callback is disabled by the StatusMask on the DataReader.
Additionally, SubscriberListener adds the following callback:
on_data_on_readers(): New data is available on any DataReader belonging to this Subscriber. There is no queuing of invocations to this callback, meaning that if several new data changes are received at once, only one callback invocation may be issued for all of them, instead of one per change. If the application is retrieving the received data on this callback, it must keep reading data until no new changes are left.
Important
For more information about callbacks and its hierarchy, please refer to Listener.
class CustomSubscriberListener : public SubscriberListener
{
public:
CustomSubscriberListener()
: SubscriberListener()
{
}
virtual ~CustomSubscriberListener()
{
}
virtual void on_data_on_readers(
Subscriber* sub)
{
static_cast<void>(sub);
std::cout << "New data available" << std::endl;
}
};
Creating a Subscriber¶
A Subscriber always belongs to a DomainParticipant.
Creation of a Subscriber is done with the create_subscriber() member function on the
DomainParticipant instance, that acts as a factory for the Subscriber.
Mandatory arguments are:
The SubscriberQos describing the behavior of the Subscriber. If the provided value is
SUBSCRIBER_QOS_DEFAULT, the value of the Default SubscriberQos is used.
Optional arguments are:
A Listener derived from SubscriberListener, implementing the callbacks that will be triggered in response to events and state changes on the Subscriber. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the SubscriberListener. By default all events are enabled.
create_subscriber() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Subscriber with default SubscriberQos and no Listener
// The value SUBSCRIBER_QOS_DEFAULT is used to denote the default QoS.
Subscriber* subscriber_with_default_qos =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber_with_default_qos)
{
// Error
return;
}
// A custom SubscriberQos can be provided to the creation method
SubscriberQos custom_qos;
// Modify QoS attributes
// (...)
Subscriber* subscriber_with_custom_qos =
participant->create_subscriber(custom_qos);
if (nullptr == subscriber_with_custom_qos)
{
// Error
return;
}
// Create a Subscriber with default QoS and a custom Listener.
// CustomSubscriberListener inherits from SubscriberListener.
// The value SUBSCRIBER_QOS_DEFAULT is used to denote the default QoS.
CustomSubscriberListener custom_listener;
Subscriber* subscriber_with_default_qos_and_custom_listener =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT, &custom_listener);
if (nullptr == subscriber_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a Subscriber¶
Instead of using a SubscriberQos, the name of a profile
can be used to create a Subscriber with the create_subscriber_with_profile()
member function on the DomainParticipant instance.
Mandatory arguments are:
A string with the name that identifies the Subscriber.
Optional arguments are:
A Listener derived from SubscriberListener, implementing the callbacks that will be triggered in response to events and state changes on the Subscriber. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the SubscriberListener. By default all events are enabled.
create_subscriber_with_profile() will return a null pointer if there was an error during
the operation, e.g. if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Subscriber using a profile and no Listener
Subscriber* subscriber_with_profile =
participant->create_subscriber_with_profile("subscriber_profile");
if (nullptr == subscriber_with_profile)
{
// Error
return;
}
// Create a Subscriber using a profile and a custom Listener.
// CustomSubscriberListener inherits from SubscriberListener.
CustomSubscriberListener custom_listener;
Subscriber* subscriber_with_profile_and_custom_listener =
participant->create_subscriber_with_profile("subscriber_profile", &custom_listener);
if (nullptr == subscriber_with_profile_and_custom_listener)
{
// Error
return;
}
Deleting a Subscriber¶
A Subscriber can be deleted with the delete_subscriber() member function on the
DomainParticipant instance where the Subscriber was created.
Note
A Subscriber can only be deleted if all Entities belonging to the Subscriber
(DataReaders) have already been deleted.
Otherwise, the function will issue an error and the Subscriber will not be deleted.
This can be performed by using the delete_contained_entities() member function of the
Subscriber.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Subscriber
Subscriber* subscriber =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
// Use the Subscriber to communicate
// (...)
// Delete the entities the subscriber created
if (subscriber->delete_contained_entities() != RETCODE_OK)
{
// Subscriber failed to delete the entities it created
return;
}
// Delete the Subscriber
if (participant->delete_subscriber(subscriber) != RETCODE_OK)
{
// Error
return;
}
DataReader¶
A DataReader is attached to exactly one
Subscriber that acts as a factory for it.
Additionally, each DataReader is bound to a single
Topic since its creation.
This Topic must exist prior to the creation of the
DataReader,
and must be bound to the data type that the DataReader wants to publish.
The effect of creating a new DataReader in a Subscriber for a specific Topic is to initiate a new subscription with the name and data type described by the Topic.
Once the DataReader is created, the application will be informed
when changes in the data value are received from remote publications.
These changes can then be retrieved using the DataReader::read_next_sample() or DataReader::take_next_sample()
member functions of the DataReader.
DataReaderQos¶
DataReaderQoS controls the behavior of the DataReader.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor/Mutator |
Mutable |
|---|---|---|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
No (*) |
|
|
No |
|
|
No |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
No |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes (*) |
|
|
Yes |
|
|
No |
|
|
|
Yes |
The following non-consolidated property-assigned QoS apply to DataReaders:
Property name |
Non-consolidated QoS |
|---|---|
partitions |
Refer to the detailed description of each QosPolicy class for more information about their usage and
default values.
Note
Reliability kind (whether the publication is reliable or best effort) is not mutable.
However, the max_blocking_time data member of ReliabilityQosPolicy can be modified
any time.
Note
Not all data members of RTPSReliableReaderQos are mutable, please refer to RTPSReliableReaderQos for more information.
The QoS value of a previously created DataReader can be modified using the
DataReader::set_qos() member function.
// Create a DataReader with default DataReaderQos
DataReader* data_reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DataReaderQos qos = data_reader->get_qos();
// Modify QoS attributes
// (...)
// Assign the new Qos to the object
data_reader->set_qos(qos);
Default DataReaderQos¶
The default DataReaderQos refers to the value returned by the
get_default_datareader_qos() member function on the
Subscriber instance.
The special value DATAREADER_QOS_DEFAULT can be used as QoS argument on
create_datareader() or
DataReader::set_qos() member functions to indicate that the current default
DataReaderQos should be used.
When the system starts, the default DataReaderQos is equivalent to
the default constructed value DataReaderQos().
The default DataReaderQos can be modified at any time using the
set_default_datareader_qos() member function on the
Subscriber instance.
Modifying the default DataReaderQos will not affect already existing
DataReader instances.
// Get the current QoS or create a new one from scratch
DataReaderQos qos_type1 = subscriber->get_default_datareader_qos();
// Modify QoS attributes
// (...)
// Set as the new default DataReaderQos
if (subscriber->set_default_datareader_qos(qos_type1) != RETCODE_OK)
{
// Error
return;
}
// Create a DataReader with the new default DataReaderQos.
DataReader* data_reader_with_qos_type1 =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
DataReaderQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default DataReaderQos
if (subscriber->set_default_datareader_qos(qos_type2) != RETCODE_OK)
{
// Error
return;
}
// Create a DataReader with the new default DataReaderQos.
DataReader* data_reader_with_qos_type2 =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader_with_qos_type2)
{
// Error
return;
}
// Resetting the default DataReaderQos to the original default constructed values
if (subscriber->set_default_datareader_qos(DATAREADER_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (subscriber->set_default_datareader_qos(DataReaderQos())
!= RETCODE_OK)
{
// Error
return;
}
set_default_datareader_qos() member function also accepts
the special value DATAREADER_QOS_DEFAULT as input argument.
This will reset the current default DataReaderQos to default constructed
value DataReaderQos().
// Create a custom DataReaderQos
DataReaderQos custom_qos;
// Modify QoS attributes
// (...)
// Create a DataWriter with a custom DataReaderQos
DataReader* data_reader = subscriber->create_datareader(topic, custom_qos);
if (nullptr == data_reader)
{
// Error
return;
}
// Set the QoS on the DataWriter to the default
if (data_reader->set_qos(DATAREADER_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (data_reader->set_qos(subscriber->get_default_datareader_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value DATAREADER_QOS_DEFAULT has different meaning depending on where it is used:
On
create_datareader()andDataReader::set_qos()it refers to the default DataReaderQos as returned byget_default_datareader_qos().On
set_default_datareader_qos()it refers to the default constructedDataReaderQos().
DataReaderListener¶
DataReaderListener is an abstract class defining the callbacks
that will be triggered in response to state changes on the DataReader.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
DataReaderListener defines the following callbacks:
on_data_available(): There is new data available for the application on the DataReader. There is no queuing of invocations to this callback, meaning that if several new data changes are received at once, only one callback invocation may be issued for all of them, instead of one per change. If the application is retrieving the received data on this callback, it must keep reading data until no new changes are left.on_subscription_matched(): The DataReader has found a DataWriter that matches the Topic and has a common partition and a compatible QoS, or has ceased to be matched with a DataWriter that was previously considered to be matched. It is also triggered when a matched DataWriter has changed its DataWriterQos.on_requested_deadline_missed(): The DataReader did not receive data within the deadline period configured on its DataReaderQos. It will be called for each deadline period and data instance for which the DataReader missed data.on_requested_incompatible_qos(): The DataReader has found a DataWriter that matches the Topic and has a common partition, but with a QoS that is incompatible with the one defined on the DataReader.on_liveliness_changed(): The liveliness status of a matched DataWriter has changed. Either a DataWriter that was inactive has become active or the other way around.on_sample_rejected(): A received data sample was rejected. See SampleRejectedStatus for further information.on_sample_lost(): A data sample was lost and will never be received. See SampleLostStatus for further information.
Important
For more information about callbacks and its hierarchy, please refer to Listener.
class CustomDataReaderListener : public DataReaderListener
{
public:
CustomDataReaderListener()
: DataReaderListener()
{
}
virtual ~CustomDataReaderListener()
{
}
void on_data_available(
DataReader* reader) override
{
static_cast<void>(reader);
std::cout << "Received new data message" << std::endl;
}
void on_subscription_matched(
DataReader* reader,
const SubscriptionMatchedStatus& info) override
{
static_cast<void>(reader);
if (info.current_count_change == 1)
{
std::cout << "Matched a remote DataWriter" << std::endl;
}
else if (info.current_count_change == -1)
{
std::cout << "Unmatched a remote DataWriter" << std::endl;
}
}
void on_requested_deadline_missed(
DataReader* reader,
const RequestedDeadlineMissedStatus& info) override
{
static_cast<void>(reader);
static_cast<void>(info);
std::cout << "Some data was not received on time" << std::endl;
}
void on_liveliness_changed(
DataReader* reader,
const LivelinessChangedStatus& info) override
{
static_cast<void>(reader);
if (info.alive_count_change == 1)
{
std::cout << "A matched DataWriter has become active" << std::endl;
}
else if (info.not_alive_count_change == 1)
{
std::cout << "A matched DataWriter has become inactive" << std::endl;
}
}
void on_sample_rejected(
DataReader* reader,
const SampleRejectedStatus& info) override
{
static_cast<void>(reader);
static_cast<void>(info);
std::cout << "A received data sample was rejected" << std::endl;
}
void on_requested_incompatible_qos(
DataReader* reader,
const RequestedIncompatibleQosStatus& info) override
{
std::cout << "Found a remote Topic with incompatible QoS (QoS ID: " << info.last_policy_id <<
")" << std::endl;
}
void on_sample_lost(
DataReader* reader,
const SampleLostStatus& info) override
{
static_cast<void>(reader);
static_cast<void>(info);
std::cout << "A data sample was lost and will not be received" << std::endl;
}
};
Creating a DataReader¶
A DataReader always belongs to a Subscriber.
Creation of a DataReader is done with the create_datareader() member function on the
Subscriber instance, that acts as a factory for the DataReader.
Mandatory arguments are:
A Topic bound to the data type that will be transmitted.
The DataReaderQos describing the behavior of the DataReader. If the provided value is
DATAREADER_QOS_DEFAULT, the value of the Default DataReaderQos is used.
Optional arguments are:
A Listener derived from DataReaderListener, implementing the callbacks that will be triggered in response to events and state changes on the DataReader. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DataReaderListener. By default all events are enabled.
create_datareader() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DataReader with default DataReaderQos and no Listener
// The value DATAREADER_QOS_DEFAULT is used to denote the default QoS.
DataReader* data_reader_with_default_qos =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader_with_default_qos)
{
// Error
return;
}
// A custom DataReaderQos can be provided to the creation method
DataReaderQos custom_qos;
// Modify QoS attributes
// (...)
DataReader* data_reader_with_custom_qos =
subscriber->create_datareader(topic, custom_qos);
if (nullptr == data_reader_with_custom_qos)
{
// Error
return;
}
// Create a DataReader with default QoS and a custom Listener.
// CustomDataReaderListener inherits from DataReaderListener.
// The value DATAREADER_QOS_DEFAULT is used to denote the default QoS.
CustomDataReaderListener custom_listener;
DataReader* data_reader_with_default_qos_and_custom_listener =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT, &custom_listener);
if (nullptr == data_reader_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a DataReader¶
Instead of using a DataReaderQos, the name of a profile
can be used to create a DataReader with the create_datareader_with_profile()
member function on the Subscriber instance.
Mandatory arguments are:
A Topic bound to the data type that will be transmitted.
A string with the name that identifies the DataReader.
Optional arguments are:
A Listener derived from DataReaderListener, implementing the callbacks that will be triggered in response to events and state changes on the DataReader. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the DataReaderListener. By default all events are enabled.
create_datareader_with_profile() will return a null pointer if there was an error during the operation,
e.g. if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DataReader using a profile and no Listener
DataReader* data_reader_with_profile =
subscriber->create_datareader_with_profile(topic, "data_reader_profile");
if (nullptr == data_reader_with_profile)
{
// Error
return;
}
// Create a DataReader using a profile and a custom Listener.
// CustomDataReaderListener inherits from DataReaderListener.
CustomDataReaderListener custom_listener;
DataReader* data_reader_with_profile_and_custom_listener =
subscriber->create_datareader_with_profile(topic, "data_reader_profile", &custom_listener);
if (nullptr == data_reader_with_profile_and_custom_listener)
{
// Error
return;
}
Creating a DataWriter with a custom PayloadPool¶
A custom PayloadPool can be passed as an argument during the creation of a DataReader. This allows for customizing the management of the information exchanged between DataWriters and DataReaders. The same configuration can be set in the opposite endpoint.
// A DataReaderQos must be provided to the creation method
DataReaderQos qos;
// Create PayloadPool
std::shared_ptr<CustomPayloadPool> payload_pool = std::make_shared<CustomPayloadPool>();
DataReader* data_reader = subscriber->create_datareader(topic, qos, nullptr, StatusMask::all(), payload_pool);
if (nullptr == data_reader)
{
// Error
return;
}
This configuration can be performed also in the RTPS layer. The customization example applies both layers.
Deleting a DataReader¶
A DataReader can be deleted with the delete_datareader() member function on the
Subscriber instance where the DataReader was created.
Note
A DataReader can only be deleted if all Entities belonging to the DataReader
(QueryConditions) have already been deleted.
Otherwise, the function will issue an error and the DataReader will not be deleted.
This can be performed by using the delete_contained_entities() member function of the
DataReader.
// Create a DataReader
DataReader* data_reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader)
{
// Error
return;
}
// Use the DataReader to communicate
// (...)
// Delete the entities the DataReader created
if (data_reader->delete_contained_entities() != RETCODE_OK)
{
// DataReader failed to delete the entities it created.
return;
}
// Delete the DataReader
if (subscriber->delete_datareader(data_reader) != RETCODE_OK)
{
// Error
return;
}
SampleInfo¶
When a sample is retrieved from the DataReader, in addition to the sample data,
a SampleInfo instance is returned.
This object contains additional information that complements the returned data value and helps on it interpretation.
For example, if the valid_data value is false, the
DataReader is not informing the application about a new value in the data instance,
but a change on its status, and the returned data value must be discarded.
Please, refer to the section Accessing received data for more information regarding how received data can be accessed on the DataReader.
The following sections describe the data members of SampleInfo
and the meaning of each one in relation to the returned sample data.
sample_state¶
sample_state indicates whether or not the corresponding data sample has already
been read previously.
It can take one of these values:
READ: This is the first time this data sample has been retrieved.
NOT_READ: The data sample has already been read or taken previously.
view_state¶
view_state indicates whether or not this is the very first sample
of this data instance that the DataReader retrieves.
It can take one of these values:
NEW: This is the first time a sample of this instance is retrieved.
NOT_NEW: Other samples of this instance have been retrieved previously.
instance_state¶
instance_state indicates whether the instance is currently in existence
or it has been disposed.
In the latter case, it also provides information about the reason for the disposal.
It can take one of these values:
ALIVE: The instance is currently in existence.
NOT_ALIVE_DISPOSED: A remote DataWriter disposed the instance.
NOT_ALIVE_NO_WRITERS: The DataReader disposed the instance because no remote DataWriter that was publishing the instance is alive.
disposed_generation_count¶
disposed_generation_count indicates the number of times the instance had become alive after it was
disposed.
no_writers_generation_count¶
no_writers_generation_count indicates the number of times the instance had become alive after it was
disposed as NOT_ALIVE_NO_WRITERS.
sample_rank¶
sample_rank indicates the number of samples of the same instance that have been received after
this one.
For example, a value of 5 means that there are 5 newer samples available on the DataReader.
Note
Currently the sample_rank is not implemented, and its value is always set to 0.
It will be implemented on a future release of Fast DDS.
generation_rank¶
generation_rank indicates the number of times the instance was disposed and become alive again
between the time the sample was received and the time the most recent sample of the same instance
that is still held in the collection was received.
Note
Currently the generation_rank is not implemented, and its value is always set to 0.
It will be implemented on a future release of Fast DDS.
absolute_generation_rank¶
absolute_generation_rank indicates the number of times the instance was disposed and become alive
again between the time the sample was received and the time the most recent sample of the same instance
(which may not be in the collection) was received.
Note
Currently the absolute_generation_rank is not implemented, and its value is always set to 0.
It will be implemented on a future release of Fast DDS.
source_timestamp¶
source_timestamp holds the time stamp provided by the DataWriter when
the sample was published.
instance_handle¶
instance_handle handles of the local instance.
publication_handle¶
publication_handle handles of the DataWriter that published the data change.
valid_data¶
valid_data is a boolean that indicates whether the data sample contains a change in the value or not.
Samples with this value set to false are used to communicate a change in the instance status, e.g.,
a change in the liveliness of the instance.
In this case, the data sample should be dismissed as all the relevant information is in the
data members of SampleInfo.
sample_identity¶
sample_identity is an extension for requester-replier configuration.
It contains the DataWriter and the sequence number of the current message, and it is used
by the replier to fill the related_sample_identity when it sends the reply.
Accessing received data¶
The application can access and consume the data values received on the DataReader by reading or taking.
Reading is done with any of the following member functions:
DataReader::read_next_sample()reads the next, non-previously accessed data value available on the DataReader, and stores it in the provided data buffer.
DataReader::read(),DataReader::read_instance(), andDataReader::read_next_instance()provide mechanisms to get a collection of samples matching certain conditions.Taking is done with any of the following member functions:
DataReader::take_next_sample()reads the next, non-previously accessed data value available on the DataReader, and stores it in the provided data buffer.
DataReader::take(),DataReader::take_instance(), andDataReader::take_next_instance()provide mechanisms to get a collection of samples matching certain conditions.When taking data, the returned samples are also removed from the DataReader, so they are no longer accessible.
When there is no data in the DataReader matching the required conditions, all the operations will return
NO_DATA and output parameter will remain unchanged.
In addition to the data values, the data access operations also provide SampleInfo instances with additional information that help interpreting the returned data values, like the originating DataWriter or the publication time stamp. Please, refer to the SampleInfo section for an extensive description of its contents.
Loaning and Returning Data and SampleInfo Sequences¶
The DataReader::read() and DataReader::take() operations (and their variants) return information to the
application in two sequences:
Received DDS data samples in a sequence of the data type
Corresponding information about each DDS sample in a SampleInfo sequence
These sequences are parameters that are passed by the application code into the
DataReader::read() and DataReader::take() operations.
When the passed sequences are empty (they are initialized but have a maximum length of 0), the middleware will
fill those sequences with memory directly loaned from the receive queue itself.
There is no copying of the data or SampleInfo when the contents of the sequences are loaned.
This is certainly the most efficient way for the application code to retrieve the data.
When doing so, however, the code must return the loaned sequences back to the middleware, so that they can be reused
by the receive queue.
If the application does not return the loan by calling the DataReader::return_loan() operation, then Fast DDS
will eventually run out of memory to store DDS data samples received from the network for that DataReader.
See the code below for an example of borrowing and returning loaned sequences.
// Sequences are automatically initialized to be empty (maximum == 0)
FooSeq data_seq;
SampleInfoSeq info_seq;
// with empty sequences, a take() or read() will return loaned
// sequence elements
ReturnCode_t ret_code = data_reader->take(data_seq, info_seq,
LENGTH_UNLIMITED, ANY_SAMPLE_STATE,
ANY_VIEW_STATE, ANY_INSTANCE_STATE);
// process the returned data
// must return the loaned sequences when done processing
data_reader->return_loan(data_seq, info_seq);
Processing returned data¶
After calling the DataReader::read() or DataReader::take() operations, accessing the data on the returned
sequences is quite easy.
The sequences API provides a length() operation returning the number of elements in the collections.
The application code just needs to check this value and use the [] operator to access the corresponding elements.
Elements on the DDS data sequence should only be accessed when the corresponding element on the SampleInfo sequence
indicate that valid data is present.
When using Data Sharing, it is also important to check that the sample is valid (i.e, not replaced,
refer to DataReader and DataWriter history coupling for further information in this regard).
// Sequences are automatically initialized to be empty (maximum == 0)
FooSeq data_seq;
SampleInfoSeq info_seq;
// with empty sequences, a take() or read() will return loaned
// sequence elements
ReturnCode_t ret_code = data_reader->take(data_seq, info_seq,
LENGTH_UNLIMITED, ANY_SAMPLE_STATE,
ANY_VIEW_STATE, ANY_INSTANCE_STATE);
// process the returned data
if (ret_code == RETCODE_OK)
{
// Both info_seq.length() and data_seq.length() will have the number of samples returned
for (FooSeq::size_type n = 0; n < info_seq.length(); ++n)
{
// Only samples with valid data should be accessed
if (info_seq[n].valid_data && data_reader->is_sample_valid(&data_seq[n], &info_seq[n]))
{
// Do something with data_seq[n]
}
}
// must return the loaned sequences when done processing
data_reader->return_loan(data_seq, info_seq);
}
Accessing data on callbacks¶
When the DataReader receives new data values from any matching DataWriter, it informs the application through two Listener callbacks:
on_data_available().on_data_on_readers().
These callbacks can be used to retrieve the newly arrived data, as in the following example.
class CustomizedDataReaderListener : public DataReaderListener
{
public:
CustomizedDataReaderListener()
: DataReaderListener()
{
}
virtual ~CustomizedDataReaderListener()
{
}
void on_data_available(
DataReader* reader) override
{
// Create a data and SampleInfo instance
Foo data;
SampleInfo info;
// Keep taking data until there is nothing to take
while (reader->take_next_sample(&data, &info) == RETCODE_OK)
{
if (info.valid_data)
{
// Do something with the data
std::cout << "Received new data value for topic "
<< reader->get_topicdescription()->get_name()
<< std::endl;
}
else
{
std::cout << "Remote writer for topic "
<< reader->get_topicdescription()->get_name()
<< " is dead" << std::endl;
}
}
}
};
Note
If several new data changes are received at once, the callbacks may be triggered just once, instead of once per change. The application must keep reading or taking until no new changes are available.
Accessing data with a waiting thread¶
Wait-sets and DataAvailable status condition¶
Instead of relying on the Listener to try and get new data values, the application can also dedicate a thread to wait until any new data is available on the DataReader. This can be done using a wait-set to wait for a change on the DataAvailable status.
// Create a DataReader
DataReader* data_reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader)
{
// Error
return;
}
// Prepare a wait-set to wait for data on the DataReader
WaitSet wait_set;
StatusCondition& condition = data_reader->get_statuscondition();
condition.set_enabled_statuses(StatusMask::data_available());
wait_set.attach_condition(condition);
// Create a data and SampleInfo instance
Foo data;
SampleInfo info;
//Define a timeout of 5 seconds
eprosima::fastrtps::Duration_t timeout (5, 0);
// Loop reading data as it arrives
// This will make the current thread to be dedicated exclusively to
// waiting and reading data until the remote DataWriter dies
while (true)
{
ConditionSeq active_conditions;
if (RETCODE_OK == wait_set.wait(active_conditions, timeout))
{
while (RETCODE_OK == data_reader->take_next_sample(&data, &info))
{
if (info.valid_data)
{
// Do something with the data
std::cout << "Received new data value for topic "
<< topic->get_name()
<< std::endl;
}
else
{
// If the remote writer is not alive, we exit the reading loop
std::cout << "Remote writer for topic "
<< topic->get_name()
<< " is dead" << std::endl;
break;
}
}
}
else
{
std::cout << "No data this time" << std::endl;
}
}
DataReader non-blocking calls¶
The same could be achieved using the DataReader::wait_for_unread_message() member function,
that blocks until a new data sample is available or the given timeout expires.
If no new data was available after the timeout expired, it will return with value false.
This function returning with value true means there is new data available on the
DataReader ready for the application to retrieve.
// Create a DataReader
DataReader* data_reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader)
{
// Error
return;
}
// Create a data and SampleInfo instance
Foo data;
SampleInfo info;
//Define a timeout of 5 seconds
eprosima::fastrtps::Duration_t timeout (5, 0);
// Loop reading data as it arrives
// This will make the current thread to be dedicated exclusively to
// waiting and reading data until the remote DataWriter dies
while (true)
{
if (data_reader->wait_for_unread_message(timeout))
{
if (RETCODE_OK == data_reader->take_next_sample(&data, &info))
{
if (info.valid_data)
{
// Do something with the data
std::cout << "Received new data value for topic "
<< topic->get_name()
<< std::endl;
}
else
{
// If the remote writer is not alive, we exit the reading loop
std::cout << "Remote writer for topic "
<< topic->get_name()
<< " is dead" << std::endl;
break;
}
}
}
else
{
std::cout << "No data this time" << std::endl;
}
}
Topic¶
A Topic conceptually fits between publications and subscriptions. Each publication channel must be unambiguously identified by the subscriptions in order to receive only the data flow they are interested in, and not data from other publications. A Topic serves this purpose, allowing publications and subscriptions that share the same Topic to match and start communicating. In that sense, the Topic acts as a description for a data flow.
Publications are always linked to a single Topic, while subscriptions are linked to a broader concept of TopicDescription.
Topic class diagram¶
Topics, keys and instances¶
By definition, a Topic is linked to a single data type, so each data sample related to a Topic could be understood as an update on the information described by the data type. However, it is possible to include a logical separation and have, within the same Topic, several instances referring to the same data type. Thus, the received data sample will be an update for a specific instance of that Topic. Therefore, a Topic identifies data of a single type, ranging from one single instance to a whole collection of instances of that given type, as shown in the figure below.
The different instances gathered under the same topic are distinguishable by means of one or more data fields that form the key to that data set. The key description has to be indicated to the middleware. The rule is simple: different data values with the same key value represent successive data samples for the same instance, while different data values with different keys represent different topic instances. If no key is provided, the data set associated with the Topic is restricted to a single instance. Please refer to Data types with a key for more information about how to set the key in eProsima Fast DDS.
Instance advantages¶
The advantage of using instances instead of creating a new DataWriter, DataReader, and Topic is that the corresponding entity is already created and discovered. Consequently, there is less memory usage, and no new discovery (with the related metatraffic involved as explained in Discovery) is necessary. Another advantage is that several QoS are applied per topic instance; e.g. the HistoryQosPolicy is kept for each instance in the DataWriter. Thus, instances could be tuned to a wide range of applications.
Instance lifecycle¶
When reading or taking data from the DataReader (as explained in
Accessing received data), a SampleInfo is also returned.
This SampleInfo provides additional information about the instance lifecycle, specifically with the
view_state, instance_state,
disposed_generation_count, and
no_writers_generation_count.
The diagram below shows the statechart of instance_state and view_state for a single
instance.
Practical applications¶
This section provides a couple of examples to help clarify the use of DDS instances.
Commercial flights tracking¶
Airspace and the air traffic going through it are typically managed by the air traffic controllers that are in charge of organizing the air traffic, preventing collisions, and providing information. In this scenario, each air traffic control center takes responsibility for a specific flight area and delivers the data to the airspace traffic management system, which unifies the flight information.
Any time an air traffic control center discovers a plane coming into its controlled flight zone, tracking information about that specific flight is notified to the airspace traffic management center. Such a flow of information could be implemented by means of DDS by creating a specific Topic where the information related to the flight location is published. In that case, the management center would be required to create, if not existing previously, the corresponding Topic and DataReader to have access to the flight information, with the corresponding memory consumption and discovery metatraffic required. On the other hand, a cleverer implementation could leverage topic instances to relay the information from the local air traffic control centers to the airspace traffic management center. The topic instances might be identified using the airline name and the flight number (i.e. IBERIA 1234) as Topic instance key. The sample data being relayed would be the location of each flight being tracked at any given time. The following IDL defines the data described model:
struct FlightPosition
{
// Unique ID: airline name
@key string<256> airline_name;
// Unique ID: flight number
@key short flight_number;
// Coordinates
double latitude;
double longitude;
double altitude;
};
Once a new flight is discovered by a control center, the corresponding instance is registered into the system:
// Create data sample
FlightPosition first_flight_position;
// Specify the flight instance
first_flight_position.airline_name("IBERIA");
first_flight_position.flight_number(1234);
// Register instance
eprosima::fastrtps::rtps::InstanceHandle_t first_flight_handle =
data_writer->register_instance(&first_flight_position);
register_instance() returns an InstanceHandle_t which can be used to efficiently call the next
operations (i.e. write(), dispose(), or unregister_instance()) over
the instance.
The returned InstanceHandle_t contains the instance keyhash so it does not have to be recalculated again from the
data sample.
In case of following this approach, the application must take charge of mapping the instance handles to the
corresponding instances.
// Update position value received from the plane
first_flight_position.latitude(39.08);
first_flight_position.longitude(-84.21);
first_flight_position.altitude(1500);
// Write sample to the instance
data_writer->write(&first_flight_position, first_flight_handle);
On the other hand, the user application could directly call the DataWriter instance operations with a NIL instance
handle.
In this case, the instance handle would be calculated every time an operation is done over the instance, which can be
time consuming depending on the specific data type being used.
// New data sample
FlightPosition second_flight_position;
// New instance
second_flight_position.airline_name("RYANAIR");
second_flight_position.flight_number(4321);
// Update plane location
second_flight_position.latitude(40.02);
second_flight_position.longitude(-84.32);
second_flight_position.altitude(5000);
// Write sample directly without registering the instance
data_writer->write(&second_flight_position);
Warning
The correct management of the instance handles in the user application is paramount.
Otherwise, a sample corresponding to a different instance could wrongly update the instance which handle the user has
passed to the operation (if a non NIL instance is provided, the instance handle is not recalculated, trusting
that the one passed by the user is the correct one).
The following code updates the first instance of this example with the information coming from the second instance.
data_writer->write(&second_flight_position, first_flight_handle);
Once the plane leaves the controlled area, the air traffic control center may unregister the instance. Unregistering implies that the DataWriter for this specific center has no more information about the unregistered instance, and in this way the matched DataReaders in the management center are notified. The flight is still in the air but out of scope of this particular DataWriter. The instance is alive but no longer tracked by this center.
data_writer->unregister_instance(&first_flight_position, first_flight_handle);
data_writer->unregister_instance(&second_flight_position, HANDLE_NIL);
Finally, when the flight lands, the instance may be disposed. This means, in this specific example, that as far as the DataWriter knows, the instance no longer exists and should be considered not alive. With this operation, the DataWriter conveys this information to the matched DataReaders.
data_writer->dispose(&first_flight_position, first_flight_handle);
data_writer->dispose(&second_flight_position, HANDLE_NIL);
From the management center point of view, the samples are read using the same DataReader subscribed to the Topic where
the instances are being published.
However, valid_data must be checked to ensure that the sample received contains a data sample.
Otherwise, a change of the instance state is being notified.
Instance lifecycle contains a diagram showing the instance statechart.
if (RETCODE_OK == data_reader->take_next_sample(&data, &info))
{
if (info.valid_data)
{
// Data sample has been received
}
else if (info.instance_state == NOT_ALIVE_DISPOSED_INSTANCE_STATE)
{
// A remote DataWriter has disposed the instance
}
else if (info.instance_state == NOT_ALIVE_NO_WRITERS_INSTANCE_STATE)
{
// None of the matched DataWriters are writing in the instance.
// The instance can be safely disposed.
}
}
Relational databases¶
Consider now that the air traffic management center wants to keep a database with the flights being tracked. Using DDS instances, maintaining a relational database is almost direct. The instance key (unique identifier of the instance) is analogous to the primary key of the database. Thus, the airspace traffic management center can keep the latest update for each instance in a table like the one below:
Instance handle [PK] |
Data |
|---|---|
1 |
Position1 |
2 |
Position2 |
3 |
Position3 |
4 |
Position4 |
5 |
Position5 |
In this case, every time a new sample is received, the corresponding instance entry in the database will be updated with
the latest known location.
Disposing the instance may translate in erasing the corresponding data from the database.
In this scenario, registering and unregistering the instances does not reflect in the database, although if the
instance_state and view_state are also persisted, then the instance lifecycle could
be tracked as well.
A DataWriter communicating that it is going to be publishing data about a specific instance is of no interest to the
database until a new data is received and then an insert is directly done with the new discovered instance.
Historical data can also be stored in the relational database, even though depending on the use case, a time series database might be considered to improve efficiency. In the scenario being considered, the sample timestamp could be used, besides the instance handle, as primary key to be able to access the historical tracking data of an specific flight.
Instance handle [PK] |
Source Timestamp [PK] |
Data |
|---|---|---|
1 |
1 |
Position1 |
2 |
1 |
Position2 |
1 |
2 |
Position3 |
1 |
3 |
Position4 |
2 |
2 |
Position5 |
In this case, looking for a specific instance handle would return the flight tracking information:
Instance handle [Fixed] |
Source Timestamp |
Data |
|---|---|---|
1 |
1 |
Position1 |
1 |
2 |
Position3 |
1 |
3 |
Position4 |
Whereas looking for a specific timestamp would allow to have a picture of the different flight locations at a specific time:
Instance handle |
Source Timestamp [Fixed] |
Data |
|---|---|---|
1 |
2 |
Position3 |
2 |
2 |
Position5 |
TopicDescription¶
TopicDescription is an abstract class that serves as the base for all classes describing a data flow.
Applications will not create instances of TopicDescription directly, they must create instances of one
of its specializations instead.
At the moment, the only specializations implemented are Topic,
and ContentFilteredTopic.
Topic¶
A Topic is a specialization of the broader concept of TopicDescription.
A Topic represents a single data flow between Publisher
and Subscriber, providing:
The name to identify the data flow.
The data type that is transmitted on that flow.
The QoS values related to the data itself.
The behavior of the Topic can be modified with the QoS values
specified on TopicQos.
The QoS values can be set at the creation of the Topic,
or modified later with the Topic::set_qos() member function.
Like other Entities, Topic accepts a Listener that will be notified of status changes on the Topic.
Please refer to Creating a Topic for more information about how to create a Topic.
TopicQos¶
TopicQos controls the behavior of the Topic.
Internally it contains the following QosPolicy objects:
QosPolicy class |
Accessor |
Mutable |
|---|---|---|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
|
|
Yes |
Refer to the detailed description of each QosPolicy-api class for more information about their usage and default values.
The QoS value of a previously created Topic can be modified using the
Topic::set_qos() member function.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic with default TopicQos
Topic* topic =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
TopicQos qos = topic->get_qos();
// Modify QoS attributes
// (...)
// Assign the new Qos to the object
topic->set_qos(qos);
Default TopicQos¶
The default TopicQos refers to the value returned by the
get_default_topic_qos() member function on the DomainParticipant instance.
The special value TOPIC_QOS_DEFAULT can be used as QoS argument on create_topic()
or Topic::set_qos() member functions to indicate that the current default TopicQos
should be used.
When the system starts, the default TopicQos is equivalent to the default constructed
value TopicQos().
The default TopicQos can be modified at any time using the
get_default_topic_qos() member function on the DomainParticipant instance.
Modifying the default TopicQos will not affect already existing Topic
instances.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
TopicQos qos_type1 = participant->get_default_topic_qos();
// Modify QoS attributes
// (...)
// Set as the new default TopicQos
if (participant->set_default_topic_qos(qos_type1) != RETCODE_OK)
{
// Error
return;
}
// Create a Topic with the new default TopicQos.
Topic* topic_with_qos_type1 =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
if (nullptr == topic_with_qos_type1)
{
// Error
return;
}
// Get the current QoS or create a new one from scratch
TopicQos qos_type2;
// Modify QoS attributes
// (...)
// Set as the new default TopicQos
if (participant->set_default_topic_qos(qos_type2) != RETCODE_OK)
{
// Error
return;
}
// Create a Topic with the new default TopicQos.
Topic* topic_with_qos_type2 =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
if (nullptr == topic_with_qos_type2)
{
// Error
return;
}
// Resetting the default TopicQos to the original default constructed values
if (participant->set_default_topic_qos(TOPIC_QOS_DEFAULT)
!= RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_topic_qos(TopicQos())
!= RETCODE_OK)
{
// Error
return;
}
get_default_topic_qos() member function also accepts the value TOPIC_QOS_DEFAULT
as input argument.
This will reset the current default TopicQos to default constructed
value TopicQos().
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a custom TopicQos
TopicQos custom_qos;
// Modify QoS attributes
// (...)
// Create a topic with a custom TopicQos
Topic* topic = participant->create_topic("TopicName", "DataTypeName", custom_qos);
if (nullptr == topic)
{
// Error
return;
}
// Set the QoS on the topic to the default
if (topic->set_qos(TOPIC_QOS_DEFAULT) != RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (topic->set_qos(participant->get_default_topic_qos())
!= RETCODE_OK)
{
// Error
return;
}
Note
The value TOPIC_QOS_DEFAULT has different meaning depending on where it is used:
On
create_topic()andTopic::set_qos()it refers to the default TopicQos as returned byget_default_topic_qos().On
get_default_topic_qos()it refers to the default constructedTopicQos().
ContentFilteredTopic¶
A ContentFilteredTopic is a specialization of the broader concept of TopicDescription.
A ContentFilteredTopic is a Topic with filtering properties.
It makes it possible to subscribe to a Topic while at the same time specify interest on a subset of the Topic’s data.
Important
Note that a ContentFilteredTopic can only be used to create a DataReader, not a DataWriter.
A ContentFilteredTopic provides a relationship between a Topic, called the related topic, and some user-defined filtering properties:
A filter expression, which establishes a logical expression on the content of the related topic. It is similar to the WHERE clause in a SQL statement.
A list of expression parameters, which give values to the parameters present in the filter expression. There must be one parameter string for each parameter in the filter expression.
Note that a ContentFilteredTopic is not an Entity, and thus it has neither QoS nor listener. A DataReader created with a ContentFilteredTopic will use the QoS from the related topic. Multiple DataReaders can be created for the same ContentFilteredTopic, and changing the filter properties of a ContentFilteredTopic will affect all DataReaders using it.
Please refer to Filtering data on a Topic and
Where is filtering applied: writer vs reader side for more information about how to use
ContentFilteredTopic.
TopicListener¶
TopicListener is an abstract class defining the callbacks that will be triggered
in response to state changes on the Topic.
By default, all these callbacks are empty and do nothing.
The user should implement a specialization of this class overriding the callbacks
that are needed on the application.
Callbacks that are not overridden will maintain their empty implementation.
TopicListener has the following callback:
on_inconsistent_topic(): A remote Topic is discovered with the same name but different characteristics as another locally created Topic.
Warning
Currently on_inconsistent_topic() is not implemented (it will never be called), and will be
implemented on a future release of Fast DDS.
class CustomTopicListener : public TopicListener
{
public:
CustomTopicListener()
: TopicListener()
{
}
virtual ~CustomTopicListener()
{
}
void on_inconsistent_topic(
Topic* topic,
InconsistentTopicStatus status) override
{
static_cast<void>(topic);
static_cast<void>(status);
std::cout << "Inconsistent topic received discovered" << std::endl;
}
};
Definition of data types¶
The definition of the data type exchanged in a Topic is divided in
two classes: the TypeSupport and the TopicDataType.
TopicDataType describes the data type exchanged between a publication and a subscription, i.e., the data corresponding to a Topic. The user has to create a specialized class for each specific type that will be used by the application.
Any specialization of TopicDataType must be registered in the DomainParticipant
before it can be used to create Topic objects.
A TypeSupport object encapsulates an instance of TopicDataType, providing the functions needed to
register the type and interact with the publication and subscription.
To register the data type, create a new TypeSupport with a TopicDataType instance
and use the register_type() member function on the TypeSupport.
Then the Topic can be created with the registered type name.
Note
Registering two different data types on the same DomainParticipant with identical names is not allowed and will issue an error. However, it is allowed to register the same data type within the same DomainParticipant, with the same or different names. If the same data type is registered twice on the same DomainParticipant with the same name, the second registering will have no effect, but will not issue any error.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Register the data type in the DomainParticipant.
// If nullptr is used as name argument, the one returned by the type itself is used
TypeSupport custom_type_support(new CustomDataType());
custom_type_support.register_type(participant, nullptr);
// The previous instruction is equivalent to the following one
// Even if we are registering the same data type with the same name twice, no error will be issued
custom_type_support.register_type(participant, custom_type_support.get_type_name());
// Create a Topic with the registered type.
Topic* topic =
participant->create_topic("topic_name", custom_type_support.get_type_name(), TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create an alias for the same data type using a different name.
custom_type_support.register_type(participant, "data_type_name");
// We can now use the aliased name to If no name is given, it uses the name returned by the type itself
Topic* another_topic =
participant->create_topic("other_topic_name", "data_type_name", TOPIC_QOS_DEFAULT);
if (nullptr == another_topic)
{
// Error
return;
}
Dynamic data types¶
Instead of directly writing the specialized TopicDataType class, it is possible to dynamically define
data types following the OMG Extensible and Dynamic Topic Types for DDS interface.
Data types can also be described on an XML file that is dynamically loaded.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Load the XML file with the type description
DomainParticipantFactory::get_instance()->load_XML_profiles_file("example_type.xml");
// Retrieve the an instance of the desired type
DynamicType::_ref_type dyn_type;
DomainParticipantFactory::get_instance()->get_dynamic_type_builder_from_xml_by_name("DynamicType", dyn_type);
// Register dynamic type
TypeSupport dyn_type_support(new DynamicPubSubType(dyn_type));
dyn_type_support.register_type(participant, nullptr);
// Create a Topic with the registered type.
Topic* topic =
participant->create_topic("topic_name", dyn_type_support.get_type_name(), TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
A complete description of the dynamic definition of types can be found on the XTypes section.
Data types with a key¶
Data types that define a set of fields to form a unique key can distinguish different data sets within the same data type.
To define a keyed Topic, the getKey() member function on the TopicDataType
has to be overridden to return the appropriate key value according to the data fields.
Additionally, the m_isGetKeyDefined data member needs to be set to true to let the entities
know that this is a keyed Topic and that getKey() should be used.
Types that do not define a key will have m_isGetKeyDefined set to false.
There are three ways to implement keys on the TopicDataType:
Adding a
@Keyannotation to the members that form the key in the IDL file when using Fast DDS-Gen.Adding the attribute
Keyto the member and its parents when using XTypes.Manually implementing the
getKey()member function on the TopicDataType and setting them_isGetKeyDefineddata member value totrue.
Data types with key are used to define data sub flows on a single Topic. Data values with the same key on the same Topic represent data from the same sub-flow, while data values with different keys on the same Topic represent data from different sub-flows. The middleware keeps these sub-flows separated, but all will be restricted to the same QoS values of the Topic. If no key is provided, the data set associated with the Topic is restricted to a single flow.
Creating a Topic¶
A Topic always belongs to a DomainParticipant.
Creation of a Topic is done with the create_topic() member function on the
DomainParticipant instance, that acts as a factory for the Topic.
Mandatory arguments are:
A string with the name that identifies the Topic.
The name of the registered data type that will be transmitted.
The TopicQos describing the behavior of the Topic. If the provided value is
TOPIC_QOS_DEFAULT, the value of the Default TopicQos is used.
Optional arguments are:
A Listener derived from TopicListener, implementing the callbacks that will be triggered in response to events and state changes on the Topic. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the TopicListener. By default all events are enabled.
create_topic() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic with default TopicQos and no Listener
// The symbol TOPIC_QOS_DEFAULT is used to denote the default QoS.
Topic* topic_with_default_qos =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
if (nullptr == topic_with_default_qos)
{
// Error
return;
}
// A custom TopicQos can be provided to the creation method
TopicQos custom_qos;
// Modify QoS attributes
// (...)
Topic* topic_with_custom_qos =
participant->create_topic("TopicName", "DataTypeName", custom_qos);
if (nullptr == topic_with_custom_qos)
{
// Error
return;
}
// Create a Topic with default QoS and a custom Listener.
// CustomTopicListener inherits from TopicListener.
// The symbol TOPIC_QOS_DEFAULT is used to denote the default QoS.
CustomTopicListener custom_listener;
Topic* topic_with_default_qos_and_custom_listener =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT, &custom_listener);
if (nullptr == topic_with_default_qos_and_custom_listener)
{
// Error
return;
}
Profile based creation of a Topic¶
Instead of using a TopicQos, the name of a profile
can be used to create a Topic with the create_topic_with_profile()
member function on the DomainParticipant instance.
Mandatory arguments are:
A string with the name that identifies the Topic.
The name of the registered data type that will be transmitted.
The name of the profile to be applied to the Topic.
Optional arguments are:
A Listener derived from TopicListener, implementing the callbacks that will be triggered in response to events and state changes on the Topic. By default empty callbacks are used.
A
StatusMaskthat activates or deactivates triggering of individual callbacks on the TopicListener. By default all events are enabled.
create_topic_with_profile() will return a null pointer if there was an error during the operation, e.g.
if the provided QoS is not compatible or is not supported.
It is advisable to check that the returned value is a valid pointer.
Note
XML profiles must have been loaded previously. See Loading profiles from an XML file.
// First load the XML with the profiles
DomainParticipantFactory::get_instance()->load_XML_profiles_file("profiles.xml");
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic using a profile and no Listener
Topic* topic_with_profile =
participant->create_topic_with_profile("TopicName", "DataTypeName", "topic_profile");
if (nullptr == topic_with_profile)
{
// Error
return;
}
// Create a Topic using a profile and a custom Listener.
// CustomTopicListener inherits from TopicListener.
CustomTopicListener custom_listener;
Topic* topic_with_profile_and_custom_listener =
participant->create_topic_with_profile("TopicName", "DataTypeName", "topic_profile", &custom_listener);
if (nullptr == topic_with_profile_and_custom_listener)
{
// Error
return;
}
Deleting a Topic¶
A Topic can be deleted with the delete_topic() member function on the
DomainParticipant instance where the Topic was created.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic
Topic* topic =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Use the Topic to communicate
// (...)
// Delete the Topic
if (participant->delete_topic(topic) != RETCODE_OK)
{
// Error
return;
}
Filtering data on a Topic¶
Creating a ContentFilteredTopic¶
A ContentFilteredTopic always belongs to a DomainParticipant.
Creation of a ContentFilteredTopic is done with the create_contentfilteredtopic() member
function on the DomainParticipant instance, that acts as a factory for the ContentFilteredTopic.
Mandatory arguments are:
A string with the name that identifies the ContentFilteredTopic.
The related
Topicbeing filtered.A string with the filter expression indicating the conditions for a sample to be returned.
A list of strings with the value of the parameters present on the filter expression.
Note
The number of parameter values cannot exceed the maximum set by the
expression_parameters QoS configuration.
The default (and absolute) maximum allowed as set by the OMG DDS Standard is 100.
Optional arguments are:
A string with the name of the filter class to use for the filter creation. This allows the user to create filters different from the standard SQL like one (please refer to Using custom filters). Defaults to
FASTDDS_SQLFILTER_NAME(DDSSQL).
Important
Setting an empty string as filter expression results in the disabling of the filtering. This can be used to enable/disable the DataReader filtering capabilities at any given time by simply updating the filter expression.
create_contentfilteredtopic() will return a null pointer if there was an error during the
operation, e.g. if the related Topic belongs to a different DomainParticipant, a Topic with the same name already
exists, syntax errors on the filter expression, or missing parameter values.
It is advisable to check that the returned value is a valid pointer.
Note
Different filter classes may impose different requirements on the related Topic, the expression, or the parameters. The default filter class, in particular, requires that a TypeObject for the related Topic’s type has been registered. When using fastddsgen the TypeObject registration code is generated by default.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create the Topic.
/* IDL
*
* struct HelloWorld
* {
* long index;
* string message;
* }
*
*/
Topic* topic =
participant->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create a ContentFilteredTopic using an expression with no parameters
std::string expression = "message like 'Hello*'";
std::vector<std::string> parameters;
ContentFilteredTopic* filter_topic =
participant->create_contentfilteredtopic("HelloWorldFilteredTopic1", topic, expression, parameters);
if (nullptr == filter_topic)
{
// Error
return;
}
// Create a ContentFilteredTopic using an expression with parameters
expression = "message like %0 or index > %1";
parameters.push_back("'*world*'");
parameters.push_back("20");
ContentFilteredTopic* filter_topic_with_parameters =
participant->create_contentfilteredtopic("HelloWorldFilteredTopic2", topic, expression, parameters);
if (nullptr == filter_topic_with_parameters)
{
// Error
return;
}
// The ContentFilteredTopic instances can then be used to create DataReader objects.
Subscriber* subscriber =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
DataReader* reader_on_filter = subscriber->create_datareader(filter_topic, DATAREADER_QOS_DEFAULT);
if (nullptr == reader_on_filter)
{
// Error
return;
}
DataReader* reader_on_filter_with_parameters =
subscriber->create_datareader(filter_topic_with_parameters, DATAREADER_QOS_DEFAULT);
if (nullptr == reader_on_filter_with_parameters)
{
// Error
return;
}
Updating the filter expression and parameters¶
A ContentFilteredTopic provides several member functions for the management of the filter expression and the expression parameters:
The filter expression can be retrieved with the
get_filter_expression()member function.The expression parameters can be retrieved with the
get_expression_parameters()member function.The expression parameters can be modified using the
set_expression_parameters()member function. The same constraints as when creating a ContentFilteredTopic apply.The filter expression can be modified along with the expression parameters using the
set_filter_expression()member function.
// This lambda prints all the information of a ContentFilteredTopic
auto print_filter_info = [](
const ContentFilteredTopic* filter_topic)
{
std::cout << "ContentFilteredTopic info for '" << filter_topic->get_name() << "':" << std::endl;
std::cout << " - Related Topic: " << filter_topic->get_related_topic()->get_name() << std::endl;
std::cout << " - Expression: " << filter_topic->get_filter_expression() << std::endl;
std::cout << " - Parameters:" << std::endl;
std::vector<std::string> parameters;
filter_topic->get_expression_parameters(parameters);
size_t i = 0;
for (const std::string& parameter : parameters)
{
std::cout << " " << i++ << ": " << parameter << std::endl;
}
};
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic
/* IDL
*
* struct HelloWorld
* {
* long index;
* string message;
* }
*
*/
Topic* topic =
participant->create_topic("HelloWorldTopic", "HelloWorldTopic", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create a ContentFilteredTopic
ContentFilteredTopic* filter_topic =
participant->create_contentfilteredtopic("HelloWorldFilteredTopic", topic, "index > 10", {});
if (nullptr == filter_topic)
{
// Error
return;
}
// Print the information
print_filter_info(filter_topic);
// Use the ContentFilteredTopic on DataReader objects.
// (...)
// Update the expression
if (RETCODE_OK !=
filter_topic->set_filter_expression("message like %0 or index > %1", {"'Hello*'", "15"}))
{
// Error
return;
}
// Print the updated information
print_filter_info(filter_topic);
// Update the parameters
if (RETCODE_OK !=
filter_topic->set_expression_parameters({"'*world*'", "222"}))
{
// Error
return;
}
// Print the updated information
print_filter_info(filter_topic);
Deleting a ContentFilteredTopic¶
A ContentFilteredTopic can be deleted with the delete_contentfilteredtopic() member function
on the DomainParticipant instance where the ContentFilteredTopic was created.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create a Topic
/* IDL
*
* struct HelloWorld
* {
* long index;
* string message;
* }
*
*/
Topic* topic =
participant->create_topic("HelloWorldTopic", "HelloWorldTopic", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create a ContentFilteredTopic
ContentFilteredTopic* filter_topic =
participant->create_contentfilteredtopic("HelloWorldFilteredTopic", topic, "index > 10", {});
if (nullptr == filter_topic)
{
// Error
return;
}
// Use the ContentFilteredTopic on DataReader objects.
// (...)
// Delete the ContentFilteredTopic
if (RETCODE_OK != participant->delete_contentfilteredtopic(filter_topic))
{
// Error
return;
}
The default SQL-like filter¶
Filter expressions used by ContentFilteredTopic API may use a subset of SQL syntax, extended with the possibility to use program variables in the SQL expression. This section shows this default SQL-like syntax and how to use it.
Grammar¶
The allowed SQL expressions are defined with the BNF-grammar below.
The following conventions are made:
“Terminals” are quoted.
TOKENSare typeset in code block with black font color.
Expression ::= FilterExpression
FilterExpression ::= Condition
Condition ::= Predicate |
Condition "AND" Condition |
Condition "OR" Condition |
"NOT" Condition |
"(" Condition ")"
Predicate ::= ComparisonPredicate |
BetweenPredicate
ComparisonPredicate ::= FIELDNAME RelOp Parameter |
Parameter RelOp FIELDNAME |
FIELDNAME RelOp FIELDNAME
BetweenPredicate ::= FIELDNAME "BETWEEN" Range |
FIELDNAME "NOT BETWEEN" Range
RelOp ::= "=" | ">" | ">=" | "<" | "<=" |
"<>" | "!=" | like | match
Range ::= Parameter "AND" Parameter
Parameter ::= BOOLEANVALUE |
INTEGERVALUE |
CHARVALUE |
FLOATVALUE |
STRINGVALUE |
ENUMERATEDVALUE |
PARAMETER
“Terminals” and TOKENS are case sensitive but both uppercase and lowercase are supported.
The syntax and meaning of the tokens used in the SQL grammar is described as follows:
FIELDNAME: is a reference to a field in the data-structure. The dot
.is used to navigate through nested structures. The number of dots that may be used in a FIELDNAME is unlimited. The FIELDNAME can refer to fields at any depth in the data structure. The names of the field are those specified in the IDL definition of the corresponding structure.FIELDNAME ::= FieldNamePart ( "." FieldNamePart )* FieldNamePart ::= Identifier ( "[" Integer "]" )?
An example of FIELDNAMEs:
"points[0] = 0 AND color.red < 100"struct Color { octet red; octet green; octet blue; }; struct Shape { long points[4]; Color color; };
BOOLEANVALUE: Can either be true of false, case sensitive.
BOOLEANVALUE ::= ["TRUE", "true", "FALSE", "false"]
INTEGERVALUE: Any series of digits, optionally preceded by a plus or minus sign, representing a decimal integer value within the range of the system. A hexadecimal number is preceded by
0xand must be a valid hexadecimal expression.INTEGERVALUE ::= (["+","-"])? Integer Integer ::= (["0"-"9"])+ | ["0x","0X"](["0"-"9", "A"-"F", "a"-"f"])+
An example of INTEGERVALUE:
value = -10
CHARVALUE: A single character enclosed between single quotes.
CHARVALUE ::= "'" Character "'" Character ::= ~["\n"]
An example of CHARVALUE:
value = 'c'
FLOATVALUE: Any series of digits, optionally preceded by a plus or minus sign and optionally including a floating point (
.). A power-of-ten expression may be postfixed, which has the syntax e:sup:n, wherenis a number, optionally preceded by a plus or minus sign.FLOATVALUE ::= (["+"], "-"])? (Integer Exponent | Integer Fractional | Integer Fractional Exponent) Fractional ::= "." Integer Exponent ::= ["e","E"] (["+"], "-"])? Integer
An example of FLOATVALUE:
value = 10.1e-10
STRINGVALUE: Any series of characters encapsulated in single quotes, except a new-line character or a right quote. A string starts with a left or right quote, but ends with a right quote.
STRINGVALUE ::= ["'"] ~["'", "\r", "\n"] ["'"]
An example of STRINGVALUE:
value = 'This is a string'
ENUMERATEDVALUE: An enumerated value is a reference to a value declared within an enumeration. Enumerated values consist of the name of the enumeration label enclosed in single quotes. The name used for the enumeration label must correspond to the label names specified in the IDL definition of the enumeration.
ENUMERATEDVALUE ::= ["'"] ~["'", "\r", "\n"] ["'"]
An example of ENUMERATEDVALUE:
value = 'ENUM_VALUE_1'
enum MyEnum { ENUM_VALUE_1, ENUM_VALUE_2, ENUM_VALUE_3 }; struct Enumerators { MyEnum value; };
PARAMETER: A parameter is of the form
%n, wherenrepresents a natural number (zero included) smaller than 100. It refers to then + 1 thargument in the given context.PARAMETER ::= ["%"] ["0"-"9"] (["0"-"9"])?
An example of PARAMETER:
value = %1
Like condition¶
The like operator is similar as the one defined by SQL. This operator can only be used with strings. There are two wildcards that could be used in conjunction with this operator
The percent sign
%(or its alias*) represents zero, one, or multiple characters.The underscore sign
_(or its alias?) represents one single character.
All wildcards can also be used in combinations.
An example of like operator
"str like '%bird%'"
struct Like
{
string str;
};
where string There are birds flying will return true.
Match condition¶
The match operator performs a full-text search using a regular expression.
This operator can only be used with strings.
It uses the Basic Regular Expression (BRE) defined by POSIX.
An example of match operator
"str match '^The'"
struct Like
{
string str;
};
where string There are birds flying will return true.
Type comparisons¶
For the supported operators in the grammar, next table shows the type compatibility.
Operator1 | Operator2 |
BOOLEAN |
INTEGER |
FLOAT |
CHAR |
STRING |
ENUM |
|---|---|---|---|---|---|---|
BOOLEAN |
✅ |
✅ |
❌ |
❌ |
❌ |
❌ |
INTEGER |
✅ |
✅ |
✅ |
❌ |
❌ |
❌ |
FLOAT |
❌ |
✅ |
✅ |
❌ |
❌ |
❌ |
CHAR |
❌ |
❌ |
❌ |
✅ |
✅ |
❌ |
STRING |
❌ |
❌ |
❌ |
✅ |
✅ |
❌ |
ENUM |
❌ |
✅ |
❌ |
❌ |
❌ |
✅ * |
(*) Only for the same enumerated type.
Example¶
Assuming Topic Shape has next IDL definition.
struct Shape
{
long x,
long y,
long z,
long width,
long height
};
An example of filter expression would be:
"x < 23 AND y > 50 AND width BETWEEN %0 AND %1"
A ContentFilteredTopic may be created using this filter expression as explained in section Creating a ContentFilteredTopic.
ContentFilteredTopic* sql_filter_topic =
participant->create_contentfilteredtopic("Shape", topic,
"x < 23 AND y > 50 AND width BETWEEN %0 AND %1",
{"10", "20"});
In this example parameters are used. Internally the ContentFilteredTopic will be created with the filter expression below, after setting the provided parameters.
"x < 23 AND y > 50 AND width BETWEEN 10 AND 20"
Using custom filters¶
Fast DDS API supports the creation and later registration of user’s custom filters to be used in the creation of a
ContentFilteredTopic.
Required steps for using a Custom Filter are:
Creating the Custom Filter¶
A custom filter must be implemented by a class which inherits from IContentFilter.
Only one function must be implemented, overriding evaluate().
Each time a sample is received by a DataReader, this function is called with next arguments.
payload- The serialized payload of the sample which the custom filter has to evaluate.sample_info- The extra information which accompanies the sample.reader_guid- The GUID of the reader for which the filter is being evaluated.
The function returns a boolean where true implies the sample is accepted and false rejects the sample.
Next snippet code shows an example of Custom Filter which deserialize the index field from a serialized sample and
rejects samples where index > low_mark_ and index < high_mark_.
class MyCustomFilter : public IContentFilter
{
public:
MyCustomFilter(
int low_mark,
int high_mark)
: low_mark_(low_mark)
, high_mark_(high_mark)
{
}
bool evaluate(
const SerializedPayload& payload,
const FilterSampleInfo& sample_info,
const GUID_t& reader_guid) const override
{
// Deserialize the `index` field from the serialized sample.
/* IDL
*
* struct HelloWorld
* {
* long index;
* string message;
* }
*/
eprosima::fastcdr::FastBuffer fastbuffer(reinterpret_cast<char*>(payload.data), payload.length);
eprosima::fastcdr::Cdr deser(fastbuffer);
// Deserialize encapsulation.
deser.read_encapsulation();
int index = 0;
// Deserialize `index` field.
try
{
deser >> index;
}
catch (eprosima::fastcdr::exception::NotEnoughMemoryException& exception)
{
return false;
}
// Custom filter: reject samples where index > low_mark_ and index < high_mark_.
if (index > low_mark_ && index < high_mark_)
{
return false;
}
return true;
}
private:
int low_mark_ = 0;
int high_mark_ = 0;
};
Creating the Factory for the Custom Filter¶
Fast DDS creates filters through a factory. Therefore a factory which provides instantiating of a Custom Filter must be implemented.
A Custom Filter’s factory has to inherit from IContentFilterFactory.
This interface requires two functions to be implemented.
Each time a Custom Filter has to be created or updated, create_contentfilteredtopic() calls
internally create_content_filter() with these arguments:
filter_class_name- Filter class name for which the factory is being called. It allows using the same factory for different filter classes.type_name- Type name of the topic being filtered.data_type- Type support object of the topic being filtered.filter_expression- Custom filter expression.filter_parameters- Values to set for the filter parameters (where custom filter expression has its pattern to substitute them).filter_instance- When a filter is being created, it will benullptron input, and will have the pointer to the created filter instance on output. When a filter is being updated, it will have a previously returned pointer on input.
This function should return the result of the operation.
When a Custom Filter should be removed, delete_contentfilteredtopic() calls internally
delete_content_filter().
The factory must remove the provided Custom Filter’s instance.
Next snippet code shows an example of Custom Filter’s factory which manages instances of the Custom Filter implemented in the previous section.
class MyCustomFilterFactory : public IContentFilterFactory
{
public:
ReturnCode_t create_content_filter(
const char* filter_class_name, // My custom filter class name is 'MY_CUSTOM_FILTER'.
const char* type_name, // This custom filter only supports one type: 'HelloWorld'.
const TopicDataType* /*data_type*/, // Not used in this implementation.
const char* filter_expression, // This Custom Filter doesn't implement a filter expression.
const ParameterSeq& filter_parameters, // Always need two parameters to be set: low_mark and high_mark.
IContentFilter*& filter_instance) override
{
// Check the ContentFilteredTopic should be created by my factory.
if (0 != strcmp(filter_class_name, "MY_CUSTOM_FILTER"))
{
return RETCODE_BAD_PARAMETER;
}
// Check the ContentFilteredTopic is created for the unique type this Custom Filter supports.
if (0 != strcmp(type_name, "HelloWorld"))
{
return RETCODE_BAD_PARAMETER;
}
// Check that the two mandatory filter parameters are set.
if (2 != filter_parameters.length())
{
return RETCODE_BAD_PARAMETER;
}
// If there is an update, delete previous instance.
if (nullptr != filter_instance)
{
delete(dynamic_cast<MyCustomFilter*>(filter_instance));
}
// Instantiation of the Custom Filter.
filter_instance = new MyCustomFilter(std::stoi(filter_parameters[0]), std::stoi(filter_parameters[1]));
return RETCODE_OK;
}
ReturnCode_t delete_content_filter(
const char* filter_class_name,
IContentFilter* filter_instance) override
{
// Check the ContentFilteredTopic should be created by my factory.
if (0 != strcmp(filter_class_name, "MY_CUSTOM_FILTER"))
{
return RETCODE_BAD_PARAMETER;
}
// Deletion of the Custom Filter.
delete(dynamic_cast<MyCustomFilter*>(filter_instance));
return RETCODE_OK;
}
};
Registering the Factory¶
To be able to use the Custom Filter in an application, the Custom Filter’s factory must be registered in the
DomainParticipant.
Next snippet code shows how to register a factory through API function
register_content_filter_factory().
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create Custom Filter Factory
MyCustomFilterFactory* factory = new MyCustomFilterFactory();
// Registration of the factory
if (RETCODE_OK !=
participant->register_content_filter_factory("MY_CUSTOM_FILTER", factory))
{
// Error
return;
}
Creating a ContentFilteredTopic using the Custom Filter¶
Creating a ContentFilteredTopic explains how to create a ContentFilteredTopic.
In the case of using a Custom Filter, create_contentfilteredtopic() has an overload adding an
argument to select the Custom Filter.
Next snippet code shows how to create a ContentFilteredTopic using the Custom Filter.
// Create a DomainParticipant in the desired domain
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Create the Topic.
Topic* topic =
participant->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create a ContentFilteredTopic selecting the Custom Filter and using no expression with two parameters
// Filter expression cannot be an empty one even when it is not used by the custom filter, as that effectively
// disables any filtering
std::string expression = " ";
std::vector<std::string> parameters;
parameters.push_back("10"); // Parameter for low_mark
parameters.push_back("20"); // Parameter for low_mark
ContentFilteredTopic* filter_topic =
participant->create_contentfilteredtopic("HelloWorldFilteredTopic1", topic, expression, parameters,
"MY_CUSTOM_FILTER");
if (nullptr == filter_topic)
{
// Error
return;
}
// The ContentFilteredTopic instances can then be used to create DataReader objects.
Subscriber* subscriber =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
DataReader* reader_on_filter = subscriber->create_datareader(filter_topic, DATAREADER_QOS_DEFAULT);
if (nullptr == reader_on_filter)
{
// Error
return;
}
Important
Even though this specific custom filtering example is not using the filter expression, mind that the expression cannot be an empty string as that disables filtering as explained in Creating a ContentFilteredTopic.
Note
Deleting a ContentFilteredTopic which uses a Custom Filter is done exactly in the same manner explained in Deleting a ContentFilteredTopic.
Where is filtering applied: writer vs reader side¶
Content filters may be evaluated on either side, as the DataWriter obtains the filter expression from the DataReader during discovery. Filtering on the writer side can save network bandwidth at the cost of increasing CPU usage on the writer.
Conditions for writer side filtering¶
A DataWriter will perform filter evaluation in the DataReader stead whenever all of the following conditions are met; filtering will otherwise be performed by the DataReader.
The DataWriter has infinite liveliness. See LivelinessQosPolicy.
Communication with the DataReader is neither intra-process nor data-sharing.
The DataReader is not using multicast.
The DataWriter is filtering for no more DataReaders than the maximum value set on
reader_filters_allocation.There is a resource-limit policy on DataWriterQos that controls the allocation behavior of writer-side filtering resources. Setting a maximum value of 0 disables filter evaluation on the writer side. A maximum value of 32 (the default value) means the writer will perform filter evaluation for up to 32 readers.
If the DataWriter is evaluating filters for
writer_resource_limits.reader_filters_allocation.maximumDataReaders, and a new filtered DataReader is created, then the filter for the newly created DataReader will be evaluated on the reader side.
Discovery race condition¶
On applications where the filter expression and/or the expression parameters are updated, there may be a situation where the DataWriter will apply the old version of the filter until it receives updated information through discovery. This may imply that a publication made a short time after the DataReader updated the filter, but before the updated discovery information is received by the DataWriter, may not be sent to the DataReader, even if the new filter would have told otherwise. Publications made after the updated discovery information is received will use the updated filter.
If some critical application considers this race condition issue unbearable, filtering on the writer side
can be disabled by setting the maximum value on reader_filters_allocation to 0.
Fast DDS-Gen for data types source code generation¶
eProsima Fast DDS comes with a built-in source code generation tool, Fast DDS-Gen, which eases the process of translating an IDL specification of a data type to a functional implementation. Thus, this tool automatically generates the source code of a data type defined using IDL. A basic use of the tool is described below. To learn about all the features that Fast DDS offers, please refer to Fast DDS-Gen section.
Basic usage¶
Fast DDS can be executed by calling fastddsgen on Linux or fastddsgen.bat on Windows.
The IDL file containing the data type definition is given with the <IDLfile> argument.
Linux |
fastddsgen [<options>] <IDLfile> [<IDLfile> ...]
|
Windows |
fastddsgen.bat [<options>] <IDLfile> [<IDLfile> ...]
|
Among the available arguments defined in Usage, the main Fast DDS-Gen options for data type source code generation are the following:
-replace: It replaces existing files in case the data type files have been previously generated.-help: It lists the currently supported platforms and Visual Studio versions.-no-typeobjectsupport: It disables the automatic generation of the TypeObject representation registration code.-example: It generates a basic example of a DDS application and the files to build it for the givenplatform. Thus, Fast DDS-Gen tool can generate a sample application using the provided data type, together with a Makefile, to compile it on Linux distributions, and a Visual Studio project for Windows. To see an example of this please refer to tutorial Building a publish/subscribe application.
Output files¶
Fast DDS-Gen outputs several files. Assuming the IDL file had the name “Mytype”, and none of the above options have been defined, these files are:
MyType.hpp: Type definition.
MyTypePubSubType.cxx/.h: Serialization and deserialization source code for the data type. It also defines the
getKey()member function of theMyTypePubSubTypeclass in case the topic implements keys (see Data types with a key).MyTypeCdrAux.hpp/.ipp: Auxiliary methods required by Fast CDR for type encoding and decoding.
MyTypeTypeObjectSupport.cxx/.hpp: Auxiliary code required for TypeObject representation generation and registration.
RTPS Layer¶
The lower level RTPS Layer of eprosima Fast DDS serves an implementation of the protocol defined in the RTPS standard. This layer provides more control over the internals of the communication protocol than the DDS Layer, so advanced users have finer control over the library’s functionalities.
Relation to the DDS Layer¶
Elements of this layer map one-to-one with elements from the DDS Layer, with a few additions. This correspondence is shown in the following table:
RTPSDomain |
|
RTPSParticipant |
|
RTPSWriter |
|
RTPSReader |
How to use the RTPS Layer¶
We will now go over the use of the RTPS Layer like we did with the DDS Layer one, explaining the new features it presents.
We recommend you to look at the two examples describing how to use the RTPS layer that come with the distribution while reading this section. They are located in examples/cpp/rtps/AsSocket and examples/cpp/rtps/Registered
Managing the Participant¶
Creating a RTPSParticipant is done with RTPSDomain::createParticipant().
RTPSParticipantAttributes structure is used to configure the RTPSParticipant upon creation.
RTPSParticipantAttributes participant_attr;
participant_attr.setName("participant");
RTPSParticipant* participant = RTPSDomain::createParticipant(0, participant_attr);
Managing the Writers and Readers¶
As the RTPS standard specifies, RTPSWriters and RTPSReaders are always associated
with a History element.
In the DDS Layer, its creation and management is hidden,
but in the RTPS Layer, you have full control over its creation and configuration.
Writers are created with RTPSDomain::createRTPSWriter() and configured with a WriterAttributes structure.
They also need a WriterHistory which is configured with a HistoryAttributes structure.
HistoryAttributes history_attr;
WriterHistory* history = new WriterHistory(history_attr);
WriterAttributes writer_attr;
RTPSWriter* writer = RTPSDomain::createRTPSWriter(participant, writer_attr, history);
Similar to the creation of Writers, Readers are created with RTPSDomain::createRTPSReader()
and configured with a ReaderAttributes structure.
A HistoryAttributes structure is used to configure the required ReaderHistory.
Note that in this case, you can provide a specialization of ReaderListener class that implements your
callbacks:
class MyReaderListener : public ReaderListener
{
// Callbacks override
};
MyReaderListener listener;
HistoryAttributes history_attr;
ReaderHistory* history = new ReaderHistory(history_attr);
ReaderAttributes reader_attr;
RTPSReader* reader = RTPSDomain::createRTPSReader(participant, reader_attr, history, &listener);
Using the History to Send and Receive Data¶
In the RTPS Protocol, Readers and Writers save the data about a topic in their associated Histories.
Each piece of data is represented by a Change, which eprosima Fast DDS implements as CacheChange_t.
Changes are always managed by the History.
You can add a new CacheChange_t to the History of the Writer to send data.
The procedure is as follows:
Request a
CacheChange_tfrom the Writer withRTPSWriter::new_change(). In order to allocate enough memory, you need to provide a callback that returns the maximum number bytes in the payload.Fill the
CacheChange_twith the data.Add it to the History with
WriterHistory::add_change().
The Writer will take care of everything to communicate the data to the Readers.
//Request a change from the writer
CacheChange_t* change = writer->new_change([]() -> uint32_t
{
return 255;
}, ALIVE);
//Write serialized data into the change
change->serializedPayload.length = sprintf((char*) change->serializedPayload.data, "My example string %d", 2) + 1;
//Insert change into the history. The Writer takes care of the rest.
history->add_change(change);
If your topic data type has several fields, you will have to provide functions to serialize and deserialize
your data in and out of the CacheChange_t.
Fast DDS-Gen does this for you.
You can receive data from within the ReaderListener::onNewCacheChangeAdded callback,
as we did in the DDS Layer:
The callback receives a
CacheChange_tparameter containing the received data.Process the data within the received
CacheChange_t.Inform the Reader’s History that the change is not needed anymore.
class MyReaderListener : public ReaderListener
{
public:
MyReaderListener()
{
}
~MyReaderListener()
{
}
void onNewCacheChangeAdded(
RTPSReader* reader,
const CacheChange_t* const change)
{
// The incoming message is enclosed within the `change` in the function parameters
printf("%s\n", change->serializedPayload.data);
// Once done, remove the change
reader->getHistory()->remove_change((CacheChange_t*)change);
}
};
Managing the Builtin Transports¶
DDS uses the Transport Layer to allow communication between DDS entities. eProsima Fast DDS comes with five transports already implemented. However, these transports are not always exclusive between them and in some cases they can be used simultaneously.
You can choose what transports you want to use by disabling the use of builtin transports and manually adding them (see TransportConfigQos) or using the default builtin transports behavior and selecting one of the configuration options listed below. Each option modifies the kind of transports that will be instantiated.
Builtin Transports Options |
Description |
|---|---|
|
No transport will be instantiated. Hence, the user must manually add
the desired |
|
UDPv4 and SHM transports will be instantiated. SHM transport has priority
over the UDPv4 |
|
UDPv6 and SHM transports will be instantiated. SHM transport has priority
over the UDPv4 |
|
Only a SHM transport will be instantiated. |
|
Only a UDPv4 transport will be instantiated. |
|
Only a UDPv6 transport will be instantiated. |
|
UDPv4, TCPv4, and SHM transports will be instantiated. However, UDP will
only be used |
RTPSParticipantAttributes participant_attr;
participant_attr.setup_transports(eprosima::fastdds::rtps::BuiltinTransports::LARGE_DATA);
RTPSParticipant* participant = RTPSDomain::createParticipant(0, participant_attr);
The same result can also be obtained using the setup_transports() wrapper
function of the DomainParticipantQos, XML profiles (see RTPS element type) or the
FASTDDS_BUILTIN_TRANSPORTS environment variable (see FASTDDS_BUILTIN_TRANSPORTS).
Note
TCPv4 transport is initialized with the following configuration:
calculate_crc,check_crcandapply_securityare set to false.
enable_tcp_nodelayis set to true.
keep_alive_threadandaccept_threaduse the default configuration.
Warning
To obtain a better performance when working with large data messages it is extremely recommended to use the builtin transports configuration options to adjust the transport to the specific needs of the application. Please refer to Large Data with configuration options for more information about how to configure it.
Configuring Readers and Writers¶
One of the benefits of using the RTPS Layer is that it provides new configuration possibilities while maintaining the options from the DDS layer. For example, you can set a Writer or a Reader as a Reliable or Best-Effort endpoint as previously:
writer_attr.endpoint.reliabilityKind = BEST_EFFORT;
Setting the data durability kind¶
The Durability parameter defines the behavior of the Writer regarding samples already sent when a new Reader matches. eProsima Fast DDS offers three Durability options:
VOLATILE (default): Messages are discarded as they are sent. If a new Reader matches after message n, it will start received from message n+1.
TRANSIENT_LOCAL: The Writer saves a record of the last k messages it has sent. If a new reader matches after message n, it will start receiving from message n-k
TRANSIENT: As TRANSIENT_LOCAL, but the record of messages will be saved to persistent storage, so it will be available if the writer is destroyed and recreated, or in case of an application crash.
To choose your preferred option:
writer_attr.endpoint.durabilityKind = TRANSIENT_LOCAL;
Because in the RTPS Layer you have control over the History, in TRANSIENT_LOCAL and TRANSIENT modes the Writer sends all changes you have not explicitly released from the History.
Configuring the History¶
The History has its own configuration structure, the HistoryAttributes.
Changing the maximum size of the payload¶
You can choose the maximum size of the Payload that can go into a CacheChange_t.
Be sure to choose a size that allows it to hold the biggest possible piece of data:
history_attr.payloadMaxSize = 250;//Defaults to 500 bytes
Changing the size of the History¶
You can specify a maximum amount of changes for the History to hold and an initial amount of allocated changes:
history_attr.initialReservedCaches = 250; //Defaults to 500
history_attr.maximumReservedCaches = 500; //Defaults to 0 = Unlimited Changes
When the initial amount of reserved changes is lower than the maximum, the History will allocate more changes as they are needed until it reaches the maximum size.
Using a custom Payload Pool¶
A Payload is defined as the data the user wants to transmit between a Writer and a Reader.
RTPS needs to add some metadata to this Payload in order to manage the communication between the endpoints.
Therefore, this Payload is encapsulated inside the SerializedPayload_t field
of the CacheChange_t,
while the rest of the fields of the CacheChange_t provide the required metadata.
WriterHistory and ReaderHistory provide an interface for the user to interact with these changes:
Changes to be transmitted by the Writer are added to its WriterHistory,
and changes already processed on the Reader can be removed from the ReaderHistory.
In this sense, the History acts as a buffer for changes that are not fully processed yet.
During a normal execution, new changes are added to the History and old ones are removed from it.
In order to manage the lifecycle of the Payloads contained in these changes,
Readers and Writers use a pool object,
an implementation of the IPayloadPool interface.
Different pool implementations allow for different optimizations.
For example, Payloads of different size could be retrieved from different preallocated memory chunks.
Writers and Readers can automatically select a default Payload pool implementation that best suits
the configuration given in HistoryAttributes.
However, a custom Payload pool can be given to RTPSDomain::createRTPSWriter() and
RTPSDomain::createRTPSReader() functions.
Writers and Readers will use the provided pool when a new CacheChange_t is requested
or released.
IPayloadPool interface¶
IPayloadPool::get_payloadoverload with size parameter:Ties an empty Payload of the requested size to a
CacheChange_tinstance. The Payload can then be filled with the required data.IPayloadPool::get_payloadoverload with SerializadPayload parameter:Copies the given Payload data to a new Payload from the pool and ties it to the
CacheChange_tinstance. This overload also takes a pointer to the pool that owns the original Payload. This allows certain optimizations, like sharing the Payload if the original one comes form this same pool, therefore avoiding the copy operation.IPayloadPool::release_payload:Returns the Payload tied to a
CacheChange_tto the pool, and breaks the tie.
Important
When implementing a custom Payload pool, make sure that the allocated Payloads fulfill the requirements of standard RTPS serialization. Specifically, the Payloads must be large enough to accommodate the serialized user data plus the 4 octets of the SerializedPayloadHeader as specified in section 10.2 of the RTPS standard.
For example, if we know the upper bound of the serialized user data, we may consider implementing a pool that always allocates Payloads of a fixed size, large enough to hold any of this data. If the serialized user data has at most N octets, then the allocated Payloads must have at least N+4 octets.
Note that the size requested to IPayloadPool::get_payload already considers this 4 octet header.
Default Payload pool implementation¶
If no custom Payload pool is provided to the Writer or Reader, Fast DDS will automatically use the
default implementation that best matches the memoryPolicy configuration of the History.
PREALLOCATED_MEMORY_MODE
All payloads will have a data buffer of fixed size,
equal to the value of payloadMaxSize,
regardless of the size requested to IPayloadPool::get_payload.
Released Payloads can be reused for another CacheChange_t.
This reduces memory allocation operations at the cost of higher memory usage.
During the initialization of the History, initialReservedCaches
Payloads are preallocated for the initially allocated CacheChange_t.
PREALLOCATED_WITH_REALLOC_MEMORY_MODE
Payloads are guaranteed to have a data buffer at least as large as the
maximum between the requested size and payloadMaxSize.
Released Payloads can be reused for another CacheChange_t.
If there is at least one free Payload with a buffer size equal or larger to the requested one,
no memory allocation is done.
During the initialization of the History, initialReservedCaches
Payloads are preallocated for the initially allocated CacheChange_t.
DYNAMIC_RESERVE_MEMORY_MODE
Every time a Payload is requested, a new one is allocated in memory with the appropriate size.
payloadMaxSize is ignored.
The memory of released Payloads is always deallocated, so there are never free Payloads in the pool.
This reduces memory usage at the cost of frequent memory allocations.
No preallocation of Payloads is done in the initialization of the History,
DYNAMIC_REUSABLE_MEMORY_MODE
Payloads are guaranteed to have a data buffer at least as large as the requested size.
payloadMaxSize is ignored.
Released Payloads can be reused for another CacheChange_t.
If there is at least one free Payload with a buffer size equal or larger to the requested one,
no memory allocation is done.
Example using a custom Payload pool¶
// A simple payload pool that reserves and frees memory each time
class CustomPayloadPool : public IPayloadPool
{
bool get_payload(
uint32_t size,
CacheChange_t& cache_change) override
{
// Reserve new memory for the payload buffer
octet* payload = new octet[size];
// Assign the payload buffer to the CacheChange and update sizes
cache_change.serializedPayload.data = payload;
cache_change.serializedPayload.length = size;
cache_change.serializedPayload.max_size = size;
// Tell the CacheChange who needs to release its payload
cache_change.payload_owner(this);
return true;
}
bool get_payload(
SerializedPayload_t& data,
IPayloadPool*& /*data_owner*/,
CacheChange_t& cache_change)
{
// Reserve new memory for the payload buffer
octet* payload = new octet[data.length];
// Copy the data
memcpy(payload, data.data, data.length);
// Tell the CacheChange who needs to release its payload
cache_change.payload_owner(this);
// Assign the payload buffer to the CacheChange and update sizes
cache_change.serializedPayload.data = payload;
cache_change.serializedPayload.length = data.length;
cache_change.serializedPayload.max_size = data.length;
return true;
}
bool release_payload(
CacheChange_t& cache_change) override
{
// Ensure precondition
if (this != cache_change.payload_owner())
{
std::cerr << "Trying to release a payload buffer allocated by a different PayloadPool." << std::endl;
return false;
}
// Dealloc the buffer of the payload
delete[] cache_change.serializedPayload.data;
// Reset sizes and pointers
cache_change.serializedPayload.data = nullptr;
cache_change.serializedPayload.length = 0;
cache_change.serializedPayload.max_size = 0;
// Reset the owner of the payload
cache_change.payload_owner(nullptr);
return true;
}
};
std::shared_ptr<CustomPayloadPool> payload_pool = std::make_shared<CustomPayloadPool>();
// A writer using the custom payload pool
HistoryAttributes writer_history_attr;
WriterHistory* writer_history = new WriterHistory(writer_history_attr);
WriterAttributes writer_attr;
RTPSWriter* writer = RTPSDomain::createRTPSWriter(participant, writer_attr, payload_pool, writer_history);
// A reader using the same instance of the custom payload pool
HistoryAttributes reader_history_attr;
ReaderHistory* reader_history = new ReaderHistory(reader_history_attr);
ReaderAttributes reader_attr;
RTPSReader* reader = RTPSDomain::createRTPSReader(participant, reader_attr, payload_pool, reader_history);
// Write and Read operations work as usual, but take the Payloads from the pool.
// Requesting a change to the Writer will provide one with an empty Payload taken from the pool
CacheChange_t* change = writer->new_change([]() -> uint32_t
{
return 255;
}, ALIVE);
// Write serialized data into the change and add it to the history
change->serializedPayload.length = sprintf((char*) change->serializedPayload.data, "My example string %d", 2) + 1;
writer_history->add_change(change);
Discovery¶
Fast DDS, as a Data Distribution Service (DDS) implementation, provides discovery mechanisms that allow for automatically finding and matching DataWriters and DataReaders across DomainParticipants so they can start sharing data. This discovery is performed, for all the mechanisms, in two phases.
Discovery phases¶
Participant Discovery Phase (PDP): During this phase the
DomainParticipantsacknowledge each other’s existence. To do that, each DomainParticipant sends periodic announcement messages, which specify, among other things, unicast addresses (IP and port) where the DomainParticipant is listening for incoming meta and user data traffic. Two given DomainParticipants will match when they exist in the same DDS Domain. By default, the announcement messages are sent using well-known multicast addresses and ports (calculated using theDomainId). Furthermore, it is possible to specify a list of addresses to send announcements using unicast (see in Initial peers). Moreover, is is also possible to configure the periodicity of such announcements (see Discovery Configuration).Endpoint Discovery Phase (EDP): During this phase, the
DataWritersandDataReadersacknowledge each other. To do that, the DomainParticipants share information about their DataWriters and DataReaders with each other, using the communication channels established during the PDP. This information contains, among other things, theTopicand data type (see Topic). For two endpoints to match, their topic and data type must coincide. Once DataWriter and DataReader have matched, they are ready for sending/receiving user data traffic.
Important
It is possible to use the PDP phase to transmit information about the host, user, and process (physical information)
in which the DomainParticipant is running.
Please refer to Physical Data in Discovery Information for more information about how to configure the transmitted
physical data.
Discovery mechanisms¶
Fast DDS provides the following discovery mechanisms:
Simple Discovery: This is the default mechanism. It upholds the RTPS standard for both PDP and EDP, and therefore provides compatibility with any other DDS and RTPS implementations.
Static Discovery: This mechanisms uses the Simple Participant Discovery Protocol (SPDP) for the PDP phase (as specified by the RTPS standard), but allows for skipping the Simple Endpoint Discovery Protocol (SEDP) phase when all the DataWriters’ and DataReaders’ IPs and ports, data types, and Topics are known beforehand.
Discovery Server: This discovery mechanism uses a centralized discovery architecture, where a DomainParticipant, referred as Server, acts as a hub for meta traffic discovery.
Manual Discovery: This mechanism is only compatible with the RTPS layer. It disables the PDP, letting the user to manually match and unmatch
RTPSParticipants,RTPSReaders, andRTPSWritersusing whatever external meta-information channel of its choice. Therefore, the user must access the RTPSParticipant implemented by the DomainParticipant and directly match the RTPS Entities.
Discovery settings¶
The following sections list and describe the settings available for each of the previously defined discovery mechanisms, as well as how to define the DomainParticipantListener discovery callbacks.
General Discovery Settings¶
Some discovery settings are shared across the different discovery mechanisms.
These settings are defined under the builtin public data member of the
WireProtocolConfigQos class.
These are:
Name |
Description |
Type |
Default |
|---|---|---|---|
The discovery protocol to use |
|
|
|
Filter discovery traffic for |
|
|
|
Indicates for how much time |
|
20 s |
|
The period for the
DomainParticipant |
|
3 s |
Discovery Protocol¶
Specifies the discovery protocol to use (see Discovery mechanisms). The possible values are:
Discovery Mechanism |
Possible values |
Description |
|---|---|---|
Simple |
|
Simple discovery protocol as specified in the RTPS standard. |
Static |
|
SPDP with manual EDP specified in XML files. |
Discovery Server |
|
The DomainParticipant acts as a hub for discovery traffic, receiving
|
|
The DomainParticipant acts as a client for discovery traffic. |
|
|
The DomainParticipant acts as a client for discovery traffic. |
|
|
Creates a SERVER DomainParticipant which has a persistent |
|
Manual |
|
Disables PDP phase, therefore there is no EDP phase. |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::SIMPLE;
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="participant_discovery_protocol">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>SIMPLE</discoveryProtocol>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
Ignore Participant flags¶
Defines a filter to ignore some discovery traffic when received. This is useful to add an extra level of DomainParticipant isolation. The possible values are:
Possible values |
Description |
|---|---|
|
All Discovery traffic is processed. |
|
Discovery traffic from another host is discarded. |
|
Discovery traffic from another process on the same host is discarded. |
|
Discovery traffic from DomainParticipant’s own process is discarded. |
|
Discovery traffic from DomainParticipant’s own host is discarded. |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.ignoreParticipantFlags =
static_cast<eprosima::fastrtps::rtps::ParticipantFilteringFlags_t>(
ParticipantFilteringFlags_t::FILTER_DIFFERENT_PROCESS |
ParticipantFilteringFlags_t::FILTER_SAME_PROCESS);
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="participant_discovery_ignore_flags">
<rtps>
<builtin>
<discovery_config>
<ignoreParticipantFlags>FILTER_DIFFERENT_PROCESS | FILTER_SAME_PROCESS</ignoreParticipantFlags>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
Note
To configure a DomainParticipant to not receive data from its own DataWriters, please refer to Ignore Local Endpoints.
Lease Duration¶
Indicates for how much time should a remote DomainParticipant consider the local DomainParticipant to be alive. If the liveliness of the local DomainParticipant has not being asserted within this time, the remote DomainParticipant considers the local DomainParticipant dead and destroys all the information regarding the local DomainParticipant and all its endpoints.
The local DomainParticipant’s liveliness is asserted on the remote DomainParticipant any time the remote DomainParticipant receives any kind of traffic from the local DomainParticipant.
The lease duration is specified as a time expressed in seconds and nanosecond using a Duration_t.
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.leaseDuration = Duration_t(10, 20);
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="participant_discovery_lease_duration">
<rtps>
<builtin>
<discovery_config>
<leaseDuration>
<sec>10</sec>
<nanosec>20</nanosec>
</leaseDuration>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
Announcement Period¶
It specifies the periodicity of the DomainParticipant’s PDP announcements. For liveliness’ sake it is recommend that the announcement period is shorter than the lease duration, so that the DomainParticipant’s liveliness is asserted even when there is no data traffic. It is important to note that there is a trade-off involved in the setting of the announcement period, i.e. too frequent announcements will bloat the network with meta traffic, but too scarce ones will delay the discovery of late joiners.
DomainParticipant’s announcement period is specified as a time expressed in seconds and nanosecond using a
Duration_t.
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.leaseDuration_announcementperiod = Duration_t(1, 2);
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="participant_discovery_lease_announcement">
<rtps>
<builtin>
<discovery_config>
<leaseAnnouncement>
<sec>1</sec>
<nanosec>2</nanosec>
</leaseAnnouncement>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
SIMPLE Discovery Settings¶
The SIMPLE discovery protocol resolves the establishment of the end-to-end connection between various DDS Entities. eProsima Fast DDS implements the SIMPLE discovery protocol to provide compatibility with the RTPS standard. The specification splits up the SIMPLE discovery protocol into two independent protocols:
Simple Participant Discovery Protocol (SPDP): specifies how DomainParticipants discover each other in the network; it announces and detects the presence of DomainParticipants within the same domain.
Simple Endpoint Discovery Protocol (SEDP): defines the protocol adopted by the discovered DomainParticipants for the exchange of information in order to discover the DDS Entities contained in each of them, i.e. the DataWriter and DataReader.
Name |
Description |
|---|---|
It defines the behavior of the DomainParticipants initial announcements. |
|
It defines the use of the SIMPLE protocol as a discovery protocol. |
|
A list of DomainParticipant’s IP/port pairs to which the SPDP announcements are sent. |
Initial Announcements¶
RTPS standard simple discovery mechanism requires the
DomainParticipants to send announcements of their presence in the domain.
These announcements are not delivered in a reliable fashion, and can be disposed of by the network.
In order to avoid the discovery delay induced by message disposal, the initial announcement can be set up to make
several shots, in order to increase proper reception chances.
See InitialAnnouncementConfig.
Initial announcements only take place upon participant creation.
Once this phase is over, the only announcements enforced are the standard ones based on the
leaseDuration_announcementperiod period (not the period).
Name |
Description |
Type |
Default |
|---|---|---|---|
count |
It defines the number of announcements to send at start-up. |
|
5 |
period |
It defines the specific period for initial announcements. |
|
100ms |
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.initial_announcements.count = 5;
pqos.wire_protocol().builtin.discovery_config.initial_announcements.period = Duration_t(0, 100000000u);
|
XML |
<participant profile_name="participant_profile_simple_discovery">
<rtps>
<builtin>
<discovery_config>
<initialAnnouncements>
<count>5</count>
<period>
<nanosec>100000000</nanosec>
</period>
</initialAnnouncements>
</discovery_config>
</builtin>
</rtps>
</participant>
|
Simple EDP Attributes¶
Name |
Description |
Type |
Default |
|---|---|---|---|
SIMPLE EDP |
It defines the use of the SIMPLE protocol as a discovery |
|
true |
Publication writer and |
It is intended for DomainParticipants that implement only |
|
true |
Publication reader and |
It is intended for DomainParticipants that implement only |
|
true |
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = true;
pqos.wire_protocol().builtin.discovery_config.m_simpleEDP.use_PublicationWriterANDSubscriptionReader = true;
pqos.wire_protocol().builtin.discovery_config.m_simpleEDP.use_PublicationReaderANDSubscriptionWriter = false;
|
XML |
<participant profile_name="participant_profile_qos_discovery_edp">
<rtps>
<builtin>
<discovery_config>
<EDP>SIMPLE</EDP>
<simpleEDP>
<PUBWRITER_SUBREADER>true</PUBWRITER_SUBREADER>
<PUBREADER_SUBWRITER>false</PUBREADER_SUBWRITER>
</simpleEDP>
</discovery_config>
</builtin>
</rtps>
</participant>
|
Initial peers¶
According to the RTPS standard (Section 9.6.1.1), each
RTPSParticipant
must listen for incoming Participant Discovery Protocol (PDP) discovery metatraffic in two different ports, one linked
to a multicast address and another one linked to a unicast address.
Fast DDS allows for the configuration of an initial peers list which contains one or more such IP-port address
pairs corresponding to remote DomainParticipants PDP discovery listening resources, so that the local
DomainParticipant will not only send its PDP traffic to the default multicast address-port specified by its domain,
but also to all the IP-port address pairs specified in the initial peers list.
A DomainParticipant’s initial peers list contains the list of IP-port address pairs of all other DomainParticipants with which it will communicate. It is a list of addresses that a DomainParticipant will use in the unicast discovery mechanism, together or as an alternative to multicast discovery. Therefore, this approach also applies to those scenarios in which multicast functionality is not available.
According to the RTPS standard (Section 9.6.1.1), the RTPSParticipants’ discovery traffic unicast listening ports are calculated using the following equation: 7400 + 250 * domainID + 10 + 2 * participantID. Thus, if for example a RTPSParticipant operates in Domain 0 (default domain) and its ID is 1, its discovery traffic unicast listening port would be: 7400 + 250 * 0 + 10 + 2 * 1 = 7412. By default eProsima Fast DDS uses as initial peers the Metatraffic Multicast Locators.
The following constitutes an example configuring an Initial Peers list with one peer on host 192.168.10.13 with DomainParticipant ID 1 in domain 0.
Note
There is also the possibility of not defining the initial peer port.
In this case, the discovery information would be sent to every port ranging from participantID zero to the
maxInitialPeersRange value set in the TransportDescriptorInterface.
Consequently, setting this value to at least the maximum expected number of DomainParticipants will ensure discovery
and communication.
C++ |
DomainParticipantQos qos;
// configure an initial peer on host 192.168.10.13.
// The port number corresponds to the well-known port for metatraffic unicast
// on participant ID `1` and domain `0`.
Locator_t initial_peer;
IPLocator::setIPv4(initial_peer, "192.168.10.13");
initial_peer.port = 7412;
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer);
|
XML |
<!--
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
-->
<participant profile_name="initial_peers_example_profile" is_default_profile="true">
<rtps>
<builtin>
<initialPeersList>
<locator>
<udpv4>
<address>192.168.10.13</address>
<port>7412</port>
</udpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
|
STATIC Discovery Settings¶
Fast DDS allows for the substitution of the SEDP protocol for the EDP phase with a static version that completely eliminates EDP meta traffic. This can become useful when dealing with limited network bandwidth and a well-known schema of DataWriters and DataReaders. If all DataWriters and DataReaders, and their Topics and data types, are known beforehand, the EDP phase can be replaced with a static configuration of peers. It is important to note that by doing this, no EDP discovery meta traffic will be generated, and only those peers defined in the configuration will be able to communicate. The STATIC discovery related settings are:
Name |
Description |
|---|---|
It activates the STATIC discovery protocol. |
|
Specifies an XML content with a description of the remote DataWriters and |
|
It defines the behavior of the DomainParticipant initial announcements (PDP phase). |
STATIC EDP¶
To activate the STATIC EDP, the SEDP must be disabled on the WireProtocolConfigQos.
This can be done either by code or using an XML configuration file:
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = false;
pqos.wire_protocol().builtin.discovery_config.use_STATIC_EndpointDiscoveryProtocol = true;
|
XML |
<participant profile_name="participant_profile_static_edp">
<rtps>
<builtin>
<discovery_config>
<EDP>STATIC</EDP>
</discovery_config>
</builtin>
</rtps>
</participant>
|
Currently two different formats of exchanging information in the Participant Discovery Phase (PDP) are supported: the default one and another that reduces the network bandwidth used. Static Discovery’s Exchange Format explains how to change this.
STATIC EDP XML Configuration Specification¶
Since activating STATIC EDP suppresses all EDP meta traffic, the information about the remote entities (DataWriters and DataReaders) must be statically specified, which is done using dedicated XML files. A DomainParticipant may load several of such configuration files so that the information about different entities can be contained in one file, or split into different files to keep it more organized. Fast DDS provides a Static Discovery example that implements this EDP discovery protocol.
The following table describes all the possible elements of a STATIC EDP XML configuration file. A full example of such file can be found in STATIC EDP XML Example.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Mandatory. |
|
0 |
|
EntityId of the DataReader/DataWriter. |
|
0 |
|
It indicates if QOS is expected inline |
|
|
|
Mandatory. |
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Mandatory. |
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The kind of topic. |
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The name of a partition of the remote peer. |
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Unicast locator of the DomainParticipant. |
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Multicast locator of the DomainParticipant. |
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See the ReliabilityQosPolicy section. |
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See the DurabilityQosPolicy section. |
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See Ownership QoS. |
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Defines the liveliness of the remote peer. |
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Locators definition¶
Locators for remote peers are configured using <unicastLocator> and <multicastLocator> tags.
These take no value, and the locators are defined using tag elements.
Locators defined with <unicastLocator> and <multicastLocator> are accumulative, so they can be repeated to
assign several remote endpoints locators to the same peer.
address: a mandatorystringrepresenting the locator address.port: an optionaluint16_trepresenting a port on that address.
Ownership QoS¶
The ownership of the topic can be configured using <ownershipQos> tag.
It takes no value, and the configuration is done using tag elements:
kind: can be one ofSHARED_OWNERSHIP_QOSorEXCLUSIVE_OWNERSHIP_QOS. This element is mandatory withing the tag.strength: an optionaluint32_tspecifying how strongly the remote DomainParticipant owns the Topic. This QoS can be set on DataWriters only. If not specified, default value is zero.
Liveliness QoS¶
The LivelinessQosPolicy of the remote peer is configured using <livelinessQos> tag.
It takes no value, and the configuration is done using tag elements:
kind: can be any ofAUTOMATIC_LIVELINESS_QOS,MANUAL_BY_PARTICIPANT_LIVELINESS_QOSorMANUAL_BY_TOPIC_LIVELINESS_QOS. This element is mandatory withing the tag.leaseDuration_ms: an optionaluint32specifying the lease duration for the remote peer. The special valueINFcan be used to indicate infinite lease duration. If not specified, default value isINF
Checking STATIC EDP XML Files¶
Before loading a static EDP XML file, it would be useful to check its validity and make sure the file will be
successfully loaded.
This verification can be performed on DomainParticipantFactory using
DomainParticipantFactory::check_xml_static_discovery(), using either XML files or the configuration directly,
as in the examples below.
// The (file://) flag is optional.
std::string file = "file://static_Discovery.xml";
DomainParticipantFactory* factory = DomainParticipantFactory::get_instance();
if (RETCODE_OK != factory->check_xml_static_discovery(file))
{
std::cout << "Error parsing xml file " << file << std::endl;
}
// The (data://) flag is required to load the configuration directly.
std::string fileData = "data://<?xml version=\"1.0\" encoding=\"utf-8\"?>" \
"<staticdiscovery>" \
"<participant>" \
"<name>HelloWorldPublisher</name>" \
"<writer>" \
"<userId>1</userId>" \
"<entityID>2</entityID>" \
"<topicName>HelloWorldTopic</topicName>" \
"<topicDataType>HelloWorld</topicDataType>" \
"</writer>" \
"</participant>" \
"</staticdiscovery>";
if (RETCODE_OK != factory->check_xml_static_discovery(fileData))
{
std::cout << "Error parsing xml file data:" << std::endl << fileData << std::endl;
}
STATIC EDP XML Example¶
The following is a complete example of a configuration XML file for two remote DomainParticipant, a DataWriter and a DataReader. This configuration must agree with the configuration used to create the remote DataReader/DataWriter. Otherwise, communication between DataReaders and DataWriters may be affected. If any non-mandatory element is missing, it will take the default value. As a rule of thumb, all the elements that were specified on the remote DataReader/DataWriter creation should be configured.
XML |
<staticdiscovery>
<participant>
<name>HelloWorldSubscriber</name>
<reader>
<userId>3</userId>
<entityID>4</entityID>
<expectsInlineQos>true</expectsInlineQos>
<topicName>HelloWorldTopic</topicName>
<topicDataType>HelloWorld</topicDataType>
<topicKind>WITH_KEY</topicKind>
<partitionQos>HelloPartition</partitionQos>
<partitionQos>WorldPartition</partitionQos>
<unicastLocator address="192.168.0.128" port="5000"/>
<unicastLocator address="10.47.8.30" port="6000"/>
<multicastLocator address="239.255.1.1" port="7000"/>
<reliabilityQos>BEST_EFFORT_RELIABILITY_QOS</reliabilityQos>
<durabilityQos>VOLATILE_DURABILITY_QOS</durabilityQos>
<ownershipQos kind="SHARED_OWNERSHIP_QOS"/>
<livelinessQos kind="AUTOMATIC_LIVELINESS_QOS" leaseDuration_ms="1000"/>
<disablePositiveAcks>
<enabled>true</enabled>
</disablePositiveAcks>
</reader>
</participant>
<participant>
<name>HelloWorldPublisher</name>
<writer>
<unicastLocator address="192.168.0.120" port="9000"/>
<unicastLocator address="10.47.8.31" port="8000"/>
<multicastLocator address="239.255.1.1" port="7000"/>
<userId>5</userId>
<entityID>6</entityID>
<topicName>HelloWorldTopic</topicName>
<topicDataType>HelloWorld</topicDataType>
<topicKind>WITH_KEY</topicKind>
<partitionQos>HelloPartition</partitionQos>
<partitionQos>WorldPartition</partitionQos>
<reliabilityQos>BEST_EFFORT_RELIABILITY_QOS</reliabilityQos>
<durabilityQos>VOLATILE_DURABILITY_QOS</durabilityQos>
<ownershipQos kind="SHARED_OWNERSHIP_QOS" strength="50"/>
<livelinessQos kind="AUTOMATIC_LIVELINESS_QOS" leaseDuration_ms="1000"/>
<disablePositiveAcks>
<enabled>true</enabled>
<duration>
<sec>300</sec>
</duration>
</disablePositiveAcks>
</writer>
</participant>
</staticdiscovery>
|
Loading STATIC EDP XML Files¶
Statically discovered remote DataReaders/DataWriters must define a unique userID on their profile, whose value must agree with the one specified in the discovery configuration XML. This is done by setting the user ID on the DataReaderQos/DataWriterQos:
C++ |
// Configure the DataWriter
DataWriterQos wqos;
wqos.endpoint().user_defined_id = 1;
// Configure the DataReader
DataReaderQos rqos;
rqos.endpoint().user_defined_id = 3;
|
XML |
<data_writer profile_name="writer_xml_conf_static_discovery">
<userDefinedID>3</userDefinedID>
</data_writer>
<data_reader profile_name="reader_xml_conf_static_discovery">
<userDefinedID>5</userDefinedID>
</data_reader>
|
On the local DomainParticipant, you can load STATIC EDP configuration content specifying the file containing it.
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.static_edp_xml_config("file://RemotePublisher.xml");
pqos.wire_protocol().builtin.discovery_config.static_edp_xml_config("file://RemoteSubscriber.xml");
|
XML |
<participant profile_name="participant_profile_static_load_xml">
<rtps>
<builtin>
<discovery_config>
<static_edp_xml_config>file://RemotePublisher.xml</static_edp_xml_config>
<static_edp_xml_config>file://RemoteSubscriber.xml</static_edp_xml_config>
</discovery_config>
</builtin>
</rtps>
</participant>
|
Or you can specify the STATIC EDP configuration content directly.
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.static_edp_xml_config(
"data://<?xml version=\"1.0\" encoding=\"utf-8\"?>" \
"<staticdiscovery><participant><name>RTPSParticipant</name></participant></staticdiscovery>");
|
Discovery Server Settings¶
This mechanism is based on a client-server discovery paradigm, i.e. the metatraffic (message exchange among DomainParticipants to identify each other) is managed by one or several server DomainParticipants (left figure), as opposed to simple discovery (right figure), where metatraffic is exchanged using a message broadcast mechanism like an IP multicast protocol. A Discovery-Server tool is available to ease Discovery Server setup and testing.
Note
DDS Domain concept does not apply when enabling the Discovery Server mechanism.
Comparison of Discovery Server and Simple discovery mechanisms¶
Key concepts¶
In this architecture there are several key concepts to understand:
The Discovery Server mechanism reuses the RTPS discovery messages structure, as well as the standard DDS DataWriters and DataReaders.
Discovery Server DomainParticipants may be clients or servers. The only difference between them is how they handle discovery traffic. The user traffic, that is, the traffic among the DataWriters and DataReaders they create, is role-independent.
All server and client discovery information will be shared with linked clients. Note that a server may act as a client for other servers.
A
SERVERis a participant to which the clients (and maybe other servers) send their discovery information. The role of the server is to re-distribute the clients (and servers) discovery information to their known clients and servers. A server may connect to other servers to receive information about their clients. Known servers will receive all the information known by the server. Known clients will only receive the information they need to establish communication, i.e. the information about the DomainParticipants, DataWriters, and DataReaders to which they match. This means that the server runs a “matching” algorithm to sort out which information is required by which client.A
BACKUPserver is a server that persists its discovery database into a file. This type of server can load the network graph from a file on start-up without the need of receiving any client’s information. It can be used to persist the server knowledge about the network between runs, thus securing the server’s information in case of unexpected shutdowns. It is important to note that the discovery times will be negatively affected when using this type of server, since periodically writing to a file is an expensive operation.A
CLIENTis a participant that connects to one or more servers from which it receives only the discovery information they require to establish communication with matching endpoints.Clients require prior knowledge of the servers to which they want to link. Basically it is reduced to the servers identity (henceforth called
GuidPrefix_t) and a list of locators where the servers are listening. These locators also define the transport protocol (UDP or TCP) the client will use to contact the server.The
GuidPrefix_tis the RTPS standard RTPSParticipant unique identifier, a 12-byte chain. This identifier allows clients to assess whether they are receiving messages from the right server, as each standard RTPS message contains this piece of information.The
GuidPrefix_tis used because the server’s IP address may not be a reliable enough server identifier, since several servers can be hosted in the same machine, thus having the same IP, and also because multicast addresses are acceptable addresses.
A
SUPER_CLIENTis a client that receives the discovery information known by the server, in opposition to clients, which only receive the information they need.Note
A
SUPER_CLIENTdoes not behave as a Server as it only receives the discovery information through the Server to which it is connected. Any DomainParticipant discovered by the Server with no endpoints will not be known by theSUPER_CLIENT.Servers do not require any prior knowledge of their clients, but their
GuidPrefix_tand locator list (where they are listening) must match the one provided to the clients. Clients send discovery messages to the servers at regular intervals (ping period) until they receive message reception acknowledgement. From then on, the server knows about the client and will inform it of the relevant discovery information. The same principle applies to a server connecting to another server.
Choosing between Client and Server¶
It is set by the Discovery Protocol general setting.
A participant can only play one role (despite the fact that a server may connect to other servers).
It is mandatory to fill this value because it defaults to SIMPLE.
The examples below shows how to set this parameter both programmatically and using XML.
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::CLIENT;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::SUPER_CLIENT;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::SERVER;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::BACKUP;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_discovery_protocol_alt" >
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<!-- alternatives
<discoveryProtocol>SERVER</discoveryProtocol>
<discoveryProtocol>SUPER_CLIENT</discoveryProtocol>
<discoveryProtocol>BACKUP</discoveryProtocol>
-->
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
The GuidPrefix as the server unique identifier¶
The GuidPrefix_t attribute belongs to the RTPS specification and univocally identifies each RTPSParticipant.
It consists on 12 bytes, and in Fast DDS is a key for the DomainParticipant used in the DDS domain.
Fast DDS defines the DomainParticipant GuidPrefix_t as a public data member of the
WireProtocolConfigQos class.
In the Discovery Server, it has the purpose to link a server to its clients.
It must be specified in server and client setups.
Server side setup¶
The examples below show how to manage the corresponding enum data member and XML tag.
C++ - Option 1: Manual setting of the |
eprosima::fastrtps::rtps::GuidPrefix_t serverGuidPrefix;
serverGuidPrefix.value[0] = eprosima::fastrtps::rtps::octet(0x44);
serverGuidPrefix.value[1] = eprosima::fastrtps::rtps::octet(0x53);
serverGuidPrefix.value[2] = eprosima::fastrtps::rtps::octet(0x00);
serverGuidPrefix.value[3] = eprosima::fastrtps::rtps::octet(0x5f);
serverGuidPrefix.value[4] = eprosima::fastrtps::rtps::octet(0x45);
serverGuidPrefix.value[5] = eprosima::fastrtps::rtps::octet(0x50);
serverGuidPrefix.value[6] = eprosima::fastrtps::rtps::octet(0x52);
serverGuidPrefix.value[7] = eprosima::fastrtps::rtps::octet(0x4f);
serverGuidPrefix.value[8] = eprosima::fastrtps::rtps::octet(0x53);
serverGuidPrefix.value[9] = eprosima::fastrtps::rtps::octet(0x49);
serverGuidPrefix.value[10] = eprosima::fastrtps::rtps::octet(0x4d);
serverGuidPrefix.value[11] = eprosima::fastrtps::rtps::octet(0x41);
DomainParticipantQos serverQos;
serverQos.wire_protocol().prefix = serverGuidPrefix;
|
C++ - Option 2: Using the |
DomainParticipantQos serverQos;
std::istringstream("44.53.00.5f.45.50.52.4f.53.49.4d.41") >> serverQos.wire_protocol().prefix;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_server_guidprefix" >
<rtps>
<prefix>44.53.00.5f.45.50.52.4f.53.49.4d.41</prefix>
</rtps>
</participant>
</profiles>
|
Note that a server can connect to other servers. Thus, the following section may also apply.
Important
When selecting a GUID prefix for the server, it is important to take into account that Fast DDS also uses this parameter to identify participants in the same process and enable intra-process communications. Setting two DomainParticipant GUID prefixes as intra-process compatible will result in no communication if the DomainParticipants run in separate processes. For more information, please refer to GUID Prefix considerations for intra-process delivery.
Warning
Launching more than one server using the same GUID prefix is undefined behavior.
Client side setup¶
Each client must keep a list of the servers to which it wants to link.
Each single element represents an individual server, and a GuidPrefix_t must be provided.
The server list must be populated with RemoteServerAttributes objects with a valid GuidPrefix_t data
member.
In XML the server list and its elements are simultaneously specified.
Note that prefix is an element of the RemoteServer tag.
C++ |
RemoteServerAttributes server;
server.ReadguidPrefix("44.53.00.5f.45.50.52.4f.53.49.4d.41");
DomainParticipantQos clientQos;
clientQos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(server);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_discovery_client_prefix">
<rtps>
<builtin>
<discovery_config>
<discoveryServersList>
<RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
<!-- Metatraffic locators -->
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
The server locator list¶
Each server must specify valid locators where it can be reached. Any client must be given proper locators to reach each of its servers. As in the above section, here there is a server and a client side setup.
Server side setup¶
The examples below show how to setup the server locator list and XML tag.
C++ |
Locator_t locator;
IPLocator::setIPv4(locator, 192, 168, 1, 133);
locator.port = 64863;
DomainParticipantQos serverQos;
serverQos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(locator);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_discovery_server_server_metatraffic">
<rtps>
<builtin>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<!-- placeholder server UDP address -->
<address>192.168.1.113</address>
<port>64863</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
Note that a server can connect to other servers, thus, the following section may also apply.
Client side setup¶
Each client must keep a list of locators associated to the servers to which it wants to link.
Each server specifies its own locator list which must be populated with RemoteServerAttributes objects with a
valid metatrafficUnicastLocatorList or metatrafficMulticastLocatorList.
In XML the server list and its elements are simultaneously specified.
Note the metatrafficUnicastLocatorList or metatrafficMulticastLocatorList are elements of the RemoteServer
tag.
C++ |
Locator_t locator;
IPLocator::setIPv4(locator, 192, 168, 1, 133);
locator.port = 64863;
RemoteServerAttributes server;
server.metatrafficUnicastLocatorList.push_back(locator);
DomainParticipantQos clientQos;
clientQos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(server);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_discovery_server_client_metatraffic">
<rtps>
<builtin>
<discovery_config>
<discoveryServersList>
<RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<!-- placeholder server UDP address -->
<address>192.168.1.113</address>
<port>64863</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
Fine tuning discovery server handshake¶
As explained above the clients send discovery messages to the servers at regular intervals (ping period) until they receive message reception acknowledgement. Mind that this period also applies for those servers which connect to other servers. The default value for this period is 450 ms.
C++ |
DomainParticipantQos participant_qos;
participant_qos.wire_protocol().builtin.discovery_config.discoveryServer_client_syncperiod =
Duration_t(0, 250000000);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_ping" >
<rtps>
<builtin>
<discovery_config>
<clientAnnouncementPeriod>
<!-- change default to 250 ms -->
<nanosec>250000000</nanosec>
</clientAnnouncementPeriod>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
Modifying remote servers list at run time¶
Once a server or client is running, it is possible to programmatically modify the participant’s list of remote
servers to which the running server or client should connect.
This is done by calling DomainParticipant::set_qos() with a DomainParticipantQos which has a modified
WireProtocolConfigQos (see WireProtocolConfigQos).
This feature allows to include a new remote server into the Discovery Server network or modify the remote server locator
in case that the remote server is relaunched with a different listening locator.
Important
The list of remote servers can only be modified to either add more servers, or modify the remote server
locator, but not to remove any of the existing ones.
This means that the new list passed to DomainParticipant::set_qos() must be a superset of the existing one.
Note
The remote server list can also be modified using the ROS_DISCOVERY_SERVER environment variable.
Please refer to FASTDDS_ENVIRONMENT_FILE for more information.
Warning
It is strongly advised to use either the API or the environment file. Using both at the same time may cause undefined behavior.
C++ |
// Get existing QoS for the server or client
DomainParticipantQos client_or_server_qos;
client_or_server->get_qos(client_or_server_qos);
/* Create a new server entry to which the client or server should connect */
RemoteServerAttributes remote_server_att;
// Set server's GUID prefix
remote_server_att.ReadguidPrefix("44.53.00.5f.45.50.52.4f.53.49.4d.42");
// Set server's listening locator for PDP
Locator_t locator;
IPLocator::setIPv4(locator, 127, 0, 0, 1);
locator.port = 11812;
remote_server_att.metatrafficUnicastLocatorList.push_back(locator);
/* Update list of remote servers for this client or server */
client_or_server_qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_att);
if (RETCODE_OK != client_or_server->set_qos(client_or_server_qos))
{
// Error
return;
}
|
Configure Discovery Server locators using names¶
All the examples provided in Discovery Server Settings use IPv4 addresses to specify the servers’ listening locators. However, Fast DDS also allows to specify locator addresses using names.
Full example¶
The following constitutes a full example on how to configure server and client both programmatically and using XML. You may also have a look at the eProsima Fast DDS Github repository, which contains an example similar to the one discussed in this section, as well as multiple other examples for different use cases.
Server side setup¶
C++ |
// Get default participant QoS
DomainParticipantQos server_qos = PARTICIPANT_QOS_DEFAULT;
// Set participant as SERVER
server_qos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::SERVER;
// Set SERVER's GUID prefix
std::istringstream("44.53.00.5f.45.50.52.4f.53.49.4d.41") >> server_qos.wire_protocol().prefix;
// Set SERVER's listening locator for PDP
Locator_t locator;
IPLocator::setIPv4(locator, 127, 0, 0, 1);
locator.port = 11811;
server_qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(locator);
/* Add a remote serve to which this server will connect */
// Set remote SERVER's GUID prefix
RemoteServerAttributes remote_server_att;
remote_server_att.ReadguidPrefix("44.53.01.5f.45.50.52.4f.53.49.4d.41");
// Set remote SERVER's listening locator for PDP
Locator_t remote_locator;
IPLocator::setIPv4(remote_locator, 127, 0, 0, 1);
remote_locator.port = 11812;
remote_server_att.metatrafficUnicastLocatorList.push_back(remote_locator);
// Add remote SERVER to SERVER's list of SERVERs
server_qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_att);
// Create SERVER
DomainParticipant* server =
DomainParticipantFactory::get_instance()->create_participant(0, server_qos);
if (nullptr == server)
{
// Error
return;
}
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_server_full_example">
<rtps>
<!-- Set SERVER's GUID prefix -->
<prefix>44.53.00.5f.45.50.52.4f.53.49.4d.41</prefix>
<builtin>
<!-- Set participant as SERVER -->
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
<!--
Set a list of remote servers to which this server connects.
This list may contain one or more <RemoteServer> tags
-->
<discoveryServersList>
<!--
Set remote server configuration:
- Prefix
- PDP listening locator
-->
<RemoteServer prefix="44.53.01.5f.45.50.52.4f.53.49.4d.41">
<metatrafficUnicastLocatorList>
<!-- Set SERVER's listening locator for PDP -->
<locator>
<udpv4>
<address>127.0.0.1</address>
<port>11812</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
<!-- Set SERVER's listening locator for PDP -->
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>127.0.0.1</address>
<port>11811</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
Client side setup¶
C++ |
// Get default participant QoS
DomainParticipantQos client_qos = PARTICIPANT_QOS_DEFAULT;
// Set participant as CLIENT
client_qos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::CLIENT;
// Set SERVER's GUID prefix
RemoteServerAttributes remote_server_att;
remote_server_att.ReadguidPrefix("44.53.00.5f.45.50.52.4f.53.49.4d.41");
// Set SERVER's listening locator for PDP
Locator_t locator;
IPLocator::setIPv4(locator, 127, 0, 0, 1);
locator.port = 11811;
remote_server_att.metatrafficUnicastLocatorList.push_back(locator);
// Add remote SERVER to CLIENT's list of SERVERs
client_qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_att);
// Set ping period to 250 ms
client_qos.wire_protocol().builtin.discovery_config.discoveryServer_client_syncperiod =
Duration_t(0, 250000000);
// Create CLIENT
DomainParticipant* client =
DomainParticipantFactory::get_instance()->create_participant(0, client_qos);
if (nullptr == client)
{
// Error
return;
}
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_client_full_example">
<rtps>
<builtin>
<discovery_config>
<!-- Set participant as CLIENT -->
<discoveryProtocol>CLIENT</discoveryProtocol>
<!--
Set list of remote servers. This list may contain one or
more <RemoteServer> tags
-->
<discoveryServersList>
<!--
Set remote server configuration:
- Prefix
- PDP listening locator
-->
<RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
<metatrafficUnicastLocatorList>
<!-- Set SERVER's listening locator for PDP -->
<locator>
<udpv4>
<address>127.0.0.1</address>
<port>11811</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
<!-- Set ping period to 250 ms -->
<clientAnnouncementPeriod>
<nanosec>250000000</nanosec>
</clientAnnouncementPeriod>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
Security¶
Configuring Security on servers and clients is done the same way as for any other participant. This section depicts the limitations imposed by the security enforcement on the communication between clients and servers, and which discovery information is propagated by a server depending on the security configuration of the clients and servers to which it is connected.
It is important to note that for enabling a secure discovery when using Discovery Server, Fast DDS must be compiled with security support (see CMake options), and the Domain Governance Document must explicitly encrypt the discovery.
As in SDP, when using this feature, the Domain Governance Document of all clients and servers connecting to a server must match that of the server, which implies that all DomainParticipants belonging to the same Discovery Sever network must configure the discovery protection in the same manner.
Although the server mediates the discovery process and creates connections between clients, the clients themselves still go through the PKI (Public Key Infrastructure) exchange in order to have a secure communication between them.
Important
In order to keep the behavior consistent with the QoS Policies, the server does not check the DomainParticipant Permissions Document of the DomainParticipants that it is connecting.
Important
Security support for Discovery Server is only supported from Fast DDS v2.10.0 onward.
DomainParticipantListener Discovery Callbacks¶
As stated in DomainParticipantListener, the DomainParticipantListener is an abstract class
defining the callbacks that will be triggered in response to state changes on the DomainParticipant.
Fast DDS defines three callbacks attached to events that may occur during discovery:
on_participant_discovery(),
on_data_reader_discovery(),
on_data_writer_discovery().
Further information about the DomainParticipantListener is provided in the DomainParticipantListener
section.
The following is an example of the implementation of DomainParticipantListener discovery callbacks.
class DiscoveryDomainParticipantListener : public DomainParticipantListener
{
/* Custom Callback on_participant_discovery */
void on_participant_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ParticipantDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
static_cast<void>(participant);
switch (info.status){
case eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DISCOVERED_PARTICIPANT:
{
/* Process the case when a new DomainParticipant was found in the domain */
std::cout << "New DomainParticipant '" << info.info.m_participantName <<
"' with ID '" << info.info.m_guid.entityId << "' and GuidPrefix '" <<
info.info.m_guid.guidPrefix << "' discovered." << std::endl;
/* The following line can be substituted to evaluate whether the discovered participant should be ignored */
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered participant
}
}
break;
case eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::CHANGED_QOS_PARTICIPANT:
/* Process the case when a DomainParticipant changed its QOS */
break;
case eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::REMOVED_PARTICIPANT:
/* Process the case when a DomainParticipant was removed from the domain */
std::cout << "DomainParticipant '" << info.info.m_participantName <<
"' with ID '" << info.info.m_guid.entityId << "' and GuidPrefix '" <<
info.info.m_guid.guidPrefix << "' left the domain." << std::endl;
break;
}
}
/* Custom Callback on_data_reader_discovery */
void on_data_reader_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ReaderDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
static_cast<void>(participant);
switch (info.status){
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::DISCOVERED_READER:
{
/* Process the case when a new datareader was found in the domain */
std::cout << "New DataReader subscribed to topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' discovered";
/* The following line can be substituted to evaluate whether the discovered datareader should be ignored */
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered datareader
}
}
break;
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::CHANGED_QOS_READER:
/* Process the case when a datareader changed its QOS */
break;
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::REMOVED_READER:
/* Process the case when a datareader was removed from the domain */
std::cout << "DataReader subscribed to topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' left the domain.";
break;
}
}
/* Custom Callback on_data_writer_discovery */
void on_data_writer_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::WriterDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
static_cast<void>(participant);
switch (info.status){
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::DISCOVERED_WRITER:
{
/* Process the case when a new datawriter was found in the domain */
std::cout << "New DataWriter publishing under topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' discovered";
/* The following line can be substituted to evaluate whether the discovered datawriter should be ignored */
bool ignoring_condition = false;
if (ignoring_condition)
{
should_be_ignored = true; // Request the ignoring of the discovered datawriter
}
}
break;
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::CHANGED_QOS_WRITER:
/* Process the case when a datawriter changed its QOS */
break;
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::REMOVED_WRITER:
/* Process the case when a datawriter was removed from the domain */
std::cout << "DataWriter publishing under topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' left the domain.";
break;
}
}
};
To use the previously implemented discovery callbacks in DiscoveryDomainParticipantListener class, which
inherits from the DomainParticipantListener, an object of this class is created and registered as a listener
of the DomainParticipant.
// Create the participant QoS and configure values
DomainParticipantQos pqos;
// Create a custom user DomainParticipantListener
DiscoveryDomainParticipantListener* plistener = new DiscoveryDomainParticipantListener();
// Pass the listener on DomainParticipant creation.
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(
0, pqos, plistener);
Important
Read more about callbacks and its hierarchy here
Transport Layer¶
The transport layer provides communication services between DDS entities, being responsible of actually sending and receiving messages over a physical transport. The DDS layer uses this service for both user data and discovery traffic communication. However, the DDS layer itself is transport independent, it defines a transport API and can run over any transport plugin that implements this API. This way, it is not restricted to a specific transport, and applications can choose the one that best suits their requirements, or create their own.
eProsima Fast DDS comes with five transports already implemented:
UDPv4: UDP Datagram communication over IPv4. This transport is created by default on a new DomainParticipant if no specific transport configuration is given (see UDP Transport).
UDPv6: UDP Datagram communication over IPv6 (see UDP Transport).
TCPv4: TCP communication over IPv4 (see TCP Transport).
TCPv6: TCP communication over IPv6 (see TCP Transport).
SHM: Shared memory communication among entities running on the same host. This transport is created by default on a new DomainParticipant if no specific transport configuration is given (see Shared Memory Transport).
Although it is not part of the transport module, intraprocess data delivery and data sharing delivery are also available to send messages between entities on some settings. The figure below shows a comparison between the different transports available in Fast DDS.
Transport API¶
The following diagram presents the classes defined on the transport API of eProsima Fast DDS. It shows the abstract API interfaces, and the classes required to implement a transport.
Transport API diagram¶
TransportDescriptorInterface¶
Any class that implements the TransportDescriptorInterface is known as a TransportDescriptor.
It acts as a builder for a given transport, meaning that is allows to configure the transport,
and then a new Transport can be built according to this configuration
using its create_transport factory member function.
Data members¶
The TransportDescriptorInterface defines the following data members:
Member |
Data type |
Description |
|---|---|---|
|
|
Maximum size of a single message in the transport. |
|
|
Number of channels opened with each initial remote peer. |
Any implementation of TransportDescriptorInterface should add as many data members as required to full configure the transport it describes.
TransportInterface¶
A Transport is any class that implements the TransportInterface.
It is the object that actually performs the message distribution over a physical transport.
Each Transport class defines its own kind, a unique identifier that is used to
check the compatibility of a Locator with a Transport, i.e.,
determine whether a Locator refers to a Transport or not.
Applications do not create the Transport instance themselves.
Instead, applications use a TransportDescriptor instance to configure the desired transport, and add
this configured instance to the list of user-defined transports of the DomainParticipant.
The DomainParticipant will use the factory function on the TransportDescriptor
to create the Transport when required.
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
udp_transport->sendBufferSize = 9216;
udp_transport->receiveBufferSize = 9216;
udp_transport->non_blocking_send = true;
// [OPTIONAL] ThreadSettings configuration
udp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{2, 2, 2, 2});
udp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{3, 3, 3, 3});
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(udp_transport);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
Data members¶
The TransportInterface defines the following data members:
Member |
Data type |
Description |
|---|---|---|
|
|
Unique identifier of the transport type. |
Note
transport_kind_ is a protected data member for internal use.
It cannot be accessed nor modified from the public API.
However, users that are implementing a custom Transport need to fill it with a unique constant value
in the new implementation.
Currently the following identifiers are used in Fast DDS:
Identifier |
Value |
Transport type |
|---|---|---|
|
0 |
None. Reserved value for internal use. |
|
1 |
UDP Transport over IPv4. |
|
2 |
UDP Transport over IPv6. |
|
4 |
TCP Transport over IPv4. |
|
8 |
TCP Transport over IPv6. |
|
16 |
Locator¶
A Locator_t uniquely identifies a communication channel with a remote peer for a particular transport.
For example, on UDP transports, the Locator will contain the information of the IP address and port
of the remote peer.
The Locator class is not abstract, and no specializations are implemented for each transport type.
Instead, transports should map the data members of the Locator class to their own channel identification
concepts.
For example, on Shared Memory Transport the address contains a unique ID
for the local host, and the port represents the shared ring buffer used to communicate buffer
descriptors.
Please refer to Listening Locators for more information about how to configure DomainParticipant to listen to incoming traffic.
Data members¶
The Locator defines the following data members:
Member |
Data type |
Description |
|---|---|---|
|
|
Unique identifier of the transport type. |
|
|
The channel port. |
|
|
The channel address. |
In TCP, the port of the locator is divided into a physical and a logical port.
The physical port is the port used by the network device, the real port that the operating system understands. It is stored in the two least significant bytes of the member
port.The logical port is the RTPS port. It is used by the RTPS protocol to distinguish different entities. It is stored in the two most significant bytes of the member
port.
In TCP, this distinction allows for several DDS applications using different RTPS ports (logical ports) to share the
same physical port, thus only requiring for a single port to be opened for all communications.
In UDP there is only the physical port, which is also the RTPS port, and is stored in the two least significant bytes
of the member port.
The locator address, represented in 16 bytes, is managed differently depending on whether the protocol used is IPv4 or IPv6.
The IPv6 address uses the 16 available bytes to represent a unique and global address.
The IPv4 address splits those 16 bytes in the following three sections, ordered from least to greatest significance:
4 bytes LAN IP: Local subnet identification (UDP and TCP).
4 bytes WAN IP: Public IP (TCP only).
8 bytes unused.
Locator IPv4 address
+--------+-----------------------------+-----------------------------+
| Unused | WAN address (62.128.41.210) | LAN address (192.168.0.113) |
+--------+-----------------------------+-----------------------------+
8 bytes (TCP only) 4 bytes 4 bytes
Locator IPv6 address
+--------------------------------------------------------------------+
| Address (2001:0000:130F:0000:0000:09C0:876A:130B) |
+--------------------------------------------------------------------+
16 bytes
Check how to manipulate the WAN address in the TCP IPv4 transport descriptor api section.
Configuring IP locators with IPLocator¶
IPLocator is an auxiliary static class that offers methods to manipulate IP based locators.
It is convenient when setting up a new UDP Transport or TCP Transport,
as it simplifies setting IPv4 and IPv6 addresses, or manipulating ports.
For example, normally users configure the physical port and do not need to worry about logical ports.
However, IPLocator allows to manage them if needed.
// We will configure a TCP locator with IPLocator
Locator_t locator;
// Get & set the physical port
uint16_t physical_port = IPLocator::getPhysicalPort(locator);
IPLocator::setPhysicalPort(locator, 5555);
// On TCP locators, we can get & set the logical port
uint16_t logical_port = IPLocator::getLogicalPort(locator);
IPLocator::setLogicalPort(locator, 7400);
// Set WAN address
IPLocator::setWan(locator, "80.88.75.55");
Fast DDS also allows to specify locator addresses using names. When an address is specified by a name, Fast DDS will query the known hosts and available DNS servers to try to resolve the IP address. This address will in turn be used to create the listening locator in the case of server, or as the address of the remote server in the case of clients (and servers that connect to other servers).
Locator_t locator;
auto response = eprosima::fastrtps::rtps::IPLocator::resolveNameDNS("localhost");
// Get the first returned IPv4
if (response.first.size() > 0)
{
IPLocator::setIPv4(locator, response.first.begin()->data());
locator.port = 11811;
}
// Use the locator to create server or client
<locator>
<udpv4>
<port>11811</port>
<address>localhost</address>
</udpv4>
</locator>
Warning
Currently, XML only supports loading IP addresses by name for UDP transport.
Chaining of transports¶
There are use cases where the user needs to pre-process out-coming information before being sent to network and also
the incoming information after being received.
Transport API offers two interfaces for implementing this kind of functionality: ChainingTransportDescriptor
and ChainingTransport.
These extensions allow to implement a new Transport which depends on another one (called here as
low_level_transport_).
The user can override the send() function, pre-processing the out-coming buffer before calling
the associated low_level_transport_.
Also, when a incoming buffer arrives to the low_level_transport_, this one calls the overridden
receive() function to allow to pre-process the buffer.
ChainingTransportDescriptor¶
Implementing ChainingTransportDescriptor allows to configure the new Transport and set the
low_level_transport_ on which it depends.
The associated low_level_transport_ can be any transport which inherits from
TransportInterface (including another ChainingTransport).
The ChainingTransportDescriptor defines the following data members:
Member |
Data type |
Description |
|---|---|---|
|
|
Transport descriptor of the |
User has to specify the low_level_transport_ in the definition of its new custom transport.
DomainParticipantQos qos;
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
// Create a descriptor for the new transport.
// The low level transport will be a UDPv4Transport.
auto custom_transport = std::make_shared<CustomChainingTransportDescriptor>(udp_transport);
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(custom_transport);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
ChainingTransport¶
This interface forces the user to implement send() and receive()
functions.
The idea is to pre-process the buffer and after, call to the next level.
class CustomChainingTransport : public eprosima::fastdds::rtps::ChainingTransport
{
public:
CustomChainingTransport(
const CustomChainingTransportDescriptor& descriptor)
: ChainingTransport(descriptor)
, descriptor_(descriptor)
{
}
eprosima::fastdds::rtps::TransportDescriptorInterface* get_configuration()
{
return &descriptor_;
}
bool send(
eprosima::fastrtps::rtps::SenderResource* low_sender_resource,
const eprosima::fastrtps::rtps::octet* send_buffer,
uint32_t send_buffer_size,
eprosima::fastrtps::rtps::LocatorsIterator* destination_locators_begin,
eprosima::fastrtps::rtps::LocatorsIterator* destination_locators_end,
const std::chrono::steady_clock::time_point& timeout) override
{
//
// Preprocess outcoming buffer.
//
// Call low level transport
return low_sender_resource->send(send_buffer, send_buffer_size, destination_locators_begin,
destination_locators_end, timeout);
}
void receive(
eprosima::fastdds::rtps::TransportReceiverInterface* next_receiver,
const eprosima::fastrtps::rtps::octet* receive_buffer,
uint32_t receive_buffer_size,
const eprosima::fastrtps::rtps::Locator_t& local_locator,
const eprosima::fastrtps::rtps::Locator_t& remote_locator) override
{
//
// Preprocess incoming buffer.
//
// Call upper level
next_receiver->OnDataReceived(receive_buffer, receive_buffer_size, local_locator, remote_locator);
}
private:
CustomChainingTransportDescriptor descriptor_;
};
UDP Transport¶
UDP is a connectionless transport, where the receiving DomainParticipant must open a UDP port listening for incoming messages, and the sending DomainParticipant sends messages to this port.
Warning
This documentation assumes the reader has basic knowledge of UDP/IP concepts, since terms like Time To Live (TTL), socket buffers, and port numbering are not explained in detail. However, it is possible to configure a basic UDP transport on Fast DDS without this knowledge.
UDPTransportDescriptor¶
eProsima Fast DDS implements UDP transport for both UDPv4 and UDPv6.
Each of these transports is independent from the other, and has its own TransportDescriptorInterface.
However, all their TransportDescriptorInterface data members are common.
The following table describes the common data members for both UDPv4 and UDPv6.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
0 |
Size of the sending buffer of the socket (octets). |
|
|
0 |
Size of the receiving buffer of the socket (octets). |
|
|
|
See Netmask filtering. |
|
|
Empty vector |
List of allowed interfaces with |
|
|
Empty vector |
List of blocked interfaces. See Blocklist. |
|
|
Empty vector |
List of allowed interfaces. See Interface Whitelist. |
|
|
1 |
Time to live, in number of hops. |
|
|
0 |
Port number for the outgoing messages. |
|
|
|
Do not block on send operations (*). |
|
Default ThreadSettings for the reception threads. |
||
|
|
ThreadSettings for the reception threads on specific ports. |
Note
When non_blocking_send is set to true, send operations will return immediately if the
buffer is full, but no error will be returned to the upper layer.
This means that the application will behave as if the datagram is sent and lost.
This value is specially useful on high-frequency best-effort writers.
When set to false, send operations will block until the network buffer has space for the
datagram.
This may hinder performance on high-frequency writers.
UDPv4TransportDescriptor¶
UDPv4TransportDescriptor has no additional data members from the common ones described in
UDPTransportDescriptor.
Note
The kind value for a UDPv4TransportDescriptor is given by the value
LOCATOR_KIND_UDPv4.
UDPv6TransportDescriptor¶
UDPv6TransportDescriptor has no additional data members from the common ones described in
UDPTransportDescriptor.
Note
The kind value for a UDPv6TransportDescriptor is given by the value
LOCATOR_KIND_UDPv6.
Enabling UDP Transport¶
Fast DDS enables a UDPv4 transport by default. Nevertheless, the application can enable other UDP transports if needed. To enable a new UDP transport in a DomainParticipant, first create an instance of UDPv4TransportDescriptor (for UDPv4) or UDPv6TransportDescriptor (for UDPv6), and add it to the user transport list of the DomainParticipant.
The examples below show this procedure in both C++ code and XML file.
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
udp_transport->sendBufferSize = 9216;
udp_transport->receiveBufferSize = 9216;
udp_transport->non_blocking_send = true;
// [OPTIONAL] ThreadSettings configuration
udp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{2, 2, 2, 2});
udp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{3, 3, 3, 3});
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(udp_transport);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com">
<transport_descriptors>
<transport_descriptor>
<transport_id>udp_transport</transport_id>
<type>UDPv4</type>
<sendBufferSize>9216</sendBufferSize>
<receiveBufferSize>9216</receiveBufferSize>
<non_blocking_send>true</non_blocking_send>
<default_reception_threads>
<scheduling_policy>2</scheduling_policy>
<priority>2</priority>
<affinity>2</affinity>
<stack_size>2</stack_size>
</default_reception_threads>
<reception_threads>
<reception_thread port="12345">
<scheduling_policy>3</scheduling_policy>
<priority>3</priority>
<affinity>3</affinity>
<stack_size>3</stack_size>
</reception_thread>
</reception_threads>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="UDPParticipant">
<rtps>
<userTransports>
<transport_id>udp_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
</rtps>
</participant>
</profiles>
<dds>
TCP Transport¶
TCP is a connection oriented transport, so the DomainParticipant must establish a TCP connection to the remote peer before sending data messages. Therefore, one of the communicating DomainParticipants (the one acting as server) must open a TCP port listening for incoming connections, and the other one (the one acting as client) must connect to this port.
Note
The server and client concepts are independent from the DDS concepts of Publisher, Subscriber, DataWriter, and DataReader. Also, these concepts are independent from the eProsima Discovery Server servers and clients (Discovery Server Settings). Any of them can act as a TCP Server or TCP Client when establishing the connection, and the DDS communication will work over this connection.
Warning
This documentation assumes the reader has basic knowledge of TCP/IP concepts, since terms like Time To Live (TTL), Cyclic Redundancy Check (CRC), Transport Layer Security (TLS), socket buffers, and port numbering are not explained in detail. However, it is possible to configure a basic TCP transport on Fast DDS without this knowledge.
TCPTransportDescriptor¶
eProsima Fast DDS implements TCP transport for both TCPv4 and TCPv6.
Each of these transports is independent from the other, and has its own TransportDescriptorInterface.
However, they share many of their features, and most of the TransportDescriptorInterface data members are common.
The following table describes the common data members for both TCPv4 and TCPv6.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
0 |
Size of the sending buffer of the socket (octets). |
|
|
0 |
Size of the receiving buffer of the socket (octets). |
|
|
|
See Netmask filtering. |
|
|
Empty vector |
List of allowed interfaces with |
|
|
Empty vector |
List of blocked interfaces. See Blocklist. |
|
|
Empty vector |
List of allowed interfaces See Interface Whitelist. |
|
|
1 |
Time to live, in number of hops. |
|
|
Empty vector |
List of ports to listen as server. If a port is set to 0, an available port will be automatically assigned. |
|
|
5000 |
Frequency of RTCP keep alive requests (in ms). |
|
|
15000 |
Time since sending the last keep alive request to consider a connection as broken (in ms). |
|
|
100 |
Maximum number of logical ports to try during RTCP negotiation. |
|
|
20 |
Maximum number of logical ports per request to try during RTCP negotiation. |
|
|
2 |
Increment between logical ports to try during RTCP negotiation. |
|
|
|
Enables the TCP_NODELAY socket option. |
|
|
|
Do not block on send operations (*). |
|
|
|
True to calculate and send CRC on message headers. |
|
|
|
True to check the CRC of incoming message headers. |
|
|
|
True to use TLS. See TLS over TCP. |
|
|
Configuration for TLS. See TLS over TCP. |
|
|
Default ThreadSettings for the reception threads. |
||
|
|
ThreadSettings for the reception threads on specific ports. |
|
|
ThreadSettings for the thread keeping alive TCP connections. |
||
|
ThreadSettings for the threads processing incoming TCP connection requests. |
||
|
|
0 |
Time to wait for logical port negotiation (in ms). If a logical port is under negotiation, it waits for the negotiation to finish up to this timeout before trying to send a message to that port. Setting this option to non-zero values increases the discovery time. Setting it to zero means no wait but could lead to loss of first messages. |
Warning
Although the member listening_ports accepts multiple ports, only the first listening port
will be effectively used. The rest of the ports will be ignored.
Note
If listening_ports is left empty, the participant will not be able to receive incoming
connections but will be able to connect to other participants that have configured their listening ports.
Note
When non_blocking_send is set to true, send operations will return immediately if the
send buffer might get full, but no error will be returned to the upper layer.
This means that the application will behave as if the packet is sent and lost.
When set to false, send operations will block until the network buffer has space for the
packet.
TCPv4TransportDescriptor¶
The following table describes the data members that are exclusive for TCPv4TransportDescriptor.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
[0, 0, 0, 0] |
Configuration for WAN. See WAN or Internet Communication over TCPv4. |
Note
The kind value for a TCPv4TransportDescriptor is given by the value
LOCATOR_KIND_TCPv4.
TCPv6TransportDescriptor¶
TCPv6TransportDescriptor has no additional data members from the common ones described in
TCPTransportDescriptor.
Note
The kind value for a TCPv6TransportDescriptor is given by the value
LOCATOR_KIND_TCPv6.
Enabling TCP Transport¶
There are several ways of enabling TCP transport in eprosima Fast DDS. According to the facet of each scenario, one method might suit better than the others.
Configuration of Builtin Transports¶
The first option is to modify the builtin transports that are responsible of the creation of the DomainParticipant
transports. The existing configuration that enables TCP transports is LARGE_DATA.
This option instantiates a UDPv4, a TCPv4 and a SHM transport, respectively. UDP protocol will be used for multicast
announcements during the participant discovery phase (see Discovery phases) while the participant liveliness and
the application data delivery occurs over TCP or SHM. This configuration enables auto discovery and does not
require to manually set up each participant IP and listening port. Hence, avoiding the typical Server-Client
configuration.
Builtin Transports can be configured using the FASTDDS_BUILTIN_TRANSPORTS environment variable (see
FASTDDS_BUILTIN_TRANSPORTS), XML profiles (see RTPS element type) or via code.
export FASTDDS_BUILTIN_TRANSPORTS=LARGE_DATA
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<!--
UDP transport for PDP and SHM/TCPv4 transport for both EDP and application data
-->
<participant profile_name="large_data_builtin_transports" is_default_profile="true">
<rtps>
<builtinTransports>LARGE_DATA</builtinTransports>
</rtps>
</participant>
</profiles>
</dds>
eprosima::fastdds::dds::DomainParticipantQos qos;
qos.setup_transports(eprosima::fastdds::rtps::BuiltinTransports::LARGE_DATA);
Note
Note that LARGE_DATA configuration of the builtin transports will also create a SHM transport along the UDP
and TCP transports. Shared Memory will be used whenever it is possible. Manual configuration will be required
if a TCP communication is required when SHM is feasible. (See Large Data Mode).
Server-Client Configuration¶
To set up a Server-Client configuration you need to create an instance of TCPv4TransportDescriptor (for TCPv4) or TCPv6TransportDescriptor (for TCPv6), and add it to the user transport list of the DomainParticipant.
Depending on the TCP transport descriptor settings and network locators defined, the DomainParticipant can act as a TCP Server or TCP Client.
TCP Server: If you provide
listening_portson the descriptor, the DomainParticipant will act as TCP server, listening for incoming remote connections on the given ports. The examples below show this procedure in both C++ code and XML file.eprosima::fastdds::dds::DomainParticipantQos qos; // Create a descriptor for the new transport. auto tcp_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>(); tcp_transport->add_listener_port(5100); // [OPTIONAL] ThreadSettings configuration tcp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}); tcp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}); tcp_transport->keep_alive_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}; tcp_transport->accept_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}; // Link the Transport Layer to the Participant. qos.transport().user_transports.push_back(tcp_transport); // Avoid using the default transport qos.transport().use_builtin_transports = false; // [OPTIONAL] Set unicast locators eprosima::fastrtps::rtps::Locator_t locator; locator.kind = LOCATOR_KIND_TCPv4; eprosima::fastrtps::rtps::IPLocator::setIPv4(locator, "192.168.1.10"); eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(locator, 5100); // [OPTIONAL] Logical port default value is 0, automatically assigned. eprosima::fastrtps::rtps::IPLocator::setLogicalPort(locator, 5100); qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(locator); qos.wire_protocol().default_unicast_locator_list.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?> <dds> <profiles xmlns="http://www.eprosima.com"> <transport_descriptors> <transport_descriptor> <transport_id>tcp_server_transport</transport_id> <type>TCPv4</type> <listening_ports> <port>5100</port> </listening_ports> <!-- Optional thread configuration --> <default_reception_threads> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </default_reception_threads> <reception_threads> <reception_thread port="12345"> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </reception_thread> </reception_threads> <keep_alive_thread> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </keep_alive_thread> <accept_thread> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </accept_thread> </transport_descriptor> </transport_descriptors> <participant profile_name="tcp_server_participant"> <rtps> <userTransports> <transport_id>tcp_server_transport</transport_id> </userTransports> <useBuiltinTransports>false</useBuiltinTransports> <!-- Optional unicast locator set --> <defaultUnicastLocatorList> <locator> <tcpv4> <address>192.168.1.10</address> <physical_port>5100</physical_port> <!-- Optional logical port set --> <port>5100</port> </tcpv4> </locator> </defaultUnicastLocatorList> <!-- Optional metatraffic unicast locator set --> <builtin> <metatrafficUnicastLocatorList> <locator> <tcpv4> <address>192.168.1.10</address> <physical_port>5100</physical_port> <!-- Optional logical port set --> <port>5100</port> </tcpv4> </locator> </metatrafficUnicastLocatorList> </builtin> </rtps> </participant> </profiles> </dds>
TCP Client: If you provide
initialPeersListto the DomainParticipant, it will act as TCP client, trying to connect to the remote servers at the given addresses and ports. The examples below show this procedure in both C++ code and XML file. See Initial peers for more information about their configuration.eprosima::fastdds::dds::DomainParticipantQos qos; // Disable the built-in Transport Layer. qos.transport().use_builtin_transports = false; // Create a descriptor for the new transport. // Do not configure any listener port auto tcp_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>(); qos.transport().user_transports.push_back(tcp_transport); // [OPTIONAL] ThreadSettings configuration tcp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}); tcp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}); tcp_transport->keep_alive_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}; tcp_transport->accept_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1}; // Set initial peers. eprosima::fastrtps::rtps::Locator_t initial_peer_locator; initial_peer_locator.kind = LOCATOR_KIND_TCPv4; eprosima::fastrtps::rtps::IPLocator::setIPv4(initial_peer_locator, "192.168.1.10"); eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(initial_peer_locator, 5100); // If the logical port is set in the server side, it must be also set here with the same value. // If not set in the server side in a unicast locator, do not set it here. eprosima::fastrtps::rtps::IPLocator::setLogicalPort(initial_peer_locator, 5100); qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer_locator);
<?xml version="1.0" encoding="UTF-8" ?> <dds> <profiles xmlns="http://www.eprosima.com"> <transport_descriptors> <transport_descriptor> <transport_id>tcp_client_transport</transport_id> <type>TCPv4</type> <!-- Optional thread configuration --> <default_reception_threads> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </default_reception_threads> <reception_threads> <reception_thread port="12345"> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </reception_thread> </reception_threads> <keep_alive_thread> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </keep_alive_thread> <accept_thread> <scheduling_policy>-1</scheduling_policy> <priority>0</priority> <affinity>0</affinity> <stack_size>-1</stack_size> </accept_thread> </transport_descriptor> </transport_descriptors> <participant profile_name="tcp_client_participant"> <rtps> <userTransports> <transport_id>tcp_client_transport</transport_id> </userTransports> <useBuiltinTransports>false</useBuiltinTransports> <builtin> <initialPeersList> <locator> <tcpv4> <address>192.168.1.10</address> <physical_port>5100</physical_port> <!-- To be set if set in server --> <port>5100</port> </tcpv4> </locator> </initialPeersList> </builtin> </rtps> </participant> </profiles> </dds>
Note
Manually setting unicast locators is optional. If not setting them or setting them with a logical
port of 0, the client’s initial peer shouldn’t set its logical port (or set it to 0). Otherwise,
initial peer’s logical port must match server’s unicast logical port.
HelloWorldExampleTCP shows how to use and configure a TCP transport.
WAN or Internet Communication over TCPv4¶
Fast DDS is able to connect through the Internet or other WAN networks when configured properly. To achieve this kind of scenarios, the involved network devices such as routers and firewalls must add the rules to allow the communication.
For example, imagine we have the scenario represented on the following figure:
A DomainParticipant acts as a TCP server listening on port
5100and is connected to the WAN through a router with public IP80.80.99.45.Another DomainParticipant acts as a TCP client and has configured the server’s IP address and port in its Initial peers list.
By using set_WAN_address(wan_ip), the WAN IP address is set on the participant’s locators that
are communicated during the discovery phase.
Like in the LAN case, manually setting unicast locators is optional. However, in this case, there are some considerations to take into account when setting its IP addresses:
Setting the WAN IP address using the
setWAN()method in unicast locators is ineffective because it gets overridden by theset_WAN_address()call.For assigning IP addresses to unicast locators, use only the
setIPv4()orsetIPv6()methods, which are LAN IP setters. There are some configurations which allow using these setters with a WAN IP address.
Depending on whether the server has manually set its metatraffic unicast locators and default unicast locators, the client needs to adjust its initial peer list accordingly:
If the server’s unicast locators are configured with the LAN IP address:
The initial peer can be set up with only the server’s WAN IP using the LAN IP setter.
Alternatively, it can be configured with both the server’s LAN and WAN IP addresses using the LAN setter for the LAN IP and the WAN setter for the WAN IP.
If the server’s unicast locators are configured with the WAN IP address:
The initial peer must be set up with only the server’s WAN IP using the LAN setter.
Alternatively, it can be configured with the WAN IP address using both the LAN and WAN setters.
If the server has not set any unicast locators:
The initial peer can be configured with only the server’s WAN IP using the LAN setter.
Alternatively, it can be configured with both the server’s LAN and WAN IP addresses using the LAN setter for the LAN IP and the WAN setter for the WAN IP.
Note
Manually setting unicast locators is optional. If not setting them or setting them with a logical
port of 0, the client’s initial peer shouldn’t set its logical port (or set it to 0). Otherwise,
initial peer’s logical port must match server’s unicast logical port.
On the server side, the router must be configured to forward to the TCP server
all traffic incoming to port 5100. Typically, a NAT routing of port 5100 to our
machine is enough. Any existing firewall should be configured as well.
In addition, to allow incoming connections through a WAN,
the TCPv4TransportDescriptor must indicate its public IP address
in the wan_addr data member.
The following examples show how to configure the DomainParticipant both in C++ and XML.
eprosima::fastdds::dds::DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto tcp_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>();
tcp_transport->add_listener_port(5100);
tcp_transport->set_WAN_address("80.80.99.45");
// [OPTIONAL] ThreadSettings configuration
tcp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
tcp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
tcp_transport->keep_alive_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1};
tcp_transport->accept_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1};
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(tcp_transport);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
// [OPTIONAL] Set unicast locators (do not use setWAN(), set_WAN_address() overwrites it)
eprosima::fastrtps::rtps::Locator_t locator;
locator.kind = LOCATOR_KIND_TCPv4;
// [RECOMMENDED] Use the LAN address of the server
eprosima::fastrtps::rtps::IPLocator::setIPv4(locator, "192.168.1.10");
// [ALTERNATIVE] Use server's WAN address. In that case, initial peers must be configured
// only with server's WAN address.
// eprosima::fastrtps::rtps::IPLocator::setIPv4(locator, "80.80.99.45");
eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(locator, 5100);
// [OPTIONAL] Logical port default value is 0, automatically assigned.
eprosima::fastrtps::rtps::IPLocator::setLogicalPort(locator, 5100);
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(locator);
qos.wire_protocol().default_unicast_locator_list.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp_server_wan_transport</transport_id>
<type>TCPv4</type>
<listening_ports>
<port>5100</port>
</listening_ports>
<wan_addr>80.80.99.45</wan_addr>
<!-- Optional thread configuration -->
<default_reception_threads>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</default_reception_threads>
<reception_threads>
<reception_thread port="12345">
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</reception_thread>
</reception_threads>
<keep_alive_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</keep_alive_thread>
<accept_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</accept_thread>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="tcp_server_wan_participant">
<rtps>
<userTransports>
<transport_id>tcp_server_wan_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<!-- Optional unicast locator set -->
<defaultUnicastLocatorList>
<locator>
<tcpv4>
<address>192.168.1.10</address>
<!-- Alternatively use WAN address -->
<!-- <address>80.80.99.45</address> -->
<physical_port>5100</physical_port>
<!-- Optional logical port set -->
<port>5100</port>
</tcpv4>
</locator>
</defaultUnicastLocatorList>
<!-- Optional metatraffic unicast locator set -->
<builtin>
<metatrafficUnicastLocatorList>
<locator>
<tcpv4>
<address>192.168.1.10</address>
<!-- Alternatively use WAN address -->
<!-- <address>80.80.99.45</address> -->
<physical_port>5100</physical_port>
<!-- Optional logical port set -->
<port>5100</port>
</tcpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
On the client side, the DomainParticipant must be configured
with the public IP address and listening_ports of the TCP server as
Initial peers.
eprosima::fastdds::dds::DomainParticipantQos qos;
// Disable the built-in Transport Layer.
qos.transport().use_builtin_transports = false;
// Create a descriptor for the new transport.
// Do not configure any listener port
auto tcp_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>();
// [RECOMMENDED] Use client's WAN address if there are more clients in other local networks.
tcp_transport->set_WAN_address("80.80.99.47");
qos.transport().user_transports.push_back(tcp_transport);
// [OPTIONAL] ThreadSettings configuration
tcp_transport->default_reception_threads(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
tcp_transport->set_thread_config_for_port(12345, eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
tcp_transport->keep_alive_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1};
tcp_transport->accept_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1};
// Set initial peers.
eprosima::fastrtps::rtps::Locator_t initial_peer_locator;
initial_peer_locator.kind = LOCATOR_KIND_TCPv4;
// [RECOMMENDED] Use both WAN and LAN server addresses
eprosima::fastrtps::rtps::IPLocator::setIPv4(initial_peer_locator, "192.168.1.10");
eprosima::fastrtps::rtps::IPLocator::setWan(initial_peer_locator, "80.80.99.45");
// [ALTERNATIVE] Use server's WAN address only. Valid if server specified its unicast locators
// with its LAN or WAN address.
// eprosima::fastrtps::rtps::IPLocator::setIPv4(initial_peer_locator, "80.80.99.45");
eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(initial_peer_locator, 5100);
// If the logical port is set in the server side, it must be also set here with the same value.
// If not set in the server side in a unicast locator, do not set it here.
eprosima::fastrtps::rtps::IPLocator::setLogicalPort(initial_peer_locator, 5100);
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer_locator);
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp_client_wan_transport</transport_id>
<type>TCPv4</type>
<!-- Recommended client's WAN set -->
<wan_addr>80.80.99.47</wan_addr>
<!-- Optional thread configuration -->
<default_reception_threads>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</default_reception_threads>
<reception_threads>
<reception_thread port="12345">
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</reception_thread>
</reception_threads>
<keep_alive_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</keep_alive_thread>
<accept_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</accept_thread>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="tcp_client_wan_participant">
<rtps>
<userTransports>
<transport_id>tcp_client_wan_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<builtin>
<initialPeersList>
<locator>
<tcpv4>
<!-- Recommended use of both WAN and LAN server addresses -->
<wan_address>80.80.99.45</wan_address>
<address>192.168.1.10</address>
<!-- Alternatively use server's WAN addresses only -->
<!-- <address>80.80.99.45</address> -->
<physical_port>5100</physical_port>
<!-- To be set if set in server -->
<port>5100</port>
</tcpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
HelloWorldExampleTCP¶
A TCP version of helloworld example can be found in the HelloWorldExampleTCP folder. It shows a publisher and a subscriber that communicate through TCP. The publisher is configured as TCP server while the Subscriber is acting as TCP client.
Shared Memory Transport¶
The shared memory (SHM) transport enables fast communications between entities running in the same processing unit/machine, relying on the shared memory mechanisms provided by the host operating system.
Note
Fast DDS utilizes the DomainParticipant’s GuidPrefix_t to identify peers running in the same host.
Two participants with identical 4 first bytes on the GuidPrefix_t are considered to be running in the same
host.
is_on_same_host_as() API is provided to check this condition.
Please, take also into account the caveats included in GUID Prefix considerations for intra-process delivery.
SHM transport provides better performance than other network transports like UDP / TCP, even when these transports use loopback interface. This is mainly due to the following reasons:
Large message support: Network protocols need to fragment data in order to comply with the specific protocol and network stacks requirements, increasing communication overhead. SHM transport allows the copy of full messages where the only size limit is the machine’s memory capacity.
Reduce the number of memory copies: When sending the same message to different endpoints, SHM transport can directly share the same memory buffer with all the destination endpoints. Other protocols require to perform one copy of the message per endpoint.
Less operating system overhead: Once initial setup is completed, shared memory transfers require much less system calls than the other protocols. Therefore, there is a performance/time consume gain by using SHM.
Definition of Concepts¶
This section describes basic concepts to help explain how the Shared Memory Transport works in order to deliver the data messages to the appropriate DomainParticipant. The purpose is not to be an exhaustive reference of the implementation, but to be a comprehensive explanation of each concept, so that users can configure the transport to their needs.
Many of the descriptions in this section will be made following the example use case depicted in the following figure, where Participant 1 sends a data message to Participant 2. Please, refer to the figure when following the definitions.
Sequence diagram for Shared Memory Transport¶
Segment¶
A Segment is a block of shared memory that can be accessed from different processes. Every DomainParticipant that has been configured with Shared Memory Transport creates a segment of shared memory. The DomainParticipant writes to this segment any data it needs to deliver to other DomainParticipants, and the remote DomainParticipants are able to read it directly using the shared memory mechanisms.
Note
Launching any of the processes with a higher privileged user (for instance, root) can lead to communication problems, as processes run by non-privileged users may not be able to write into the memory segment.
Every segment has a segmentId, a 16-character UUID that uniquely identifies each shared memory segment. These segmentIds are used to identify and access the segment of each DomainParticipant.
Segment Buffer¶
A buffer allocated in the shared memory Segment. It works as a container for a DDS message that is placed in the Segment. In other words, each message that the DomainParticipant writes on the Segment will be placed in a different buffer.
Buffer Descriptor¶
It acts as a pointer to a specific Segment Buffer in a specific Segment. It contains the segmentId and the offset of the Segment Buffer from the base of the Segment. When communicating a message to other DomainParticipants, Shared Memory Transport only distributes the Buffer Descriptor, avoiding the copy of the message from a DomainParticipant to another. With this descriptor, the receiving DomainParticipant can access the message written in the buffer, as is uniquely identifies the Segment (through the segmentId) and the Segment Buffer (through its offset).
Port¶
Represents a channel to communicate Buffer Descriptors. It is implemented as a ring-buffer in shared memory, so that any DomainParticipant can potentially read or write information on it. Each port has a unique identifier, a 32 bit number that can be used to refer to the port. Every DomainParticipant that has been configured with Shared Memory Transport creates a port to receive Buffer Descriptors. The identifier of this port is shared during the Discovery, so that remote peers know which port to use when they want to communicate with each DomainParticipant.
DomainParticipants create a listener to their receiving port, so that they can be notified when a new Buffer Descriptor is pushed to the port.
Port Health Check¶
Every time a DomainParticipant opens a Port (for reading or writing), a health check is performed to assess its correctness. The reason is that if one of the processes involved crashes while using a Port, that port can be left inoperative. If the attached listeners do not respond in a given timeout, the Port is considered damaged, and it is destroyed and created again.
Data-sharing delivery¶
Fast DDS allows to speed up communications between entities within the same machine by sharing the history of the DataWriter with the DataReader through shared memory. This prevents any of the overhead involved in the transport layer, effectively avoiding any data copy between DataWriter and DataReader.
Note
Fast DDS utilizes the DomainParticipant’s GuidPrefix_t to identify peers running in the same host.
Two participants with identical 4 first bytes on the GuidPrefix_t are considered to be running in the same
host.
is_on_same_host_as() API is provided to check this condition.
Please, take also into account the caveats included in GUID Prefix considerations for intra-process delivery.
Use of Data-sharing delivery does not prevent data copies between the application and the DataReader and DataWriter. These can be avoided in some cases using Zero-Copy communication.
Note
Although Data-sharing delivery uses shared memory, it differs from Shared Memory Transport in that Shared Memory is a full-compliant transport. That means that with Shared Memory Transport the data being transmitted must be copied from the DataWriter history to the transport and from the transport to the DataReader. With Data-sharing these copies can be avoided.
Overview¶
When the DataWriter is created, Fast DDS will pre-allocate a pool of
max_samples + extra_samples samples that reside
in a shared memory mapped file.
When publishing new data, the DataWriter will take a sample from this pool and add it to its history,
and notify the DataReader which sample from the pool has the new data.
The DataReader will have access to the same shared memory mapped file, and will be able to access the data published by the DataWriter.
Constraints¶
This feature is available only if the following requirements are met:
The DataWriter and DataReader have access to the same shared memory.
The Topic has a bounded TopicDataType, i.e., its
is_bounded()member function returns true.The Topic is not keyed.
The DataWriter is configured with
PREALLOCATED_MEMORY_MODEorPREALLOCATED_WITH_REALLOC_MEMORY_MODE.
There is also a limitation with the DataReader’s HistoryQos. Using Data-sharing mechanism, the DataWriter’s history is shared with the DataReaders. This means that the effective HistoryQos depth on the DataReader is, at most, the Datawriter’s HistoryQos depth. To avoid confusions, set the DataReaders’ history depth to a value equal or less than the DataWriter’s.
Data-sharing delivery configuration¶
Data-sharing delivery can be configured in the DataWriter and the DataReader using DataSharingQosPolicy. Four attributes can be configured:
The data-sharing delivery kind
The shared memory directory
The data-sharing domain identifiers.
The maximum number of data-sharing domain identifiers.
Data-Sharing delivery kind¶
Can be set to one of three modes:
AUTO: If both a DataWriter and DataReader meet the requirements, data-sharing delivery will be used between them. This is the default value.
ON: Like AUTO, but the creation of the entity will fail if the requirements are not met.
OFF: No data-sharing delivery will be used on this entity.
The following matrix shows when two entities are data-sharing compatible according to their configuration (given that the entity creation does not fail and that both entities have access to a shared memory):
Reader |
||||
ON |
OFF |
AUTO |
||
Writer |
ON |
Only if they have common domain IDs |
No |
Only if they have common domain IDs |
OFF |
No |
No |
No |
|
AUTO |
Only if they have common domain IDs |
No |
Only if the TopicDataType is bounded |
|
Data-sharing domain identifiers¶
Each entity defines a set of identifiers that represent a domain to which the entity belongs. Two entities will be able to use data-sharing delivery between them only if both have at least a common domain.
Users can define the domains of a DataWriter or DataReader with the DataSharingQosPolicy. If no domain identifier is provided by the user, the system will create one automatically. This automatic data-sharing domain will be unique for the machine where the entity is running. That is, all entities running on the same machine, and for which the user has configured no user-specific domains, will be able to use data-sharing delivery (given that the rest of requirements are met).
During the discovery phase, entities will exchange their domain identifiers and check if they can use Data-sharing to communicate.
Note
Even though a data-sharing domain identifier is a 64 bit integer, user-defined identifiers are restricted to 16 bit integers.
Maximum number of Data-sharing domain identifiers¶
The maximum number of domain identifiers that are expected to be received from a remote entity during discovery. If the remote entity defines (and sends) more than this number of domain identifiers, the discovery will fail.
By default there is no limit to the number of identifiers.
The default value can be changed with the max_domains() function.
Defining a finite number allows to preallocate the required memory
to receive the list of identifiers during the entity creation,
avoiding dynamic memory allocations afterwards.
Note that a value of 0 means no limit.
DataReader and DataWriter history coupling¶
With traditional Transport Layer delivery, the DataReader and DataWriter keep separate and independent histories, each one with their own copy of the sample. Once the sample is sent through the transport and received by the DataReader, the DataWriter is free to remove the sample from its history without affecting the DataReader.
With data-sharing delivery, the DataReader directly accesses the data instance created by the DataWriter. This means that the samples in both the history of the DataReader and the DataWriter refer to the same object in the shared memory. Therefore, there is a strong coupling in the behavior of the DataReader and DataWriter histories.
Important
If the DataWriter reuses the same sample to publish new data, the DataReader loses access to the old data sample.
Note
The DataWriter can remove the sample from its history, and it will still be available on the DataReader, unless the same sample from the pool is reused to publish a new one.
Data acknowledgement¶
With data-sharing delivery, sample acknowledgment from the DataReader occurs the first time
a sample is retrieved by the application (using DataReader::read_next_sample(),
DataReader::take_next_sample(), or any of their variations).
Once the data has been accessed by the application,
the DataWriter is free to reuse that sample to publish new data.
The DataReader detects when a sample has been reused
and automatically removes it from its history.
This means that subsequent attempts to access the same sample from the DataReader may return no sample at all.
Blocking reuse of samples until acknowledged¶
With KEEP_LAST_HISTORY_QOS or BEST_EFFORT_RELIABILITY_QOS configurations,
the DataWriter can remove samples from its history to add new ones,
even if they were not acknowledged by the DataReader.
In situations where the publishing rate is consistently faster
than the rate at which the DataReader can process the samples,
this can lead to every sample being reused before the application
has a chance to process it, thus blocking the communication at application level.
In order to avoid this situation,
the samples in the preallocated pool are never reused unless they have been acknowledged,
i.e., they have been processed by the application at least once.
If there is no reusable sample in the pool,
the writing operation in the DataWriter will be blocked until one is available
or until max_blocking_time is reached.
Note that the DataWriter history is not affected by this behavior, samples will be removed from the history by standard rules. Only the reuse of pool samples is affected. This means that the DataWriter history can be empty and the write operation be still blocked because all samples in the pool are unacknowledged.
The chance of the DataWriter blocking on a write operation can be reduced
using extra_samples.
This will make the pool to allocate more samples than the history size,
so that the DataWriter has more chances to get a free sample,
while the DataReader can still access samples that have been removed from the
DataWriter history.
Intra-process delivery¶
eProsima Fast DDS allows to speed up communications between entities within the same process by avoiding any of the overhead involved in the transport layer. Instead, the Publisher directly calls the reception functions of the Subscriber. This not only avoids the copy or send operations of the transport, but also ensures the message is received by the Subscriber, avoiding the acknowledgement mechanism.
This feature is enabled by default, and can be configured using XML profiles (see Intra-process delivery profiles). Currently the following options are available:
INTRAPROCESS_OFF: The feature is disabled.
INTRAPROCESS_USER_DATA_ONLY: Discovery metadata keeps using ordinary transport.
INTRAPROCESS_FULL: Default value. Both user data and discovery metadata using Intra-process delivery.
XML |
<library_settings>
<intraprocess_delivery>FULL</intraprocess_delivery> <!-- OFF | USER_DATA_ONLY | FULL -->
</library_settings>
|
GUID Prefix considerations for intra-process delivery¶
Fast DDS utilizes the DomainParticipant’s GuidPrefix_t to identify peers running in the same process.
Two participants with identical 8 first bytes on the GuidPrefix_t are considered to be running in the same
process, and therefore intra-process delivery is used.
is_on_same_process_as() API is provided to check this condition.
This mechanism works out-of-the-box when letting Fast DDS set the GUID prefixes for the created DomainParticipants.
However, special consideration is required when setting the GuidPrefix_t manually, either programmatically or when
using XML.
Important
Fast DDS assigns GUID prefixes considering several host parameters. Among them, the network interfaces enabled. Thus, if at runtime, the network interfaces change, any new DomainParticipant will have a different GUID prefix and will be considered to be running on another host.
eprosima::fastrtps::rtps::GuidPrefix_t guid_prefix;
guid_prefix.value[0] = eprosima::fastrtps::rtps::octet(0x77);
guid_prefix.value[1] = eprosima::fastrtps::rtps::octet(0x73);
guid_prefix.value[2] = eprosima::fastrtps::rtps::octet(0x71);
guid_prefix.value[3] = eprosima::fastrtps::rtps::octet(0x85);
guid_prefix.value[4] = eprosima::fastrtps::rtps::octet(0x69);
guid_prefix.value[5] = eprosima::fastrtps::rtps::octet(0x76);
guid_prefix.value[6] = eprosima::fastrtps::rtps::octet(0x95);
guid_prefix.value[7] = eprosima::fastrtps::rtps::octet(0x66);
guid_prefix.value[8] = eprosima::fastrtps::rtps::octet(0x65);
guid_prefix.value[9] = eprosima::fastrtps::rtps::octet(0x82);
guid_prefix.value[10] = eprosima::fastrtps::rtps::octet(0x82);
guid_prefix.value[11] = eprosima::fastrtps::rtps::octet(0x79);
DomainParticipantQos participant_qos;
participant_qos.wire_protocol().prefix = guid_prefix;
DomainParticipantQos participant_qos;
std::istringstream("77.73.71.85.69.76.95.66.65.82.82.79") >> participant_qos.wire_protocol().prefix;
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_guidprefix" >
<rtps>
<prefix>77.73.71.85.69.76.95.66.65.82.82.79</prefix>
</rtps>
</participant>
</profiles>
TLS over TCP¶
Warning
This documentation assumes the reader has basic knowledge of TLS concepts since terms like Certificate Authority (CA), Private Key, Rivest–Shamir–Adleman (RSA) cryptosystem, and Diffie-Hellman encryption protocol are not explained in detail.
Fast DDS allows configuring TCP Transports to use TLS (Transport Layer Security).
In order to set up TLS, the TCPTransportDescriptor must
have its apply_security data member set to true, and its
tls_config data member filled with the desired configuration on the
TCPTransportDescriptor.
The following is an example of configuration of TLS on the TCP server.
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto tls_transport = std::make_shared<TCPv4TransportDescriptor>();
tls_transport->sendBufferSize = 9216;
tls_transport->receiveBufferSize = 9216;
tls_transport->add_listener_port(5100);
// Create the TLS configuration
using TLSOptions = eprosima::fastdds::rtps::TCPTransportDescriptor::TLSConfig::TLSOptions;
tls_transport->apply_security = true;
tls_transport->tls_config.password = "test";
tls_transport->tls_config.cert_chain_file = "server.pem";
tls_transport->tls_config.private_key_file = "serverkey.pem";
tls_transport->tls_config.tmp_dh_file = "dh2048.pem";
tls_transport->tls_config.add_option(TLSOptions::DEFAULT_WORKAROUNDS);
tls_transport->tls_config.add_option(TLSOptions::SINGLE_DH_USE);
tls_transport->tls_config.add_option(TLSOptions::NO_SSLV2);
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(tls_transport);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<transport_descriptors>
<transport_descriptor>
<transport_id>tls_transport_server</transport_id>
<type>TCPv4</type>
<tls>
<password>test</password>
<private_key_file>serverkey.pem</private_key_file>
<cert_chain_file>server.pem</cert_chain_file>
<tmp_dh_file>dh2048.pem</tmp_dh_file>
<options>
<option>DEFAULT_WORKAROUNDS</option>
<option>SINGLE_DH_USE</option>
<option>NO_SSLV2</option>
</options>
</tls>
<sendBufferSize>9216</sendBufferSize>
<receiveBufferSize>9216</receiveBufferSize>
<listening_ports>
<port>5100</port>
</listening_ports>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TLSServerParticipant">
<rtps>
<userTransports>
<transport_id>tls_transport_server</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
The corresponding configuration on the TCP client is shown in the following example.
DomainParticipantQos qos;
// Set initial peers.
Locator_t initial_peer_locator;
initial_peer_locator.kind = LOCATOR_KIND_TCPv4;
IPLocator::setIPv4(initial_peer_locator, "192.168.1.10");
initial_peer_locator.port = 5100;
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer_locator);
// Create a descriptor for the new transport.
auto tls_transport = std::make_shared<TCPv4TransportDescriptor>();
// Create the TLS configuration
using TLSOptions = eprosima::fastdds::rtps::TCPTransportDescriptor::TLSConfig::TLSOptions;
using TLSVerifyMode = eprosima::fastdds::rtps::TCPTransportDescriptor::TLSConfig::TLSVerifyMode;
tls_transport->apply_security = true;
tls_transport->tls_config.verify_file = "ca.pem";
tls_transport->tls_config.add_verify_mode(TLSVerifyMode::VERIFY_PEER);
tls_transport->tls_config.add_verify_mode(TLSVerifyMode::VERIFY_FAIL_IF_NO_PEER_CERT);
tls_transport->tls_config.add_option(TLSOptions::DEFAULT_WORKAROUNDS);
tls_transport->tls_config.add_option(TLSOptions::SINGLE_DH_USE);
tls_transport->tls_config.add_option(TLSOptions::NO_SSLV2);
tls_transport->tls_config.server_name = "my_server.com";
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(tls_transport);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<transport_descriptors>
<transport_descriptor>
<transport_id>tls_transport_client</transport_id>
<type>TCPv4</type>
<tls>
<verify_file>ca.pem</verify_file>
<verify_mode>
<verify>VERIFY_PEER</verify>
<verify>VERIFY_FAIL_IF_NO_PEER_CERT</verify>
</verify_mode>
<options>
<option>DEFAULT_WORKAROUNDS</option>
<option>SINGLE_DH_USE</option>
<option>NO_SSLV2</option>
</options>
<server_name>my_server.com</server_name>
</tls>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TLSClientParticipant">
<rtps>
<userTransports>
<transport_id>tls_transport_client</transport_id>
</userTransports>
<builtin>
<initialPeersList>
<locator>
<tcpv4>
<address>192.168.1.10</address>
<physical_port>5100</physical_port>
</tcpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
The following table describes the data members that are configurable on TLSConfig.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
|
Password of the |
|
|
|
Path to the private key certificate file. |
|
|
|
Path to the private key RSA certificate file. |
|
|
|
Path to the public certificate chain file. |
|
|
|
Path to the Diffie-Hellman parameters file. |
|
|
|
Path to the CA (Certification- Authority) file. |
|
|
|
Establishes the verification mode mask. |
|
|
|
Establishes the SSL Context options mask. |
|
|
Empty vector |
Paths where the system will look for verification files. |
|
|
-1 |
Maximum allowed depth for verifying intermediate |
|
|
|
Look for verification files on the default paths. |
|
|
|
Role that the transport will take on handshaking. |
|
|
|
Server name or host name required in case |
Note
Fast DDS uses the Boost.Asio library to handle TLS secure connections. These data members are used to build the asio library context, and most of them are mapped directly into this context without further manipulation. You can find more information about the implications of each member on the Boost.Asio context documentation.
TLS Verification Mode¶
The verification mode defines how the peer node will be verified.
The following table describes the available verification options.
Several verification options can be combined in the same TCPTransportDescriptor
using the add_verify_mode() member function.
Value |
Description |
|---|---|
|
Perform no verification. |
|
Perform verification of the peer. |
|
Fail verification if the peer has no certificate.
Ignored unless |
|
Do not request client certificate on renegotiation.
Ignored unless |
Note
For a complete description of the different verification modes, please refer to the OpenSSL documentation.
TLS Options¶
These options define which TLS features are to be supported.
The following table describes the available options.
Several options can be combined in the same TransportDescriptor
using the add_option() member function.
Value |
Description |
|---|---|
|
Implement various bug workarounds. See Boost.Asio context. |
|
Disable compression. |
|
Disable SSL v2. |
|
Disable SSL v3. |
|
Disable TLS v1. |
|
Disable TLS v1.1. |
|
Disable TLS v1.2. |
|
Disable TLS v1.3. |
|
Always create a new key when using Diffie-Hellman parameters. |
TLS Handshake Role¶
The role can take the following values:
Value |
Description |
|---|---|
|
Configured as client if connector, and as server if acceptor |
|
Configured as client. |
|
Configured as server. |
Listening Locators¶
Listening Locators are used to receive incoming traffic on the DomainParticipant. These Locators can be classified according to the communication type and to the nature of the data.
According to the communication type we have:
Multicast locators: Listen to multicast communications.
Unicast locators: Listen to unicast communications.
According to the nature of the data we have:
Metatraffic locators: Used to receive metatraffic information, usually used by built-in endpoints to perform discovery.
User locators: Used by the endpoints created by the user to receive user Topic data changes.
Applications can provide their own Listening Locators, or use the Default Listening Locators provided by eProsima Fast DDS.
Adding Listening Locators¶
Users can add custom Listening Locators to the DomainParticipant using the DomainParticipantQos. Depending on the field where the Locator is added, it will be treated as a multicast, unicast, user or metatraffic Locator.
Note
Both UDP and TCP unicast Locators support to have a null address. In that case, Fast DDS automatically gets and uses local network addresses.
Note
Both UDP and TCP Locators support to have a zero port. In that case, Fast DDS automatically calculates and uses well-known ports for that type of traffic. See Well Known Ports for details about the well-known ports.
Warning
TCP does not support multicast scenarios, so the network architecture must be carefully planned.
Metatraffic Multicast Locators¶
Users can set their own metatraffic multicast locators within the WireProtocolConfigQos:
builtin.metatrafficMulticastLocatorList.
DomainParticipantQos qos;
// This locator will open a socket to listen network messages
// on UDPv4 port 22222 over multicast address 239.255.0.1
eprosima::fastrtps::rtps::Locator_t locator;
IPLocator::setIPv4(locator, 239, 255, 0, 1);
locator.port = 22222;
// Add the locator to the DomainParticipantQos
qos.wire_protocol().builtin.metatrafficMulticastLocatorList.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="CustomMetatrafficMulticastParticipant">
<rtps>
<builtin>
<metatrafficMulticastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>239.255.0.1</address>
<port>22222</port>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
Metatraffic Unicast Locators¶
Users can set their own metatraffic unicast locators within the WireProtocolConfigQos:
builtin.metatrafficUnicastLocatorList.
DomainParticipantQos qos;
// This locator will open a socket to listen network messages
// on UDPv4 port 22223 over address 192.168.0.1
eprosima::fastrtps::rtps::Locator_t locator;
IPLocator::setIPv4(locator, 192, 168, 0, 1);
locator.port = 22223;
// Add the locator to the DomainParticipantQos
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="CustomMetatrafficUnicastParticipant">
<rtps>
<builtin>
<metatrafficUnicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
<port>22223</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
User-traffic Multicast Locators¶
Users can set their own user-traffic multicast locators within the WireProtocolConfigQos:
default_multicast_locator_list.
DomainParticipantQos qos;
// This locator will open a socket to listen network messages
// on UDPv4 port 22224 over multicast address 239.255.0.1
eprosima::fastrtps::rtps::Locator_t locator;
IPLocator::setIPv4(locator, 239, 255, 0, 1);
locator.port = 22224;
// Add the locator to the DomainParticipantQos
qos.wire_protocol().default_multicast_locator_list.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="CustomUsertrafficMulticastParticipant">
<rtps>
<defaultMulticastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>239.255.0.1</address>
<port>22224</port>
</udpv4>
</locator>
</defaultMulticastLocatorList>
</rtps>
</participant>
</profiles>
User-traffic Unicast Locators¶
Users can set their own user-traffic unicast locators within the WireProtocolConfigQos:
default_unicast_locator_list.
DomainParticipantQos qos;
// This locator will open a socket to listen network messages
// on UDPv4 port 22225 over address 192.168.0.1
eprosima::fastrtps::rtps::Locator_t locator;
IPLocator::setIPv4(locator, 192, 168, 0, 1);
locator.port = 22225;
// Add the locator to the DomainParticipantQos
qos.wire_protocol().default_unicast_locator_list.push_back(locator);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="CustomUsertrafficUnicastParticipant">
<rtps>
<defaultUnicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
<port>22225</port>
</udpv4>
</locator>
</defaultUnicastLocatorList>
</rtps>
</participant>
</profiles>
Default Listening Locators¶
If the application does not define any Listening Locators, eProsima Fast DDS automatically enables a set of listening UDPv4 locators by default. This allows out-of-the-box communication in most cases, without the need of further configuring the Transport Layer.
If the application does not define any metatraffic Locator (neither unicast nor multicast), Fast DDS enables one multicast Locator that will be used during Discovery, and one unicast Locator that will be used for peer-to-peer communication with already discovered DomainParticipants.
If the application does not define any user-traffic Locator (neither unicast nor multicast), Fast DDS enables one unicast Locator that will be used for peer-to-peer communication of Topic data.
For example, it is possible to prevent multicast traffic adding a single metatraffic unicast Locator as described in Disabling all Multicast Traffic.
Default Listening Locators always use Well Known Ports.
Well Known Ports¶
The DDSI-RTPS V2.2 standard (Section 9.6.1.1) defines a set of rules to calculate well-known ports for default Locators, so that DomainParticipants can communicate with these default Locators. Well-known ports are also selected automatically by Fast DDS when a Locator is configured with port number 0.
Well-known ports are calculated using the following predefined rules:
Traffic type |
Well-known port expression |
|---|---|
Metatraffic multicast |
|
Metatraffic unicast |
|
User multicast |
|
User unicast |
|
The values used in these rules are explained on the following table.
The default values can be modified using the port member of the
WireProtocolConfigQos on the DomainParticipantQos.
Symbol |
Meaning |
Default value |
QoS field |
|---|---|---|---|
|
DomainID gain |
250 |
|
|
ParticipantId gain |
2 |
|
|
Port Base number |
7400 |
|
|
Additional offset |
0 |
|
|
Additional offset |
10 |
|
|
Additional offset |
1 |
|
|
Additional offset |
11 |
|
Announced Locators¶
In order for communication to take place, DDS entities need to exchange the list of addresses and ports where they can be reached. Apart from the default announced locators, which correspond to addresses of the interfaces in the host where the application is running, the user can configure additional locators with addresses and ports on other networks, when routing rules have been correspondingly set up.
Default Announced Locators¶
The default list of announced locators will be constructed from the listening locators, as follows:
If the address field of the locator is a null address (i.e. 0.0.0.0 for UDPv4), a locator of the same kind and port will be announced for each of the addresses of the network interfaces of the host.
If the address field of the locator is not a null address, a single locator with that address will be announced.
External Locators¶
The user can configure a set of external locators for each of the lists of unicast locators:
builtin.metatraffic_external_unicast_locatorson WireProtocolConfigQosdefault_external_unicast_locatorson WireProtocolConfigQosexternal_unicast_locatorson RTPSEndpointQos
An external locator is made up of the standard locator fields (kind, address, and port), plus the following attributes:
An externality that indicates the number of hops from the host where the application is running to the LAN represented by the external locator.
A cost indicating the communication cost relative to other locators on the same externality level.
A mask with the number of significant bits on the LAN represented by the external locator.
Externality levels¶
The main purpose of the external locators is to enable communication across different levels of interconnected LANs. Communication will be performed using the locators of the innermost LAN available.
As an example, consider a network topology where the application is running on a host connected to a LAN of an office, which in turn connects to a LAN for all the offices in the same floor, which in turn connects to a LAN for the building.
With the default configuration, communication will only occur between hosts on the LAN for the office. This is considered the externality level 0, which is reserved for the LANs directly connected to the network interfaces of the host where the application is running. This is the externality level that will be used on the matching algorithm for the default announced locators. The floor LAN will be configured as externality level 1, whereas the building LAN will be configured as externality level 2.
Note that in order for the communication to be successful, routing rules should most probably need to be added to the different network routers.
Important
Externality level 0 is automatically populated by Fast DDS and cannot be configured by the application.
Matching algorithm¶
When a remote entity is discovered, its list of announced locators is processed to select the ones on the innermost externality level where the communication can be established. The highest externality level is checked first.
If the discovered addresses for one level are equal to the ones announced by the local entity, it means they are on the same host at that level, and the algorithm proceeds to an inner level. If the discovered addresses are not equal to the ones announced by the local entity, processing stops at the current level.
When the externality level on which the communication will be established has been decided, the algorithm will:
Remove locators that match with addresses on any other externality level.
Keep locators that match with the selected externality level.
For the locators with an address that does not match with any of the locators announced by the local entity:
Keep them when
ignore_non_matching_locatorsisfalse(default behavior)Remove them when
ignore_non_matching_locatorsistrue
Additional considerations¶
Since using external locators increases the number of locators announced, the allocation limits for locators discovery would need to be adjusted for your application.
Participants running on the same host, but using different addresses on their
builtin.metatraffic_external_unicast_locators will discard shared memory transport locators.
Data sharing communication is not affected by this limitation.
Warning
Interface whitelist will be deprecated in future versions of Fast DDS. The use of the new interfaces allowlist is recommended.
Interface Whitelist¶
Using Fast DDS, it is possible to limit the network interfaces used by TCP Transport and
UDP Transport.
This is achieved by adding the interfaces to the interfaceWhiteList
field in the TCPTransportDescriptor or UDPTransportDescriptor.
Thus, the communication interfaces used by the DomainParticipants whose TransportDescriptorInterface defines an
interfaceWhiteList is limited to the interfaces’ addresses defined in that list,
therefore avoiding the use of the rest of the network interfaces available in the system.
The interfaces in interfaceWhiteList can be specified both by IP address or interface
name.
For example:
Interface whitelist filled with IP address:
DomainParticipantQos qos; // Create a descriptor for the new transport. auto tcp_transport = std::make_shared<TCPv4TransportDescriptor>(); // Add loopback to the whitelist by IP address tcp_transport->interfaceWhiteList.emplace_back("127.0.0.1"); // Link the Transport Layer to the Participant. qos.transport().user_transports.push_back(tcp_transport); // Avoid using the builtin transports qos.transport().use_builtin_transports = false;
<?xml version="1.0" encoding="UTF-8" ?> <profiles xmlns="http://www.eprosima.com"> <transport_descriptors> <transport_descriptor> <transport_id>CustomTcpTransportWhitelistAddress</transport_id> <type>TCPv4</type> <interfaceWhiteList> <address>127.0.0.1</address> </interfaceWhiteList> </transport_descriptor> </transport_descriptors> <participant profile_name="CustomTcpTransportWhitelistAddressParticipant"> <rtps> <useBuiltinTransports>false</useBuiltinTransports> <userTransports> <transport_id>CustomTcpTransportWhitelistAddress</transport_id> </userTransports> </rtps> </participant> </profiles>
Interface whitelist filled with interface names:
DomainParticipantQos qos; // Create a descriptor for the new transport. auto tcp_transport = std::make_shared<TCPv4TransportDescriptor>(); // Add loopback to the whitelist by interface name tcp_transport->interfaceWhiteList.emplace_back("lo"); // Link the Transport Layer to the Participant. qos.transport().user_transports.push_back(tcp_transport); // Avoid using the builtin transports qos.transport().use_builtin_transports = false;
<?xml version="1.0" encoding="UTF-8" ?> <profiles xmlns="http://www.eprosima.com"> <transport_descriptors> <transport_descriptor> <transport_id>CustomTcpTransportWhitelistName</transport_id> <type>TCPv4</type> <interfaceWhiteList> <interface>lo</interface> </interfaceWhiteList> </transport_descriptor> </transport_descriptors> <participant profile_name="CustomTcpTransportWhitelistNameParticipant"> <rtps> <useBuiltinTransports>false</useBuiltinTransports> <userTransports> <transport_id>CustomTcpTransportWhitelistName</transport_id> </userTransports> </rtps> </participant> </profiles>
Important
If none of the values in the transport descriptor’s whitelist match the interfaces on the host, then all the interfaces in the whitelist are filtered out and therefore no communication will be established through that transport.
Warning
The interface whitelist feature applies to network interfaces. Therefore, it is only available on TCP Transport and UDP Transport.
Warning
The configuration options described in this section apply to network interfaces. Therefore, it is only available on TCP Transport and UDP Transport.
Interfaces configuration¶
By default, Fast DDS makes use of all active network interfaces found in the system to communicate (note: applies to UDP Transport and TCP Transport). However, it is possible for a user to indicate a specific set of network interfaces to be used by the library, and/or configure some of them in a specific manner.
Netmask filtering¶
The standard behaviour in Fast-DDS is to attempt data transmission to any remote locator for which a compatible transport (based on kind) is registered. This may result in a non-optimum resource utilization, as messages could be sent from an interface to an unreachable destination given a particular network architecture. In this situation, a user may decide to enable the netmask filtering feature, which would prevent this behavior by only sending data from a network interface to remote locators within the same subnetwork.
This configuration option can be set at participant, transport and interface levels, and its possible values are:
Value |
Description |
|---|---|
|
Enable netmask filtering. |
|
Disable netmask filtering. |
|
Use container’s netmask filter configuration. |
An AUTO netmask filter configuration means that its effective value will be given by that of
its “container”, which in the case of an allowlist entry would be the
transport descriptor where it is included, and in the case of a transport descriptor
would be the participant where it is registered.
However not all configurations are valid; this is, for example, a transport’s netmask filter configuration cannot
be OFF if it is ON for the participant where this transport
is registered.
Likewise, the netmask filter configuration for an allowlist entry cannot be ON if it is
OFF for the transport descriptor where this allowlist is defined.
Note
Due to implementation details, it is required to set ignore_non_matching_locators to true (see Matching algorithm) both in participants and endpoints when enabling the netmask filtering feature at participant or transport level without defining an allowlist or blocklist.
Additional considerations need to be taken into account when using netmask filtering in combination with external locators. In particular, it is not possible to enable netmask filtering in all entries of an allowlist when a set of local external locators (with an externality greater than 0) is defined for a participant or endpoint. The reason for this is that a matching remote external locator would then (most likely) be effectively ignored, as no network interface would be able to reach it according to its network mask.
Netmask filtering can be enabled at participant level both via C++ API or XML configuration:
// Configure netmask filtering at participant level
qos.transport().netmask_filter = NetmaskFilterKind::AUTO;
qos.wire_protocol().ignore_non_matching_locators = true; // Required if not defining an allowlist or blocklist
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<participant profile_name="CustomTcpParticipantNetmaskFilterParticipant">
<rtps>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<netmask_filter>ON</netmask_filter>
</rtps>
</participant>
</profiles>
For socket (UDP/TCP) transport descriptors:
// Create a descriptor for the new transport.
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
// Configure netmask filtering at transport level
udp_transport->netmask_filter = NetmaskFilterKind::AUTO;
qos.wire_protocol().ignore_non_matching_locators = true; // Required if not defining an allowlist or blocklist
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>CustomTcpTransportNetmaskFilter</transport_id>
<type>TCPv4</type>
<netmask_filter>ON</netmask_filter>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="CustomTcpTransportNetmaskFilterParticipant">
<rtps>
<useBuiltinTransports>false</useBuiltinTransports>
<userTransports>
<transport_id>CustomTcpTransportNetmaskFilter</transport_id>
</userTransports>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
</rtps>
</participant>
</profiles>
See Allowlist to learn how to configure netmask filtering for specific network devices.
Allowlist¶
Using Fast DDS, it is possible to limit the network interfaces used by TCP Transport
and UDP Transport.
This is achieved by adding the interfaces to the allowlist field in the
TCPTransportDescriptor or UDPTransportDescriptor.
Thus, the communication interfaces used by the DomainParticipants whose TransportDescriptorInterface defines an
allowlist is limited to the interfaces defined in that list, therefore
avoiding the use of the rest of the network interfaces available in the system.
The interfaces in allowlist can be specified both by IP address
or interface name.
Additionally, each entry added to the allowlist may specify a netmask filter
configuration value (AUTO by default).
For example:
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
// Add allowed interface by device name
udp_transport->interface_allowlist.emplace_back("eth0", NetmaskFilterKind::OFF);
// Add allowed interface by IP address (using default netmask filter AUTO)
udp_transport->interface_allowlist.emplace_back("127.0.0.1");
// Add allowed interface with explicit AllowedNetworkInterface construction
AllowedNetworkInterface another_allowed_interface("docker0", NetmaskFilterKind::OFF);
udp_transport->interface_allowlist.emplace_back(another_allowed_interface);
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(udp_transport);
// Avoid using the builtin transports
qos.transport().use_builtin_transports = false;
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>CustomTcpTransportAllowlist</transport_id>
<type>TCPv4</type>
<interfaces>
<allowlist>
<interface name="wlp59s0" netmask_filter="ON"/>
<interface name="192.168.1.10" netmask_filter="OFF"/>
</allowlist>
</interfaces>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="CustomTcpTransportAllowlistParticipant">
<rtps>
<useBuiltinTransports>false</useBuiltinTransports>
<userTransports>
<transport_id>CustomTcpTransportAllowlist</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
Important
If none of the values in the transport descriptor’s allowlist match the interfaces on the host, then all the interfaces in the allowlist are filtered out and therefore no communication will be established through that transport.
Blocklist¶
Apart from defining a list of allowed interfaces, it is also possible to define a list of
interfaces that should be blocked.
This is accomplished through the blocklist field present in the
TCPTransportDescriptor or UDPTransportDescriptor.
Note
This list takes precedence over the allowlist, so if a network interface is in both lists, it will be blocked.
The interfaces in blocklist can be specified both by IP address
or interface name.
For example:
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
// Add blocked interface by device name
udp_transport->interface_blocklist.emplace_back("docker0");
// Add blocked interface by IP address
udp_transport->interface_blocklist.emplace_back("127.0.0.1");
// Add blocked interface with explicit BlockedNetworkInterface construction
BlockedNetworkInterface another_blocked_interface("eth0");
udp_transport->interface_blocklist.emplace_back(another_blocked_interface);
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(udp_transport);
// Avoid using the builtin transports
qos.transport().use_builtin_transports = false;
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>CustomTcpTransportBlocklist</transport_id>
<type>TCPv4</type>
<interfaces>
<blocklist>
<interface name="127.0.0.1"/>
<interface name="docker0"/>
</blocklist>
</interfaces>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="CustomTcpTransportBlocklistParticipant">
<rtps>
<useBuiltinTransports>false</useBuiltinTransports>
<userTransports>
<transport_id>CustomTcpTransportBlocklist</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
Disabling all Multicast Traffic¶
If all the peers are known beforehand and have been configured on the Initial Peers List, all multicast traffic can be completely disabled.
By defining a custom Metatraffic Unicast Locators, the local DomainParticipant creates a unicast meta traffic receiving resource for each address-port pair specified in the list, avoiding the creation of the default metatraffic multicast and unicast locators. This prevents the DomainParticipant from listening to any discovery data from multicast sources.
Consideration should be given to the assignment of the ports in the
metatrafficUnicastLocatorList, avoiding the assignment of ports that are not available or do
not match the address-port listed in the publisher participant Initial Peers List.
The following is an example of how to disable all multicast traffic configuring one metatraffic unicast locator.
DomainParticipantQos qos;
// Metatraffic Multicast Locator List will be empty.
// Metatraffic Unicast Locator List will contain one locator, with null address and null port.
// Then Fast DDS will use all network interfaces to receive network messages using a well-known port.
Locator_t default_unicast_locator;
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(default_unicast_locator);
// Initial peer will be UDPv4 address 192.168.0.1. The port will be a well-known port.
// Initial discovery network messages will be sent to this UDPv4 address.
Locator_t initial_peer;
IPLocator::setIPv4(initial_peer, 192, 168, 0, 1);
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="disable_multicast" is_default_profile="true">
<rtps>
<builtin>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<initialPeersList>
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
Persistence Service¶
Using default QoS, the DataWriter history is only available for DataReader throughout the DataWriter’s life. This means that the history does not persist between DataWriter initializations and therefore it is on an empty state on DataWriter creation. Similarly, the DataReader history does not persist the DataReader’s life, thus also being empty on DataReader creation. However, eProsima Fast DDS offers the possibility to configure the DataWriter’s history to be stored in a persistent database, so that the DataWriter can load its history from it on creation. Furthermore, DataReaders can be configured to store the last notified change in the database, so that they can recover their state on creation.
This mechanism allows recovering a previous state on starting the Data Distribution Service, thus adding robustness to applications in the case of, for example, unexpected shutdowns. Configuring the persistence service, DataWriters and DataReaders can resume their operation from the state in which they were when the shutdown occurred.
Note
Mind that DataReaders do not store their history into the database, but rather the last notified change from the DataWriter. This means that they will resume operation where they left, but they will not have the previous information, since that was already notified to the application.
Configuration¶
The configuration of the persistence service is accomplished by setting of the appropriate DataWriter and DataReader
DurabilityQosPolicy, and by specifying the suitable properties for each entity’s (DomainParticipant, DataWriter,
or DataReader) PropertyPolicyQos.
For the Persistence Service to have any effect, the
DurabilityQosPolicyKindneeds to be set toTRANSIENT_DURABILITY_QOS.A persistence identifier (
Guid_t) must be set for the entity using the propertydds.persistence.guid. This identifier is used to load the appropriate data from the database, and also to synchronize DataWriter and DataReader between restarts. The GUID consists of 16 bytes separated into two groups:The first 12 bytes correspond to the
GuidPrefix_t.The last 4 bytes correspond to the
EntityId_t.
The persistence identifier is specified using a string of 12 dot-separated bytes, expressed in hexadecimal base, followed by a vertical bar separator (
|) and another 4 dot-separated bytes, also expressed in hexadecimal base (see Example). For selecting an appropriate GUID for the DataReader and DataWriter, please refer to RTPS standard (section 9.3.1 The Globally Unique Identifier (GUID)).A persistence plugin must be configured for managing the database using property
dds.persistence.plugin(see PERSISTENCE:SQLITE3 built-in plugin):
PERSISTENCE:SQLITE3 built-in plugin¶
This plugin provides persistence through a local database file using SQLite3 API.
To activate the plugin, dds.persistence.plugin property must be added to the PropertyPolicyQos of the
DomainParticipant, DataWriter, or DataReader with value builtin.SQLITE3.
Furthermore, dds.persistence.sqlite3.filename property must be added to the entities PropertyPolicyQos,
specifying the database file name.
These properties are summarized in the following table:
Property name |
Property value |
|---|---|
|
|
|
Name of the file used for persistent storage. |
Note
To avoid undesired delays caused by concurrent access to the SQLite3 database, it is advisable to specify a different database file for each DataWriter and DataReader.
Important
The plugin set in the PropertyPolicyQos of DomainParticipant only applies if that of the DataWriter/DataReader does no exist or is invalid.
Example¶
This example shows how to configure the persistence service using PERSISTENCE:SQLITE3 built-in plugin plugin both from C++ and using eProsima Fast DDS XML profile files (see XML profiles).
/*
* In order for this example to be self-contained, all the entities are created programatically, including the data
* type and type support. This has been done using Fast DDS Dynamic Types API, but it could be substituted with a
* Fast DDS-Gen generated type support if an IDL file is available. The Dynamic Type created here is the equivalent
* of the following IDL:
*
* struct persistence_topic_type
* {
* unsigned long index;
* string message;
* };
*/
// Configure persistence service plugin for DomainParticipant
DomainParticipantQos pqos;
pqos.properties().properties().emplace_back("dds.persistence.plugin", "builtin.SQLITE3");
pqos.properties().properties().emplace_back("dds.persistence.sqlite3.filename", "persistence.db");
DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(0, pqos);
/********************************************************************************************************
* CREATE TYPE AND TYPE SUPPORT
*********************************************************************************************************
* This part could be replaced if IDL file and Fast DDS-Gen are available.
* The type is created with name "persistence_topic_type"
* Additionally, create a data object and populate it, just to show how to do it
********************************************************************************************************/
// Create a struct builder for a type with name "persistence_topic_type"
const std::string topic_type_name = "persistence_topic_type";
TypeDescriptor::_ref_type struct_type_descriptor {traits<TypeDescriptor>::make_shared()};
struct_type_descriptor->kind(TK_STRUCTURE);
struct_type_descriptor->name(topic_type_name);
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(struct_type_descriptor)};
// The type consists of two members, and index and a message. Add members to the struct.
MemberDescriptor::_ref_type index_member_descriptor {traits<MemberDescriptor>::make_shared()};
index_member_descriptor->name("index");
index_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(TK_UINT32));
struct_builder->add_member(index_member_descriptor);
MemberDescriptor::_ref_type message_member_descriptor {traits<MemberDescriptor>::make_shared()};
message_member_descriptor->name("message");
message_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
create_string_type(static_cast<uint32_t>(LENGTH_UNLIMITED))->build());
struct_builder->add_member(message_member_descriptor);
// Build the type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create type support and register the type
TypeSupport type_support(new DynamicPubSubType(struct_type));
type_support.register_type(participant);
// Create data sample a populate data. This is to be used when calling `writer->write()`
DynamicData::_ref_type dyn_helloworld {DynamicDataFactory::get_instance()->create_data(struct_type)};
dyn_helloworld->set_uint32_value(0, 0);
dyn_helloworld->set_string_value(1, "HelloWorld");
/********************************************************************************************************
* END CREATE TYPE AND TYPE SUPPORT
********************************************************************************************************/
// Create a topic
Topic* topic = participant->create_topic("persistence_topic_name", topic_type_name, TOPIC_QOS_DEFAULT);
// Create a publisher and a subscriber with default QoS
Publisher* publisher = participant->create_publisher(PUBLISHER_QOS_DEFAULT, nullptr);
Subscriber* subscriber = participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT, nullptr);
// Configure DataWriter's durability and persistence GUID so it can use the persistence service
DataWriterQos dwqos = DATAWRITER_QOS_DEFAULT;
dwqos.durability().kind = TRANSIENT_DURABILITY_QOS;
dwqos.properties().properties().emplace_back("dds.persistence.guid",
"77.72.69.74.65.72.5f.70.65.72.73.5f|67.75.69.64");
DataWriter* writer = publisher->create_datawriter(topic, dwqos);
// Configure DataReaders's durability and persistence GUID so it can use the persistence service
DataReaderQos drqos = DATAREADER_QOS_DEFAULT;
drqos.durability().kind = TRANSIENT_DURABILITY_QOS;
drqos.properties().properties().emplace_back("dds.persistence.guid",
"72.65.61.64.65.72.5f.70.65.72.73.5f|67.75.69.64");
DataReader* reader = subscriber->create_datareader(topic, drqos);
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<!-- DomainParticipant configuration -->
<participant profile_name="persistence_service_participant">
<rtps>
<propertiesPolicy>
<properties>
<!-- Select persistence plugin -->
<property>
<name>dds.persistence.plugin</name>
<value>builtin.SQLITE3</value>
</property>
<!-- Database file name -->
<property>
<name>dds.persistence.sqlite3.filename</name>
<value>persistence_service.db</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
<!-- DataWriter configuration -->
<data_writer profile_name="persistence_service_data_writer">
<qos>
<!-- Set durability to TRANSIENT_DURABILITY_QOS -->
<durability>
<kind>TRANSIENT</kind>
</durability>
</qos>
<propertiesPolicy>
<properties>
<!-- Persistence GUID -->
<property>
<name>dds.persistence.guid</name>
<value>77.72.69.74.65.72.5f.70.65.72.73.5f|67.75.69.64</value>
</property>
</properties>
</propertiesPolicy>
</data_writer>
<data_reader profile_name="persistence_service_data_reader">
<qos>
<!-- Set durability to TRANSIENT_DURABILITY_QOS -->
<durability>
<kind>TRANSIENT</kind>
</durability>
</qos>
<propertiesPolicy>
<properties>
<!-- Persistence GUID -->
<property>
<name>dds.persistence.guid</name>
<value>72.65.61.64.65.72.5f.70.65.72.73.5f|67.75.69.64</value>
</property>
</properties>
</propertiesPolicy>
</data_reader>
</profiles>
</dds>
Note
For instructions on how to create DomainParticipants, DataReaders, and DataWriters, please refer to Profile based creation of a DomainParticipant, Profile based creation of a DataWriter, and Profile based creation of a DataReader respectively.
Security¶
The DDS Security specification includes five security builtin plugins.
Authentication plugin: DDS:Auth:PKI-DH. This plugin provides authentication for each DomainParticipant joining a DDS Domain using a trusted Certificate Authority (CA). Support mutual authentication between DomainParticipants and establish a shared secret.
Access Control plugin: DDS:Access:Permissions. This plugin provides access control to DomainParticipants which perform protected operations.
Cryptographic plugin: DDS:Crypto:AES-GCM-GMAC. This plugin provides authenticated encryption using Advanced Encryption Standard (AES) in Galois Counter Mode (AES-GCM).
Logging plugin: DDS:Logging:DDS_LogTopic. This plugin logs security events.
Data Tagging: DDS:Tagging:DDS_Discovery. This plugin enables the addition of security labels to the data. Thus it is possible to specify classification levels of the data. In the DDS context it can be used as a complement to access control, creating an access control based on data tagging; for message prioritization; and to prevent its use by the middleware to be used instead by the application or service.
Note
Currently the DDS:Tagging:DDS_Discovery plugin is not implemented in Fast DDS. Its implementation is expected for future release of Fast DDS.
In compliance with the DDS Security specification, Fast DDS provides secure communication by implementing pluggable security at three levels: a) DomainParticipants authentication (DDS:Auth:PKI-DH), b) access control of Entities (DDS:Access:Permissions), and c) data encryption (DDS:Crypto:AES-GCM-GMAC). Furthermore, for the monitoring of the security plugins and logging relevant events, Fast DDS implements the logging plugin (DDS:Logging:DDS_LogTopic).
By default, Fast DDS does not compile any security support, but it can be activated adding -DSECURITY=ON at CMake
configuration step.
For more information about Fast DDS compilation, see Linux installation from sources and Windows installation from sources.
Security plugins can be activated through the DomainParticipantQos properties.
A Property is defined by its name (std::string)
and its value (std::string).
Warning
For the full understanding of this documentation it is required the user to have basic knowledge of network security since terms like Certificate Authority (CA), Public Key Infrastructure (PKI), and Diffie-Hellman encryption protocol are not explained in detail. However, it is possible to configure basic system security settings, i.e. authentication, access control and encryption, to Fast DDS without this knowledge.
The following sections describe how to configure each of these properties to set up the Fast DDS security plugins.
Authentication plugin: DDS:Auth:PKI-DH¶
This is the starting point for all the security mechanisms. The authentication plugin provides the mechanisms and operations required for DomainParticipants authentication at discovery. If the security module was activated at Fast DDS compilation, when a DomainParticipant is either locally created or discovered, it needs to be authenticated in order to be able to communicate in a DDS Domain. Therefore, when a DomainParticipant detects a remote DomainParticipant, both try to authenticate themselves using the activated authentication plugin. If the authentication process finishes successfully both DomainParticipant match and the discovery mechanism continues. On failure, the remote DomainParticipant is rejected.
The authentication plugin implemented in Fast DDS is referred to as “DDS:Auth:PKI-DH”, in compliance with the DDS Security specification. The DDS:Auth:PKI-DH plugin uses a trusted Certificate Authority (CA) and the ECDSA Digital Signature Algorithms to perform the mutual authentication. It also establishes a shared secret using Elliptic Curve Diffie-Hellman (ECDH) Key Agreement Methods. This shared secret can be used by other security plugins as Cryptographic plugin: DDS:Crypto:AES-GCM-GMAC.
The DDS:Auth:PKI-DH authentication plugin, can be activated setting the DomainParticipantQos
properties()
dds.sec.auth.plugin with the value builtin.PKI-DH.
The following table outlines the properties used for the DDS:Auth:PKI-DH plugin configuration.
Property name |
Property value |
|---|---|
identity_ca |
URI to the X.509 v3 certificate of the Identity CA in PEM format. |
identity_certificate |
URI to an X.509 v3 certificate signed by the Identity CA in PEM format |
identity_crl (optional) |
URI to a X.509 Certificate Revocation List (CRL). |
private_key |
URI to access the private Private Key for the Participant. |
password (optional) |
A password used to decrypt the private_key. |
Note
All listed properties have “dds.sec.auth.builtin.PKI-DH.” prefix.
For example: dds.sec.auth.builtin.PKI-DH.identity_ca.
The following is an example of how to set the properties of DomainParticipantQoS for the DDS:Auth:PKI-DH plugin configuration.
C++ |
DomainParticipantQos pqos;
// Activate DDS:Auth:PKI-DH plugin
pqos.properties().properties().emplace_back("dds.sec.auth.plugin",
"builtin.PKI-DH");
// Configure DDS:Auth:PKI-DH plugin
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.identity_ca",
"file://maincacert.pem");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.identity_certificate",
"file://partcert.pem");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.identity_crl",
"file://crl.pem");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.private_key",
"file://partkey.pem");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.password",
"domainParticipantPassword");
|
XML |
<participant profile_name="secure_domainparticipant_conf_auth_plugin_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate DDS:Auth:PKI-DH plugin -->
<property>
<name>dds.sec.auth.plugin</name>
<value>builtin.PKI-DH</value>
</property>
<!-- Configure DDS:Auth:PKI-DH plugin -->
<property>
<name>dds.sec.auth.builtin.PKI-DH.identity_ca</name>
<value>file://maincacert.pem</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.identity_certificate</name>
<value>file://partcert.pem</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.identity_crl</name>
<value>file://crl.pem</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.private_key</name>
<value>file://partkey.pem</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.password</name>
<value>domainParticipantPassword</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
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Generation of X.509 certificates¶
An X.509 digital certificate is a document that has been encrypted and/or digitally signed according to RFC 5280. The X.509 certificate refers to the Public Key Infrastructure (PKI) certificate of the IETF , and specifies the standard formats for public-key certificates and a certification route validation algorithm. A simple way to generate these certificates for a proprietary PKI structure is through the OpenSSL toolkit. This section explains how to build a certificate infrastructure from the trusted CA certificate to the end-entity certificate, i.e. the DomainParticipant.
Generating the CA certificate for self-signing¶
First, since multiple certificates will need to be issued, one for each of the DomainParticipants, a dedicated CA is set up, and the CA’s certificate is installed as the root key of all DomainParticipants. Thus, the DomainParticipants will accept all certificates issued by our own CA. To create a proprietary CA certificate, a configuration file must first be written with the CA information. An example of the CA configuration file is shown below. The OpenSSL commands shown in this example are compatible with both Linux and Windows Operating Systems (OS). However, all other commands are only compatible with Linux OS.
# File: maincaconf.cnf
# OpenSSL example Certificate Authority configuration file
####################################################################
[ ca ]
default_ca = CA_default # The default ca section
####################################################################
[ CA_default ]
dir = . # Where everything is kept
certs = $dir/certs # Where the issued certs are kept
crl_dir = $dir/crl # Where the issued crl are kept
database = $dir/index.txt # database index file.
unique_subject = no # Set to 'no' to allow creation of
# several ctificates with same subject.
new_certs_dir = $dir
certificate = $dir/maincacert.pem # The CA certificate
serial = $dir/serial # The current serial number
crlnumber = $dir/crlnumber # the current crl number
# must be commented out to leave a V1 CRL
crl = $dir/crl.pem # The current CRL
private_key = $dir/maincakey.pem # The private key
RANDFILE = $dir/private/.rand # private random number file
name_opt = ca_default # Subject Name options
cert_opt = ca_default # Certificate field options
default_days= 1825 # how long to certify for
default_crl_days = 30 # how long before next CRL
default_md = sha256 # which md to use.
preserve = no # keep passed DN ordering
policy = policy_match
# For the CA policy
[ policy_match ]
countryName = match
stateOrProvinceName = match
organizationName = match
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
[ req ]
prompt = no
#default_bits = 1024
#default_keyfile = privkey.pem
distinguished_name= req_distinguished_name
#attributes = req_attributes
#x509_extensions = v3_ca # The extentions to add to the self signed cert
string_mask = utf8only
[ req_distinguished_name ]
countryName = ES
stateOrProvinceName = MA
localityName = Tres Cantos
0.organizationName = eProsima
commonName = eProsima Main Test CA
emailAddress = mainca@eprosima.com
After writing the configuration file, next commands generate the certificate using the Elliptic Curve Digital Signature Algorithm (ECDSA).
openssl ecparam -name prime256v1 > ecdsaparam
openssl req -nodes -x509 \
-days 3650 \
-newkey ec:ecdsaparam \
-keyout maincakey.pem \
-out maincacert.pem \
-config maincaconf.cnf
Generating the DomainParticipant certificate¶
As was done for the CA, a DomainParticipant certificate configuration file needs to be created first.
# File: partconf.cnf
prompt = no
string_mask = utf8only
distinguished_name = req_distinguished_name
[ req_distinguished_name ]
countryName = ES
stateOrProvinceName = MA
localityName = Tres Cantos
organizationName = eProsima
emailAddress = example@eprosima.com
commonName = DomainParticipantName
After writing the DomainParticipant certificate configuration file, next commands generate the X.509 certificate, using ECDSA, for a DomainParticipant.
openssl ecparam -name prime256v1 > ecdsaparam
openssl req -nodes -new \
-newkey ec:ecdsaparam \
-config partconf.cnf \
-keyout partkey.pem \
-out partreq.pem
openssl ca -batch -create_serial \
-config maincaconf.cnf \
-days 3650 \
-in partreq.pem \
-out partcert.pem
Generating the Certificate Revocation List (CRL)¶
Finally, the CRL is created. This is a list of the X.509 certificates revoked by the certificate issuing CA before they reach their expiration date. Any certificate that is on this list will no longer be trusted. To create a CRL using OpenSSL just run the following commands.
echo -ne '00' > crlnumber
openssl ca -gencrl \
-config maincaconf.cnf \
-cert maincacert.pem \
-keyfile maincakey.pem \
-out crl.pem
As an example, below is shown how to add the X.509 certificate of a DomainParticipant to the CRL.
openssl ca \
-config maincaconf.cnf \
-cert maincacert.pem \
-keyfile maincakey.pem \
-revoke partcert.pem
openssl ca -gencrl \
-config maincaconf.cnf \
-cert maincacert.pem \
-keyfile maincakey.pem \
-out crl.pem
Access control plugin: DDS:Access:Permissions¶
The access control plugin provides the mechanisms and operations required for validating the DomainParticipant permissions. If the security module was activated at Fast DDS compilation, after a remote DomainParticipant is authenticated, its permissions need to be validated and enforced.
Access rights that each DomainParticipant has over a resource are defined using the access control plugin. For the proper functioning of a DomainParticipant in a DDS Domain, the DomainParticipant must be authorized to operate in that specific domain. The DomainParticipant is responsible for creating the DataWriters and DataReaders that communicate over a certain Topic. Hence, a DomainParticipant must have the permissions needed to create a Topic, to publish through its DataWriters under defined Topics, and to subscribe via its DataReaders to other Topics. Access control plugin can configure the Cryptographic plugin as its usage is based on the DomainParticipant’s permissions.
The authentication plugin implemented in Fast DDS is referred to as “DDS:Access:Permissions”, in compliance with the DDS Security specification. This plugin is explained in detail below.
This builtin plugin provides access control using a permissions document signed by a trusted CA. The DDS:Access:Permissions plugin requires three documents for its configuration which contents are explained in detail below.
The Permissions CA certificate.
The Domain governance signed by the Permissions CA.
The DomainParticipant permissions signed by the Permissions CA.
The DDS:Access:Permissions authentication plugin, can be activated setting the DomainParticipantQos
properties()
dds.sec.access.plugin with the value builtin.Access-Permissions.
The following table outlines the properties used for the DDS:Access:Permissions plugin configuration.
Property name |
Property value |
|---|---|
permissions_ca |
URI to the X509 certificate of the Permissions CA. |
governance |
URI to shared Governance Document signed by the Permissions CA |
permissions |
URI to the Participant permissions document signed by the |
Note
All listed properties have “dds.sec.access.builtin.Access-Permissions.” prefix.
For example: dds.sec.access.builtin.Access-Permissions.permissions_ca.
The following is an example of how to set the properties of DomainParticipantQos for the DDS:Access:Permissions configuration.
C++ |
DomainParticipantQos pqos;
// Activate DDS:Access:Permissions plugin
pqos.properties().properties().emplace_back("dds.sec.access.plugin",
"builtin.Access-Permissions");
// Configure DDS:Access:Permissions plugin
pqos.properties().properties().emplace_back(
"dds.sec.access.builtin.Access-Permissions.permissions_ca",
"file://certs/maincacert.pem");
pqos.properties().properties().emplace_back(
"dds.sec.access.builtin.Access-Permissions.governance",
"file://certs/governance.smime");
pqos.properties().properties().emplace_back(
"dds.sec.access.builtin.Access-Permissions.permissions",
"file://certs/permissions.smime");
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XML |
<participant profile_name="secure_domainparticipant_conf_access_control_plugin_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate DDS:Access:Permissions plugin -->
<property>
<name>dds.sec.access.plugin</name>
<value>builtin.Access-Permissions</value>
</property>
<!-- Configure DDS:Access:Permissions plugin -->
<property>
<name>dds.sec.access.builtin.Access-Permissions.permissions_ca</name>
<value>file://maincacet.pem</value>
</property>
<property>
<name>dds.sec.access.builtin.Access-Permissions.governance</name>
<value>file://governance.smime</value>
</property>
<property>
<name>dds.sec.access.builtin.Access-Permissions.permissions</name>
<value>file://permissions.smime</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
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Permissions CA Certificate¶
This is an X.509 certificate that contains the Public Key of the CA that will be used to sign the Domain Governance Document and the DomainParticipant Permissions Document.
Domain Governance Document¶
Domain Governance document is an XML document that specifies the mechanisms to secure the DDS Domain. It shall be signed by the Permissions CA in S/MIME format. The XML scheme of this document is defined in Domain Governance XSD. The following is an example of the Domain Governance XML file contents.
1<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2 xsi:noNamespaceSchemaLocation="omg_shared_ca_domain_governance.xsd">
3 <domain_access_rules>
4 <domain_rule>
5 <domains>
6 <id_range>
7 <min>0</min>
8 <max>230</max>
9 </id_range>
10 </domains>
11 <allow_unauthenticated_participants>false</allow_unauthenticated_participants>
12 <enable_join_access_control>true</enable_join_access_control>
13 <discovery_protection_kind>ENCRYPT</discovery_protection_kind>
14 <liveliness_protection_kind>ENCRYPT</liveliness_protection_kind>
15 <rtps_protection_kind>ENCRYPT</rtps_protection_kind>
16 <topic_access_rules>
17 <topic_rule>
18 <topic_expression>HelloWorldTopic</topic_expression>
19 <enable_discovery_protection>true</enable_discovery_protection>
20 <enable_liveliness_protection>false</enable_liveliness_protection>
21 <enable_read_access_control>true</enable_read_access_control>
22 <enable_write_access_control>true</enable_write_access_control>
23 <metadata_protection_kind>ENCRYPT</metadata_protection_kind>
24 <data_protection_kind>ENCRYPT</data_protection_kind>
25 </topic_rule>
26 </topic_access_rules>
27 </domain_rule>
28 </domain_access_rules>
29</dds>
The Governance XSD file and the Governance XML example can also be downloaded from the eProsima Fast DDS Github repository.
Domain Rules¶
It allows the application of rules to the DDS Domain. The domain rules define aspects of the DDS Domain such as:
Whether the discovery data should be protected and the type of protection: MAC only or encryption followed by MAC.
Whether the whole RTPS message should be encrypted.
Whether the liveliness of the messages should be protected.
Whether a non-authenticated DomainParticipant can access or not to the unprotected discovery metatraffic and unprotected Topics.
Whether an authenticated DomainParticipant can access the domain without evaluating the access control policies.
Whether discovery information on a certain Topic should be sent with secure DataWriters.
Whether or not the access to Topics should be restricted to DomainParticipants with the appropriate permission to read them.
Whether the metadata sent on a certain Topic should be protected and the type of protection.
Whether payload data on a certain Topic should be protected and the type of protection.
The domain rules are evaluated in the same order as they appear in the document.
A rule only applies to a particular DomainParticipant if the domain section matches the DDS
Domain_Id to which the DomainParticipant belongs.
If multiple rules match, the first rule that matches is the only one that applies.
Each domain rule is delimited by the <domain_rule> XML element tag.
Some domain rules may have an additional configuration if enabled. This configuration defines the level of protection that the rule applies to the domain:
NONE: no cryptographic transformation is applied.
SIGN: cryptographic transformation based on Message Authentication Code (MAC) is applied, without additional encryption.
ENCRYPT: the data is encrypted and followed by a MAC computed on the ciphertext, also known as Encrypt-then-MAC.
The following table summarizes the elements and sections that each domain rule may contain.
Type |
Name |
XML element tag |
Values |
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The following describes the possible configurations of each of the elements and sections listed above that are contained in the domain rules.
Domains¶
This element is delimited by the <domains> XML element tag.
The value in this element identifies the collection of DDS Domains to which the rule applies.
The <domains> element can contain:
A single domain identifier:
<domains>
<id>1</id>
</domains>
A range of domain identifiers:
<domains>
<id_range>
<min>1</min>
<max>10</max>
</id_range>
</domains>
Or a combination of both, a list of domain identifiers and ranges of domain identifiers.
Allow Unauthenticated Participants¶
This element is delimited by the <allow_unauthenticated_participants> XML element tag.
It indicates whether the matching of a DomainParticipant with a remote DomainParticipant requires authentication.
The possible values for this element are:
false: the DomainParticipant shall enforce the authentication of remote DomainParticipants and disallow matching those that cannot be successfully authenticated.true: the DomainParticipant shall allow matching other DomainParticipants (event if the remote DomainParticipant cannot authenticate) as long as there is not an already valid authentication with the same DomainParticipant’s GUID.
In accordance with the DDS Security specification, the following premises should be considered:
Topics protected with
enable_read_access_controlorenable_write_access_controlwill not communicate regardless of the allow_unauthenticated_participants flag value.If RTPS Protection Kind is not
NONEand Allow Unauthenticated Participants is enabled, the entity creation will fail with an error.Authentication is always attempted first regardless of
<allow_unauthenticated_participants>configuration.
Enable Join Access Control¶
This element is delimited by the <enable_join_access_control> XML element tag.
Indicates whether the matching of the participant with a remote DomqainParticipant requires authorization by the
DDS:Access:Permissions plugin.
Its possible values are:
false: the DomainParticipant shall not check the permissions of the authenticated remote DomainParticipant.true: the DomainParticipant shall check the permissions of the authenticated remote DomainParticipant.
Discovery Protection Kind¶
This element is delimited by the <discovery_protection_kind> XML element tag.
Indicates whether the secure channel of the endpoint discovery phase needs to be encrypted.
The possible values are:
NONE: the secure channel shall not be protected.SIGN: the secure channel shall be protected by MAC.ENCRYPT: the secure channel shall be encrypted.
Liveliness Protection Kind¶
This element is delimited by the <liveliness_protection_kind> XML element tag.
Indicates whether the secure channel of the liveliness mechanism needs to be encrypted.
The possible values are:
NONE: the secure channel shall not be protected.SIGN: the secure channel shall be protected by MAC.ENCRYPT: the secure channel shall be encrypted.
RTPS Protection Kind¶
This element is delimited by the <rtps_protection_kind> XML element tag.
Indicates whether the whole RTPS Message needs to be encrypted.
The possible values are:
NONE: whole RTPS Messages shall not be protected.SIGN: whole RTPS Messages shall be protected by MAC.ENCRYPT: whole RTPS Messages shall be encrypted.
Topic Rule¶
This element is delimited by the <topic_rule> XML element tag and appears within the Topic Access Rules Section
whose XML element tag is <topic_access_rules>.
The following table summarizes the elements and sections that each domain rule may contain.
Elements |
XML element tag |
Values |
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The topic expression within the rules selects a set of Topic names.
The rule applies to any DataReader or DataWriter associated with a Topic whose name matches the Topic expression
name.
The topic access rules are evaluated in the same order as they appear within the <topic_access_rules> section.
If multiple rules match, the first rule that matches is the only one that applies.
If no matching <topic_rule> is found, the entity creation will fail.
This element is delimited by the <topic_expression> XML element tag.
The value in this element identifies the set of Topic names to which the rule applies.
The rule applies to any DataReader or DataWriter associated with a Topic whose name matches the value.
The Topic name expression syntax and matching shall use the syntax and rules of the POSIX fnmatch() function as
specified in IEEE 1003.1-2017.
This element is delimited by the <enable_discovery_protection> XML element tag.
Indicates whether the entity related discovery information shall go through the secure channel of endpoint discovery
phase.
false: the entity discovery information shall be sent by an unsecured channel of discovery.true: the information shall be sent by the secure channel.
This element is delimited by the <enable_liveliness_protection> XML element tag.
Indicates whether the entity related liveliness information shall go through the secure channel of liveliness
mechanism.
false: the entity liveliness information shall be sent by an unsecured channel of liveliness.true: the information shall be sent by the secure channel.
This element is delimited by the <enable_read_access_control> XML element tag.
Indicates whether read access to the Topic is protected.
false: then local Subscriber creation and remote Subscriber matching can proceed without further access-control mechanisms imposed.true: they shall be checked using Access control plugin.
This element is delimited by the <enable_write_access_control> XML element tag.
Indicates whether write access to the Topic is protected.
false: then local Publisher creation and remote Publisher matching can proceed without further access-control mechanisms imposed.true: they shall be checked using Access control plugin.
This element is delimited by the <metadata_protection_kind> XML element tag.
Indicates whether the entity’s RTPS submessages shall be encrypted by the Cryptographic plugin.
NONE: shall not be protected.SIGN: shall be protected by MAC.ENCRYPT: shall be encrypted.
This element is delimited by the <data_protection_kind> XML element tag.
Indicates whether the data payload shall be encrypted by the Cryptographic plugin.
NONE: shall not be protected.SIGN: shall be protected by MAC.ENCRYPT: shall be encrypted.
1<?xml version="1.0" encoding="UTF-8"?>
2<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
3 elementFormDefault="qualified" attributeFormDefault="unqualified">
4 <xs:element name="dds" type="DomainAccessRulesNode" />
5 <xs:complexType name="DomainAccessRulesNode">
6 <xs:sequence minOccurs="1" maxOccurs="1">
7 <xs:element name="domain_access_rules"
8 type="DomainAccessRules" />
9 </xs:sequence>
10 </xs:complexType>
11 <xs:complexType name="DomainAccessRules">
12 <xs:sequence minOccurs="1" maxOccurs="unbounded">
13 <xs:element name="domain_rule" type="DomainRule" />
14 </xs:sequence>
15 </xs:complexType>
16 <xs:complexType name="DomainRule">
17 <xs:sequence minOccurs="1" maxOccurs="1">
18 <xs:element name="domains" type="DomainIdSet" />
19 <xs:element name="allow_unauthenticated_participants"
20 type="xs:boolean" />
21 <xs:element name="enable_join_access_control"
22 type="xs:boolean" />
23 <xs:element name="discovery_protection_kind"
24 type="ProtectionKind" />
25 <xs:element name="liveliness_protection_kind"
26 type="ProtectionKind" />
27 <xs:element name="rtps_protection_kind"
28 type="ProtectionKind" />
29 <xs:element name="topic_access_rules"
30 type="TopicAccessRules" />
31 </xs:sequence>
32 </xs:complexType>
33 <xs:complexType name="DomainIdSet">
34 <xs:choice minOccurs="1" maxOccurs="unbounded">
35 <xs:element name="id" type="DomainId" />
36 <xs:element name="id_range" type="DomainIdRange" />
37 </xs:choice>
38 </xs:complexType>
39 <xs:simpleType name="DomainId">
40 <xs:restriction base="xs:nonNegativeInteger" />
41 </xs:simpleType>
42 <xs:complexType name="DomainIdRange">
43 <xs:choice>
44 <xs:sequence>
45 <xs:element name="min" type="DomainId" />
46 <xs:element name="max" type="DomainId" minOccurs="0" />
47 </xs:sequence>
48 <xs:element name="max" type="DomainId" />
49 </xs:choice>
50 </xs:complexType>
51 <xs:simpleType name="ProtectionKind">
52 <xs:restriction base="xs:string">
53 <xs:enumeration value="ENCRYPT_WITH_ORIGIN_AUTHENTICATION" />
54 <xs:enumeration value="SIGN_WITH_ORIGIN_AUTHENTICATION" />
55 <xs:enumeration value="ENCRYPT" />
56 <xs:enumeration value="SIGN" />
57 <xs:enumeration value="NONE" />
58 </xs:restriction>
59 </xs:simpleType>
60 <xs:simpleType name="BasicProtectionKind">
61 <xs:restriction base="ProtectionKind">
62 <xs:enumeration value="ENCRYPT" />
63 <xs:enumeration value="SIGN" />
64 <xs:enumeration value="NONE" />
65 </xs:restriction>
66 </xs:simpleType>
67 <xs:complexType name="TopicAccessRules">
68 <xs:sequence minOccurs="1" maxOccurs="unbounded">
69 <xs:element name="topic_rule" type="TopicRule" />
70 </xs:sequence>
71 </xs:complexType>
72 <xs:complexType name="TopicRule">
73 <xs:sequence minOccurs="1" maxOccurs="1">
74 <xs:element name="topic_expression" type="TopicExpression" />
75 <xs:element name="enable_discovery_protection"
76 type="xs:boolean" />
77 <xs:element name="enable_liveliness_protection"
78 type="xs:boolean" />
79 <xs:element name="enable_read_access_control"
80 type="xs:boolean" />
81 <xs:element name="enable_write_access_control"
82 type="xs:boolean" />
83 <xs:element name="metadata_protection_kind"
84 type="ProtectionKind" />
85 <xs:element name="data_protection_kind"
86 type="BasicProtectionKind" />
87 </xs:sequence>
88 </xs:complexType>
89 <xs:simpleType name="TopicExpression">
90 <xs:restriction base="xs:string" />
91 </xs:simpleType>
92</xs:schema>
Back to the Domain Governance Document.
DomainParticipant Permissions Document¶
The permissions document is an XML file which contains the permissions of a DomainParticipant and binds them to the DomainParticipant distinguished name defined in the DDS:Auth:PKI-DH plugin. The permissions document shall be signed by the Permissions CA in S/MIME format. The XML scheme of this document is defined in DomainParticipant Permissions XSD. The following is an example of the DomainParticipant Permissions XML file contents.
1<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2 xsi:noNamespaceSchemaLocation="http://www.omg.org/spec/DDS-Security/20170801/omg_shared_ca_permissions.xsd">
3 <permissions>
4 <grant name="ParticipantPermissions">
5 <subject_name>emailAddress=example@eprosima.com, CN=DomainParticipantName, O=eProsima, ST=MA, C=ES</subject_name>
6 <validity>
7 <not_before>2013-06-01T13:00:00</not_before>
8 <not_after>2038-06-01T13:00:00</not_after>
9 </validity>
10 <allow_rule>
11 <domains>
12 <id_range>
13 <min>0</min>
14 <max>230</max>
15 </id_range>
16 </domains>
17 <publish>
18 <topics>
19 <topic>HelloWorldTopic</topic>
20 </topics>
21 </publish>
22 </allow_rule>
23 <default>DENY</default>
24 </grant>
25
26 <!-- Fill the subject name with the information specified in the Participant certificate -->
27 <grant name="OtherParticipantPermissions">
28 <subject_name> emailAddress=xxx@eprosima.com, CN=xxx, OU=x, O=x, ST=XX, C=XX</subject_name>
29 <validity>
30 <not_before>2013-06-01T13:00:00</not_before>
31 <not_after>2038-06-01T13:00:00</not_after>
32 </validity>
33 <allow_rule>
34 <domains>
35 <id_range>
36 <min>0</min>
37 <max>230</max>
38 </id_range>
39 </domains>
40 <subscribe>
41 <topics>
42 <topic>HelloWorldTopic</topic>
43 </topics>
44 </subscribe>
45 </allow_rule>
46 <default>DENY</default>
47 </grant>
48 </permissions>
49</dds>
The Permissions XSD file and the Permissions XML example can also be downloaded from the eProsima Fast DDS Github repository.
Grant Section¶
This section is delimited by the <grant> XML element tag.
Each grant section contains three sections:
Subject name
Validity
Rules
Subject name¶
This section is delimited by XML element <subject_name>.
The subject name identifies the DomainParticipant to which the permissions apply.
Each subject name can only appear in a single <permissions> section within the XML Permissions document.
The contents of the subject name element shall be the X.509 subject name of the DomainParticipant that was given in
the authorization X.509 Certificate.
Validity¶
This section is delimited by the XML element <validity>.
It reflects the valid dates for the permissions.
Rules¶
This section contains the permissions assigned to the DomainParticipant.
The rules are applied in the same order that appears in the document.
If the criteria for the rule matched the Domain join, publish or subscribe operation that is being attempted,
then the allow or deny decision is applied.
If the criteria for a rule does not match the operation being attempted, the evaluation shall proceed to the next rule.
If all rules have been examined without a match, then the decision specified by the <default> rule is applied.
The default rule, if present, must appear after all allow and deny rules.
If the default rule is not present, the implied default decision is DENY.
For the grant to match there shall be a match of the topics and partitions criteria.
Allow rules are delimited by the XML element <allow_rule>.
Deny rules are delimited by the XML element``<deny_rule>``.
Both contain the same element children.
Domains Section¶
This section is delimited by the XML element <domains>.
The value in this element identifies the collection of DDS Domains to which the rule applies.
The syntax is the same as for the Domains of the Domain Governance Document.
Format of the Allowed/Denied Actions sections¶
The sections for each of the three actions have a similar format. The only difference is the name of the XML element used to delimit the action:
Action |
XML element tag |
|---|---|
Allow/Deny Publish |
|
Allow/Deny Subscribe |
|
Allow/Deny Relay |
|
Each action contains two conditions.
Allowed/Denied Topics Condition
Allowed/Denied Partitions Condition
Topics Condition¶
This section is delimited by the <topics> XML element.
It defines the Topic names that must be matched for the allow/deny rule to apply.
Topic names may be given explicitly or by means of Topic name expressions.
Each explicit topic name or Topic name expressions appears separately in a <topic> sub-element within the
<topics> element.
The Topic name expression syntax and matching shall use the syntax and rules of the POSIX fnmatch() function as
specified in
<topics>
<topic>Plane</topic>
<topic>Hel*</topic>
</topics>
Partitions Condition¶
This section is delimited by the <partitions> XML element.
It limits the set Partitions names that may be associated with the (publish, subscribe, relay) action for the rule to
apply.
Partition names expression syntax and matching shall use the syntax and rules of the POSIX fnmatch() function as
specified in IEEE 1003.1-2017.
If there is no <partitions> section within a rule, then the default “empty string” partition is assumed.
<partitions>
<partition>A</partition>
<partition>B*</partition>
</partitions>
1<?xml version="1.0" encoding="utf-8"?>
2<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
3 elementFormDefault="qualified" attributeFormDefault="unqualified">
4 <xs:element name="dds" type="PermissionsNode" />
5 <xs:complexType name="PermissionsNode">
6 <xs:sequence minOccurs="1" maxOccurs="1">
7 <xs:element name="permissions" type="Permissions" />
8 </xs:sequence>
9 </xs:complexType>
10 <xs:complexType name="Permissions">
11 <xs:sequence minOccurs="1" maxOccurs="unbounded">
12 <xs:element name="grant" type="Grant" />
13 </xs:sequence>
14 </xs:complexType>
15 <xs:complexType name="Grant">
16 <xs:sequence minOccurs="1" maxOccurs="1">
17 <xs:element name="subject_name" type="xs:string" />
18 <xs:element name="validity" type="Validity" />
19 <xs:sequence minOccurs="1" maxOccurs="unbounded">
20 <xs:choice minOccurs="1" maxOccurs="1">
21 <xs:element name="allow_rule" minOccurs="0" type="Rule" />
22 <xs:element name="deny_rule" minOccurs="0" type="Rule" />
23 </xs:choice>
24 </xs:sequence>
25 <xs:element name="default" type="DefaultAction" />
26 </xs:sequence>
27 <xs:attribute name="name" type="xs:string" use="required" />
28 </xs:complexType>
29 <xs:complexType name="Validity">
30 <xs:sequence minOccurs="1" maxOccurs="1">
31 <xs:element name="not_before" type="xs:dateTime" />
32 <xs:element name="not_after" type="xs:dateTime" />
33 </xs:sequence>
34 </xs:complexType>
35 <xs:complexType name="Rule">
36 <xs:sequence minOccurs="1" maxOccurs="1">
37 <xs:element name="domains" type="DomainIdSet" />
38 <xs:sequence minOccurs="0" maxOccurs="unbounded">
39 <xs:element name="publish" type="Criteria" />
40 </xs:sequence>
41 <xs:sequence minOccurs="0" maxOccurs="unbounded">
42 <xs:element name="subscribe" type="Criteria" />
43 </xs:sequence>
44 <xs:sequence minOccurs="0" maxOccurs="unbounded">
45 <xs:element name="relay" type="Criteria" />
46 </xs:sequence>
47 </xs:sequence>
48 </xs:complexType>
49 <xs:complexType name="DomainIdSet">
50 <xs:choice minOccurs="1" maxOccurs="unbounded">
51 <xs:element name="id" type="DomainId" />
52 <xs:element name="id_range" type="DomainIdRange" />
53 </xs:choice>
54 </xs:complexType>
55 <xs:simpleType name="DomainId">
56 <xs:restriction base="xs:nonNegativeInteger" />
57 </xs:simpleType>
58 <xs:complexType name="DomainIdRange">
59 <xs:choice>
60 <xs:sequence>
61 <xs:element name="min" type="DomainId" />
62 <xs:element name="max" type="DomainId" minOccurs="0" />
63 </xs:sequence>
64 <xs:element name="max" type="DomainId" />
65 </xs:choice>
66 </xs:complexType>
67 <xs:complexType name="Criteria">
68 <xs:all minOccurs="1">
69 <xs:element name="topics" minOccurs="1"
70 type="TopicExpressionList" />
71 <xs:element name="partitions" minOccurs="0"
72 type="PartitionExpressionList" />
73 <xs:element name="data_tags" minOccurs="0" type="DataTags" />
74 </xs:all>
75 </xs:complexType>
76 <xs:complexType name="TopicExpressionList">
77 <xs:sequence minOccurs="1" maxOccurs="unbounded">
78 <xs:element name="topic" type="TopicExpression" />
79 </xs:sequence>
80 </xs:complexType>
81 <xs:complexType name="PartitionExpressionList">
82 <xs:sequence minOccurs="1" maxOccurs="unbounded">
83 <xs:element name="partition" type="PartitionExpression" />
84 </xs:sequence>
85 </xs:complexType>
86 <xs:simpleType name="TopicExpression">
87 <xs:restriction base="xs:string" />
88 </xs:simpleType>
89 <xs:simpleType name="PartitionExpression">
90 <xs:restriction base="xs:string" />
91 </xs:simpleType>
92 <xs:complexType name="DataTags">
93 <xs:sequence minOccurs="1" maxOccurs="unbounded">
94 <xs:element name="tag" type="TagNameValuePair" />
95 </xs:sequence>
96 </xs:complexType>
97 <xs:complexType name="TagNameValuePair">
98 <xs:sequence minOccurs="1" maxOccurs="unbounded">
99 <xs:element name="name" type="xs:string" />
100 <xs:element name="value" type="xs:string" />
101 </xs:sequence>
102 </xs:complexType>
103 <xs:simpleType name="DefaultAction">
104 <xs:restriction base="xs:string">
105 <xs:enumeration value="ALLOW" />
106 <xs:enumeration value="DENY" />
107 </xs:restriction>
108 </xs:simpleType>
109</xs:schema>
Back to the DomainParticipant Permissions Document.
Signing documents using x509 certificate¶
Domain Governance Document and DomainParticipant Permissions Document have to be signed using an X.509 certificate. Generation of an X.509 certificate is explained in Generation of X.509 certificates. Next commands sign the necessary documents for its use by the DDS:Access:Permissions plugin.
# Governance document: governance.xml
openssl smime -sign -in governance.xml -text -out governance.smime -signer maincacert.pem -inkey maincakey.pem
# Permissions document: permissions.xml
openssl smime -sign -in permissions.xml -text -out permissions.smime -signer maincacert.pem -inkey maincakey.pem
Cryptographic plugin: DDS:Crypto:AES-GCM-GMAC¶
The cryptographic plugin provides the tools and operations required to support encryption and decryption, digests computation, message authentication codes computation and verification, key generation, and key exchange for DomainParticipants, DataWriters and DataReaders. Encryption can be applied over three different levels of DDS protocol:
The whole RTPS messages.
The RTPS submessages of a specific DDS Entity (DataWriter or DataReader).
The payload (user data) of a particular DataWriter.
The authentication plugin implemented in Fast DDS is referred to as “DDS:Crypto:AES-GCM-GMAC”, in compliance with the DDS Security specification. This plugin is explained in detail below.
The DDS:Crypto:AES-GCM-GMAC plugin provides authentication encryption using Advanced Encryption Standard (AES) in Galois Counter Mode (AES-GCM). It supports 128 bits and 256 bits AES key sizes. It may also provide additional DataReader-specific Message Authentication Codes (MACs) using Galois MAC (AES-GMAC).
The DDS:Crypto:AES-GCM-GMAC authentication plugin, can be activated setting the DomainParticipantQos
properties()
dds.sec.crypto.plugin with the value builtin.AES-GCM-GMAC.
Moreover, this plugin needs the activation of the Authentication plugin: DDS:Auth:PKI-DH.
The DDS:Crypto:AES-GCM-GMAC plugin is configured using the Access control plugin: DDS:Access:Permissions, i.e the cryptography
plugin is configured through the properties and configuration files of the access control plugin.
The following is an example of how to set the properties of DomainParticipantQoS for the DDS:Crypto:AES-GCM-GMAC configuration.
DomainParticipantQos pqos;
// Activate DDS:Crypto:AES-GCM-GMAC plugin
pqos.properties().properties().emplace_back("dds.sec.crypto.plugin",
"builtin.AES-GCM-GMAC");
<participant profile_name="secure_domainparticipant_conf_crypto_plugin_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate DDS:Crypto:AES-GCM-GMAC plugin -->
<property>
<name>dds.sec.crypto.plugin</name>
<value>builtin.AES-GCM-GMAC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
Logging plugin: DDS:Logging:DDS_LogTopic¶
The logging plugin provides the necessary operations to log the security events triggered by the other security plugins supported by Fast DDS (Authentication plugin: DDS:Auth:PKI-DH, Access control plugin: DDS:Access:Permissions, and Cryptographic plugin: DDS:Crypto:AES-GCM-GMAC). Therefore, the aforementioned security plugins will use the logging plugin to log their events. These events can be reporting of expected behavior, as well as security breaches and errors.
The logging plugin implemented in Fast DDS collects all security event data of a DomainParticipant and saves them in a local file. The log messages generated by the logging plugin include an ID that uniquely identifies the DomainParticipant that triggered the event, the DDS Domain identifier to which the DomainParticipant belongs, and a time-stamp.
The logging plugin implemented in Fast DDS is referred to as “DDS:Logging:DDS_LogTopic”, in compliance with the DDS Security specification. This plugin is explained in detail below. This plugin can be configured to filter according to up to eight levels of severity of the messages.
The DDS:Logging:DDS_LogTopic authentication plugin, can be activated setting the DomainParticipantQos
properties()
dds.sec.log.plugin with the value builtin.DDS_LogTopic.
The following table outlines the properties used for the DDS:Logging:DDS_LogTopic plugin configuration.
Property name |
Property value |
|
|---|---|---|
Value |
Definition |
|
logging_level |
|
System is unusable. Should not continue use. |
|
Should be corrected immediately. |
|
|
A failure in primary application. |
|
|
General error conditions. Default value. |
|
|
May indicate future error if action not taken. |
|
|
Unusual, but nor erroneous event or condition. |
|
|
Normal operational. Requires no action. |
|
|
Normal operational. |
|
log_file |
Path of the file in which the log messages are to be saved. |
|
Note
All listed properties have “dds.sec.log.builtin.DDS_LogTopic.” prefix.
For example: dds.sec.log.builtin.DDS_LogTopic.logging_level.
The following is an example of how to set the properties of DomainParticipantQoS for the DDS:Logging:DDS_LogTopic plugin configuration.
C++ |
DomainParticipantQos pqos;
// Activate DDS:Logging:DDS_LogTopic plugin
pqos.properties().properties().emplace_back("dds.sec.log.plugin",
"builtin.DDS_LogTopic");
// Configure DDS:Logging:DDS_LogTopic plugin
pqos.properties().properties().emplace_back(
"dds.sec.log.builtin.DDS_LogTopic.logging_level",
"EMERGENCY_LEVEL");
pqos.properties().properties().emplace_back(
"dds.sec.log.builtin.DDS_LogTopic.log_file",
"myLogFile.log");
|
XML |
<participant profile_name="secure_domainparticipant_conf_logging_plugin_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate DDS:Auth:PKI-DH plugin -->
<property>
<name>dds.sec.log.plugin</name>
<value>builtin.DDS_LogTopic</value>
</property>
<!-- Configure DDS:Auth:PKI-DH plugin -->
<property>
<name>dds.sec.log.builtin.DDS_LogTopic.logging_level</name>
<value>EMERGENCY_LEVEL</value>
</property>
<property>
<name>dds.sec.log.builtin.DDS_LogTopic.log_file</name>
<value>myLogFile.log</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
|
PKCS#11 support¶
The private key property used for the DDS:Auth:PKI-DH plugin configuration can be specified using a PKCS#11 compliant URI that represents a key stored in a HSM (Hardware Security Module). When a PKCS#11 URI is given, the private key is never taken out of the HSM, providing a more secure setup.
Support for PKCS#11 URIs is provided by the libp11 library. This library provides a PKCS#11 engine for OpenSSL that acts as a proxy between OpenSSL and the HSM driver provided by the manufacturer. To make OpenSSL aware of the new engine, the OpenSSL configuration file might need to be updated. For details on how to set up the PKCS#11 engine in different platforms follow the dedicated documentation:
Libp11 and SoftHSM libraries on Windows.
Libp11 and SoftHSM libraries on Linux distributions
Also, the following section contains the list of PropertyPolicyQos that can be set within Fast DDS Security: Security Property QoS Settings.
Logging¶
eProsima Fast DDS provides an extensible built-in logging module that exposes the following main functionalities:
Three different logging levels:
Log::Kind::Info,Log::Kind::Warning, andLog::Kind::Error(see Logging Messages).Message filtering according to different criteria: category, content, or source file (see Filters).
Output to STDOUT, STDERR and/or log files (see Consumers).
This section is devoted to explain the use, configuration, and extensibility of Fast DDS’ logging module.
Module Structure¶
The logging module provides the following classes:
Logis the core class of the logging module. This singleton is not only in charge of the logging operations (see Logging Messages), but it also provides configuration APIs to set different logging configuration aspects (see Module Configuration), as well as logging filtering at various levels (see Filters). It contains zero or moreLogConsumerobjects. The singleton’s consuming thread feeds the log entries added to the logging queue using the macros defined in Logging Messages to the log consumers sequentially (see Logging Thread).Warning
LogAPI exposes member functionLog::QueueLog(). However, this function is not intended to be used directly. To add messages to the log queue, use the methods described in Logging Messages.LogConsumeris the base class for all the log consumers (see Consumers). It includes the member functions that derived classes should overload to consume log entries.OStreamConsumerderives fromLogConsumer. It defines how to consume log entries for outputting to anstd::ostreamobject. It includes a member function that derived classes must overload to define the desiredstd::ostreamobject.1.
StdoutConsumerderives fromOStreamConsumer. It defines STDOUT as the outputstd::ostreamobject (see StdoutConsumer).2.
StdoutErrConsumerderives fromOStreamConsumer. It defines aLog::Kindthreshold so that if theLog::Kindis equal to or more severe than the selected threshold, the output defined will be STDERR. Otherwise, it defines STDOUT as the output (see StdoutErrConsumer).3.
FileConsumerderives fromOStreamConsumer. It defines an user specified file as the outputstd::ostreamobject (see FileConsumer).
Logging module class diagram¶
The module can be further extended by creating new consumer classes deriving from LogConsumer and/or
OStreamConsumer.
To enable a custom consumer just follow the instructions on Register Consumers.
Log Entry Specification¶
Log entries created by StdoutConsumer, StdoutErrConsumer and FileConsumer (eProsima Fast DDS built-in Consumers) adhere to the following structure:
<Timestamp> [<Category> <Verbosity Level>] <Message> (<File Name>:<Line Number>) -> Function <Function Name>
An example of such log entry is given by:
2020-05-27 11:45:47.447 [DOCUMENTATION_CATEGORY Error] This is an error message (example.cpp:50) -> Function main
Note
File Name and Line Number, as well as Function Name are only present when enabled. See Module Configuration for details.
Logging Thread¶
Calls to the macros presented in Logging Messages merely add the log entry to a ready-to-consume queue.
Upon creation, the logging module spawns a thread that awakes every time an entry is added to the queue.
When awaken, this thread feeds all the entries in the queue to all the registered Consumers.
Once the work is done, the thread falls back into idle state.
This strategy prevents the module from blocking the application thread when a logging operation is performed.
However, sometimes applications may want to wait until the logging routine is done to continue their operation.
The logging module provides this capability via the member function Log::Flush().
Furthermore, it is possible to completely eliminate the thread and its resources using member function
Log::KillThread().
In addition, it is possible to configure certain settings of this logging thread via the member function
Log::SetThreadConfig().
// Block current thread until the log queue is empty.
Log::Flush();
// Stop the loggin thread and free its resources.
Log::KillThread();
// Configure ThreadSettings for the logging thread
Log::SetThreadConfig(eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1});
Warning
A call to any of the macros present in Logging Messages will spawn the logging thread even if it has
been previously killed with Log::KillThread().
Logging Messages¶
The logging of messages is handled by three dedicated macros, one for each available verbosity level (see Verbosity Level):
EPROSIMA_LOG_INFO: Logs messages withLog::Kind::Infoverbosity.EPROSIMA_LOG_WARNING: Logs messages withLog::Kind::Warningverbosity.EPROSIMA_LOG_ERROR: Logs messages withLog::Kind::Errorverbosity.
Said macros take exactly two arguments, a category and a message, and produce a log entry showing the message itself plus some meta information depending on the module’s configuration (see Log Entry Specification and Log Entry).
EPROSIMA_LOG_INFO(DOCUMENTATION_CATEGORY, "This is an info message");
EPROSIMA_LOG_WARNING(DOCUMENTATION_CATEGORY, "This is an warning message");
EPROSIMA_LOG_ERROR(DOCUMENTATION_CATEGORY, "This is an error message");
There exist some old log macros used in previous versions: logInfo, logWarning and logError.
These macros are still available as long as user does not manually disable them by ENABLE_OLD_LOG_MACROS
CMake option or in-site macro ENABLE_OLD_LOG_MACROS_ before including Log module.
See section Old Log macros disable for more information.
Warning
Note that each message level is deactivated when CMake options LOG_NO_INFO, LOG_NO_WARNING or
LOG_NO_ERROR are set to ON respectively.
For more information about how to enable and disable each individual logging macro, please refer to
Disable Logging Module.
Module Configuration¶
The logging module offers a variety of configuration options. The different components of a log entry (see Log Entry Specification) can be configured as explained in Log Entry. Furthermore, the logging module allows for registering several log consumer, allowing applications to direct the logging output to different destinations (see Register Consumers). In addition, some of the logging features can be configured using eProsima Fast DDS XML configuration files (see XML Configuration).
Log Entry¶
All the different components of a log entry are summarized in the following table (please refer to each component’s section for further explanation):
Component |
Optional |
Default |
|---|---|---|
NO |
ENABLED |
|
NO |
ENABLED |
|
NO |
ENABLED |
|
NO |
ENABLED |
|
YES |
DISABLED |
|
YES |
ENABLED |
Timestamp¶
The log timestamp follows the ISO 8601 standard for local timestamps, i.e. YYYY-MM-DD hh:mm:ss.sss. This component cannot be further configured or disabled.
Category¶
Log entries have a category assigned when producing the log via the macros presented in Logging Messages. The category component can be used to filter log entries so that only those categories specified in the filter are consumed (see Filters). This component cannot be further configured or disabled.
Verbosity Level¶
eProsima Fast DDS logging module provides three verbosity levels defined by the Log::Kind enumeration,
those are:
Log::Kind::Error: Used to log error messages.Log::Kind::Warning: Used to log error and warning messages.Log::Kind::Info: Used to log error, warning, and info messages.
The logging module’s verbosity level defaults to Log::Kind::Error, which means that only messages logged with
EPROSIMA_LOG_ERROR would be consumed.
The verbosity level can be set and retrieved using member functions Log::SetVerbosity() and Log::GetVerbosity()
respectively.
// Set log verbosity level to Log::Kind::Info
Log::SetVerbosity(Log::Kind::Info);
// Get log verbosity level
Log::Kind verbosity_level = Log::GetVerbosity();
Warning
Setting any of the CMake options LOG_NO_INFO, LOG_NO_WARNING or LOG_NO_ERROR to ON
will completely disable the corresponding verbosity level.
LOG_NO_INFO is set to ON for Single-Config generators as default value if not in Debug mode.
Message¶
This component constitutes the body of the log entry. It is specified when producing the log via the macros presented in Logging Messages. The message component can be used to filter log entries so that only those entries whose message pattern-matches the filter are consumed (see Filters). This component cannot be further configured or disabled.
File Context¶
This component specifies the origin of the log entry in terms of file name and line number (see
Logging Messages for a log entry example featuring this component).
This is useful when tracing code flow for debugging purposes.
The file context component can be enabled/disabled using the member function Log::ReportFilenames().
// Enable file name and line number reporting
Log::ReportFilenames(true);
// Disable file name and line number reporting
Log::ReportFilenames(false);
Function Name¶
This component specifies the origin of the log entry in terms of the function name (see
Logging Messages for a log entry example featuring this component).
This is useful when tracing code flow for debugging purposes.
The function name component can be enabled/disabled using the member function Log::ReportFunctions().
// Enable function name reporting
Log::ReportFunctions(true);
// Disable function name reporting
Log::ReportFunctions(false);
Register Consumers¶
eProsima Fast DDS logging module supports zero or more consumers logging the entries
registered in the logging queue with the methods described in Logging Messages.
To register a consumer, the Log class exposes member function Log::RegisterConsumer()
// Create a FileConsumer consumer that logs entries in "archive.log"
std::unique_ptr<FileConsumer> file_consumer(new FileConsumer("archive.log"));
// Register the consumer. Log entries will be logged to STDOUT and "archive.log"
Log::RegisterConsumer(std::move(file_consumer));
The consumers list can be emptied with member function Log::ClearConsumers().
// Clear all the consumers. Log entries are discarded upon consumption.
Log::ClearConsumers();
Note
Registering and configuring consumers can also be done using Fast DDS XML configuration files. Please refer to XML Configuration for details.
Warning
Log::ClearConsumers() empties the consumers lists.
All log entries are discarded until a new consumer is register via Log::RegisterConsumer(), or until
Log::Reset() is called.
Reset Configuration¶
The logging module’s configuration can be reset to default settings with member function Log::Reset().
Warning
Resetting the module’s configuration entails:
Setting Verbosity Level to
Log::Kind::Error.Disabling File Context component.
Enabling Function Name component.
Clear all Filters.
Clear all consumers and reset the default consumer according to CMake option
LOG_CONSUMER_DEFAULT.
XML Configuration¶
eProsima Fast DDS allows for registering and configuring log consumers using XML configuration files. Please refer to Log profiles for details.
Filters¶
eProsima Fast DDS logging module allows for log entry filtering when consuming the logs, so that an application execution output can be limited to specific areas of interest. Beside the Verbosity Level, Fast DDS provides three different filtering possibilities.
It is worth mentioning that filters are applied in the specific order presented above, meaning that file name filtering is only applied to the entries that pattern-match the category filter, and content filtering is only applied to the entries that pattern-match both category and file name filters.
Category Filtering¶
Log entries can be filtered upon consumption according to their Category component using regular
expressions.
Each time an entry is ready to be consumed, the category filter is applied using std::regex_search().
To set a category filter, member function Log::SetCategoryFilter() is used:
// Set filter using regular expression
Log::SetCategoryFilter(std::regex("(CATEGORY_1)|(CATEGORY_2)"));
// Would be consumed
EPROSIMA_LOG_ERROR(CATEGORY_1, "First log entry");
// Would be consumed
EPROSIMA_LOG_ERROR(CATEGORY_2, "Second log entry");
// Would NOT be consumed
EPROSIMA_LOG_ERROR(CATEGORY_3, "Third log entry");
The previous example would produce the following output:
2020-05-27 15:07:05.771 [CATEGORY_FILTER_1 Error] First log entry -> Function main
2020-05-27 15:07:05.771 [CATEGORY_FILTER_2 Error] Second log entry -> Function main
File Name Filtering¶
Log entries can be filtered upon consumption according to their File Context component using
regular expressions.
Each time an entry is ready to be consumed, the file name filter is applied using std::regex_search().
To set a file name filter, member function Log::SetFilenameFilter() is used:
// Filename: example.cpp
// Enable file name and line number reporting
Log::ReportFilenames(true);
// Set filter using regular expression so filename must match "example"
Log::SetFilenameFilter(std::regex("example"));
// Would be consumed
EPROSIMA_LOG_ERROR(CATEGORY, "First log entry");
// Set filter using regular expression so filename must match "other"
Log::SetFilenameFilter(std::regex("other"));
// Would NOT be consumed
EPROSIMA_LOG_ERROR(CATEGORY, "Second log entry");
The previous example would produce the following output:
2020-05-27 15:07:05.771 [CATEGORY Error] First log entry (example.cpp:50) -> Function main
Note
File name filters are applied even when the File Context entry component is disabled.
Content Filtering¶
Log entries can be filtered upon consumption according to their Message component using regular
expressions.
Each time an entry is ready to be consumed, the content filter is applied using std::regex_search().
To set a content filter, member function Log::SetErrorStringFilter() is used:
// Set filter using regular expression so message component must match "First"
Log::SetErrorStringFilter(std::regex("First"));
// Would be consumed
EPROSIMA_LOG_ERROR(CATEGORY, "First log entry");
// Would NOT be consumed
EPROSIMA_LOG_ERROR(CATEGORY, "Second log entry");
The previous example would produce the following output:
2020-05-27 15:07:05.771 [CATEGORY Error] First log entry -> Function main
Reset Logging Filters¶
The logging module’s filters can be reset with member function Log::Reset().
Warning
Resetting the module’s filters entails:
Setting Verbosity Level to
Log::Kind::Error.Disabling File Context component.
Enabling Function Name component.
Clear all Filters.
Clear all consumers and reset the default consumer according to CMake option
LOG_CONSUMER_DEFAULT.
Consumers¶
Consumers are classes that take a Log::Entry and produce a log output accordingly.
eProsima Fast DDS provides three different log consumers that output log entries to different streams:
StdoutConsumer: Outputs log entries to STDOUT
StdoutErrConsumer: Outputs log entries to STDOUT or STDERR depending on the given threshold.
FileConsumer: Outputs log entries to a user specified file.
StdoutConsumer¶
StdoutConsumer outputs log entries to STDOUT stream following the convection specified in
Log Entry Specification.
It is the default and only log consumer of the logging module if the CMake option LOG_CONSUMER_DEFAULT is set to
AUTO, STDOUT, or not set at all.
It can be registered and unregistered using the methods explained in
Register Consumers and Reset Configuration.
// Create a StdoutConsumer consumer that logs entries to stdout stream.
std::unique_ptr<StdoutConsumer> stdout_consumer(new StdoutConsumer());
// Register the consumer.
Log::RegisterConsumer(std::move(stdout_consumer));
StdoutErrConsumer¶
StdoutErrConsumer uses a Log::Kind threshold to filter the output of the log entries.
Those log entries whose Log::Kind is equal to or more severe than the given threshold output to STDERR.
Other log entries output to STDOUT.
By default, the threshold is set to Log::Kind::Warning.
StdoutErrConsumer::stderr_threshold() allows the user to modify the default threshold.
Additionally, if CMake option LOG_CONSUMER_DEFAULT is set to STDOUTERR, the logging module will use this consumer
as the default log consumer.
// Create a StdoutErrConsumer consumer that logs entries to stderr only when the Log::Kind is equal to ERROR
std::unique_ptr<StdoutErrConsumer> stdouterr_consumer(new StdoutErrConsumer());
stdouterr_consumer->stderr_threshold(Log::Kind::Error);
// Register the consumer
Log::RegisterConsumer(std::move(stdouterr_consumer));
FileConsumer¶
FileConsumer provides the logging module with log-to-file logging capabilities.
Applications willing to hold a persistent execution log record can specify a logging file using this consumer.
Furthermore, the application can choose whether the file stream should be in “write” or “append” mode, according to the
behaviour defined by std::fstream::open().
// Create a FileConsumer consumer that logs entries in "archive_1.log", opening the file in "write" mode.
std::unique_ptr<FileConsumer> write_file_consumer(new FileConsumer("archive_1.log", false));
// Create a FileConsumer consumer that logs entries in "archive_2.log", opening the file in "append" mode.
std::unique_ptr<FileConsumer> append_file_consumer(new FileConsumer("archive_2.log", true));
// Register the consumers.
Log::RegisterConsumer(std::move(write_file_consumer));
Log::RegisterConsumer(std::move(append_file_consumer));
Disable Logging Module¶
Setting the Verbosity Level, translates into entries not being added to the log queue if the entry’s level has lower importance than the set one. This check is performed when calling the macros defined in Logging Messages. However, it is possible to fully disable each macro (and therefore each verbosity level individually) at build time.
EPROSIMA_LOG_INFOis fully disabled by either:Setting CMake option
LOG_NO_INFOtoON(default for Single-Config generators ifCMAKE_BUILD_TYPEis other thanDebug).Defining macro
HAVE_LOG_NO_INFOto1.
EPROSIMA_LOG_WARNINGis fully disabled by either:Setting CMake option
LOG_NO_WARNINGtoON.Defining macro
HAVE_LOG_NO_WARNINGto1.
EPROSIMA_LOG_ERRORis fully disabled by either:Setting CMake option
LOG_NO_ERRORtoON.Defining macro
HAVE_LOG_NO_ERRORto1.
Applying either of the previously described methods will set the macro to be empty at configuration time, thus allowing the compiler to optimize the call out. This is done so that all the debugging messages present on the library are optimized out at build time if not building for debugging purposes, thus preventing them to impact performance.
INTERNAL_DEBUG CMake option activates log macros compilation, so the arguments of the macros are compiled.
However:
It does not activate the log Warning and Error messages, i.e. the messages are not written in the log queue.
EPROSIMA_LOG_INFOhas a special behaviour to simplify working with Multi-Config capability IDEs. If CMake optionLOG_NO_INFOisOFF, or the C++ definitionHAVE_LOG_NO_INFOis0, then logging is enabled only forDebugconfiguration. In this scenario, settingFASTDDS_ENFORCE_LOG_INFOtoONwill enableEPROSIMA_LOG_INFOeven on nonDebugconfigurations. This is specially useful when using the Fast DDS’ logging module in an external application which links with Fast DDS compiled inRelease. In that case, applications wanting to use all three levels of logging can simply add the following code prior to including any Fast DDS header:#define HAVE_LOG_NO_INFO 0 #define FASTDDS_ENFORCE_LOG_INFO 1
Warning
INTERNAL_DEBUG can be automatically set to ON if CMake option EPROSIMA_BUILD is set to ON.
Old Log macros disable¶
Before version 2.8.2, Fast DDS project used log macros: logInfo, logWarning and
logError, which may collide with other libraries.
These log macros have been replaced by new ones with a more specific format: (e.g. EPROSIMA_LOG_INFO).
In order to disable old macros compilation, use CMake option ENABLE_OLD_LOG_MACROS = ON
or define ENABLE_OLD_LOG_MACROS_ 0 before including the log module
#include <fastdds/dds/log/Log.hpp>.
Warning
These macros will be deprecated in future versions of Fast DDS. The use of the new format ones is encouraged.
XML profiles¶
eProsima Fast DDS allows for loading XML configuration files, each one containing one or more XML profiles. In addition to the API functions for loading user XML files, Fast DDS tries to locate and load several XML files upon initialization. Fast DDS offers the following options:
Load an XML file named DEFAULT_FASTDDS_PROFILES.xml located in the current execution path.
Load an XML file which location is defined using the environment variable
FASTDDS_DEFAULT_PROFILES_FILE(see FASTDDS_DEFAULT_PROFILES_FILE).Load the configuration parameters directly from the classes’ definitions without looking for the DEFAULT_FASTDDS_PROFILES.xml in the working directory (see SKIP_DEFAULT_XML).
Load directly the XML as a string data buffer.
An XML profile is defined by a unique name that is used to reference the XML profile during the creation of an Entity, the Transport configuration, or the DynamicTypes definition.
Both options can be complemented, i.e. it is possible to load multiple XML files but these must not have XML profiles with the same name. This section explains how to configure DDS entities using XML profiles. This includes the description of all the configuration values available for each of the XML profiles, as well as how to create complete XML files.
Creating an XML profiles file¶
An XML file can contain several XML profiles.
These XML profiles are defined within the <dds> element, and in turn, within the <profiles> XML elements.
The possible topologies for the definition of XML profiles are specified in Rooted vs Standalone profiles definition.
It is worth mentioning that the first element of the xml profile must have the xmlns attribute with the link
xmlns="http://www.eprosima.com", in both rooted or standalone definitions.
That link defines the reference of the xsd schema that the xml document complies with.
The available profile types are:
Log profiles, and
The following sections will show implementation examples for each of these profiles.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<domainparticipant_factory profile_name="domainparticipant_factory_profile">
<!-- ... -->
</domainparticipant_factory>
<participant profile_name="participant_profile">
<!-- ... -->
</participant>
<data_writer profile_name="datawriter_profile">
<!-- ... -->
</data_writer>
<data_reader profile_name="datareader_profile">
<!-- ... -->
</data_reader>
<topic profile_name="topic_profile">
<!-- ... -->
</topic>
<transport_descriptors>
<!-- ... -->
</transport_descriptors>
</profiles>
<library_settings>
<!-- ... -->
</library_settings>
<log>
<!-- ... -->
</log>
<types>
<!-- ... -->
</types>
</dds>
Note
The Example section shows an XML file with all the possible configurations and profile types. This example is useful as a quick reference to look for a particular property and how to use it. The Fast DDS XSD scheme can be used as a quick reference too.
Loading and applying profiles¶
In case the user defines the Entity profiles via XML files, it is required to load these
XML files using the load_XML_profiles_file() public member function before creating any
entity.
It is also possible to load directly the XML information as a string data buffer using the
load_XML_profiles_string() public member function.
Moreover, create_participant_with_profile(),
create_publisher_with_profile(), create_subscriber_with_profile(),
create_datawriter_with_profile(), and create_datareader_with_profile()
member functions expect a profile name as an argument.
Fast DDS searches the given profile name over all the loaded XML profiles, applying the profile to the entity
if founded.
if (RETCODE_OK ==
DomainParticipantFactory::get_instance()->load_XML_profiles_file("my_profiles.xml"))
{
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant_with_profile(
0, "participant_xml_profile");
Topic* topic =
participant->create_topic("TopicName", "DataTypeName", TOPIC_QOS_DEFAULT);
Publisher* publisher = participant->create_publisher_with_profile("publisher_xml_profile");
DataWriter* datawriter = publisher->create_datawriter_with_profile(topic, "datawriter_xml_profile");
Subscriber* subscriber = participant->create_subscriber_with_profile("subscriber_xml_profile");
DataReader* datareader = subscriber->create_datareader_with_profile(topic, "datareader_xml_profile");
}
// Load XML as string data buffer
std::string xml_profile =
"\
<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\
<dds>\
<profiles xmlns=\"http://www.eprosima.com\" >\
<data_writer profile_name=\"test_datawriter_profile\" is_default_profile=\"true\">\
<qos>\
<durability>\
<kind>TRANSIENT_LOCAL</kind>\
</durability>\
</qos>\
</data_writer>\
</profiles>\
</dds>\
";
if (RETCODE_OK ==
DomainParticipantFactory::get_instance()->load_XML_profiles_string(xml_profile.c_str(),
xml_profile.length()))
{
// Create DDS entities with profiles
}
For simplicity, the create_participant_with_default_profile() method takes the default
profile set in the environment to create a participant.
It requires the XML profile to have been already loaded.
Please, refer to XML profiles for further information regarding loading profiles.
Warning
It is worth mentioning that if the same XML profile file is loaded multiple times, the second loading of the file will result in an error together with the consequent error log.
Note
To load dynamic types from XML files see the Loading XML Types profile in Fast DDS application subsection of Dynamic Types profiles.
Rooted vs Standalone profiles definition¶
Fast DDS offers various options for the definition of XML profiles. These options are:
Stand-alone: The element defining the XML profile is the root element of the XML file. Elements
<dds>,<profiles>,<library_settings>,<types>, and<log>can be defined in a stand-alone manner.Rooted: The element defining the XML profile is the child element of another element. For example, the
<participant>,<data_reader>,<data_writer>,<topic>, and<transport_descriptors>elements must be defined as child elements of the<profiles>element.
The following is an example of the definition of the <types> XML profile using the two previously discussed
approaches.
Stand-alone |
<?xml version="1.0" encoding="UTF-8" ?>
<types xmlns="http://www.eprosima.com">
<type>
<!-- Type definition -->
</type>
<type>
<!-- Type definition -->
<!-- Type definition -->
</type>
</types>
|
Rooted |
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<types>
<type>
<!-- Type definition -->
</type>
<type>
<!-- Type definition -->
<!-- Type definition -->
</type>
</types>
</dds>
|
Note
Make sure that the first element of the xml profile must have the xmlns tag with the link
xmlns="http://www.eprosima.com", in both rooted or standalone definitions.
Modifying predefined XML profiles¶
Some scenarios may require to modify some of the QoS after loading the XML profiles. For such cases the Types of Entities which act as factories provide methods to get the QoS from the XML profile. This allows the user to read and modify predefined XML profiles before applying them to a new entity.
if (RETCODE_OK ==
DomainParticipantFactory::get_instance()->load_XML_profiles_file("my_profiles.xml"))
{
DomainParticipantQos participant_qos;
DomainParticipantFactory::get_instance()->get_participant_qos_from_profile(
"participant_xml_profile",
participant_qos);
// Name obtained in another section of the code
participant_qos.name() = custom_name;
// Modify number of preallocations (this overrides the one set in the XML profile)
participant_qos.allocation().send_buffers.preallocated_number = 10;
// Create participant using the modified XML Qos
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(
0, participant_qos);
}
Dynamic content by leveraging environment variables¶
For deployment scenarios that require part of the XML content to be dynamically generated, Fast DDS supports using
environment variables on the text content of any XML tag.
The format for environment variables expansion is ${ENV_VAR_NAME}, where ENV_VAR_NAME follows the restrictions
from IEEE 1003.1:
Note
Environment variable names … consist solely of uppercase letters, digits, and the ‘_’ (underscore) from the characters defined in Portable Character Set and do not begin with a digit.
More than one environment variable can be used, and they can be mixed with literal text.
The expansion will take place when the XML file is loaded, so changing the value of an environment variable afterwards will have no effect.
The following is an example of an XML allowing a participant to exclusively communicate with the participants on a
fixed IP address, taken from REMOTE_IP_ADDRESS environment variable.
It also gives the participant a name that mixes literal text with the content from two environment variables.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="env_var_parsing_example">
<rtps>
<name>This is app '${MY_APP_NAME}' running on host '${MY_HOST_NAME}'</name>
<builtin>
<initialPeersList>
<locator>
<udpv4>
<address>${REMOTE_IP_ADDRESS}</address>
</udpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
</dds>
Warning
The Fast DDS XSD schema does not support the environment variables expansion feature, so validation of an XML file with environment variables expansion expressions will fail.
DomainParticipantFactory profiles¶
The DomainParticipantFactory profiles allow the definition of the configuration of DomainParticipantFactory
through XML files.
These profiles are defined within the <domainparticipant_factory> XML tags.
DomainParticipantFactory XML attributes¶
The <domainparticipant_factory> element has two attributes defined: profile_name and is_default_profile.
Name |
Description |
Use |
|---|---|---|
|
Sets the name under which the |
Mandatory |
|
Sets the |
Optional |
DomainParticipantFactory configuration¶
The <domainparticipant_factory> element has the following children elements:
Name |
Description |
Values |
|---|---|---|
|
DomainParticipantFactory QoS. |
QoS element type¶
Name |
Description |
Values |
|---|---|---|
|
Entity factory QoS Policy. |
|
|
ThreadSettings for the SHM watchdog thread. |
|
|
ThreadSettings for the File watch threads. See Concurrency and multithreading. |
Example
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com">
<domainparticipant_factory profile_name="domainparticipant_factory_profile_name">
<qos>
<entity_factory>
<autoenable_created_entities>true</autoenable_created_entities>
</entity_factory>
<shm_watchdog_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</shm_watchdog_thread>
<file_watch_threads>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</file_watch_threads>
</qos>
</domainparticipant_factory>
</profiles>
<dds>
DomainParticipant profiles¶
The DomainParticipant profiles allow the definition of the configuration of DomainParticipants through
XML files.
These profiles are defined within the <participant> XML tags.
DomainParticipant XML attributes¶
The <participant> element has two attributes defined: profile_name and is_default_profile.
Name |
Description |
Use |
|---|---|---|
|
Sets the name under which the |
Mandatory |
|
Sets the |
Optional |
DomainParticipant configuration¶
The <participant> element has two child elements: <domainId> and <rtps>.
All the DomainParticipant configuration options belong to the <rtps> element, except for the DDS DomainId
which is defined by the <domainId> element.
Below a list with the configuration XML elements is presented:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
DomainId to be used by the DomainParticipant. See Profile based creation of a DomainParticipant. |
|
0 |
|
Fast DDS DomainParticipant configurations. |
RTPS element type¶
The following is a list with all the possible child XML elements of the <rtps> element.
These elements allow the user to define the DomainParticipant configuration.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
The DomainParticipant’s name. |
|
|
|
List of default reception unicast locators |
|
|
|
List of default reception multicast |
|
|
|
List of External Locators |
||
|
Whether to ignore locators received on |
|
false |
|
Size in bytes of the send socket buffer. |
|
0 |
|
Size in bytes of the reception socket |
|
0 |
|
Participant’s netmask |
|
|
|
|
||
|
Allows defining the port and gains related |
||
|
DomainParticipant’s identifier. Typically |
|
0 |
|
Transport descriptors to be used by the |
|
|
|
Boolean field to indicate the system |
|
true |
|
Configuration option to determine which transports |
||
|
Additional configuration properties. |
||
|
Configuration regarding allocation behavior. |
||
|
Additional information attached to the DomainParticipant |
|
Empty |
|
DomainParticipant’s |
|
Empty |
|
ThreadSettings for the builtin flow controllers sender thread. |
||
|
ThreadSettings participant’s timed events thread. |
||
|
ThreadSettings for the discovery server thread. |
||
|
ThreadSettings for the threads used by the builtin TypeLookup service |
||
|
ThreadSettings for the builtin transports reception threads. |
||
|
ThreadSettings for the security log thread. |
Example
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="domainparticipant_profile_name">
<domainId>4</domainId>
<rtps>
<name>DomainParticipant Name</name>
<defaultUnicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
</defaultUnicastLocatorList>
<defaultMulticastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<port>7400</port>
<address>192.168.2.41</address>
</udpv4>
</locator>
</defaultMulticastLocatorList>
<default_external_unicast_locators>
<!-- EXTERNAL_LOCATOR_LIST -->
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>23456</port>
</udpv4>
</default_external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<sendSocketBufferSize>8192</sendSocketBufferSize>
<listenSocketBufferSize>8192</listenSocketBufferSize>
<netmask_filter>ON</netmask_filter>
<builtin>
<!-- BUILTIN -->
</builtin>
<port>
<portBase>7400</portBase>
<domainIDGain>200</domainIDGain>
<participantIDGain>10</participantIDGain>
<offsetd0>0</offsetd0>
<offsetd1>1</offsetd1>
<offsetd2>2</offsetd2>
<offsetd3>3</offsetd3>
</port>
<participantID>99</participantID>
<userTransports>
<transport_id>TransportId1</transport_id>
<transport_id>TransportId2</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<builtinTransports>DEFAULT</builtinTransports>
<propertiesPolicy>
<!-- PROPERTIES_POLICY -->
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
</properties>
</propertiesPolicy>
<allocation>
<!-- ALLOCATION -->
</allocation>
<userData>
<value>3.4.7.0.C</value>
</userData>
<prefix>72.61.73.70.66.61.72.6d.74.65.73.74</prefix>
<builtin_controllers_sender_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</builtin_controllers_sender_thread>
<timed_events_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</timed_events_thread>
<discovery_server_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</discovery_server_thread>
<typelookup_service_thread>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</typelookup_service_thread>
<builtin_transports_reception_threads>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</builtin_transports_reception_threads>
<security_log_thread>
<priority>0</priority>
<affinity>0</affinity>
Note
LOCATOR_LISTmeans a LocatorListType is expected.EXTERNAL_LOCATOR_LISTmeans a ExternalLocatorListType is expected.For
BUILTINdetails, please refer to Builtin parameters.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
ALLOCATIONdetails, please refer to ParticipantAllocationType.
Builtin parameters¶
By calling the wire_protocol() member function of the DomainParticipantQos,
it is possible to
access the builtin public data member of the WireProtocolConfigQos
class.
This section specifies the available XML members for the configuration of this
builtin parameters.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
This is the main element within |
||
|
Restricts multicast metatraffic |
|
|
|
Indicates whether to use the |
|
|
|
Metatraffic Unicast Locator List. |
A set of |
|
|
Metatraffic Multicast Locator List. |
A set of |
|
|
The list of IP-port address |
A set of |
|
|
List of External Locators |
||
|
Memory policy for DataReaders. |
|
|
|
Memory policy for DataWriters. |
|
|
|
Maximum DataReader’s History |
|
512 |
|
Maximum DataWriter’s History |
|
512 |
|
Number of different ports |
|
100 |
Example
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="72.61.73.70.66.61.72.6d.74.65.73.74">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<locator>
<udpv4>
<address>192.168.10.58</address>
<port>24565</port>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
</RemoteServer>
</discoveryServersList>
<ignoreParticipantFlags>FILTER_DIFFERENT_HOST</ignoreParticipantFlags>
<EDP>SIMPLE</EDP>
<simpleEDP>
<PUBWRITER_SUBREADER>true</PUBWRITER_SUBREADER>
<PUBREADER_SUBWRITER>true</PUBREADER_SUBWRITER>
</simpleEDP>
<leaseDuration>
<!-- DURATION -->
<sec>20</sec>
</leaseDuration>
<leaseAnnouncement>
<!-- DURATION -->
<sec>3</sec>
</leaseAnnouncement>
<initialAnnouncements>
<!-- INITIAL_ANNOUNCEMENTS -->
<count>10</count>
<period>
<nanosec>50</nanosec>
</period>
</initialAnnouncements>
<clientAnnouncementPeriod>
<nanosec>250000000</nanosec>
</clientAnnouncementPeriod>
<static_edp_xml_config>file://filename1.xml</static_edp_xml_config>
<static_edp_xml_config>file://filename2.xml</static_edp_xml_config>
<static_edp_xml_config>file://filename3.xml</static_edp_xml_config>
</discovery_config>
<avoid_builtin_multicast>true</avoid_builtin_multicast>
<use_WriterLivelinessProtocol>false</use_WriterLivelinessProtocol>
<metatrafficUnicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
<initialPeersList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</initialPeersList>
<metatraffic_external_unicast_locators>
<!-- EXTERNAL_LOCATOR_LIST -->
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>34567</port>
</udpv4>
</metatraffic_external_unicast_locators>
<readerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</readerHistoryMemoryPolicy>
<writerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</writerHistoryMemoryPolicy>
<readerPayloadSize>512</readerPayloadSize>
<writerPayloadSize>512</writerPayloadSize>
<mutation_tries>55</mutation_tries>
</builtin>
discovery_config¶
Through the <discovery_config> element, Fast DDS allows the configuration of the discovery mechanism via an XML
file.
Please refer to the Discovery section for more detail on the various types of discovery mechanisms and
configurable settings.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Indicates which discovery protocol |
|
|
|
|||
|
|||
|
|||
|
|||
|
Describes servers from which it receives |
||
|
Restricts metatraffic using several |
|
|
|
If set to |
|
|
|
|||
|
Attributes of the Simple Discovery |
||
|
Indicates how long the DomainParticipant |
20s |
|
|
The period for the DomainParticipant to |
3s |
|
|
Allows the user to configure the number |
||
|
The period for the DomainParticipant to |
450 ms |
|
|
The XML filename(s) with the static EDP |
|
Contains a list of <RemoteServer> (server) elements, which are defined by the GuidPrefix_t and their own
locator list which must be populated with RemoteServerAttributes.
The DomainParticipant set as client would discover the servers described in this section.
Server attributes
The <RemoteServer> element has a mandatory attribute defined: prefix.
Name |
Description |
Use |
|---|---|---|
|
RTPS standard participant unique identifier, a 12-byte chain. |
Mandatory |
RemoteServer configuration
Each client (or a server connecting to another server) must keep a list of locators associated to the servers
to which it wants to link.
Those locator would be defined as metatrafficUnicastLocatorList or metatrafficMulticastLocatorList.
Name |
Description |
Values |
|---|---|---|
|
Metatraffic Unicast Locator List. |
A set of |
|
Metatraffic Multicast Locator List. |
A set of |
Example
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP CLIENT" is_default_profile="true">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="72.61.73.70.66.61.72.6d.74.65.73.74">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<locator>
<udpv4>
<address>192.168.10.58</address>
<port>24565</port>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
Possible values |
Description |
|---|---|
|
All Discovery traffic is processed. |
|
Discovery traffic from another host is discarded. |
|
Discovery traffic from another process on the same host is discarded. |
|
Discovery traffic from DomainParticipant’s own process is discarded. |
This option also supports the OR (|) operator to filter discovery traffic from other configurations.
For instance, FILTER_DIFFERENT_PROCESS|FILTER_SAME_PROCESS value discards discovery traffic from the
DomainParticipant’s own host.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Indicates if the participant must use |
|
|
|
Indicates if the participant must use |
|
|
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Number of initial discovery messages to send at the period
specified by |
|
5 |
|
The period for the DomainParticipant to send its discovery messages. |
100 ms |
Port Configuration¶
According to the RTPS standard (Section 9.6.1.1), the
RTPSParticipants’ discovery traffic unicast listening ports are calculated using the following equation:
\(7400 + 250 * DomainId + 10 + 2 * ParticipantId\).
Therefore the following parameters can be specified:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Base |
|
7400 |
|
Gain in DomainId. |
|
250 |
|
Gain in |
|
2 |
|
Multicast metadata offset. |
|
0 |
|
Unicast metadata offset. |
|
10 |
|
Multicast user data offset. |
|
1 |
|
Unicast user data offset. |
|
11 |
Warning
Changing these default parameters may break compatibility with other RTPS compliant implementations, as well as with other Fast DDS applications with default port settings.
ParticipantAllocationType¶
The ParticipantAllocationType defines the <allocation> element, which allows setting of the parameters
related with the allocation behavior on the DomainParticipant.
Please refer to ParticipantResourceLimitsQos for a detailed documentation on DomainParticipants allocation
configuration.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Defines the limits for the remote locators’ collections. |
||
|
DomainParticipant Allocation Configuration to specify the |
||
|
DomainParticipant Allocation Configuration to specify the |
||
|
DomainParticipant Allocation Configuration related to the |
||
|
Maximum size of the partitions submessage. |
|
|
|
Maximum size of the user data submessage. |
|
|
|
Maximum size of the properties submessage. |
|
|
|
Allocation behaviour for the send buffer |
Example
<allocation>
<remote_locators>
<max_unicast_locators>4</max_unicast_locators>
<max_multicast_locators>1</max_multicast_locators>
</remote_locators>
<total_participants>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</total_participants>
<total_readers>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</total_readers>
<total_writers>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</total_writers>
<max_partitions>256</max_partitions>
<max_user_data>256</max_user_data>
<max_properties>512</max_properties>
<send_buffers>
<preallocated_number>127</preallocated_number>
<dynamic>true</dynamic>
</send_buffers>
<!-- content_filter cannot be configured using XML (yet) -->
</allocation>
Remote Locators Allocations¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Maximum number of unicast locators expected on a |
|
4 |
|
Maximum number of multicast locators expected on a |
|
1 |
Send buffers¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Initial number of send buffers to allocate. See |
|
0 |
|
Whether the number of send buffers is allowed to grow. |
|
false |
Note
The default value 0 of <preallocated_number> will perform an initial guess of the number of buffers
required, based on the number of threads from which a send operation could be started.
So it does not mean there are no buffers, instead it would use the maximum amount of buffers available.
DataWriter profiles¶
The DataWriter profiles allow for configuring DataWriters from an XML file.
These profiles are defined within the <data_writer> XML tags.
DataWriter XML attributes¶
The <data_writer> element has two attributes defined: profile_name and is_default_profile.
Name |
Description |
Use |
|---|---|---|
|
Sets the name under which the |
Mandatory |
|
Sets the |
Optional |
DataWriter configuration¶
The DataWriter configuration is performed through the XML elements listed in the following table.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
TopicType configuration of the DataWriter. |
||
|
DataWriter QoS configuration. |
||
|
It configures some time related parameters |
||
|
List of input unicast locators. |
|
|
|
List of input multicast locators. |
|
|
|
List of External Locators |
||
|
Whether to ignore locators received on |
|
false |
|
Memory allocation kind for DataWriter’s |
|
|
|
Additional configuration properties. |
||
|
Used for |
|
-1 |
|
Sets the |
|
-1 |
|
Sets the limits of the collection of matched |
Example
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<data_writer profile_name="datawriter_profile_name">
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
</historyQos>
</topic>
<qos>
<!-- QOS -->
</qos>
<times> <!-- writerTimesType -->
<initialHeartbeatDelay>
<nanosec>12</nanosec>
</initialHeartbeatDelay>
<heartbeatPeriod>
<sec>3</sec>
</heartbeatPeriod>
<nackResponseDelay>
<nanosec>5</nanosec>
</nackResponseDelay>
<nackSupressionDuration>
<sec>0</sec>
</nackSupressionDuration>
</times>
<unicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</multicastLocatorList>
<external_unicast_locators>
<!-- EXTERNAL_LOCATOR_LIST -->
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>12345</port>
</udpv4>
</external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<!-- PROPERTIES_POLICY -->
<propertiesPolicy>
<properties>
<property>
<name>PropertyName</name>
<value>PropertyValue</value>
</property>
</properties>
</propertiesPolicy>
<userDefinedID>55</userDefinedID>
<entityID>66</entityID>
<matchedSubscribersAllocation>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</matchedSubscribersAllocation>
<!-- reader_filters_allocation cannot be configured using XML (yet) -->
</data_writer>
</profiles>
</dds>
Note
LOCATOR_LISTmeans a LocatorListType is expected.EXTERNAL_LOCATOR_LISTmeans a ExternalLocatorListType is expected.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
QOSdetails, please refer to QoS.TOPIC_TYPEis detailed in section TopicType.
WriterTimes¶
These parameters are included within RTPSReliableWriterQos in the WriterTimes structure.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Initial heartbeat delay. |
12 ms |
|
|
Periodic heartbeat period. |
3 s |
|
|
Delay to apply to the response of an ACKNACK message. |
5 ms |
|
|
This time allows the DataWriter to ignore NACK |
0 ms |
DataReader profiles¶
The DataReader profiles allow declaring DataReaders from an XML file.
These profiles are defined within the <data_reader> XML tags.
DataReader XML attributes¶
The <data_reader> element has two attributes defined: profile_name and is_default_profile.
Name |
Description |
Use |
|---|---|---|
|
Sets the name under which the |
Mandatory |
|
Sets the |
Optional |
DataReader configuration¶
The DataReader configuration is performed through the XML elements listed in the following table.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
TopicType configuration of the DataReader. |
||
|
Subscriber QoS configuration. |
||
|
It allows configuring some time related |
||
|
List of input unicast locators. |
List of LocatorListType |
|
|
List of input multicast locators. |
List of LocatorListType |
|
|
List of External Locators |
||
|
Whether to ignore locators received on |
|
false |
|
It indicates if QoS is expected inline. |
|
|
|
Memory allocation kind for DataReaders’s |
|
|
|
Additional configuration properties. |
||
|
Used for StaticEndpointDiscovery. |
|
-1 |
|
Set the |
|
-1 |
|
Sets the limits of the collection of matched |
Example
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<data_reader profile_name="data_reader_profile_name">
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
</historyQos>
</topic>
<qos>
<!-- QOS -->
</qos>
<times> <!-- readerTimesType -->
<initialAcknackDelay>
<nanosec>70</nanosec>
</initialAcknackDelay>
<heartbeatResponseDelay>
<nanosec>5</nanosec>
</heartbeatResponseDelay>
</times>
<unicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4>
<address>192.168.0.1</address>
</udpv4>
</locator>
</multicastLocatorList>
<external_unicast_locators>
<!-- EXTERNAL_LOCATOR_LIST -->
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>12345</port>
</udpv4>
</external_unicast_locators>
<ignore_non_matching_locators>true</ignore_non_matching_locators>
<expectsInlineQos>true</expectsInlineQos>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<!-- PROPERTIES_POLICY -->
<propertiesPolicy>
<properties>
<property>
<name>PropertyName</name>
<value>PropertyValue</value>
</property>
</properties>
</propertiesPolicy>
<userDefinedID>55</userDefinedID>
<entityID>66</entityID>
<matchedPublishersAllocation>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</matchedPublishersAllocation>
</data_reader>
</profiles>
</dds>
Note
LOCATOR_LISTmeans it expects a LocatorListType.EXTERNAL_LOCATOR_LISTmeans a ExternalLocatorListType is expected.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
QOSdetails, please refer to QoS.TOPIC_TYPEis detailed in section TopicType.
ReaderTimes¶
These parameters are included within RTPSReliableReaderQos in the ReaderTimes structure.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Initial ACKNACK delay. |
70 ms |
|
|
Response time delay when receiving a Heartbeat. |
5 ms |
Topic profiles¶
The topic profiles allow for configuring Topic from an XML file.
These profiles are defined within the <topic> XML tags.
Topic XML attributes¶
The <topic> element has two attributes defined: profile_name and is_default_profile.
Name |
Description |
Use |
|---|---|---|
|
Sets the name under which the |
Mandatory |
|
Sets the |
Optional |
Topic configuration¶
This XML element allows the configuration of the TopicQos.
Name |
Description |
Values |
|---|---|---|
|
It controls the behavior of Fast DDS |
|
|
It controls the resources that Fast DDS |
Example
<topic profile_name="topic_example">
<historyQos>
<kind>KEEP_LAST</kind>
<depth>20</depth>
</historyQos>
<resourceLimitsQos>
<max_samples>5</max_samples>
<max_instances>2</max_instances>
<max_samples_per_instance>1</max_samples_per_instance>
<allocated_samples>20</allocated_samples>
<extra_samples>10</extra_samples>
</resourceLimitsQos>
</topic>
Transport descriptors¶
This section defines the XML elements available for configuring the transport layer parameters in Fast DDS.
These elements are defined within the XML tag <transports_descriptors>.
The <transport_descriptors> can contain one or more <transport_descriptor> XML elements.
Each <transport_descriptor> element defines a configuration for a specific type of transport protocol.
Each of these <transport_descriptor> elements are uniquely identified by a transport ID with the <transport_id>
XML tag.
Once the user defines a valid <transports_descriptor>, i.e. defines the transport layer parameters, these
can be loaded
into the XML profile of the DomainParticipant using the <transport_id> XML tag.
An example of how to load the <transport_descriptor> into the XML profile of the DomainParticipant is found in
DomainParticipant profiles.
The following table lists all the available XML elements that can be defined within the <transport_descriptor>
element for the configuration of the transport layer.
A more detailed explanation of each of these elements can be found in Transport Layer.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Unique name to identify each transport descriptor. |
|
|
|
Type of the transport descriptor. |
UDPv4 |
UDPv4 |
UDPv6 |
|||
TCPv4 |
|||
TCPv6 |
|||
SHM |
|||
|
Size in bytes of the send socket buffer. |
|
0 |
|
Size in bytes of the reception socket |
|
0 |
|
The maximum size in bytes of the transport’s |
|
65500 |
|
Number of channels opened with each initial |
|
4 |
|
Transport’s Netmask filtering |
OFF |
AUTO |
AUTO |
|||
ON |
|||
|
Allows defining an Interfaces configuration. |
||
|
Allows defining an interfaces Whitelist. |
||
|
Time To Live (UDP only). See |
|
1 |
|
Whether to set the non-blocking send mode on |
|
|
|
Port used for output bound. |
|
0 |
|
Public WAN address when using TCPv4 |
IPv4 formatted |
|
|
Frequency in milliseconds for sending
RTCP |
|
50000 |
|
Time in milliseconds since the last |
|
10000 |
|
The maximum number of logical ports to try |
|
100 |
|
The maximum number of logical ports per |
|
20 |
|
Increment between logical ports to try during |
|
2 |
|
Local port to work as TCP acceptor for input |
|
|
|
Allows to define TLS related parameters and |
||
|
Calculates the Cyclic Redundancy Code (CRC) |
|
|
|
Check the CRC for error control (TCP |
|
|
|
Socket option for disabling the Nagle |
|
|
|
Time to wait for logical port negotiation (in ms)
|
|
|
|
Size (in bytes) of the shared-memory segment. |
|
262144 |
|
Capacity (in number of messages) available to |
|
512 |
|
Maximum time-out (in milliseconds) used when |
|
1000 |
|
Complete path (including file) where RTPS |
|
Empty |
The following XML code shows an example of transport protocol configuration using all configurable parameters. More examples of transports descriptors can be found in the Transport Layer section.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<transport_descriptors>
<transport_descriptor>
<transport_id>my_udpv4_transport</transport_id>
<type>UDPv4</type>
<sendBufferSize>8192</sendBufferSize>
<receiveBufferSize>8192</receiveBufferSize>
<maxMessageSize>16384</maxMessageSize>
<maxInitialPeersRange>100</maxInitialPeersRange>
<netmask_filter>AUTO</netmask_filter>
<interfaces>
<allowlist>
<interface name="wlp59s0" netmask_filter="ON"/>
</allowlist>
<blocklist>
<interface name="127.0.0.1"/>
<interface name="docker0"/>
</blocklist>
</interfaces>
<interfaceWhiteList>
<address>192.168.1.41</address>
<interface>lo</interface>
</interfaceWhiteList>
<TTL>250</TTL>
<non_blocking_send>false</non_blocking_send>
<output_port>5101</output_port>
<wan_addr>80.80.55.44</wan_addr>
<keep_alive_frequency_ms>5000</keep_alive_frequency_ms>
<keep_alive_timeout_ms>25000</keep_alive_timeout_ms>
<max_logical_port>9000</max_logical_port>
<logical_port_range>100</logical_port_range>
<logical_port_increment>2</logical_port_increment>
<listening_ports>
<port>5100</port>
<port>5200</port>
</listening_ports>
<tls><!-- TLS Section --></tls>
<calculate_crc>false</calculate_crc>
<check_crc>false</check_crc>
<enable_tcp_nodelay>false</enable_tcp_nodelay>
<segment_size>262144</segment_size>
<port_queue_capacity>512</port_queue_capacity>
<healthy_check_timeout_ms>1000</healthy_check_timeout_ms>
<rtps_dump_file>rtsp_messages.log</rtps_dump_file>
</transport_descriptor>
</transport_descriptors>
</profiles>
</dds>
Note
The Real-time Transport Control Protocol (RTCP) is the control protocol for communications with RTPS over TCP/IP connections.
TLS Configuration¶
Fast DDS provides mechanisms to configure the Transport Layer Security (TLS) protocol parameters
through the <tls> XML element of its <transport_descriptor>.
Please, refer to TLS over TCP for a detailed explanation of the entire TLS configuration in Fast DDS.
More information on how to set up secure communication in Fast DDS can be found in the Security section.
Warning
For the full understanding of this section, a basic knowledge of network security in terms of SSL/TLS, Certificate Authority (CA), Public Key Infrastructure (PKI), and Diffie-Hellman is required; encryption protocols are not explained in detail.
The full list of available XML elements that can be defined within the <tls> element to configure the TLS
protocol are listed in the following table:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Password of the
|
|
|
|
Path to the private key certificate file. |
|
|
|
Path to the private key RSA certificate file. |
|
|
|
Path to the public certificate chain file. |
|
|
|
Path to the Diffie-Hellman parameters file |
|
|
|
Path to the Certification Authority (CA) file. |
|
|
|
Establishes the verification
mode mask. Several |
|
|
|
|||
|
|||
|
|||
|
Establishes the SSL Context
options mask. Several |
|
|
|
|||
|
|||
|
|||
|
|||
|
|||
|
|||
|
|||
|
|||
|
Paths where the system will
look for verification |
|
|
|
Maximum allowed depth to
verify intermediate |
|
|
|
Specifies whether the system
will look on the |
|
|
|
Role that the transport will
take on handshaking. |
|
|
|
|||
|
|||
|
server name or host name required in case Server Name Indication (SNI) is used. |
|
An example of TLS protocol parameter configuration is shown below.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<transport_descriptors>
<transport_descriptor>
<transport_id>Test</transport_id>
<type>TCPv4</type>
<tls>
<password>Password</password>
<private_key_file>Key_file.pem</private_key_file>
<rsa_private_key_file>RSA_file.pem</rsa_private_key_file>
<cert_chain_file>Chain.pem</cert_chain_file>
<tmp_dh_file>DH.pem</tmp_dh_file>
<verify_file>verify.pem</verify_file>
<verify_mode>
<verify>VERIFY_PEER</verify>
</verify_mode>
<options>
<option>NO_TLSV1</option>
<option>NO_TLSV1_1</option>
</options>
<verify_paths>
<verify_path>Path1</verify_path>
<verify_path>Path2</verify_path>
<verify_path>Path3</verify_path>
</verify_paths>
<verify_depth>55</verify_depth>
<default_verify_path>true</default_verify_path>
<handshake_role>SERVER</handshake_role>
<server_name>my_server.com</server_name>
</tls>
</transport_descriptor>
<!-->
</profiles>
Intra-process delivery profiles¶
This section defines the XML elements available for configuring the Intra-process delivery settings
parameters in Fast DDS.
These elements are defined within the XML tag <library_settings>.
Intra-process delivery configuration¶
The Intra-process delivery configuration is performed through the XML elements listed in the following table.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Speed up communications between entities within the same process by avoiding |
|
|
Example
<library_settings>
<intraprocess_delivery>FULL</intraprocess_delivery> <!-- OFF | USER_DATA_ONLY | FULL -->
</library_settings>
Log profiles¶
eProsima Fast DDS allows for registering and configuring Log consumers using XML
configuration files.
Please refer to Logging for more information on Fast DDS extensible Logging built-in module.
The logging profiles are defined within the <log> XML tags.
The <log> element has two child elements: <use_default> and <consumer>.
These are described in the following table.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
If set to |
|
|
|
Defines the class and configuration of the consumer to |
||
|
ThreadSettings for the logging thread. |
The following constitutes an example of an XML configuration file that sets the Log to use one
StdoutConsumer, one StdoutErrConsumer, and one FileConsumer:
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<log>
<!--
Clear consumers
-->
<use_default>false</use_default>
<!--
StdoutConsumer does not have any properties
-->
<consumer>
<class>StdoutConsumer</class>
</consumer>
<!--
StdoutErrConsumer with threshold set to Log::Kind::Error
-->
<consumer>
<class>StdoutErrConsumer</class>
<property>
<name>stderr_threshold</name>
<value>Log::Kind::Error</value>
</property>
</consumer>
<!--
FileConsumer openning "execution.log" in append mode
-->
<consumer>
<class>FileConsumer</class>
<property>
<name>filename</name>
<value>execution.log</value>
</property>
<property>
<name>append</name>
<value>true</value>
</property>
</consumer>
<!--
ThreadSettings for the log's consumer thread
-->
<thread_settings>
<scheduling_policy>-1</scheduling_policy>
<priority>0</priority>
<affinity>0</affinity>
<stack_size>-1</stack_size>
</thread_settings>
</log>
</dds>
ConsumerDataType¶
Name |
Description |
Values |
|---|---|---|
|
The class of the consumer. |
|
|
||
|
||
|
This element is used to configure the log consumer and only applies |
PropertyType¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Name of the property to be configured. |
|
|
|
|||
|
|||
|
The value of the property. |
||
|
|
output.log |
|
|
|
|
|
|
|
|
Dynamic Types profiles¶
Fast DDS supports the implementation of Dynamic Language Binding by defining them through XML files. Thus the topic data types can be modified without the need to modify the source code of the DDS application.
XML Structure¶
The definition of data type profiles in the XML file is done with the types tag.
Each types element can contain one or more Type definitions.
Defining several types within a types element or a single type for each types element has the same
result.
Below, an example of a stand-alone types definition via XML is shown.
<types xmlns="http://www.eprosima.com">
<type>
<!-- Type definition -->
</type>
<type>
<!-- Type definition -->
<!-- Type definition -->
</type>
</types>
Note
For more information on the difference between stand-alone and rooted definitions please refer to section Rooted vs Standalone profiles definition.
Type definition¶
Below, the types supported by eProsima Fast DDS are presented. For further information about the supported Dynamic Language Binding, please, refer to Supported Types. For each type listed below, an example of how to build the type’s XML profile is provided.
Primitive types¶
Primitive types are built-in types and they should be declared as members of an aggregated type (Structure types or
Union types).
Primitive types are declared by attribute type and the possible values are listed in the table below.
Please, refer to Primitive Types for more information on primitive types.
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All of them are declared as follows:
<struct name="PrimitivesStruct">
<member name="my_bool" type="boolean"/>
<member name="my_octet" type="byte"/>
<member name="my_char" type="char8"/>
<member name="my_wchar" type="char16"/>
<member name="my_long" type="int32"/>
<member name="my_ulong" type="uint32"/>
<member name="my_int8" type="int8"/>
<member name="my_uint8" type="uint8"/>
<member name="my_short" type="int16"/>
<member name="my_ushort" type="uint16"/>
<member name="my_longlong" type="int64"/>
<member name="my_ulonglong" type="uint64"/>
<member name="my_float" type="float32"/>
<member name="my_double" type="float64"/>
<member name="my_longdouble" type="float128"/>
</struct>
struct PrimitivesStruct
{
boolean my_bool;
octet my_octet;
char my_char;
wchar my_wchar;
long my_long;
unsigned long my_ulong;
int8 my_int8;
uint8 my_uint8;
short my_short;
unsigned short my_ushort;
long long my_longlong;
unsigned long long my_ulonglong;
float my_float;
double my_double;
long double my_longdouble;
};
String Types¶
String types should be defined as members of an aggregated type (Structure types or Union types).
String types are defined with attribute type set to string or wstring.
An optional attribute stringMaxLength might used to set a maximum length for the string collection.
Please, refer to String Types for more information on string types.
<struct name="StringsStruct">
<member name="my_string" type="string"/>
<member name="my_wstring" type="wstring"/>
<member name="my_bounded_string" type="string" stringMaxLength="41925"/>
<member name="my_bounded_wstring" type="wstring" stringMaxLength="20925"/>
</struct>
struct StringsStruct
{
string my_string;
wstring my_wstring;
string<41925> my_bounded_string;
wstring<20925> my_bounded_wstring;
};
Enumeration Types¶
Enumeration types are defined using the <enum> tag.
Attribute name and at least one <enumerator> child element are mandatory.
Enumeration literals are defined using the <enumerator> tag with mandatory attribute name.
Optionally, unsigned integer attribute value might be added to set a specific value for the enumeration literal.
Note
value attribute is equivalent to @value builtin annotation which is not still supported in neither
the plain (IDL) nor Dynamic Language Binding.
Please, refer to Enumeration Types for more information on enumeration types.
<enum name="MyEnum">
<enumerator name="A" value="0"/>
<enumerator name="B" value="1"/>
<enumerator name="C"/>
</enum>
<struct name="EnumStruct">
<member name="my_enum" type="nonBasic" nonBasicTypeName="MyEnum"/>
</struct>
enum MyEnum
{
A,
B,
C
};
struct EnumStruct
{
MyEnum my_enum;
};
Bitmask Types¶
Bitmask types are defined using the <bitmask> tag.
Attribute name and at least on <bit_value> child element are mandatory.
Optionally, bit_bound attribute might be set to specify the bitmask bound (by default 32 bits).
Bitflag elements are defined using the <bit_value> tag with mandatory attribute name.
Optionally, position attribute might be defined to set the bitflag position within the bitmask.
Please, refer to Bitmask Types for more information on bitmask types.
<bitmask name="MyBitMask" bit_bound="8">
<bit_value name="flag0" position="0"/>
<bit_value name="flag1"/>
<bit_value name="flag2"/>
<bit_value name="flag5" position="5"/>
</bitmask>
<struct name="BitmaskStruct">
<member name="my_bitmask" type="nonBasic" nonBasicTypeName="MyBitMask"/>
</struct>
@bit_bound(8)
bitmask MyBitMask
{
@position(0) flag0,
flag1,
flag2,
@position(5) flag5
};
struct BitmaskStruct
{
MyBitMask my_bitmask;
};
Alias Types¶
Alias types are defined using the <typedef> tag.
Attributes name and type are mandatory.
Depending on the aliased type, some other mandatory and/or optional attributes might be necessary or available.
Non-primitive types must define the type attribute as nonBasic and include the nonBasicTypeName
attribute with the name of the aliased type.
Please, refer to Alias Types for more information on alias types.
<typedef name="MyAliasedEnum" type="nonBasic" nonBasicTypeName="MyEnum"/>
<!-- XSD does not allow to set bounds to aliased strings -->
<typedef name="MyAliasedBoundedString" type="string"/>
<typedef name="MyRecursiveAlias" type="nonBasic" nonBasicTypeName="MyAliasedEnum"/>
<struct name="AliasStruct">
<member name="my_aliased_enum" type="nonBasic" nonBasicTypeName="MyAliasedEnum"/>
<member name="my_aliased_bounded_string" type="nonBasic" nonBasicTypeName="MyAliasedBoundedString"/>
<member name="my_recursive_alias" type="nonBasic" nonBasicTypeName="MyRecursiveAlias"/>
</struct>
typedef MyEnum MyAliasedEnum;
typedef string<100> MyAliasedBoundedString;
typedef MyAliasedEnum MyRecursiveAlias;
struct AliasStruct
{
MyAliasedEnum my_aliased_enum;
MyAliasedBoundedString my_aliased_bounded_string;
MyRecursiveAlias my_recursive_alias;
};
Sequence Types¶
Sequence types should be defined as members of an aggregated type (Structure types or Union types).
Sequence types are defined with mandatory attributes type set to the collection’s element type, and
sequenceMaxLength used to set the maximum collection’s length.
Unbounded sequences should set sequenceMaxLength attribute to -1.
Please, refer to Sequence types for more information on sequence types.
<struct name="SequenceStruct">
<member name="bitmask_sequence" type="nonBasic" nonBasicTypeName="MyBitMask" sequenceMaxLength="-1"/>
<member name="short_sequence" sequenceMaxLength="5" type="int16"/>
</struct>
struct SequenceStruct
{
sequence<MyBitmask> bitmask_sequence;
sequence<short, 5> short_sequence;
};
Array Types¶
Array types should be defined as members of an aggregated type (Structure types or Union types).
Array types are defined with mandatory attributes type set to the collection’s element type, and
arrayDimensions used to set the collection’s dimensions.
The format of arrayDimensions attribute value is the size of each dimension separated by commas.
Please, refer to Array types for more information on array types.
<struct name="ArrayStruct">
<member name="long_array" type="int32" arrayDimensions="2,3,4"/>
</struct>
struct ArrayStruct
{
long long_array[2][3][4];
};
Map Types¶
Map types should be defined as members of an aggregated type (Structure types or Union types).
Map types are defined with mandatory attributes type set to the map’s value type, key_type set to the
map’s key type, and mapMaxLength used to set the maximum map’s number of key-value pairs.
Unbounded maps should set mapMaxLength attribute to -1.
Please, refer to Map Types for more information on map types.
<struct name="MapStruct">
<member name="string_alias_unbounded_map" type="nonBasic" nonBasicTypeName="MyAliasedBoundedString" key_type="string" mapMaxLength="-1"/>
<member name="short_long_map" type="int32" key_type="int16" mapMaxLength="2"/>
</struct>
struct MapStruct
{
map<string, MyAliasedBoundedString> string_alias_unbounded_map;
map<short, long, 2> short_long_map;
};
Structure Types¶
Structure types are defined using the <struct> tag with mandatory attribute name.
Structure inheritance may be configured setting optional attribute baseType.
XML Structure Types require at least one member defined.
Note
IDL specification introduced in version 4.1 the possibility of void content structures. Empty structures are not supported in XML Types profiles yet.
Structure members are defined using the <member> tag with mandatory attributes name and type.
Depending on the member type, some other mandatory and/or optional attributes might be necessary or available.
Non-primitive types must define the type attribute as nonBasic and include the nonBasicTypeName
attribute with the name of the member type.
Note
Currently, XML Types profiles does not support setting the member ID or marking a member as key.
Please, refer to Structure Types for more information on structure types.
<struct name="InnerStruct">
<!-- XML does not support setting Member ID -->
<member name="first" type="int32"/>
</struct>
<!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
<!-- <struct name="ParentStruct">
<member name="first" type="float32"/>
<member name="second" type="int64"/>
</struct>
<struct name="ComplexStruct" baseType="ParentStruct">
<member name="complex_member" type="nonBasic" nonBasicTypeName="InnerStruct"/>
</struct> -->
struct InnerStruct
{
@id(0x10) long first;
};
struct ParentStruct
{
float first;
long long second;
};
struct ComplexStruct : ParentStruct
{
InnerStruct complex_member;
};
Union Types¶
Union types are defined using the <union> tag with mandatory attribute name.
A mandatory discriminator child must be defined using <discriminator> tag.
Discriminator element requires <type> as mandatory attribute.
Union types also require at least one case child defined using the <case> tag.
Each case child requires at least one label child using the <caseDiscriminator> tag.
value attribute is mandatory and defines the label value.
Several labels might be defined using several <caseDiscriminator> elements.
Each case child must have exclusively one union member defined.
Union members are defined using the <member> tag with mandatory attributes name and type.
Depending on the member type, some other mandatory and/or optional attributes might be necessary or available.
Non-primitive types must define the type attribute as nonBasic and include the nonBasicTypeName
attribute with the name of the member type.
At least one union member must be defined for the union type to be consistent.
Note
Currently, XML Types profiles does not support setting the member ID or marking a member as key.
Please, refer to Union Types for more information on the union types.
<union name="InnerUnion">
<discriminator type="int16"/>
<case>
<caseDiscriminator value="0"/>
<member name="first" type="nonBasic" nonBasicTypeName="PrimitivesStruct"/>
</case>
<case>
<caseDiscriminator value="1"/>
<caseDiscriminator value="default"/>
<member name="second" type="int64"/>
</case>
</union>
<union name="ComplexUnion">
<discriminator type="int32"/>
<case>
<caseDiscriminator value="0"/>
<caseDiscriminator value="1"/>
<member name="third" type="int32"/>
</case>
<case>
<caseDiscriminator value="default"/>
<member name="fourth" type="nonBasic" nonBasicTypeName="InnerUnion"/>
</case>
</union>
union InnerUnion switch (short)
{
case 0:
@id(0x10) PrimitivesStruct first;
case 1:
default:
long long second;
};
union ComplexUnion switch (long)
{
case 0:
case 1:
long third;
default:
InnerUnion fourth;
};
Bitset Types¶
Bitset types are defined using the <bitset> tag with mandatory attribute name.
Bitset inheritance may be configured setting optional attribute baseType.
At least one bitfield child must be defined using bitfield tag.
Bitfield elements require mandatory attribute bit_bound with the number of bits managed by the bitfield (maximum
64 bits).
Optionally, attributes name and type might be defined.
An anonymous bitfield (attribute name not set) is not accessible and serves as padding between named bitfields.
The type attribute can ease bitfield management explicitly setting an integer type that handles the bitfield.
Please, refer to Bitset Types for more information about the bitset types.
<bitset name="ParentBitset">
<bitfield name="a" bit_bound="3"/>
<bitfield name="b" bit_bound="1"/>
<bitfield bit_bound="4"/>
<bitfield name="c" bit_bound="10"/>
<bitfield name="d" bit_bound="12" type="int16"/>
</bitset>
<!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
<!--<bitset name="ChildBitSet" baseType="ParentBitSet">
<bitfield name="e" bit_bound="1"/>
<bitfield name="f" bit_bound="20" type="uint32"/>
</bitset>
<struct name="BitsetStruct">
<member name="my_bitset" type="nonBasic" nonBasicTypeName="ChildBitSet"/>
</struct>-->
bitset ParentBitSet
{
bitfield<3> a;
bitfield<1> b;
bitfield<4>;
bitfield<10> c;
bitfield<12, short> d;
};
bitset ChildBitSet : ParentBitSet
{
bitfield<1> e;
bitfield<20, unsigned long> f;
};
struct BitsetStruct
{
ChildBitSet my_bitset;
};
Loading XML Types profile in Fast DDS application¶
Fast DDS application can use types defined in XML configuration files once those files have been loaded into the
DomainParticipantFactory using load_XML_profiles_file().
Types might be retrieved using DomainParticipantFactory::get_dynamic_type_builder_from_xml_by_name().
After getting the DynamicType, objects of DynamicPubSubType class might be instantiated and used to write/read
data.
// Create a DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Load the XML File
if (RETCODE_OK ==
DomainParticipantFactory::get_instance()->load_XML_profiles_file("my_profiles.xml"))
{
// Retrieve instance of the desired type
DynamicType::_ref_type my_struct_type;
if (RETCODE_OK !=
DomainParticipantFactory::get_instance()->get_dynamic_type_builder_from_xml_by_name(
"MyStruct", my_struct_type))
{
// Error
return;
}
// Register MyStruct type
TypeSupport my_struct_type_support(new DynamicPubSubType(my_struct_type));
my_struct_type_support.register_type(participant, nullptr);
}
else
{
std::cout << "Cannot open XML file \"types.xml\". "
<< "Please, set the correct path to the XML file"
<< std::endl;
}
Common¶
The preceding XML profiles define some XML elements that are common to several profiles. This section aims to explain these common elements.
LocatorListType¶
It represents a list of Locator_t.
LocatorListType is used inside other configuration parameter labels that expect a list of locators,
for example, in <defaultUnicastLocatorList>.
Therefore, LocatorListType is defined as a set of <locator> elements.
The <locator> element has a single child element that defines the transport protocol for which the locator is
defined. These are: <udpv4>, <tcpv4>, <udpv6>, and <tcpv6>.
The table presented below outlines each possible Locator’s field.
Note
SHM transport locators cannot be configured as they are automatically handled by SHM.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
RTPS port number of the locator. |
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0 |
|
TCP’s physical port. |
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0 |
|
IP address of the locator. |
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Empty |
|
The LAN ID uniquely identifies the LAN the |
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Empty |
|
WAN IPv4 address (TCPv4 only). |
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|
Example
The following example shows the implementation of one locator of each transport protocol in
<defaultUnicastLocatorList>.
<defaultUnicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, typical UDP usage -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
<udpv4>
<!-- Access as physical, typical UDP usage -->
<port>7600</port>
<address>localhost</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), useful in TCP transports -->
<physical_port>5100</physical_port>
<port>7400</port>
<unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
<wan_address>80.80.99.45</wan_address>
<address>192.168.1.55</address>
</tcpv4>
</locator>
<locator>
<udpv6>
<port>8844</port>
<address>::1</address>
</udpv6>
<udpv6>
<port>8888</port>
<address>localhost</address>
</udpv6>
</locator>
<locator>
<tcpv6>
<!-- Both physical and logical (port), useful in TCP transports -->
<physical_port>5100</physical_port>
<port>7400</port>
<address>fe80::55e3:290:165:5af8</address>
</tcpv6>
</locator>
</defaultUnicastLocatorList>
ExternalLocatorListType¶
It represents a list of external locator entries.
Each entry can be a <udpv4> or a <udpv6> tag.
These tags can be configured with the following attributes:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Number of hops from the participant’s host to the |
|
1 |
|
Communication cost relative to other locators on |
|
0 |
|
Number of significant bits on the LAN represented |
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24 |
They should contain the following tags:
Name |
Description |
Values |
|---|---|---|
|
UDP port number of the locator. |
|
|
IP address of the locator. |
|
Example
The following example shows the implementation of one locator of each transport protocol in
<default_external_unicast_locators>.
<default_external_unicast_locators>
<udpv4 externality="1" cost="0" mask="24">
<address>100.100.100.10</address>
<port>23456</port>
</udpv4>
<udpv6 externality="2" cost="0" mask="48">
<address>::1</address>
<port>1234</port>
</udpv6>
</default_external_unicast_locators>
PropertiesPolicyType¶
PropertiesPolicyType defines the <propertiesPolicy> element.
It allows the user to define a set of generic properties inside a <properties> element.
It is useful at defining extended or custom configuration parameters.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Name to identify the property. |
|
|
|
Property’s value. |
|
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|
Indicates if it is going to be serialized along with the |
|
|
Example
<propertiesPolicy>
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
<property>
<name>Property2Name</name>
<value>Property2Value</value>
<propagate>true</propagate>
</property>
</properties>
</propertiesPolicy>
DurationType¶
DurationType expresses a period of time and it is commonly used inside other XML elements, such as in
<leaseAnnouncement> or <leaseDuration>.
A DurationType is defined by at least one mandatory element of two possible ones: <sec> plus <nanosec>.
An infinite value can be specified by using the values DURATION_INFINITY,
DURATION_INFINITE_SEC and DURATION_INFINITE_NSEC.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Number of seconds. |
|
0 |
|
Number of nanoseconds. |
|
0 |
Example
<discovery_config>
<leaseDuration>
<sec>DURATION_INFINITY</sec>
</leaseDuration>
<leaseAnnouncement>
<sec>1</sec>
<nanosec>856000</nanosec>
</leaseAnnouncement>
</discovery_config>
TopicType¶
This XML element allows the configuration of the specific HistoryQosPolicy and ResourceLimitsQosPolicy QoS of the Datawriters and DataReaders in which this element is defined inside of. Also, it sets the TopicQos configuration with the policies detailed.
Name |
Description |
Values |
|---|---|---|
|
It controls the behavior of Fast DDS |
|
|
It controls the resources that Fast DDS |
Example
<data_writer profile_name="dataWriter_topic_example">
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
<depth>20</depth>
</historyQos>
<resourceLimitsQos>
<max_samples>5</max_samples>
<max_instances>2</max_instances>
<max_samples_per_instance>1</max_samples_per_instance>
<allocated_samples>20</allocated_samples>
<extra_samples>10</extra_samples>
</resourceLimitsQos>
</topic>
</data_writer>
HistoryQoS¶
It controls the behavior of Fast DDS when the value of an instance changes before it is finally communicated to some of its existing DataReaders. Please refer to HistoryQosPolicyKind for further information on HistoryQoS.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Fast DDS will only attempt to keep the latest values
of the instance |
|
|
Fast DDS will attempt to maintain and deliver all the
values of the instance |
|
||
|
It must be consistent with the ResourceLimitsQos
|
|
1 |
ResourceLimitsQos¶
It controls the resources that Fast DDS can use in order to meet the requirements imposed by the application and other QoS settings. Please refer to ResourceLimitsQosPolicy for further information on ResourceLimitsQos.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
It must verify that:
|
|
5000 |
|
It defines the maximum number of instances. |
|
10 |
|
It must verify that: HistoryQos
|
|
400 |
|
It controls the maximum number of samples to be stored. |
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100 |
|
The number of extra samples to allocate on the pool. |
|
1 |
ThreadSettings¶
It controls some OS settings for the Fast DDS created threads. Please refer to ThreadSettings for further information on ResourceLimitsQos.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Configures the scheduling policy used for the thread. |
|
-1 |
|
Configures the thread’s priority. |
|
-2^31 |
|
On some systems (Windows, Linux), this is a bit mask for setting |
|
0 |
|
Configures the thread’s stack size in bytes. |
|
-1 |
BuiltinTransports¶
It controls the builtin transports that will be used during the initialization of the DomainParticipant. Please refer to Managing the Builtin Transports for further information on builtin transports.
This type must follow this configuration:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Defines the builtin transport mode. |
|
|
The <builtinTransport> tag can be configured with the following attributes:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Maximum message size that will be specified in
the transport layer. |
|
65500 |
|
Size of the send and receive socket buffers. Valid values: from 0 to (2^32)-1. |
|
OS default |
|
Whether to use non-blocking send calls or not.
Valid values: |
|
|
|
Timeout duration for logical port negotiation.
Valid values: from 1 to (2^32)-1. |
|
0 |
QoS¶
The Quality of Service (QoS) is used to specify the behavior of the Service, allowing the user to define how each Entity will behave. Please refer to the Policy section for more information on QoS.
Name |
Description |
Values |
|---|---|---|
|
||
|
See DeadlineQosPolicy. |
|
|
||
|
||
|
See DurabilityQosPolicy. |
|
|
||
|
See GroupDataQosPolicy. |
|
|
||
|
See LifespanQosPolicy. |
|
|
See LivelinessQosPolicy. |
|
|
See OwnershipQosPolicy. |
|
|
||
|
See PartitionQosPolicy. |
|
|
See PublishModeQosPolicy. |
|
|
See ReliabilityQosPolicy. |
|
|
See TopicDataQosPolicy. |
|
|
See UserDataQosPolicy. |
Example
<data_writer profile_name="pub_topic_qos">
<qos> <!-- writerQosPoliciesType -->
<data_sharing>
<kind>AUTOMATIC</kind>
<shared_dir>/home</shared_dir>
<max_domains>10</max_domains>
<domain_ids>
<domainId>0</domainId>
<domainId>11</domainId>
</domain_ids>
</data_sharing>
<deadline>
<period>
<sec>1</sec>
</period>
</deadline>
<!-- DataWriter specific QoS -->
<disable_heartbeat_piggyback>true</disable_heartbeat_piggyback>
<disablePositiveAcks>
<enabled>true</enabled>
<duration>
<sec>1</sec>
</duration>
</disablePositiveAcks>
<durability>
<kind>VOLATILE</kind>
</durability>
<groupData>
<value>1.a.2</value>
</groupData>
<!-- QoS policy pending implementation -->
<latencyBudget>
<duration>
<sec>1</sec>
</duration>
</latencyBudget>
<lifespan>
<duration>
<sec>1</sec>
</duration>
</lifespan>
<liveliness>
<kind>AUTOMATIC</kind>
<lease_duration>
<sec>1</sec>
</lease_duration>
<announcement_period>
<sec>1</sec>
</announcement_period>
</liveliness>
<ownership>
<kind>EXCLUSIVE</kind>
</ownership>
<!-- DataWriter specific QoS -->
<ownershipStrength>
<value>50</value>
</ownershipStrength>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
<!-- DataWriter specific QoS -->
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
<reliability>
<kind>BEST_EFFORT</kind>
<max_blocking_time>
<sec>1</sec>
</max_blocking_time>
</reliability>
<topicData>
<value>2.b.1</value>
</topicData>
<userData>
<value>3.c.0</value>
</userData>
</qos>
Data-Sharing¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See DataSharingKind |
|
|
|
Directory used for the memory-mapped files. |
|
Empty |
|
Maximum number of Data-Sharing domain IDs |
|
0 (unlimited) |
|
List of Data-Sharing domain IDs configured |
|
Empty list |
Name |
Description |
Values |
|---|---|---|
|
Domain ID to be used by the endpoint for Data-Sharing. |
|
Deadline¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See DeadlineQosPolicy. |
|
DisableHeartbeatPiggyback¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
Important
This configuration is only available for DataWriter QoS profile configuration.
DisablePositiveAcks¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
|
|
|
Durability¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
DataReaders: |
Entity Factory¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
GroupData¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See GroupDataQosPolicy. |
|
Empty |
LatencyBudget¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
0 |
Lifespan¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See LifespanQosPolicy. |
|
Liveliness¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
|
|
|||
|
|||
|
See LivelinessQosPolicy. |
|
|
|
See LivelinessQosPolicy. |
|
Ownership¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
Ownership Strength¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
0 |
Important
This configuration is only available for DataWriter QoS profile configuration.
Partition¶
Name |
Description |
Values |
|---|---|---|
|
It comprises a set of |
|
PublishMode¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See PublishModeQosPolicy. |
|
|
|
Important
This configuration is only available for DataWriter QoS profile configuration.
ReliabilityQosPolicy¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
DataReaders: |
|
|
|||
|
See ReliabilityQosPolicy. |
100 ms |
TopicData¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See TopicDataQosPolicy. |
|
Empty |
UserData¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See UserDataQosPolicy. |
|
Empty |
HistoryMemoryPolicy¶
Indicates the way the memory is managed in terms of dealing with the CacheChanges of the RTPSEndpointQos.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Four different options as described |
|
|
Example
<data_writer profile_name="data_writer_historyMemoryPolicy">
<!-- ... -->
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
</data_writer>
<data_reader profile_name="data_reader_historyMemoryPolicy">
<!-- ... -->
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
</data_reader>
Allocation Configuration¶
The <allocation> element allows to control the allocation behavior of internal collections for which the number
of elements depends on the number of entities in the system.
For instance, there are collections inside a DataWriter which depend on the number of DataReaders matching with it.
Please refer to ParticipantResourceLimitsQos for a detailed documentation on DomainParticipant allocation,
and to Tuning allocations for detailed information on how to tune allocation related parameters.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Number of elements for which space is initially allocated. |
|
0 |
|
Maximum number of elements for which space will be allocated. |
|
0 (Means no limit) |
|
Number of new elements that will be allocated when more space is |
|
1 |
Example¶
In this section, there is a full XML example with all possible configuration.
Warning
This example can be used as a quick reference, but it may not be correct due to incompatibility or exclusive properties. Do not take it as a working example.
1<?xml version="1.0" encoding="UTF-8" ?>
2<dds xmlns="http://www.eprosima.com">
3 <profiles>
4 <transport_descriptors>
5 <!-- TCP sample transport descriptor -->
6 <transport_descriptor>
7 <transport_id>ExampleTransportId1</transport_id>
8 <type>TCPv4</type>
9 <sendBufferSize>8192</sendBufferSize>
10 <receiveBufferSize>8192</receiveBufferSize>
11 <maxMessageSize>16384</maxMessageSize>
12 <maxInitialPeersRange>100</maxInitialPeersRange>
13 <netmask_filter>AUTO</netmask_filter>
14 <interfaces>
15 <allowlist>
16 <interface name="wlp59s0" netmask_filter="ON"/>
17 </allowlist>
18 <blocklist>
19 <interface name="127.0.0.1"/>
20 <interface name="docker0"/>
21 </blocklist>
22 </interfaces>
23 <interfaceWhiteList>
24 <address>192.168.1.41</address>
25 <interface>lo</interface>
26 </interfaceWhiteList>
27 <wan_addr>80.80.55.44</wan_addr>
28 <keep_alive_frequency_ms>5000</keep_alive_frequency_ms>
29 <keep_alive_timeout_ms>25000</keep_alive_timeout_ms>
30 <max_logical_port>200</max_logical_port>
31 <logical_port_range>20</logical_port_range>
32 <logical_port_increment>2</logical_port_increment>
33 <listening_ports>
34 <port>5100</port>
35 <port>5200</port>
36 </listening_ports>
37 <tls>
38 <password>Password</password>
39 <private_key_file>Key_file.pem</private_key_file>
40 <rsa_private_key_file>RSA_file.pem</rsa_private_key_file>
41 <cert_chain_file>Chain.pem</cert_chain_file>
42 <tmp_dh_file>DH.pem</tmp_dh_file>
43 <verify_file>verify.pem</verify_file>
44 <verify_mode>
45 <verify>VERIFY_PEER</verify>
46 </verify_mode>
47 <options>
48 <option>NO_TLSV1</option>
49 <option>NO_TLSV1_1</option>
50 </options>
51 <verify_paths>
52 <verify_path>Path1</verify_path>
53 <verify_path>Path2</verify_path>
54 <verify_path>Path3</verify_path>
55 </verify_paths>
56 <verify_depth>55</verify_depth>
57 <default_verify_path>true</default_verify_path>
58 <handshake_role>SERVER</handshake_role>
59 <server_name>my_server.com</server_name>
60 </tls>
61 <calculate_crc>false</calculate_crc>
62 <check_crc>false</check_crc>
63 <enable_tcp_nodelay>false</enable_tcp_nodelay>
64 <default_reception_threads>
65 <scheduling_policy>-1</scheduling_policy>
66 <priority>0</priority>
67 <affinity>0</affinity>
68 <stack_size>-1</stack_size>
69 </default_reception_threads>
70 <reception_threads>
71 <reception_thread port="12345">
72 <scheduling_policy>-1</scheduling_policy>
73 <priority>0</priority>
74 <affinity>0</affinity>
75 <stack_size>-1</stack_size>
76 </reception_thread>
77 </reception_threads>
78 </transport_descriptor>
79 <!-- UDP sample transport descriptor. Several options are common with TCP -->
80 <transport_descriptor>
81 <transport_id>ExampleTransportId2</transport_id>
82 <type>UDPv6</type>
83 <TTL>250</TTL>
84 <non_blocking_send>false</non_blocking_send>
85 <output_port>5101</output_port>
86 <default_reception_threads>
87 <scheduling_policy>-1</scheduling_policy>
88 <priority>0</priority>
89 <affinity>0</affinity>
90 <stack_size>-1</stack_size>
91 </default_reception_threads>
92 <reception_threads>
93 <reception_thread port="12345">
94 <scheduling_policy>-1</scheduling_policy>
95 <priority>0</priority>
96 <affinity>0</affinity>
97 <stack_size>-1</stack_size>
98 </reception_thread>
99 </reception_threads>
100 </transport_descriptor>
101 <!-- SHM sample transport descriptor -->
102 <transport_descriptor>
103 <transport_id>SHM_SAMPLE_DESCRIPTOR</transport_id>
104 <type>SHM</type> <!-- REQUIRED -->
105 <maxMessageSize>524288</maxMessageSize> <!-- OPTIONAL uint32 valid of all transports-->
106 <segment_size>1048576</segment_size> <!-- OPTIONAL uint32 SHM only-->
107 <port_queue_capacity>1024</port_queue_capacity> <!-- OPTIONAL uint32 SHM only-->
108 <healthy_check_timeout_ms>250</healthy_check_timeout_ms> <!-- OPTIONAL uint32 SHM only-->
109 <rtps_dump_file>test_file.dump</rtps_dump_file> <!-- OPTIONAL string SHM only-->
110 <default_reception_threads> <!-- OPTIONAL -->
111 <scheduling_policy>-1</scheduling_policy>
112 <priority>0</priority>
113 <affinity>0</affinity>
114 <stack_size>-1</stack_size>
115 </default_reception_threads>
116 <reception_threads> <!-- OPTIONAL -->
117 <reception_thread port="12345">
118 <scheduling_policy>-1</scheduling_policy>
119 <priority>0</priority>
120 <affinity>0</affinity>
121 <stack_size>-1</stack_size>
122 </reception_thread>
123 </reception_threads>
124 <dump_thread>
125 <scheduling_policy>-1</scheduling_policy>
126 <priority>0</priority>
127 <affinity>0</affinity>
128 <stack_size>-1</stack_size>
129 </dump_thread>
130 </transport_descriptor>
131 </transport_descriptors>
132
133 <domainparticipant_factory profile_name="domainparticipant_factory_profile_name">
134 <qos>
135 <entity_factory>
136 <autoenable_created_entities>true</autoenable_created_entities>
137 </entity_factory>
138 <shm_watchdog_thread>
139 <scheduling_policy>-1</scheduling_policy>
140 <priority>0</priority>
141 <affinity>0</affinity>
142 <stack_size>-1</stack_size>
143 </shm_watchdog_thread>
144 <file_watch_threads>
145 <scheduling_policy>-1</scheduling_policy>
146 <priority>0</priority>
147 <affinity>0</affinity>
148 <stack_size>-1</stack_size>
149 </file_watch_threads>
150 </qos>
151 </domainparticipant_factory>
152
153 <participant profile_name="participant_profile_example">
154 <domainId>4</domainId>
155 <rtps>
156 <name>Participant Name</name> <!-- String -->
157
158 <defaultUnicastLocatorList>
159 <locator>
160 <udpv4>
161 <!-- Access as physical, like UDP -->
162 <port>7400</port>
163 <address>localhost</address>
164 </udpv4>
165 </locator>
166 <locator>
167 <tcpv4>
168 <!-- Both physical and logical (port), like TCP -->
169 <physical_port>5100</physical_port>
170 <port>7400</port>
171 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
172 <wan_address>80.80.99.45</wan_address>
173 <address>192.168.1.55</address>
174 </tcpv4>
175 </locator>
176 <locator>
177 <udpv6>
178 <port>8844</port>
179 <address>::1</address>
180 </udpv6>
181 </locator>
182 </defaultUnicastLocatorList>
183
184 <defaultMulticastLocatorList>
185 <locator>
186 <udpv4>
187 <!-- Access as physical, like UDP -->
188 <port>7400</port>
189 <address>192.168.1.41</address>
190 </udpv4>
191 </locator>
192 <locator>
193 <tcpv4>
194 <!-- Both physical and logical (port), like TCP -->
195 <physical_port>5100</physical_port>
196 <port>7400</port>
197 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
198 <wan_address>80.80.99.45</wan_address>
199 <address>192.168.1.55</address>
200 </tcpv4>
201 </locator>
202 <locator>
203 <udpv6>
204 <port>8844</port>
205 <address>::1</address>
206 </udpv6>
207 </locator>
208 </defaultMulticastLocatorList>
209
210 <default_external_unicast_locators>
211 <!-- EXTERNAL_LOCATOR_LIST -->
212 <udpv4 externality="1" cost="0" mask="24">
213 <address>100.100.100.10</address>
214 <port>23456</port>
215 </udpv4>
216 <udpv6 externality="1" cost="1" mask="48">
217 <address>::1</address>
218 <port>1234</port>
219 </udpv6>
220 </default_external_unicast_locators>
221
222 <ignore_non_matching_locators>true</ignore_non_matching_locators>
223 <sendSocketBufferSize>8192</sendSocketBufferSize>
224 <listenSocketBufferSize>8192</listenSocketBufferSize>
225 <netmask_filter>AUTO</netmask_filter>
226
227 <builtin>
228 <discovery_config>
229 <discoveryProtocol>NONE</discoveryProtocol>
230 <discoveryServersList>
231 <RemoteServer prefix="72.61.73.70.66.61.72.6d.74.65.73.74">
232 <metatrafficUnicastLocatorList>
233 <locator>
234 <udpv4>
235 <address>192.168.10.57</address>
236 <port>56542</port>
237 </udpv4>
238 </locator>
239 </metatrafficUnicastLocatorList>
240 <metatrafficMulticastLocatorList>
241 <locator>
242 <udpv4>
243 <address>192.168.10.58</address>
244 <port>24565</port>
245 </udpv4>
246 </locator>
247 </metatrafficMulticastLocatorList>
248 </RemoteServer>
249 <RemoteServer prefix="72.61.73.70.66.61.72.6d.74.65.73.75">
250 <metatrafficUnicastLocatorList>
251 <locator>
252 <udpv4>
253 <address>192.168.10.59</address>
254 <port>56543</port>
255 </udpv4>
256 </locator>
257 </metatrafficUnicastLocatorList>
258 <metatrafficMulticastLocatorList>
259 <locator>
260 <udpv4>
261 <address>192.168.10.60</address>
262 <port>34565</port>
263 </udpv4>
264 </locator>
265 </metatrafficMulticastLocatorList>
266 </RemoteServer>
267 </discoveryServersList>
268 <ignoreParticipantFlags>FILTER_DIFFERENT_PROCESS|FILTER_SAME_PROCESS</ignoreParticipantFlags>
269 <EDP>SIMPLE</EDP>
270 <simpleEDP>
271 <PUBWRITER_SUBREADER>true</PUBWRITER_SUBREADER>
272 <PUBREADER_SUBWRITER>true</PUBREADER_SUBWRITER>
273 </simpleEDP>
274 <leaseDuration>
275 <sec>DURATION_INFINITY</sec>
276 </leaseDuration>
277 <leaseAnnouncement>
278 <sec>1</sec>
279 <nanosec>856000</nanosec>
280 </leaseAnnouncement>
281 <initialAnnouncements>
282 <count>10</count>
283 <period>
284 <nanosec>50</nanosec>
285 </period>
286 </initialAnnouncements>
287 <clientAnnouncementPeriod>
288 <nanosec>250000000</nanosec>
289 </clientAnnouncementPeriod>
290 <static_edp_xml_config>filename1.xml</static_edp_xml_config>
291 <static_edp_xml_config>filename2.xml</static_edp_xml_config>
292 <static_edp_xml_config>filename3.xml</static_edp_xml_config>
293 </discovery_config>
294
295 <avoid_builtin_multicast>true</avoid_builtin_multicast>
296 <use_WriterLivelinessProtocol>false</use_WriterLivelinessProtocol>
297
298 <metatrafficUnicastLocatorList>
299 <locator>
300 <udpv4>
301 <!-- Access as physical, like UDP -->
302 <port>7400</port>
303 <address>192.168.1.41</address>
304 </udpv4>
305 </locator>
306 <locator>
307 <tcpv4>
308 <!-- Both physical and logical (port), like TCP -->
309 <physical_port>5100</physical_port>
310 <port>7400</port>
311 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
312 <wan_address>80.80.99.45</wan_address>
313 <address>192.168.1.55</address>
314 </tcpv4>
315 </locator>
316 <locator>
317 <udpv6>
318 <port>8844</port>
319 <address>::1</address>
320 </udpv6>
321 </locator>
322 </metatrafficUnicastLocatorList>
323
324 <metatrafficMulticastLocatorList>
325 <locator>
326 <udpv4>
327 <!-- Access as physical, like UDP -->
328 <port>7400</port>
329 <address>192.168.1.41</address>
330 </udpv4>
331 </locator>
332 <locator>
333 <tcpv4>
334 <!-- Both physical and logical (port), like TCP -->
335 <physical_port>5100</physical_port>
336 <port>7400</port>
337 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
338 <wan_address>80.80.99.45</wan_address>
339 <address>192.168.1.55</address>
340 </tcpv4>
341 </locator>
342 <locator>
343 <udpv6>
344 <port>8844</port>
345 <address>::1</address>
346 </udpv6>
347 </locator>
348 </metatrafficMulticastLocatorList>
349
350 <initialPeersList>
351 <locator>
352 <udpv4>
353 <!-- Access as physical, like UDP -->
354 <port>7400</port>
355 <address>192.168.1.41</address>
356 </udpv4>
357 </locator>
358 <locator>
359 <tcpv4>
360 <!-- Both physical and logical (port), like TCP -->
361 <physical_port>5100</physical_port>
362 <port>7400</port>
363 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
364 <wan_address>80.80.99.45</wan_address>
365 <address>192.168.1.55</address>
366 </tcpv4>
367 </locator>
368 <locator>
369 <udpv6>
370 <port>8844</port>
371 <address>::1</address>
372 </udpv6>
373 </locator>
374 </initialPeersList>
375
376 <metatraffic_external_unicast_locators>
377 <udpv4 externality="1" cost="0" mask="24">
378 <address>100.100.100.10</address>
379 <port>34567</port>
380 </udpv4>
381 </metatraffic_external_unicast_locators>
382
383 <readerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</readerHistoryMemoryPolicy>
384 <writerHistoryMemoryPolicy>PREALLOCATED</writerHistoryMemoryPolicy>
385 <readerPayloadSize>512</readerPayloadSize>
386 <writerPayloadSize>512</writerPayloadSize>
387 <mutation_tries>55</mutation_tries>
388 </builtin>
389
390 <port>
391 <portBase>7400</portBase>
392 <domainIDGain>200</domainIDGain>
393 <participantIDGain>10</participantIDGain>
394 <offsetd0>0</offsetd0>
395 <offsetd1>1</offsetd1>
396 <offsetd2>2</offsetd2>
397 <offsetd3>3</offsetd3>
398 </port>
399
400 <participantID>99</participantID>
401
402 <userTransports>
403 <transport_id>ExampleTransportId1</transport_id>
404 <transport_id>ExampleTransportId2</transport_id>
405 </userTransports>
406
407 <useBuiltinTransports>false</useBuiltinTransports>
408
409 <builtinTransports max_msg_size="50KB" sockets_size="50KB" non_blocking="false">DEFAULT</builtinTransports>
410
411 <propertiesPolicy>
412 <properties>
413 <property>
414 <name>Property1Name</name>
415 <value>Property1Value</value>
416 <propagate>false</propagate>
417 </property>
418 <property>
419 <name>Property2Name</name>
420 <value>Property2Value</value>
421 <propagate>false</propagate>
422 </property>
423 </properties>
424 </propertiesPolicy>
425
426 <allocation>
427 <remote_locators>
428 <max_unicast_locators>4</max_unicast_locators> <!-- uint32 -->
429 <max_multicast_locators>1</max_multicast_locators> <!-- uint32 -->
430 </remote_locators>
431 <total_participants>
432 <initial>0</initial>
433 <maximum>0</maximum>
434 <increment>1</increment>
435 </total_participants>
436 <total_readers>
437 <initial>0</initial>
438 <maximum>0</maximum>
439 <increment>1</increment>
440 </total_readers>
441 <total_writers>
442 <initial>0</initial>
443 <maximum>0</maximum>
444 <increment>1</increment>
445 </total_writers>
446 <max_partitions>256</max_partitions>
447 <max_user_data>256</max_user_data>
448 <max_properties>512</max_properties>
449 <send_buffers>
450 <preallocated_number>127</preallocated_number>
451 <dynamic>true</dynamic>
452 </send_buffers>
453 </allocation>
454
455 <builtin_controllers_sender_thread>
456 <scheduling_policy>-1</scheduling_policy>
457 <priority>0</priority>
458 <affinity>0</affinity>
459 <stack_size>-1</stack_size>
460 </builtin_controllers_sender_thread>
461
462 <timed_events_thread>
463 <scheduling_policy>-1</scheduling_policy>
464 <priority>0</priority>
465 <affinity>0</affinity>
466 <stack_size>-1</stack_size>
467 </timed_events_thread>
468
469 <discovery_server_thread>
470 <scheduling_policy>-1</scheduling_policy>
471 <priority>0</priority>
472 <affinity>0</affinity>
473 <stack_size>-1</stack_size>
474 </discovery_server_thread>
475
476 <typelookup_service_thread>
477 <scheduling_policy>-1</scheduling_policy>
478 <priority>0</priority>
479 <affinity>0</affinity>
480 <stack_size>-1</stack_size>
481 </typelookup_service_thread>
482
483 <builtin_transports_reception_threads>
484 <scheduling_policy>-1</scheduling_policy>
485 <priority>0</priority>
486 <affinity>0</affinity>
487 <stack_size>-1</stack_size>
488 </builtin_transports_reception_threads>
489
490 <security_log_thread>
491 <scheduling_policy>-1</scheduling_policy>
492 <priority>0</priority>
493 <affinity>0</affinity>
494 <stack_size>-1</stack_size>
495 </security_log_thread>
496 </rtps>
497 </participant>
498
499 <data_writer profile_name="datawriter_profile_example">
500 <topic>
501 <historyQos>
502 <kind>KEEP_LAST</kind>
503 <depth>20</depth>
504 </historyQos>
505 <resourceLimitsQos>
506 <max_samples>5</max_samples>
507 <max_instances>2</max_instances>
508 <max_samples_per_instance>1</max_samples_per_instance>
509 <allocated_samples>20</allocated_samples>
510 <extra_samples>10</extra_samples>
511 </resourceLimitsQos>
512 </topic>
513 <qos> <!-- dataWriterQosPoliciesType -->
514 <data_sharing>
515 <kind>AUTOMATIC</kind>
516 <shared_dir>/home</shared_dir>
517 <max_domains>10</max_domains>
518 <domain_ids>
519 <domainId>0</domainId>
520 <domainId>11</domainId>
521 </domain_ids>
522 </data_sharing>
523 <deadline>
524 <period>
525 <sec>1</sec>
526 </period>
527 </deadline>
528 <disable_heartbeat_piggyback>true</disable_heartbeat_piggyback>
529 <disablePositiveAcks>
530 <enabled>true</enabled>
531 <duration>
532 <sec>1</sec>
533 </duration>
534 </disablePositiveAcks>
535 <durability>
536 <kind>VOLATILE</kind>
537 </durability>
538 <!-- QoS policy pending implementation -->
539 <latencyBudget>
540 <duration>
541 <sec>1</sec>
542 </duration>
543 </latencyBudget>
544 <lifespan>
545 <duration>
546 <sec>5</sec>
547 </duration>
548 </lifespan>
549 <liveliness>
550 <kind>AUTOMATIC</kind>
551 <lease_duration>
552 <sec>1</sec>
553 <nanosec>856000</nanosec>
554 </lease_duration>
555 <announcement_period>
556 <sec>1</sec>
557 <nanosec>856000</nanosec>
558 </announcement_period>
559 </liveliness>
560 <ownership>
561 <kind>EXCLUSIVE</kind>
562 </ownership>
563 <ownershipStrength>
564 <value>50</value>
565 </ownershipStrength>
566 <partition>
567 <names>
568 <name>part1</name>
569 <name>part2</name>
570 </names>
571 </partition>
572 <publishMode>
573 <kind>ASYNCHRONOUS</kind>
574 </publishMode>
575 <reliability>
576 <kind>BEST_EFFORT</kind>
577 <max_blocking_time>
578 <sec>1</sec>
579 <nanosec>856000</nanosec>
580 </max_blocking_time>
581 </reliability>
582 </qos>
583
584 <times>
585 <initialHeartbeatDelay>
586 <sec>1</sec>
587 <nanosec>856000</nanosec>
588 </initialHeartbeatDelay>
589 <heartbeatPeriod>
590 <sec>1</sec>
591 <nanosec>856000</nanosec>
592 </heartbeatPeriod>
593 <nackResponseDelay>
594 <sec>1</sec>
595 <nanosec>856000</nanosec>
596 </nackResponseDelay>
597 <nackSupressionDuration>
598 <sec>1</sec>
599 <nanosec>856000</nanosec>
600 </nackSupressionDuration>
601 </times>
602
603 <unicastLocatorList>
604 <locator>
605 <udpv4>
606 <!-- Access as physical, like UDP -->
607 <port>7400</port>
608 <address>192.168.1.41</address>
609 </udpv4>
610 </locator>
611 <locator>
612 <tcpv4>
613 <!-- Both physical and logical (port), like TCP -->
614 <physical_port>5100</physical_port>
615 <port>7400</port>
616 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
617 <wan_address>80.80.99.45</wan_address>
618 <address>192.168.1.55</address>
619 </tcpv4>
620 </locator>
621 <locator>
622 <udpv6>
623 <port>8844</port>
624 <address>::1</address>
625 </udpv6>
626 </locator>
627 </unicastLocatorList>
628
629 <multicastLocatorList>
630 <locator>
631 <udpv4>
632 <!-- Access as physical, like UDP -->
633 <port>7400</port>
634 <address>192.168.1.41</address>
635 </udpv4>
636 </locator>
637 <locator>
638 <tcpv4>
639 <!-- Both physical and logical (port), like TCP -->
640 <physical_port>5100</physical_port>
641 <port>7400</port>
642 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
643 <wan_address>80.80.99.45</wan_address>
644 <address>192.168.1.55</address>
645 </tcpv4>
646 </locator>
647 <locator>
648 <udpv6>
649 <port>8844</port>
650 <address>::1</address>
651 </udpv6>
652 </locator>
653 </multicastLocatorList>
654
655 <external_unicast_locators>
656 <udpv4 externality="1" cost="0" mask="24">
657 <address>100.100.100.10</address>
658 <port>12345</port>
659 </udpv4>
660 </external_unicast_locators>
661
662 <ignore_non_matching_locators>true</ignore_non_matching_locators>
663 <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
664
665 <propertiesPolicy>
666 <properties>
667 <property>
668 <name>Property1Name</name>
669 <value>Property1Value</value>
670 <propagate>false</propagate>
671 </property>
672 <property>
673 <name>Property2Name</name>
674 <value>Property2Value</value>
675 <propagate>false</propagate>
676 </property>
677 </properties>
678 </propertiesPolicy>
679
680 <userDefinedID>45</userDefinedID>
681 <entityID>76</entityID>
682
683 <matchedSubscribersAllocation>
684 <initial>3</initial>
685 <maximum>3</maximum>
686 <increment>0</increment>
687 </matchedSubscribersAllocation>
688 </data_writer>
689
690 <data_reader profile_name="datareader_profile_example">
691 <topic>
692 <historyQos>
693 <kind>KEEP_LAST</kind>
694 <depth>20</depth>
695 </historyQos>
696 <resourceLimitsQos>
697 <max_samples>5</max_samples>
698 <max_instances>2</max_instances>
699 <max_samples_per_instance>1</max_samples_per_instance>
700 <allocated_samples>20</allocated_samples>
701 <extra_samples>10</extra_samples>
702 </resourceLimitsQos>
703 </topic>
704 <qos> <!-- dataReaderQosPoliciesType -->
705 <data_sharing>
706 <kind>AUTOMATIC</kind>
707 <shared_dir>/home</shared_dir>
708 <max_domains>10</max_domains>
709 <domain_ids>
710 <domainId>0</domainId>
711 <domainId>11</domainId>
712 </domain_ids>
713 <data_sharing_listener_thread>
714 <scheduling_policy>-1</scheduling_policy>
715 <priority>0</priority>
716 <affinity>0</affinity>
717 <stack_size>-1</stack_size>
718 </data_sharing_listener_thread>
719 </data_sharing>
720 <deadline>
721 <period>
722 <sec>1</sec>
723 </period>
724 </deadline>
725 <disablePositiveAcks>
726 <enabled>true</enabled>
727 <duration>
728 <sec>1</sec>
729 </duration>
730 </disablePositiveAcks>
731 <durability>
732 <kind>PERSISTENT</kind>
733 </durability>
734 <!-- QoS policy pending implementation -->
735 <latencyBudget>
736 <duration>
737 <sec>1</sec>
738 </duration>
739 </latencyBudget>
740 <lifespan>
741 <duration>
742 <sec>5</sec>
743 </duration>
744 </lifespan>
745 <liveliness>
746 <kind>MANUAL_BY_PARTICIPANT</kind>
747 <lease_duration>
748 <sec>1</sec>
749 <nanosec>856000</nanosec>
750 </lease_duration>
751 <announcement_period>
752 <sec>1</sec>
753 <nanosec>856000</nanosec>
754 </announcement_period>
755 </liveliness>
756 <ownership>
757 <kind>EXCLUSIVE</kind>
758 </ownership>
759 <partition>
760 <names>
761 <name>part1</name>
762 <name>part2</name>
763 </names>
764 </partition>
765 <reliability>
766 <kind>BEST_EFFORT</kind>
767 <max_blocking_time>
768 <sec>1</sec>
769 <nanosec>856000</nanosec>
770 </max_blocking_time>
771 </reliability>
772 </qos>
773
774 <times>
775 <initialAcknackDelay>
776 <sec>1</sec>
777 <nanosec>856000</nanosec>
778 </initialAcknackDelay>
779 <heartbeatResponseDelay>
780 <sec>1</sec>
781 <nanosec>856000</nanosec>
782 </heartbeatResponseDelay>
783 </times>
784
785 <unicastLocatorList>
786 <locator>
787 <udpv4>
788 <!-- Access as physical, like UDP -->
789 <port>7400</port>
790 <address>192.168.1.41</address>
791 </udpv4>
792 </locator>
793 <locator>
794 <tcpv4>
795 <!-- Both physical and logical (port), like TCP -->
796 <physical_port>5100</physical_port>
797 <port>7400</port>
798 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
799 <wan_address>80.80.99.45</wan_address>
800 <address>192.168.1.55</address>
801 </tcpv4>
802 </locator>
803 <locator>
804 <udpv6>
805 <port>8844</port>
806 <address>::1</address>
807 </udpv6>
808 </locator>
809 </unicastLocatorList>
810
811 <multicastLocatorList>
812 <locator>
813 <udpv4>
814 <!-- Access as physical, like UDP -->
815 <port>7400</port>
816 <address>192.168.1.41</address>
817 </udpv4>
818 </locator>
819 <locator>
820 <tcpv4>
821 <!-- Both physical and logical (port), like TCP -->
822 <physical_port>5100</physical_port>
823 <port>7400</port>
824 <unique_lan_id>192.168.1.1.1.1.2.55</unique_lan_id>
825 <wan_address>80.80.99.45</wan_address>
826 <address>192.168.1.55</address>
827 </tcpv4>
828 </locator>
829 <locator>
830 <udpv6>
831 <port>8844</port>
832 <address>::1</address>
833 </udpv6>
834 </locator>
835 </multicastLocatorList>
836
837 <external_unicast_locators>
838 <udpv4 externality="1" cost="0" mask="24">
839 <address>100.100.100.10</address>
840 <port>12345</port>
841 </udpv4>
842 </external_unicast_locators>
843
844 <ignore_non_matching_locators>true</ignore_non_matching_locators>
845 <expectsInlineQos>true</expectsInlineQos>
846 <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
847
848 <propertiesPolicy>
849 <properties>
850 <property>
851 <name>Property1Name</name>
852 <value>Property1Value</value>
853 <propagate>false</propagate>
854 </property>
855 <property>
856 <name>Property2Name</name>
857 <value>Property2Value</value>
858 <propagate>false</propagate>
859 </property>
860 </properties>
861 </propertiesPolicy>
862
863 <userDefinedID>55</userDefinedID>
864 <entityID>66</entityID>
865
866 <matchedPublishersAllocation>
867 <initial>1</initial>
868 <maximum>1</maximum>
869 <increment>0</increment>
870 </matchedPublishersAllocation>
871 </data_reader>
872
873 <topic profile_name="topic_profile_example">
874 <historyQos>
875 <kind>KEEP_LAST</kind>
876 <depth>20</depth>
877 </historyQos>
878 <resourceLimitsQos>
879 <max_samples>5</max_samples>
880 <max_instances>2</max_instances>
881 <max_samples_per_instance>1</max_samples_per_instance>
882 <allocated_samples>20</allocated_samples>
883 <extra_samples>10</extra_samples>
884 </resourceLimitsQos>
885 </topic>
886 </profiles>
887
888 <library_settings>
889 <intraprocess_delivery>USER_DATA_ONLY</intraprocess_delivery>
890 </library_settings>
891
892 <log>
893 <use_default>false</use_default>
894
895 <consumer>
896 <class>StdoutConsumer</class>
897 </consumer>
898
899 <consumer>
900 <class>StdoutErrConsumer</class>
901 <property>
902 <name>stderr_threshold</name>
903 <value>Log::Kind::Warning</value>
904 </property>
905 </consumer>
906
907 <consumer>
908 <class>FileConsumer</class>
909 <property>
910 <name>filename</name>
911 <value>execution.log</value>
912 </property>
913 <property>
914 <name>append</name>
915 <value>TRUE</value>
916 </property>
917 </consumer>
918
919 <thread_settings>
920 <scheduling_policy>-1</scheduling_policy>
921 <priority>0</priority>
922 <affinity>0</affinity>
923 <stack_size>-1</stack_size>
924 </thread_settings>
925 </log>
926
927 <types>
928 <type> <!-- Types can be defined in its own type of tag or sharing the same tag -->
929 <enum name="MyAloneEnumType">
930 <enumerator name="A" value="0"/>
931 <enumerator name="B" value="1"/>
932 <enumerator name="C"/>
933 </enum>
934 </type>
935 <type>
936 <!-- All possible members struct type -->
937 <struct name="MyFullStruct">
938 <!-- Primitives & basic -->
939 <member name="my_bool" type="boolean"/>
940 <member name="my_char" type="char8"/>
941 <member name="my_wchar" type="char16"/>
942 <member name="my_byte" type="byte"/>
943 <member name="my_octet" type="octet"/>
944 <member name="my_uint8" type="uint8"/>
945 <member name="my_short" type="int16"/>
946 <member name="my_long" type="int32"/>
947 <member name="my_unsignedshort" type="uint16"/>
948 <member name="my_unsignedlong" type="uint32"/>
949 <member name="my_longlong" type="int64"/>
950 <member name="my_unsignedlonglong" type="uint64"/>
951 <member name="my_float" type="float32"/>
952 <member name="my_double" type="float64"/>
953 <member name="my_longdouble" type="float128"/>
954 <member name="my_string" type="string"/>
955 <member name="my_wstring" type="wstring"/>
956
957 <!-- string my_boundedString[41925] -->
958 <member name="my_boundedString" type="string" stringMaxLength="41925"/>
959 <!-- wstring my_boundedWString[41925] -->
960 <member name="my_boundedWString" type="wstring" stringMaxLength="41925"/>
961
962 <!-- short short_sequence[5]; -->
963 <member name="short_sequence" sequenceMaxLength="5" type="int16"/>
964
965 <!-- long long_array[2][3][4]; -->
966 <member name="long_array" arrayDimensions="2,3,4" type="int32"/>
967
968 <!-- map<long,long,2> my_map_inner -->
969 <member name="my_map" type="int32" key_type="int32" mapMaxLength="2"/>
970 </struct>
971
972 <typedef name="inner_map" type="char8" key_type="int16"/>
973 <struct name="MyComplexStruct">
974 <!-- Complex types -->
975 <member name="my_other_struct" type="nonBasic" nonBasicTypeName="MyFullStruct"/>
976 <!-- map<long,map<long,long,2>,2> my_map_map; -->
977 <member name="my_map_map" type="nonBasic" nonBasicTypeName="inner_map" key_type="int32" mapMaxLength="2"/>
978 </struct>
979
980 <enum name="MyEnum">
981 <enumerator name="A" value="0"/>
982 <enumerator name="B" value="1"/>
983 <enumerator name="C"/>
984 </enum>
985
986 <typedef name="MyAlias1" type="nonBasic" nonBasicTypeName="MyEnum"/>
987 <typedef name="MyAlias2" type="int32" arrayDimensions="2,2"/>
988
989 <struct name="MyStruct">
990 <member name="first" type="int32"/>
991 <member name="second" type="int64"/>
992 </struct>
993
994 <!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
995 <!-- <struct name="OtherInheritedStruct" baseType="MyStruct">
996 <member name="my_enum" type="nonBasic" nonBasicTypeName="MyEnum"/>
997 <member name="my_struct" type="nonBasic" nonBasicTypeName="MyFullStruct" arrayDimensions="5"/>
998 </struct> -->
999
1000 <union name="MyUnion1">
1001 <discriminator type="byte"/>
1002 <case>
1003 <caseDiscriminator value="0"/>
1004 <caseDiscriminator value="1"/>
1005 <member name="first" type="int32"/>
1006 </case>
1007 <case>
1008 <caseDiscriminator value="2"/>
1009 <member name="second" type="nonBasic" nonBasicTypeName="MyStruct"/>
1010 </case>
1011 <case>
1012 <caseDiscriminator value="default"/>
1013 <member name="third" type="int64"/>
1014 </case>
1015 </union>
1016
1017 <bitset name="MyBitSet">
1018 <bitfield name="a" bit_bound="3"/>
1019 <bitfield name="b" bit_bound="10"/>
1020 <bitfield name="c" bit_bound="12" type="int16"/>
1021 </bitset>
1022
1023 <!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
1024 <!-- <bitset name="OtherInheritedBitSet" baseType="MyBitSet">
1025 <bitfield bit_bound="8"/>
1026 <bitfield bit_bound="15" type="byte"/>
1027 </bitset> -->
1028
1029 <bitmask name="MyBitMask" bit_bound="8">
1030 <bit_value name="flag0" position="0"/>
1031 <bit_value name="flag1"/>
1032 </bitmask>
1033 </type>
1034 </types>
1035</dds>
Environment variables¶
This is the list of environment variables that affect the behavior of Fast DDS:
FASTDDS_DEFAULT_PROFILES_FILE¶
Defines the location of the default profile configuration XML file. If this variable is set and its value corresponds with an existing file, Fast DDS will load its profiles. For more information about XML profiles, please refer to XML profiles.
Linux |
export FASTDDS_DEFAULT_PROFILES_FILE=/home/user/profiles.xml
|
Windows |
set FASTDDS_DEFAULT_PROFILES_FILE=C:\profiles.xml
|
SKIP_DEFAULT_XML¶
Skips looking for a default profile configuration XML file. If this variable is set to 1, Fast DDS will load the configuration parameters directly from the classes’ definitions without looking for the DEFAULT_FASTDDS_PROFILES.xml in the working directory. For more information about XML profiles, please refer to XML profiles.
Linux |
export SKIP_DEFAULT_XML=1
|
Windows |
set SKIP_DEFAULT_XML=1
|
FASTDDS_BUILTIN_TRANSPORTS¶
Setting this variable allows to modify the builtin transports that are initialized during the DomainParticipant creation. It is a simple way of changing the default configuration of the Transport Layer and it directly affects how DDS entities communicate between them.
All existing values, along with a brief description, are shown below:
Builtin Transports Options |
Description |
|---|---|
|
No transport will be instantiated. Hence, the user must manually add
the desired |
|
UDPv4 and SHM transports will be instantiated. SHM transport has priority
over the UDPv4 |
|
UDPv6 and SHM transports will be instantiated. SHM transport has priority
over the UDPv4 |
|
Only a SHM transport will be instantiated. |
|
Only a UDPv4 transport will be instantiated. |
|
Only a UDPv6 transport will be instantiated. |
|
UDPv4, TCPv4, and SHM transports will be instantiated. However, UDP will
only be used |
Note
The environment variable is only used in the case where use_builtin_transports is set
to TRUE. In any other case, the environment variable has no effect.
Note
TCPv4 transport is initialized with the following configuration:
calculate_crc,check_crcandapply_securityare set to false.enable_tcp_nodelayis set to true.keep_alive_threadandaccept_threaduse the default configuration.
Configuring builtin transports options¶
Fast DDS offers a straightforward method to configure three main parameters of every builtin transport via the
environment variable.
However, this feature proves particularly valuable when employing the LARGE_DATA builtin
transports option.
The LARGE_DATA mode has been designed to improve performance when working with large data.
However, according to each specific use case, the user might want to configure several options to better fit their
needs.
This mode can also be configured with the tcp_negotiation_timeout parameter:
Builtin Transports Options |
Description |
Type |
|---|---|---|
|
It determines the maximum message size that will be specified |
uint32_t |
|
It determines the size of the send and receive socket buffers. |
uint32_t |
|
It determines whether to use non-blocking send calls or not. |
bool |
|
It determines the time to wait for logical port negotiation. |
uint32_t |
The environment variable accepts several types of units to specify the values of the parameters. Also, both lowercase and uppercase letters are valid. The following list shows the available units and their corresponding symbols:
B: Bytes. This is the default unit, so it is not necessary to specify it.KB: Kilobytes.MB: Megabytes.GB: Gigabytes.KIB: Kibibyte.MIB: Mebibyte.GIB: Gibibyte.
export FASTDDS_BUILTIN_TRANSPORTS=LARGE_DATA?max_msg_size=200KB&sockets_size=1MB&non_blocking=true&tcp_negotiation_timeout=50
Note
When working with LARGE_DATA, it is recommended to set the max_msg_size and sockets_size to a value
large enough to accommodate the largest data message and to set the non_blocking to TRUE.
Note that activating the non_blocking option with a small message size (with fragmentation)
can lead to an increase of messages drop rate and produce undesired results.
For more information, please refer to Large Data with configuration options.
Warning
Setting a max_msg_size higher than 65500 KB is only possible when using the LARGE_DATA builtin transports
option.
Trying to set it with any other builtin transports will result in an error and the creation of the participant
will fail.
ROS_DISCOVERY_SERVER¶
Warning
The environment variable is only used in the case where discovery protocol
is set to SIMPLE, SERVER, or BACKUP.
In any other case, the environment variable has no effect.
Setting this variable configures the DomainParticipant to connect to one or more servers using the Discovery Server discovery mechanism.
If
ROS_DISCOVERY_SERVERis defined, and theDomainParticipant’s discovery protocol is set toSIMPLE, then Fast DDS will instead configure it asCLIENTof the given server.If
ROS_DISCOVERY_SERVERis defined, and theDomainParticipant’s discovery protocol is set toSERVERorBACKUP, then the variable is used to add remote servers to the given server, leaving the discovery protocol asSERVERorBACKUPrespectively.The value of the variable must list the locator of the server in the form of:
An IPv4 address like
192.168.2.23. The UDP protocol is used by default. The UDP port can be appended using : as in192.168.2.23:35665.An IPv6 address that follows RFC3513 address convention like
1080::8:800:200C:417A. Again, it uses the UDP protocol by default. An UDP port can be appended like in[1080::8:800:200C:417A]:35665. Note the use of square brackets to avoid ambiguities.TCPv4 specifier + IPv4 address like
TCPv4:[127.0.0.1]. The TCP protocol is used to communicate with the server. The TCP port can be appended using : as inTCPv4:[127.0.0.1]:42100.TCPv6 specifier + IPv6 address like
TCPv6:[::1]. The TCP protocol is used to communicate with the server. The TCP port can be appended using : as inTCPv6:[::1]:42100.A DNS name can be specified. This name will be used to query known hosts and available DNS servers to try to resolve valid IP addresses. Several formats are acceptable:
Plain domain name:
eprosima.com. This will include all available IP addresses.Domain name + port:
eprosima.com:35665. As above but using a specific port.UDPv4 specifier + domain name:
UDPv4:[eprosima.com]. Only the first IPv4 address resolved will be used.UDPv4 specifier + domain name + port:
UDPv4:[eprosima.com]:35665. As above but using a specific port.UDPv6 specifier + domain name:
UDPv6:[<dns>]. Only the first IPv6 address resolved will be used.UDPv6 specifier + domain name + port:
UDPv6:[<dns>]:35665. As above but using a specific port.TCPv4 specifier + domain name:
TCPv4:[eprosima.com]. Only the first IPv4 address resolver will be used.TCPv4 specifier + domain name + port:
TCPv4:[eprosima.com]:42100. As above but using a specific port.TCPv6 specifier + domain name:
TCPv6:[<dns>]. Only the first IPv4 address resolver will be used.TCPv6 specifier + domain name + port:
TCPv6:[<dns>]:42100. As above but using a specific port.
If no port is specified when using default UDP transport, the default port 11811 is used.
If no port is specified when using TCP transport, the default port 42100 is used.
To set more than one server’s address, they must be separated by semicolons.
The server’s ID is determined by their position in the list. Two semicolons together means the corresponding ID is free.
When using IPv6 with DNS, the specified domain name space (<dns>) must be able to resolve to an IPv6 address. Otherwise an error will be raised.
The following example shows how to set the address of two remote discovery servers with addresses ‘84.22.259.329:8888’ and ‘localhost:1234’ and IDs 0 and 2 respectively.
Linux
Windows
Important
IP addresses specified in ROS_DISCOVERY_SERVER must be either valid IPv4/IPv6 addresses or domain names.
If a name can be resolved into several addresses, it is possible to either use them all or restrict the selection to
the first IPv4 using the UDPv4: or TCPv4 prefixes or to the first IPv6 address using the UDPv6: or TCPv6
prefixes.
Important
This environment variable is meant to be used in combination with Fast DDS discovery CLI.
The server’s ID is used by Fast DDS to derived the GuidPrefix_t of the server.
If the server is not instantiated using the CLI, the server’s GUID prefix should adhere to the same schema
as the one generated from the CLI.
Else, the clients configured with this environment variable will not be able to establish a connection with
the server, thus not being able to connect to other clients either.
The server’s GUID prefixes generated by the CLI comply with the following schema:
44.53.<server-id-in-hex>.5f.45.50.52.4f.53.49.4d.41.
This prefix schema has been chosen for its ASCII translation: DS<id_in_hex>_EPROSIMA.
Important
This environment variable can be changed at runtime adding new remote servers to a SERVER, BACKUP or CLIENT
(that has been initialized with this environment variable previously) if loaded from an environment file using
FASTDDS_ENVIRONMENT_FILE.
ROS_SUPER_CLIENT¶
If the DomainParticipant’s discovery protocol is set to SIMPLE,
and ROS_SUPER_CLIENT is set to TRUE, the participant is automatically promoted to a SUPER_CLIENT.
Important
This environment variable is meant to be used in combination with ROS_DISCOVERY_SERVER to promote a participant from SIMPLE to SUPER_CLIENT.
The participant will have the servers list defined in ROS_DISCOVERY_SERVER.
The possible values are: TRUE, true, True, 1, FALSE, false, False, 0.
Important
If the variable is not set, the default behavior of Fast DDS is equivalent to the case in which the variable is set to false.
The following example shows how to set the environment variable to true.
Linux
Windows
FASTDDS_STATISTICS¶
Warning
The environment variable is only used in the case where the CMake option FASTDDS_STATISTICS has been enabled. In any other case, the environment variable has no effect. Please, refer to CMake options for more information.
Setting this variable configures the DomainParticipant to enable the statistics DataWriters which topics are contained in the list set in this environment variable. The elements of the list should be separated by semicolons and match the statistics topic name aliases.
For example, to enable the statistics DataWriters that report the latency measurements, the environment variable should be set as follows:
Linux
Windows
Important
This environment variable can be used together with the XML profiles (for more information please refer to Automatically enabling statistics DataWriters). The statistics DataWriters that will be enabled is the union between the ones specified in the XML file (if loaded) and the ones stated in the environment variable (if set).
FASTDDS_ENVIRONMENT_FILE¶
Setting this environment variable to an existing json file allows to load the environment variables from the file
instead of from the environment.
This allows to change the value of some environment variables at run time with just modifying and saving the changes to
the file.
The environment value can be either an absolute or relative path.
The file format is as follows:
{
"environment_variable_name_1": "environment_variable_value_1",
"environment_variable_name_2": "environment_variable_value_2"
}
Important
The environment variables set in the environment file have precedence over the environment.
Warning
Currently only ROS_DISCOVERY_SERVER environment variable allows for changes at run time. (see
Modifying remote servers list at run time)
PropertyPolicyQos Options¶
This section contains the list of PropertyPolicyQos that can be set with Fast DDS:
Non consolidated QoS¶
The PropertyPolicyQos Options are used to develop new eProsima Extensions QoS. Before consolidating a new QoS Policy, it is usually set using this generic QoS Policy. Consequently, this section is prone to frequent updates so the user is advised to check latest changes after upgrading to a different release version.
DataWriter operating mode QoS Policy¶
By default, Fast DDS DataWriters are enabled using push mode.
This implies that they will add new samples into their queue, and then immediately deliver them to matched readers.
For writers that produce non periodic bursts of data, this may imply saturating the network with a lot of packets,
increasing the possibility of losing them on unreliable (i.e. UDP) transports.
Depending on their QoS, DataReaders may also have to ignore some received samples, so they will have to be resent.
Configuring the DataWriters on pull mode offers an alternative by letting each reader pace its own data stream.
It works by the writer notifying the reader what it is available, and waiting for it to request only as much as it
can handle.
At the cost of greater latency, this model can deliver reliability while using far fewer packets than push mode.
DataWriters periodically announce the state of their queue by means of a heartbeat. Upon reception of the heartbeat, DataReaders will request the DataWriter to send the samples they want to process. Consequently, the publishing rate can be tuned setting the heartbeat period accordingly. See Tuning Heartbeat Period for more details.
PropertyPolicyQos name |
PropertyPolicyQos value |
Default value |
|---|---|---|
|
|
|
C++ |
DataWriterQos wqos;
// Enable pull mode
wqos.properties().properties().emplace_back(
"fastdds.push_mode",
"false");
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="pull_mode_datawriter_xml_profile">
<propertiesPolicy>
<properties>
<!-- Enable pull mode -->
<property>
<name>fastdds.push_mode</name>
<value>false</value>
</property>
</properties>
</propertiesPolicy>
</data_writer>
</profiles>
|
Note
Communication to readers running on the same process (Intra-process delivery) will always use
push mode.Communication to
BEST_EFFORT_RELIABILITY_QOSreaders will always usepush mode.
Warning
It is inconsistent to enable the
pull modeand also set theReliabilityQosPolicyKindtoBEST_EFFORT_RELIABILITY_QOS.It is inconsistent to enable the
pull modeand also set theheartbeatPeriodtoc_TimeInfinite.
Unique network flows QoS Policy¶
Warning
This section is still under work.
Statistics Module Settings¶
Fast DDS Statistics Module uses the PropertyPolicyQos to indicate the statistics DataWriters that are enabled automatically (see Automatically enabling statistics DataWriters). In this case, the property value is a semicolon separated list containing the statistics topic name aliases of those DataWriters that the user wants to enable.
PropertyPolicyQos name |
PropertyPolicyQos value |
Default value |
|---|---|---|
|
Semicolon separated list of statistics topic name aliases |
|
C++ |
DomainParticipantQos pqos;
// Activate Fast DDS Statistics module
pqos.properties().properties().emplace_back("fastdds.statistics",
"HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC");
|
XML |
<participant profile_name="statistics_domainparticipant_conf_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate Fast DDS Statistics Module -->
<property>
<name>fastdds.statistics</name>
<value>HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
|
Physical Data in Discovery Information¶
It is possible to include the information conveyed in the PHYSICAL_DATA_TOPIC into the participant discovery message, a.k.a DATA[p] (see Discovery phases). This is done by setting the following properties within the PropertyPolicyQos:
PropertyPolicyQos name |
PropertyPolicyQos value |
Default value without |
Default value with |
|---|---|---|---|
|
Name of the host computer in which |
Not set |
|
|
Name of the user running the application |
Not set |
|
|
Name of the process running the application |
Not set |
|
Whenever any of these properties is defined within the DomainParticipantQos, the DomainParticipant DATA[p]
will contained the set value.
Furthermore, if any of these properties is set to a value of "", which is the default when FASTDDS_STATISTICS is
defined (see CMake options), Fast DDS will automatically populate the value using the following convention:
"fastdds.physical_data.host": Host name as returned by asio::ip::host_name(), followed by":<default data sharing domain id>""fastdds.physical_data.user": Name of the user running the application, or"unknown"if it could not be retrieved."fastdds.physical_data.process": The process ID of the process in which the application is running.
All the previous entails that adding physical information to the DATA[p] can be done regardless of whether
FASTDDS_STATISTICS is defined, and that it is possible to let Fast DDS set some default values into the
reported host, user, and process:
If
FASTDDS_STATISTICSis defined, and the user does not specify otherwise, Fast DDS will set default values to the physical properties of the DATA[p].If
FASTDDS_STATISTICSis defined, and the user sets values to the properties, the user settings are honored.If
FASTDDS_STATISTICSis defined, and the user removes the physical properties from theDomainParticipantQos, then no physical information is transmitted in the DATA[p].If
FASTDDS_STATISTICSis not defined, it is still possible to transmit physical information in the DATA[p] by setting the aforementioned properties:If set to
"", then Fast DDS will populate their value according to the described rules.If set to something other than
"", then the set value will be transmitted in the DATA[p] as-is.
In case FASTDDS_STATISTICS is defined, and the reporting of statistics over the DISCOVERY_TOPIC is enabled (see
Statistics Module Settings), then the physical information included in the DATA[p] is also transmitted over
the DISCOVERY_TOPIC (see PHYSICAL_DATA_TOPIC) whenever one DomainParticipant discovers
another one.
/* Create participant which announces default physical properties */
DomainParticipantQos pqos_default_physical;
// NOTE: If FASTDDS_STATISTICS is defined, then setting the properties to "" is not necessary
pqos_default_physical.properties().properties().emplace_back("fastdds.physical_data.host", "");
pqos_default_physical.properties().properties().emplace_back("fastdds.physical_data.user", "");
pqos_default_physical.properties().properties().emplace_back("fastdds.physical_data.process", "");
DomainParticipant* participant_with_physical = DomainParticipantFactory::get_instance()->create_participant(0,
pqos_default_physical);
/* Create participant which announces custom physical properties */
DomainParticipantQos pqos_custom_physical;
// NOTE: If FASTDDS_STATISTICS is defined, then clear the properties before setting them
// pqos_custom_physical.properties().properties().clear()
pqos_custom_physical.properties().properties().emplace_back("fastdds.physical_data.host", "custom_hostname");
pqos_custom_physical.properties().properties().emplace_back("fastdds.physical_data.user", "custom_username");
pqos_custom_physical.properties().properties().emplace_back("fastdds.physical_data.process", "custom_process");
DomainParticipant* participant_custom_physical = DomainParticipantFactory::get_instance()->create_participant(0,
pqos_custom_physical);
/* Create participant which does not announce physical properties */
DomainParticipantQos pqos_no_physical;
pqos_no_physical.properties().properties().clear();
DomainParticipant* participant_without_physical = DomainParticipantFactory::get_instance()->create_participant(
0, pqos_no_physical);
/* Load physical properties from default XML file */
DomainParticipantFactory::get_instance()->load_profiles();
DomainParticipantQos pqos_default_xml_physical =
DomainParticipantFactory::get_instance()->get_default_participant_qos();
DomainParticipant* participant_default_xml_physical =
DomainParticipantFactory::get_instance()->create_participant(0, pqos_default_xml_physical);
/* Load physical properties from specific XML file */
DomainParticipantFactory::get_instance()->load_XML_profiles_file("somefile.xml");
DomainParticipantFactory::get_instance()->load_profiles();
DomainParticipantQos pqos_custom_xml_physical =
DomainParticipantFactory::get_instance()->get_default_participant_qos();
DomainParticipant* participant_custom_xml_physical =
DomainParticipantFactory::get_instance()->create_participant(0, pqos_custom_xml_physical);
<?xml version="1.0" encoding="utf-8"?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="statistics_participant" is_default_profile="true">
<rtps>
<propertiesPolicy>
<properties>
<property>
<name>fastdds.physical_data.host</name>
<value>custom_hostname</value>
</property>
<property>
<name>fastdds.physical_data.user</name>
<value>custom_username</value>
</property>
<property>
<name>fastdds.physical_data.process</name>
<value>custom_process</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
</profiles>
</dds>
Important
The properties set using XML override those in the default QoS, which means that it is possible to set the physical
properties using XML regardless of whether FASTDDS_STATISTICS is defined.
However, it is not possible to remove the properties using XML, meaning that an application using Fast DDS with
FASTDDS_STATISTICS enabled which does not want for the physical information to be transmitted in the
DomainParticipant DATA[p] must remove the properties using the aforementioned C++ API.
Endpoint Partitions¶
Fast DDS uses this PropertyPolicyQos to define which partitions does an endpoint belong to. This property follows the same logic regarding matching as the PartitionQosPolicy that can be defined for Publishers and Subscribers.
This property’s value is a semicolon separated list containing the partition names the user wants this endpoint to belong to.
Important
If both a Publisher and one of its DataWriters have conflicting partition configuration, this is, a DataWriter has this property defined while the Publisher has the PartitionQosPolicy defined, the DataWriter configuration takes precedence and the Publisher PartitionQosPolicy is ignored for this endpoint. This applies to Subscribers and their DataReaders as well.
This property will be automatically set when creating DataReaders and DataWriters using the create_with_profile functions. It cannot be changed after the entity has been created.
PropertyPolicyQos name |
PropertyPolicyQos value |
Default value |
|---|---|---|
|
Semicolon separated list of partition names |
|
C++ |
DataWriterQos wqos;
// Add partitions
wqos.properties().properties().emplace_back(
"partitions",
"part1;part2");
DataReaderQos rqos;
// Add partitions
rqos.properties().properties().emplace_back(
"partitions",
"part1;part2");
|
XML |
<data_writer profile_name="pub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</data_writer>
<data_reader profile_name="sub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</data_reader>
|
Static Discovery’s Exchange Format¶
Static Discovery exchanges data in the Participant Discovery Phase (PDP).
Currently there are two different exchange formats which can be selected using the property
dds.discovery.static_edp.exchange_format.
PropertyPolicyQos value |
Description |
Default |
|---|---|---|
|
Standard exchange format for Static Discovery. |
✅ |
|
Format which reduces the necessary network bandwidth to transmit Static |
DomainParticipantQos participant_qos;
participant_qos.properties().properties().emplace_back(
"dds.discovery.static_edp.exchange_format",
"v1_Reduced"
);
<participant profile_name="participant_xml_conf_static_discovery_format_profile">
<rtps>
<propertiesPolicy>
<properties>
<property>
<name>dds.discovery.static_edp.exchange_format</name>
<value>v1_Reduced</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
SHM transport meta-traffic enforcement¶
A DomainParticipant will by default configure both a UDP Transport and a Shared Memory Transport. When a participant on another process in the same host is discovered, the endpoint discovery might be done using either transport.
Avoiding Shared Memory communication for discovery traffic can save valuable resources.
The behavior regarding this can be configured using the property fastdds.shm.enforce_metatraffic.
PropertyPolicyQos value |
Description |
Default |
|---|---|---|
|
Use other transports for meta-traffic. |
✅ |
|
Enable SHM transport unicast communications. |
|
|
Enable SHM transport unicast and multicast communications. |
Note
When SHM is the only transport configured for a participant, the setting of this property is ignored,
and considered to be "all".
DomainParticipantQos participant_qos;
// SHM transport will listen for unicast meta-traffic
participant_qos.properties().properties().emplace_back(
"fastdds.shm.enforce_metatraffic",
"unicast");
<participant profile_name="participant_xml_conf_shm_enforce_metatraffic_profile">
<rtps>
<propertiesPolicy>
<properties>
<property>
<name>fastdds.shm.enforce_metatraffic</name>
<value>unicast</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
Flow Controller Settings¶
When using Flow Controllers, the DataWriter may need specific parameters to be set.
Properties related with this feature lie on the fastdds.sfc namespace.
Property
fastdds.sfc.priorityis used to set the priority of the DataWriter forHIGH_PRIORITYandPRIORITY_WITH_RESERVATIONflow controllers. Allowed values are from -10 (highest priority) to 10 (lowest priority). If the property is not present, it will be set to the lowest priority.Property
fastdds.sfc.bandwidth_reservationis used to set the percentage of the bandwidth that the DataWriter is requesting forPRIORITY_WITH_RESERVATIONflow controllers. Allowed values are from 0 to 100, and express a percentage of the total flow controller limit. If the property is not present, it will be set to 0 (no bandwidth is reserved for the DataWriter).
Persistence Service Settings¶
Warning
This section is still under work.
Security Plugins Settings¶
As described in the Security section, the security plugins admit a set of settings that can be configured.
Authentication plugin settings¶
The DDS:Auth:PKI-DH authentication plugin, can be activated setting the DomainParticipantQos
properties()
dds.sec.auth.plugin with the value builtin.PKI-DH.
The following table outlines the properties used for the DDS:Auth:PKI-DH plugin configuration.
PropertyPolicyQos name |
PropertyPolicyQos value |
|---|---|
|
URI to the X.509 v3 certificate of the Identity CA in PEM format. |
|
URI to an X.509 v3 certificate signed by the Identity CA in PEM format |
|
URI to a X.509 Certificate Revocation List (CRL). |
|
URI to access the private Private Key for the Participant. |
|
A password used to decrypt the private_key. |
Note
All properties listed above have the dds.sec.auth.builtin.PKI-DH." prefix.
For example: dds.sec.auth.builtin.PKI-DH.identity_ca. For examples
and further information, please refer to the Authentication plugin: DDS:Auth:PKI-DH section.
Authentication handshake settings¶
The authentication phase starts when discovery information is received from the remote DomainParticipants. At this moment, the participant sends a handshake request until a handshake response is received from the remote participant. Some parameters are involved in the behavior of this exchange:
max_handshake_requestscontrols the maximum number of handshake requests to be sent.initial_handshake_resend_periodrepresents the initial waiting time (in milliseconds) for the first handshake request that has to be resent.handshake_resend_period_gainis the gain against which the period is multiplied between two handshake requests.
Hence, the period of time to wait for sending a new handshake request is computed at each iteration as the period between the last two handshake requests multiplied by the gain (so that the period increases).
The following table lists the
settings to configure the authentication handshake behavior within
the dds.sec.auth.builtin.PKI-DH plugin:
PropertyPolicyQos name |
PropertyPolicyQos value |
PropertyPolicyQos bounds |
Default value |
|---|---|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
Note
All listed properties have the dds.sec.auth.builtin.PKI-DH. prefix.
For example: dds.sec.auth.builtin.PKI-DH.max_handshake_requests.
The following is an example of how to set the properties of DomainParticipantQoS for the authentication handshake configuration.
C++ |
DomainParticipantQos pqos;
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.max_handshake_requests",
"5");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.initial_handshake_resend_period",
"250");
pqos.properties().properties().emplace_back(
"dds.sec.auth.builtin.PKI-DH.handshake_resend_period_gain",
"1.5");
|
XML |
<participant profile_name="secure_domainparticipant_conf_auth_handshake_props_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<property>
<name>dds.sec.auth.builtin.PKI-DH.max_handshake_requests</name>
<value>5</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.initial_handshake_resend_period</name>
<value>250</value>
</property>
<property>
<name>dds.sec.auth.builtin.PKI-DH.handshake_resend_period_gain</name>
<value>1.5</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
|
Cryptographic plugin settings¶
The DDS:Crypto:AES-GCM-GMAC authentication plugin,
can be activated setting the DomainParticipantQos properties()
dds.sec.crypto.plugin with the value builtin.AES-GCM-GMAC.
Moreover, this plugin needs the activation of the Authentication plugin: DDS:Auth:PKI-DH.
The DDS:Crypto:AES-GCM-GMAC plugin is configured using the
Access control plugin: DDS:Access:Permissions, i.e the cryptography plugin is configured through the properties
and configuration files of the access control plugin.
For further information and examples in this regard please refer to Cryptographic plugin: DDS:Crypto:AES-GCM-GMAC.
Logging plugin settings¶
The DDS:Logging:DDS_LogTopic authentication plugin,
can be activated setting the DomainParticipantQos properties()
dds.sec.log.plugin with the value builtin.DDS_LogTopic.
The following table outlines the properties used for the DDS:Logging:DDS_LogTopic plugin configuration.
For further information and examples follow the dedicated documentation: Logging plugin: DDS:Logging:DDS_LogTopic.
Logging Module Settings¶
Warning
This section is still under work.
Ignore Local Endpoints¶
By default, Fast DDS will automatically match all the endpoints (meaning DataReaders and DataWriters) belonging to a
given DomainParticipant as soon as they share the same Topic and have compatible Qos.
This however can result in undesired feedback whenever an application creates a DataReader and a DataWriter under
the same DomainParticipant on a shared Topic.
Although this feedback can be filtered out at the application level upon data reception by filtering out messages coming
from a DataWriter belonging to the same DomainParticipant on the DataReader receiving the data (by looking at the
GuidPrefix_t), this entails for a data sample to go all the way to the DataReaderListener just to be discarded
by an overcomplicated application business logic.
For this reason, Fast DDS offers the possibility of instructing the DomainParticipant to avoid the matching of local
endpoints through the following property:
PropertyPolicyQos name |
PropertyPolicyQos value |
Default value |
|---|---|---|
|
|
|
DomainParticipantQos participant_qos;
// Avoid local matching of this participant's endpoints
participant_qos.properties().properties().emplace_back(
"fastdds.ignore_local_endpoints",
"true");
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="ignore_local_endpoints_domainparticipant_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Avoid local matching of this participant's endpoints -->
<property>
<name>fastdds.ignore_local_endpoints</name>
<value>true</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
</profiles>
</dds>
Note
An invalid value of fastdds.ignore_local_endpoints results in the default behaviour.
Statistics Module¶
The Fast DDS Statistics module is an extension of Fast DDS that enables the recollection of data concerning the DDS
communication.
The collected data is published using DDS over dedicated topics using builtin DataWriters within the
Statistics module.
Consequently, by default, Fast DDS does not compile this module because it may entail affecting the application’s
performance.
Nonetheless, the Statistics module and the Monitor Service can be activated using the -DFASTDDS_STATISTICS=ON
at CMake configuration step.
For more information about Fast DDS compilation, see Linux installation from sources and Windows installation from sources.
Besides enabling the Statistics Module compilation, the user must enable those DataWriters that are publishing data on the topics of interest for the user’s application. Therefore, the standard DDS Layer has been extended. The following section explains this DDS extended API.
Note
Please refer to Statistics QoS Troubleshooting for any problems related to the statistics module.
Statistics Module DDS Layer¶
This section explains the extended DDS API provided for the Statistics Module. First, the Statistics Topic List is presented together with the corresponding collected data. Next, the methods to enable/disable the corresponding DataWriters are explained. Then, the recommended QoS for enabling the DataWriters and creating the user’s DataReaders that subscribe to the Statistics topics are described. Finally, a guide on how to overcome common problems when using the module are presented.
Statistics Topic names¶
Data collected by the Fast DDS Statistics module is published in one of the topics listed below. In order to simplify its use, the API provides aliases for the different statistics topics (see Topic names). The following table shows the correlation between the topic name and the corresponding alias.
Topic name |
Alias |
|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
HISTORY_LATENCY_TOPIC¶
The _fastdds_statistics_history2history_latency statistics topic collects data related with the latency between any
two matched endpoints.
This measurement provides information about the DDS overall latency independent of the user’s application overhead.
Specifically, the measured latency corresponds to the time spent between the instant when the sample is written to the
DataWriter’s history and the time when the sample is added to the DataReader’s history and the notification is issued to
the corresponding user’s callback.
NETWORK_LATENCY_TOPIC¶
The _fastdds_statistics_network_latency statistics topic collects data related with the network latency (expressed
in ns) between any two communicating locators.
This measurement provides information about the transport layer latency.
The measured latency corresponds to the time spent between the message being written in the RTPSMessageGroup until the
message being received in the MessageReceiver.
Important
In the case of TCP Transport, the reported latency also includes the time spent on the datagram’s CRC related operations. Mind that is possible to disable CRC operations when defining the TCPTransportDescriptor.
PUBLICATION_THROUGHPUT_TOPIC¶
The _fastdds_statistics_publication_throughput statistics topic collects the amount of data (expressed in B/s)
that is being sent by each DataWriter.
This measurement provides information about the publication’s throughput.
SUBSCRIPTION_THROUGHPUT_TOPIC¶
The _fastdds_statistics_subscription_throughput statistics topic collects the amount of data (expressed in B/s)
that is being received by each DataReader.
This measurement provides information about the subscription’s throughput.
RTPS_SENT_TOPIC¶
The _fastdds_statistics_rtps_sent statistics topic collects the number of RTPS packets and bytes that are being sent
from each DDS entity to each locator.
RTPS_LOST_TOPIC¶
The _fastdds_statistics_rtps_lost statistics topic collects the number of RTPS packets and bytes that are being lost
in the transport layer (dropped somewhere in between) in the communication between each DDS entity and locator.
HEARTBEAT_COUNT_TOPIC¶
The _fastdds_statistics_heartbeat_count statistics topic collects the number of heartbeat messages sent by each
user’s DataWriter.
This topic does not apply to builtin (related to Discovery) and statistics DataWriters.
Heartbeat messages are only sent if the ReliabilityQosPolicy is set to RELIABLE_RELIABILITY_QOS.
These messages report the DataWriter’s status.
ACKNACK_COUNT_TOPIC¶
The _fastdds_statistics_acknack_count statistics topic collects the number of acknack messages sent by each user’s
DataReader.
This topic does not apply to builtin DataReaders (related to Discovery).
Acknack messages are only sent if the ReliabilityQosPolicy is set to RELIABLE_RELIABILITY_QOS.
These messages report the DataReader’s status.
NACKFRAG_COUNT_TOPIC¶
The _fastdds_statistics_nackfrag_count statistics topic collects the number of nackfrag messages sent by each user’s
DataReader.
This topic does not apply to builtin DataReaders (related to Discovery).
Nackfrag messages are only sent if the ReliabilityQosPolicy is set to RELIABLE_RELIABILITY_QOS.
These messages report the data fragments that have not been received yet by the DataReader.
GAP_COUNT_TOPIC¶
The _fastdds_statistics_gap_count statistics topic collects the number of gap messages sent by each user’s
DataWriter.
This topic does not apply to builtin (related to Discovery) and statistics DataWriters.
Gap messages are only sent if the ReliabilityQosPolicy is set to RELIABLE_RELIABILITY_QOS.
These messages report that some specific samples are not relevant to a specific DataReader.
DATA_COUNT_TOPIC¶
The _fastdds_statistics_data_count statistics topic collects the total number of user’s data messages and data
fragments (in case that the message size is large enough to require RTPS fragmentation) that have been sent by each
user’s DataWriter.
This topic does not apply to builtin (related to Discovery) and statistics DataWriters.
RESENT_DATAS_TOPIC¶
The _fastdds_statistics_resent_data statistics topic collects the total number of user’s data messages and data
fragments (in case that the message size is large enough to require RTPS fragmentation) that have been necessary to
resend by each user’s DataWriter.
This topic does not apply to builtin (related to Discovery) and statistics DataWriters.
SAMPLE_DATAS_TOPIC¶
The _fastdds_statistics_sample_datas statistics topic collects the number of user’s data messages (or data fragments
in case that the message size is large enough to require RTPS fragmentation) that have been sent by the user’s
DataWriter to completely deliver a single sample.
This topic does not apply to builtin (related to Discovery) and statistics DataWriters.
PDP_PACKETS_TOPIC¶
The _fastdds_statistics_pdp_packets statistics topic collects the number of PDP discovery traffic RTPS packets
transmitted by each DDS DomainParticipant.
PDP packets are the data messages exchanged during the PDP discovery phase (see Discovery phases for more
information).
EDP_PACKETS_TOPIC¶
The _fastdds_statistics_edp_packets statistics topic collects the number of EDP discovery traffic RTPS packets
transmitted by each DDS DomainParticipant.
EDP packets are the data messages exchanged during the EDP discovery phase (see Discovery phases for more
information).
DISCOVERY_TOPIC¶
The _fastdds_statistics_discovered_entity statistics topic reports the time when each local DomainParticipant
discovers any remote DDS entity (with the exception of those DDS entities related with the Fast DDS Statistics
module).
This topic also carries the PHYSICAL_DATA_TOPIC information for the case of discovered DomainParticipant; if the
discovered entity is either a DataReader or DataWriter, then the physical information is empty (see
Physical Data in Discovery Information for more information about how to configure the physical data conveyed on the
discovery messages).
PHYSICAL_DATA_TOPIC¶
The _fastdds_statistics_physical_data statistics topic reports the host, user and process where the
Fast DDS Statistics module is running.
Statistics Domain Participant¶
In order to start collecting data in one of the statistics topics (Statistics Topic names), the corresponding
statistics DataWriter should be enabled.
In fact, Fast DDS Statistics module can be enabled and disabled at runtime.
For this purpose, Fast DDS Statistics module exposes an extended DDS DomainParticipant API:
Enable statistics DataWriters¶
Statistics DataWriters can be enabled in different ways.
It can be done automatically (see Automatically enabling statistics DataWriters).
Alternatively, Statistics DataWriters can be enabled at run time using one of two methods:
enable_statistics_datawriter() or enable_statistics_datawriter_with_profile().
enable_statistics_datawriter() method requires as parameters:
Name of the statistics topic to be enabled (see Statistics Topic names for the statistics topic list).
DataWriter QoS profile (see Statistics DataWriter recommended QoS for the recommended profile).
It is possible to define specific desired QoS through DataWriter profile on the FASTDDS_DEFAULT_PROFILES_FILE
(see XML profiles).
enable_statistics_datawriter_with_profile() method enables a DataWriter by searching a specific DataWriter XML profile.
On those profiles, specific QoS can be set.
enable_statistics_datawriter_with_profile() method requires as parameters:
Name of the XML profile to use to fill the QoS structure of the DataWriter.
Name of the statistics topic name to be enabled. (see Statistics Topic names for the statistics topic list).
Disable statistics DataWriters¶
Statistics DataWriters are disabled using the method disable_statistics_datawriter().
This method requires as parameter:
Name of the statistics topic to be disabled (see Statistics Topic names for the statistics topic list).
Obtain pointer to the extended DomainParticipant class¶
The DomainParticipant is created using the create_participant() provided by the
DomainParticipantFactory.
This method returns a pointer to the DDS standard DomainParticipant created.
In order to obtain the pointer to the child DomainParticipant which extends the DDS API, the
static method narrow() is provided.
Example¶
The following example shows how to use the Statistics module extended DDS API:
// Create a DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Obtain pointer to child class
eprosima::fastdds::statistics::dds::DomainParticipant* statistics_participant =
eprosima::fastdds::statistics::dds::DomainParticipant::narrow(participant);
// Enable statistics DataWriter
if (statistics_participant->enable_statistics_datawriter(eprosima::fastdds::statistics::GAP_COUNT_TOPIC,
eprosima::fastdds::statistics::dds::STATISTICS_DATAWRITER_QOS) != RETCODE_OK)
{
// Error
return;
}
// Use the DomainParticipant to communicate
// (...)
// Disable statistics DataWriter
if (statistics_participant->disable_statistics_datawriter(eprosima::fastdds::statistics::GAP_COUNT_TOPIC) !=
RETCODE_OK)
{
// Error
return;
}
// Delete DomainParticipant
if (DomainParticipantFactory::get_instance()->delete_participant(participant) != RETCODE_OK)
{
// Error
return;
}
Automatically enabling statistics DataWriters¶
The statistics DataWriters can be directly enabled using the DomainParticipantQos
properties() fastdds.statistics.
The value of this property is a semicolon separated list containing the
statistics topic name aliases of those DataWriters that the user wants to enable.
The property can be set either programmatically or loading an XML file.
If the property is set in both ways, the priority would depend on the API and the QoS profile provided:
XML settings have priority if
create_participant_with_profile()is called with a valid participant profile.XML settings also have priority if
create_participant()is called usingPARTICIPANT_QOS_DEFAULTand a participant profile exists in the XML file with theis_default_profileoption set totrue(DomainParticipant XML attributes).The property set programmatically is used only when
create_participant()is called with the specific QoS.
Another way of enabling statistics DataWriters, compatible with the previous one, is setting the
FASTDDS_STATISTICS environment variable.
The statistics DataWriters that will be enabled when the DomainParticipant is enabled would be the union between
those specified in the properties() fastdds.statistics and those included with the
environment variable.
The following examples show how to use all the previous methods:
C++ |
DomainParticipantQos pqos;
// Activate Fast DDS Statistics module
pqos.properties().properties().emplace_back("fastdds.statistics",
"HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC");
|
XML |
<participant profile_name="statistics_domainparticipant_conf_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate Fast DDS Statistics Module -->
<property>
<name>fastdds.statistics</name>
<value>HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
|
Environment Variable Linux |
export FASTDDS_STATISTICS="HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC"
|
Environment Variable Windows |
set FASTDDS_STATISTICS=HISTORY_LATENCY_TOPIC;ACKNACK_COUNT_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC
|
Note
These are all the statistics topics:
HISTORY_LATENCY_TOPIC;NETWORK_LATENCY_TOPIC;PUBLICATION_THROUGHPUT_TOPIC;SUBSCRIPTION_THROUGHPUT_TOPIC;RTPS_SENT_TOPIC;RTPS_LOST_TOPIC;HEARTBEAT_COUNT_TOPIC;ACKNACK_COUNT_TOPIC;NACKFRAG_COUNT_TOPIC;GAP_COUNT_TOPIC;DATA_COUNT_TOPIC;RESENT_DATAS_TOPIC;SAMPLE_DATAS_TOPIC;PDP_PACKETS_TOPIC;EDP_PACKETS_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC
Note
Be aware that automatically enabling the statistics DataWriters using all these methods implies using the recommended
QoS profile STATISTICS_DATAWRITER_QOS. For more information, please refer to Statistics DataWriter recommended QoS.
However, if an XML profile is defined, the QoS applied are those defined in the profile,
and for those QoS that are not specified in that profile, the default library QoS are applied
(see DataWriterQos for the standard eProsima’s DataWriter QoS),
and not the recommended QoS for the Statistics DataWriters.
For the creation of an automatically enabled Datawriter, the priority for setting its QoS is the following:
First, if a specific profile exists for the statistics topic, that one is applied.
If that is not the case but a generic profile for statistics DataWriters exists, that one is applied.
If no profile is defined in XML file, the recommended statistics QoS are applied.
Note
The generic DataWriter profile defined in the FASTDDS_DEFAULT_PROFILES_FILE XML needs to be named as GENERIC_STATISTICS_PROFILE.
The specific DataWriter profile defined in the FASTDDS_DEFAULT_PROFILES_FILE XML needs to be named using the
same statistic topic alias or name (see Statistics Topic names for the alias corresponding to each statistic
topic) that has been used in the DomainParticipantQos properties() fastdds.statistics
(see Statistics Module Settings) or the FASTDDS_STATISTICS environment variable,
where the enabling of the corresponding statistics
topic has been set.
Statistics recommended QoS¶
Although the statistics DataWriters can be enabled using any valid QoS profile, the recommended profile is presented below. Also, the DataReaders created by the user to receive the data being published by the statistics DataWriters can use any compatible QoS profile. However, a recommended DataReader QoS profile is also provided.
Statistics DataWriter recommended QoS¶
The following table shows the recommended DataWriterQos profile for enabling the statistics DataWriters.
This profile enables the pull mode operating mode on the statistics DataWriters.
This entails that the DataWriters will only send information upon the reception of acknack submessages sent by the
monitoring DataReader.
This QoS profile is always used when the statistics DataWriters are
auto-enabled.
The recommended profile can be accessed through the constant STATISTICS_DATAWRITER_QOS.
Qos Policy |
Value |
|---|---|
|
|
|
|
|
|
|
|
|
|
|
10 |
|
|
Statistics DataReader recommended QoS¶
The following table shows the recommended DataReaderQos profile for creating the monitoring DataReaders.
The recommended profile can be accessed through constant STATISTICS_DATAREADER_QOS.
Qos Policy |
Value |
|---|---|
|
|
|
|
|
|
|
100 |
|
|
Troubleshooting¶
This section aims to give quick solutions to overcome the most common problems arising from the use of the statistics module.
Monitoring application is not receiving any statistic data¶
Sometimes, especially in the case of monitoring large applications with many DataWriters and DataReaders, it may happen
that the application monitoring Fast DDS statistics does not receive any data.
This is generally caused by the default configuration of the statistics DataWriters, which includes the
push_mode set to false (i.e. pull_mode), the History Kind set to KEEP_LAST, and the
History Depth set to 10.
With this configuration, the following may happen:
Fast DDS adds new samples to one of the statistics DataWriters.
The DataWriter notifies the DataReader of the availability of said samples.
The DataReader sends a request to the DataWriter to “pull” those samples.
Before the request arrives to the DataWriter, some new statistics samples are added to that same DataWriter, which causes the previous samples to be overwritten.
Once the DataReader request arrives to the DataWriter, since the requested samples have been overwritten, they are not available any more, so the DataWriter send a notification to the DataReader informing of the presence of the newer samples instead.
The loop starts again.
The easiest fix to overcome this situation is to simply increase the History Depth of the DataWriter to create Some buffer to answer to requests:
<?xml version="1.0" encoding="utf-8"?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="statistics_domainparticipant_conf_xml_general_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate various Fast DDS Statistics Module DataWriters -->
<property>
<name>fastdds.statistics</name>
<value>HISTORY_LATENCY_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
<!-- Generic profile for all the statistics DataWriter -->
<data_writer profile_name="GENERIC_STATISTICS_PROFILE">
<!-- Configure History QoS as KEEP_LAST 20 -->
<!-- History depth depends on the user application constraints (publication rate for instance) -->
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
<depth>20</depth>
</historyQos>
</topic>
<!-- Enable pull mode -->
<propertiesPolicy>
<properties>
<property>
<name>fastdds.push_mode</name>
<value>false</value>
</property>
</properties>
</propertiesPolicy>
<!-- Set durability, reliability, and publication mode -->
<qos>
<durability>
<kind>TRANSIENT_LOCAL</kind>
</durability>
<reliability>
<kind>RELIABLE</kind>
</reliability>
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
</qos>
</data_writer>
</profiles>
</dds>
<?xml version="1.0" encoding="utf-8"?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<participant profile_name="statistics_domainparticipant_conf_xml_specific_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Activate various Fast DDS Statistics Module DataWriters -->
<property>
<name>fastdds.statistics</name>
<value>HISTORY_LATENCY_TOPIC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
<!-- Generic profile for a specific statistics DataWriters -->
<data_writer profile_name="HISTORY_LATENCY_WRITER">
<!-- Configure History QoS as KEEP_LAST 20 -->
<!-- History depth depends on the user application constraints (publication rate for instance) -->
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
<depth>20</depth>
</historyQos>
</topic>
<!-- Enable pull mode -->
<propertiesPolicy>
<properties>
<property>
<name>fastdds.push_mode</name>
<value>false</value>
</property>
</properties>
</propertiesPolicy>
<!-- Set durability, reliability, and publication mode -->
<qos>
<durability>
<kind>TRANSIENT_LOCAL</kind>
</durability>
<reliability>
<kind>RELIABLE</kind>
</reliability>
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
</qos>
</data_writer>
</profiles>
</dds>
Note
Increasing the History Depth of the statistics DataWriters has an impact on memory usage, as sufficient space is pre-allocated for each of the DataWriter’s histories to hold that number of samples per topic instance.
Monitor Service¶
The Fast DDS Monitor Service is a feature of Fast DDS that grants the user the ability to collect data about the entities existing within a particular domain (i.e DomainParticipants, DataReaders, DataWriters) as well as the capability of detecting possible misconfigurations among them.
Introduction¶
The Monitor Service targets any application implementing the subscription side of
the Monitor Service Status Topic,
giving the possibility of retrieving the Monitoring Information
of the local entities (incompatible QoS, deadlines missed,
active connections,…).
Keywords¶
Proxy: An entity that acts on behalf of another entity.
Proxy Data: The way in which a Proxy can be described.
Monitoring Information: The collection of different sources of information and statuses of an entity, including: the Proxy Data, incompatible QoS, connections, liveliness, deadlines missed, inconsistent topics and lost sample status.
Description¶
Enabling the service makes each DomainParticipant publish its local entities, each one with its related
Monitoring Information.
The Monitor Service is disabled by default, as it may entail a performance cost. Further information on the Monitor Service topics and how to configure it is described in the following sections.
The Monitor Service is available in both the DDS Layer and RTPS Layer.
Note
If the service is activated within a RTPS context, not all the Monitoring Information
may be published by the service.
Use Cases¶
The Monitor Service can be particularly useful in the following scenarios:
Collecting the
Monitoring Informationof any local entity of a remote DomainParticipant in order to extend the default discovery information (see Discovery) about it.Troubleshooting issues regarding discovery or entity-matching, leveraging the information of the current locators in use, for example.
Recreating an entity graph of a certain domain given that all participants are able to discover each other.
Monitor Service Topics¶
The following table depicts the properties of the topics within the Monitor Service:
Topic name |
Topic Alias |
TopicDataType |
|
MONITOR_SERVICE_TOPIC |
Monitor Service Status Topic¶
The Monitor Service Status Topic carries information about the
monitoring information of the local entities of a
particular DomainParticipant.
The monitoring information can be divided into different statuses
identified by a StatusKind.
The possible values are described in the following table:
Value |
Name |
Description |
0 |
|
Collection of Parameters describing the
|
1 |
|
List of connections that this entity is using with its matched remote entities. |
2 |
|
Status of the Incompatible QoS of that entity. |
3 |
|
Status of Inconsistent topics that the topic of that entity has. |
4 |
|
Tracks the status of the number of times a writer lost liveliness. |
5 |
|
Tracks the status of the number of times the liveliness changed in a reader. |
6 |
|
The Status of the number of deadlines missed of a sample for that entity. |
7 |
|
Tracks the status of the number of times this entity lost samples. |
Note
If the service is enabled in a RTPS layer context, not all
the statuses will be published,
only the ProxyInfo and ConnectionList.
The Monitor Service Status Topic publishes new data when new updates are received from any
of the DomainParticipant’s local entities (on-event driven) with a minimum waiting time between
publications.
In addition, it is in charge of notifying about any disposal or liveliness lost.
Monitor Service Status Data¶
The MonitorServiceStatusData data structure comprises the following fields:
local_entity:
Guid_tof the local entity.status_kind: StatusKind enumeration identifying the status.
value: The value of the status.
MonitorServiceStatusData
@Key GUID local_entity
@Key StatusKind status_kind
Data value
Note
The local_entity and status_kind are keyed fields, hence making use of instances (see Topics, keys and instances). In this case, the pair <local_entity, status_kind> identifies a unique instance.
Each of the StatusKind enumeration values maps to a corresponding Data value.
The actual field names for the different values are described below:
entity_proxy: Collection of the serialized Quality of Service Parameters in the form of a
ParameterList.connection_list: Defines how is this entity communicating with its matched entities. Each of the elements is of Connection type (depicted below).
Connection
uint32_t mode //INTRAPROCESS, DATASHARING, TRANSPORT
LocatorList announced_locators
LocatorList used_locators
incompatible_qos_status: Status of the Incompatible QoS of that entity.
DataWriter Incompatible QoS Offered.
DataReader Incompatible QoS Requested.
inconsistent_topic_status: Status of Inconsistent topics of the topic of that entity. Asked to the topic of the requested entity.
liveliness_lost_status: Tracks the status of the number of times that liveliness was lost by a DataWriter.
liveliness_changed_status: Tracks the status of the number of times that liveliness was lost by a DataReader.
deadline_status: The Status of the number of deadlines missed that were registered in that entity.
sample_lost_status: The number of samples that entity lost.
The following table depicts the relation between each of the StatusKind values and the Data field:
StatusKind Value |
StatusKind Name |
Data field Name |
IDL Data field Type |
0 |
|
entity_proxy |
sequence<octet> |
1 |
|
connection_list |
sequence<Connection> |
2 |
|
incompatible_qos_status |
IncompatibleQoSStatus |
3 |
|
inconsistent_topic_status |
InconsistentTopicStatus |
4 |
|
liveliness_lost_status |
LivelinessLostStatus |
5 |
|
liveliness_changed_status |
LivelinessChangedStatus |
6 |
|
deadline_missed_status |
DeadlineMissedStatus |
7 |
|
sample_lost_status |
SampleLostStatus |
Monitor Service Configuration¶
The Monitor Service can be activated using the -DFASTDDS_STATISTICS=ON at CMake configuration step
(for further information regarding the Fast DDS compilation, see Linux installation from sources and Windows installation from sources).
Once the Monitor Service feature is activated, it can be programmatically enabled in both DDS Layer and
RTPS Layer through the enable_monitor_service() and
disable_monitor_service() calls.
In addition, leveraging the PropertyPolicyQos there is new Property defined
for the purpose: fastdds.enable_monitor_service.
The following table depicts the different ways in which the Monitor Service can be enabled or disabled:
DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(0,
PARTICIPANT_QOS_DEFAULT);
// Obtain pointer to child class
eprosima::fastdds::statistics::dds::DomainParticipant* statistics_participant =
eprosima::fastdds::statistics::dds::DomainParticipant::narrow(participant);
// Enable Fast DDS Monitor Service through API
statistics_participant->enable_monitor_service();
// Disable Fast DDS Monitor Service through API
statistics_participant->disable_monitor_service();
DomainParticipantQos pqos;
// Enable Fast DDS Monitor Service through properties
pqos.properties().properties().emplace_back("fastdds.enable_monitor_service",
"true");
// Enable Fast DDS Monitor Service through statistics properties (other way)
pqos.properties().properties().emplace_back("fastdds.statistics",
"MONITOR_SERVICE_TOPIC");
DomainParticipant* participant_with_mon_srv = DomainParticipantFactory::get_instance()->create_participant(0,
pqos);
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="monitor_service_participant_xml_profile">
<rtps>
<propertiesPolicy>
<properties>
<!-- Enable Monitor Service -->
<property>
<name>fastdds.enable_monitor_service</name>
<value>true</value>
</property>
<!-- Include Monitor Service in the Fast DDS Statistics (other way to enable it) -->
<property>
<name>fastdds.statistics</name>
<value>MONITOR_SERVICE_TOPIC</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
</profiles>
export FASTDDS_STATISTICS="MONITOR_SERVICE_TOPIC"
set FASTDDS_STATISTICS=MONITOR_SERVICE_TOPIC
Endpoints QoS¶
For any consumer application of the Monitor Service, the following endpoint QoS of the Monitor Service Status Topic DataWriter should be taken into consideration:
Endpoint |
QoS |
Value |
MONITOR_STATUS_WRITER |
|
|
|
|
|
|
|
XTypes¶
eProsima Fast DDS supports the OMG Extensible and Dynamic Topic Types for DDS specification (also known as XTypes). This specification defines the following concepts:
DDS supported type system, including the concept of extensible types that might evolve in time.
Note
This section also defines the type compatibility rules among evolved types which is still unsupported in Fast DDS.
Type representation, including IDL and TypeObject representations.
Data representation over the wire.
Language binding, defining both a plain and a dynamic language binding. eProsima Fast DDS-Gen generates the plain language binding given an IDL type representation. Dynamic Language Binding section explains the required API to define and set/read the data types.
DDS builtin mechanism to automatically discover remote data types. More information in Remote Data Types Discovery section.
Remote Data Types Discovery¶
DDS-XTypes specification defines an internal mechanism to discover the remote data types at runtime and match depending on the extensible types compatibility rules configured using the TypeConsistencyEnforcementQosPolicy.
Note
eProsima Fast DDS does not support XTypes compatibility check yet.
The remote data type discovery mechanism is based on the exchange of the data type information optimized in order to
reduce the required bandwidth.
On the one hand, TypeInformation structure defined in the IDL below (extracted from Annex B of the
DDS-XTypes specification), is used to communicate the Topic Data Type and its dependencies.
@extensibility(APPENDABLE) @nested
struct TypeIdentfierWithSize
{
TypeIdentifier type_id;
unsigned long typeobject_serialized_size;
};
@extensibility(APPENDABLE) @nested
struct TypeIdentifierWithDependencies
{
TypeIdentfierWithSize typeid_with_size;
long dependent_type_id_count;
sequence<TypeIdentfierWithSize> dependent_typeids;
};
@extensibility(MUTABLE) @nested
struct TypeInformation
{
@id(0x1001) TypeIdentifierWithDependencies minimal;
@id(0x1002) TypeIdentifierWithDependencies complete;
};
TypeInformation includes the TypeIdentifier, the data type information hashed which identifies almost
univocally the data type.
The data type information is contained in the TypeObject union:
@extensibility(APPENDABLE) @nested
union TypeObject switch(octet)
{
case EK_COMPLETE:
CompleteTypeObject complete;
case EK_MINIMAL:
MinimalTypeObject minimal;
};
The CompleteTypeObject includes the data type full description.
On the other hand, MinimalTypeObject only includes the minimum required information in order to check type
compatibility.
Important
Current TypeObject representation implementation does not support forward declarations or recursive data types
defined using the @external annotation.
Please, remember to disable TypeObject generation code using -no-typeobjectsupport option when generating
the code using Fast DDS-Gen.
Prerequisites¶
The remote data type discovery feature only works if some requisites are met:
The local data types must be registered into the
ITypeObjectRegistry. The types are automatically registered when callingregister_type()/register_type()if the code required for registration has been generated using eProsima Fast DDS-Gen. Fast DDS-Gen generates the required files (<IDLFileName>TypeObjectSupport.cxx/.hpp) by default.Note
-no-typeobjectsupportoption disables the generation of these files and effectively disables the discovery of remote types.Note
Currently there is no support to register the TypeObject when the data type is defined using the Dynamic Language Binding. Consequently, local types defined using the dynamic language binding API, are not going to be discovered by remote DomainParticipants.
TypeInformationshould be received with the DomainParticipant’s endpoint discovery information. A DomainParticipant that does not inform about itsTypeInformationwould not trigger the remote data type discovery mechanism.
If the prerequisites are not met, endpoint matching relies on type name and topic name in order to match the discovered endpoints.
Remote types discovery example¶
Please, refer to Remote type discovery and endpoint matching for more information about how to leverage this feature.
Dynamic Language Binding¶
The Dynamic Language Binding API allows to define data types at runtime instead of having the types predefined as it is required by the Plain Language Binding. This API includes both the type definition and, the getters and setters required to use the defined types. Type definition can also be done using a XML configuration file as explained in Dynamic Types profiles section.
This section presents first the Dynamic Language Binding API, and then the supported types and specific examples defining and using those types.
Dynamic Language Binding Interfaces¶
This section briefly presents the Dynamic Language Binding API. For more information, please refer both to the DDS-XTypes specification and the API reference.
TypeDescriptor¶
TypeDescriptor is in charge of describing the state of a type.
Objects of this interface have value semantics allowing the TypeDescriptor data to be deeply copied and compared.
AnnotationDescriptor¶
AnnotationDescriptor is in charge of describing the user-defined applied annotation to a specific element.
Objects of this interface have value semantics allowing the AnnotationDescriptor data to be deeply copied and compared.
MemberDescriptor¶
MemberDescriptor is in charge of describing the state of a specific member of a type.
Objects of this interface have value semantics allowing the MemberDescriptor data to be deeply copied and compared.
VerbatimTextDescriptor¶
VerbatimTextDescriptor is in charge of describing the @verbatim builtin annotation application.
Objects of this interface have value semantics allowing the VerbatimTextDescriptor data to be deeply copied and
compared.
DynamicTypeBuilderFactory¶
The DynamicTypeBuilderFactory serves as a singleton which instance is responsible for both creating and deleting
DynamicTypeBuilder objects.
This class provides the generic DynamicTypeBuilderFactory::create_type API, and also specific APIs to define other
basic types such as strings, sequences, etc.
More information can be found in Supported Types section.
DynamicType¶
DynamicType objects represents a specific type definition.
Once the DynamicType has been built, it cannot be modified.
Objects of this interface have reference semantics, so the API receives a nil-reference which is then returned pointing
to the correct DynamicType address.
DynamicTypeMember¶
DynamicTypeMember represents a data member of a DynamicType.
Objects of this interface have reference semantics, so the API receives a nil-reference which is then returned pointing
to the correct DynamicTypeMember address.
DynamicTypeBuilder¶
DynamicTypeBuilder interface allows the instantiation of concrete DynamicType objects and serves as a transitional
state for configuring the DynamicType before its creation.
Upon definition, DynamicTypeBuilderFactory leverages the information contained in the builder to create
the DynamicType.
DynamicTypeBuilder::build allows for creating the fully constructed DynamicType.
Builders remain reusable after DynamicType creation, ensuring changes to the builder do not affect previously
created types.
DynamicDataFactory¶
DynamicDataFactory serves as a singleton which instance is responsible for both creating and deleting
DynamicData objects from a given DynamicType instance.
DynamicData¶
DynamicData represents a data instance of a DynamicType, providing functionalities to access
and modify data values.
Each DynamicData object corresponds to an object of the type represented by its DynamicType.
Offering reflective getters and setters, DynamicData enables manipulation of individual data samples.
Supported Types¶
This section describes the supported Type System including examples of how to instantiate those specific types using the Dynamic Language Binding API and the XML configuration file. The C++ examples also include instantiating the corresponding DynamicData sample, and setting and reading a value.
Primitive Types¶
Primitive types are self-describing and can be created without configuration parameters.
The DynamicTypeBuilderFactory interface exposes the method DynamicTypeBuilderFactory::get_primitive_type
to allow users to directly get the corresponding primitive DynamicType.
The DynamicData class provides specific getters and setters for each primitive data type.
The following table shows the supported primitive types and their corresponding TypeKind.
The TypeKind is used to query the DynamicTypeBuilderFactory for the specific primitive DynamicType.
C++ Type |
TypeKind |
|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The example below shows how to create an structure with primitive members.
struct PrimitivesStruct
{
boolean my_bool;
octet my_octet;
char my_char;
wchar my_wchar;
long my_long;
unsigned long my_ulong;
int8 my_int8;
uint8 my_uint8;
short my_short;
unsigned short my_ushort;
long long my_longlong;
unsigned long long my_ulonglong;
float my_float;
double my_double;
long double my_longdouble;
};
<struct name="PrimitivesStruct">
<member name="my_bool" type="boolean"/>
<member name="my_octet" type="byte"/>
<member name="my_char" type="char8"/>
<member name="my_wchar" type="char16"/>
<member name="my_long" type="int32"/>
<member name="my_ulong" type="uint32"/>
<member name="my_int8" type="int8"/>
<member name="my_uint8" type="uint8"/>
<member name="my_short" type="int16"/>
<member name="my_ushort" type="uint16"/>
<member name="my_longlong" type="int64"/>
<member name="my_ulonglong" type="uint64"/>
<member name="my_float" type="float32"/>
<member name="my_double" type="float64"/>
<member name="my_longdouble" type="float128"/>
</struct>
// Define a struct type with various primitive members
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("PrimitivesStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define and add primitive members to the struct
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_bool");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BOOLEAN));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_octet");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BYTE));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_char");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR8));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_wchar");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR16));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_long");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT32));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_ulong");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT32));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_int8");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT8));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_uint8");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT8));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_short");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_ushort");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT16));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_longlong");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT64));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_ulonglong");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT64));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_float");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_FLOAT32));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_double");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_FLOAT64));
struct_builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_longdouble");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_FLOAT128));
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for a member of type int32_t
int32_t in_value {2};
int32_t out_value {0};
data->set_int32_value(data->get_member_id_by_name("my_long"), in_value);
data->get_int32_value(out_value, data->get_member_id_by_name("my_long"));
For a detailed explanation about the XML definition of this type, please refer to XML Primitive Types.
Type promotions¶
The Dynamic Language Binding also supports type promotion, enabling implicit promotion of types during both get()
and set() operations.
This means that a smaller type can be implicitly promoted to a larger type, but not the other way around.
The following promotions are supported:
TypeKind |
Allowed promotions |
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(none) |
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(any) |
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String Types¶
String types are one-dimensional collections of characters (TK_CHAR8 or TK_CHAR16.
The latest are also known as wide strings or wstring).
The TypeKinds used to identify string types are TK_STRING8 and TK_STRING16.
The string may be bounded, setting a maximum length, or unbounded.
This is configured using TypeDescriptor bound property.
DynamicTypeBuilderFactory exposes the functions DynamicTypeBuilderFactory::create_string_type and
DynamicTypeBuilderFactory::create_wstring_type that eases string creation providing the corresponding maximum length
parameter (LENGTH_UNLIMITED is used for unbounded strings).
DynamicData class provides also with specific getters and setters: DynamicData::get_string_value,
DynamicData::get_wstring_value, DynamicData::set_string_value, and DynamicData::set_wstring_value.
struct StringsStruct
{
string my_string;
wstring my_wstring;
string<41925> my_bounded_string;
wstring<20925> my_bounded_wstring;
};
<struct name="StringsStruct">
<member name="my_string" type="string"/>
<member name="my_wstring" type="wstring"/>
<member name="my_bounded_string" type="string" stringMaxLength="41925"/>
<member name="my_bounded_wstring" type="wstring" stringMaxLength="20925"/>
</struct>
// Define a struct type to contain the strings
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("StringsStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define and add string members to the struct
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_string");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
create_string_type(static_cast<uint32_t>(LENGTH_UNLIMITED))->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_STRING8);
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR8));
type_descriptor->bound().push_back(static_cast<uint32_t>(LENGTH_UNLIMITED));
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor)->build());
*/
struct_builder->add_member(member_descriptor);
member_descriptor->name("my_wstring");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
create_wstring_type(static_cast<uint32_t>(LENGTH_UNLIMITED))->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_STRING16);
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR16));
type_descriptor->bound().push_back(static_cast<uint32_t>(LENGTH_UNLIMITED));
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor)->build());
*/
struct_builder->add_member(member_descriptor);
member_descriptor->name("my_bounded_string");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
create_string_type(41925)->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_STRING8);
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR8));
type_descriptor->bound().push_back(41925);
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor)->build());
*/
struct_builder->add_member(member_descriptor);
member_descriptor->name("my_bounded_wstring");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
create_wstring_type(20925)->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_STRING16);
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_CHAR16));
type_descriptor->bound().push_back(20925);
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor)->build());
*/
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for a string member
std::string in_value {"helloworld"};
std::string out_value;
data->set_string_value(data->get_member_id_by_name("my_string"), in_value);
data->get_string_value(out_value, data->get_member_id_by_name("my_string"));
For a detailed explanation about the XML definition of this type, please refer to XML String Types.
Enumeration Types¶
An enumeration contains a set of supported values (enumeration literals) and a selected value among those supported.
The TypeKind used to identify enumeration types is TK_ENUM.
The enumeration literals must be configured using the DynamicTypeBuilder by calling the
DynamicTypeBuilder::add_member function for the respective supported values.
The MemberDescriptor passed to the previous function must determine the enumeration literal name by using
name property.
The underlying primitive type related to the enumeration is configured using MemberDescriptor type
property.
This primitive type is determined when adding the first enumeration literal.
For the enumeration type to be consistent, the remaining enumeration literals must be of the same primitive type.
Additionally, the enumeration literal value might be set using MemberDescriptor default_value property.
The behavior is the same as setting the @value builtin annotation.
Note
Currently, Fast DDS-Gen does not support @value builtin annotation.
As the enumeration type is basically a primitive type which might take only some specific values defined with the enumeration literals, the corresponding DynamicData getters and setters are the ones corresponding to the underlying primitive type (and any other method promotable to that specific primitive type).
enum MyEnum
{
A,
B,
C
};
struct EnumStruct
{
MyEnum my_enum;
};
<enum name="MyEnum">
<enumerator name="A" value="0"/>
<enumerator name="B" value="1"/>
<enumerator name="C"/>
</enum>
<struct name="EnumStruct">
<member name="my_enum" type="nonBasic" nonBasicTypeName="MyEnum"/>
</struct>
enum MyEnum : uint32_t
{
A,
B,
C
};
// Define a struct type to contain an enum
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("EnumStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define the enum type
TypeDescriptor::_ref_type enum_type_descriptor {traits<TypeDescriptor>::make_shared()};
enum_type_descriptor->kind(TK_ENUM);
enum_type_descriptor->name("MyEnum");
DynamicTypeBuilder::_ref_type enum_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(enum_type_descriptor)};
// Add enum literals to the enum type
MemberDescriptor::_ref_type enum_member_descriptor {traits<MemberDescriptor>::make_shared()};
enum_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT32));
enum_member_descriptor->name("A");
enum_builder->add_member(enum_member_descriptor);
enum_member_descriptor = traits<MemberDescriptor>::make_shared();
enum_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT32));
enum_member_descriptor->name("B");
enum_builder->add_member(enum_member_descriptor);
enum_member_descriptor = traits<MemberDescriptor>::make_shared();
enum_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT32));
enum_member_descriptor->name("C");
enum_builder->add_member(enum_member_descriptor);
// Build the enum type
DynamicType::_ref_type enum_type = enum_builder->build();
// Add an enum member to the struct
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_enum");
member_descriptor->type(enum_type);
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for an enum member
MyEnum in_value {MyEnum::C};
/* Alternative
uint32_t in_value {2}; // Selecting MyEnum::C
*/
uint32_t out_value {0};
data->set_uint32_value(data->get_member_id_by_name("my_enum"), in_value);
data->get_uint32_value(out_value, data->get_member_id_by_name("my_enum"));
For a detailed explanation about the XML definition of this type, please refer to XML Enumeration Types.
Bitmask Types¶
Bitmask types are a collection of boolean flags (bitflags) that can be set individually.
The TypeKind used to identify bitmask types is TK_BITMASK.
The bitmasks bound, maximum number of bits, must be set using the TypeDescriptor bound property.
The maximum bound allowed is 64 bits.
The bitflags must be configured using the DynamicTypeBuilder by calling the DynamicTypeBuilder::add_member
function.
Each bitflag is described using a MemberDescriptor defining the bitflag name using the name property.
The underlying primitive type related to bitflags must be of kind TK_BOOLEAN and must be set in
MemberDescriptor type property.
The MemberDescriptor id property might be used to indicate the bitflag position within the bitmask.
This behavior is the same as setting the @position builtin annotation.
If the position is not specified, sequential order is followed.
The DynamicTypeBuilderFactory exposes the function DynamicTypeBuilderFactory::create_bitmask_type to
facilitate the creation of bitmask types.
Bitmask types can be manipulated either using the DynamicData::get_boolean_value/DynamicData::set_boolean_value in
order to set a specific bitflag, or by using the unsigned integer setter/getter corresponding to the bitmask bound.
In this latest case, only bitflags are going to be set (bits not named are always unset).
@bit_bound(8)
bitmask MyBitMask
{
@position(0) flag0,
flag1,
flag2,
@position(5) flag5
};
struct BitmaskStruct
{
MyBitMask my_bitmask;
};
<bitmask name="MyBitMask" bit_bound="8">
<bit_value name="flag0" position="0"/>
<bit_value name="flag1"/>
<bit_value name="flag2"/>
<bit_value name="flag5" position="5"/>
</bitmask>
<struct name="BitmaskStruct">
<member name="my_bitmask" type="nonBasic" nonBasicTypeName="MyBitMask"/>
</struct>
// Define a struct type to contain a bitmask
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("BitmaskStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define the bitmask type
DynamicTypeBuilder::_ref_type bitmask_builder {DynamicTypeBuilderFactory::get_instance()->create_bitmask_type(8)};
/* Alternative
TypeDescriptor::_ref_type bitmask_type_descriptor {traits<TypeDescriptor>::make_shared()};
bitmask_type_descriptor->kind(TK_BITMASK);
bitmask_type_descriptor->name("MyBitMask");
bitmask_type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(
TK_BOOLEAN));
bitmask_type_descriptor->bound().push_back(8);
DynamicTypeBuilder::_ref_type bitmask_builder {DynamicTypeBuilderFactory::get_instance()->create_type(
bitmask_type_descriptor)};
*/
// Add bitfield members to the bitmask type
MemberDescriptor::_ref_type bitfield_member_descriptor {traits<MemberDescriptor>::make_shared()};
bitfield_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BOOLEAN));
bitfield_member_descriptor->name("flag0");
bitfield_member_descriptor->id(0);
bitmask_builder->add_member(bitfield_member_descriptor);
bitfield_member_descriptor = traits<MemberDescriptor>::make_shared();
bitfield_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BOOLEAN));
bitfield_member_descriptor->name("flag1");
bitmask_builder->add_member(bitfield_member_descriptor);
bitfield_member_descriptor = traits<MemberDescriptor>::make_shared();
bitfield_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BOOLEAN));
bitfield_member_descriptor->name("flag2");
bitmask_builder->add_member(bitfield_member_descriptor);
bitfield_member_descriptor = traits<MemberDescriptor>::make_shared();
bitfield_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_BOOLEAN));
bitfield_member_descriptor->name("flag5");
bitfield_member_descriptor->id(5);
bitmask_builder->add_member(bitfield_member_descriptor);
// Build the bitmask type
DynamicType::_ref_type bitmask_type = bitmask_builder->build();
// Add a bitmask member to the struct
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_bitmask");
member_descriptor->type(bitmask_type);
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for bitmask member.
uint8_t in_value {3}; // Setting both "flag0" and "flag1" simultaneously.
uint8_t out_value {0};
data->set_uint8_value(data->get_member_id_by_name("my_bitmask"), in_value);
data->get_uint8_value(out_value, data->get_member_id_by_name("my_bitmask"));
// Set and retrieve specific bitflag
bool in_bitflag_value = true;
bool out_bitflag_value = false;
DynamicData::_ref_type bitmask_data = data->loan_value(data->get_member_id_by_name("my_bitmask"));
bitmask_data->set_boolean_value(bitmask_data->get_member_id_by_name("flag5"), in_bitflag_value);
bitmask_data->get_boolean_value(out_bitflag_value, bitmask_data->get_member_id_by_name("flag5"));
For a detailed explanation about the XML definition of this type, please refer to XML Bitmask Types.
Alias Types¶
Alias types provide an alternative name to an already existing type.
The TypeKind used to identify aliases is TK_ALIAS.
Besides defining the alias name, the underlying type must be set using TypeDescriptor base_type property.
Alias recursion is supported by defining another alias type as the base type.
Once the DynamicData is created, information can be accessed as if working with the base type.
typedef MyEnum MyAliasedEnum;
typedef string<100> MyAliasedBoundedString;
typedef MyAliasedEnum MyRecursiveAlias;
struct AliasStruct
{
MyAliasedEnum my_aliased_enum;
MyAliasedBoundedString my_aliased_bounded_string;
MyRecursiveAlias my_recursive_alias;
};
<typedef name="MyAliasedEnum" type="nonBasic" nonBasicTypeName="MyEnum"/>
<!-- XSD does not allow to set bounds to aliased strings -->
<typedef name="MyAliasedBoundedString" type="string"/>
<typedef name="MyRecursiveAlias" type="nonBasic" nonBasicTypeName="MyAliasedEnum"/>
<struct name="AliasStruct">
<member name="my_aliased_enum" type="nonBasic" nonBasicTypeName="MyAliasedEnum"/>
<member name="my_aliased_bounded_string" type="nonBasic" nonBasicTypeName="MyAliasedBoundedString"/>
<member name="my_recursive_alias" type="nonBasic" nonBasicTypeName="MyRecursiveAlias"/>
</struct>
// Define a struct type to contain the alias
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("AliasStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define an alias type for the enum
TypeDescriptor::_ref_type aliasenum_type_descriptor {traits<TypeDescriptor>::make_shared()};
aliasenum_type_descriptor->kind(TK_ALIAS);
aliasenum_type_descriptor->name("MyAliasedEnum");
aliasenum_type_descriptor->base_type(enum_type);
DynamicTypeBuilder::_ref_type aliasenum_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(aliasenum_type_descriptor)};
// Build the alias type
DynamicType::_ref_type aliasenum_type = aliasenum_builder->build();
// Define an alias type for a bounded string
TypeDescriptor::_ref_type alias_bounded_string_type_descriptor {traits<TypeDescriptor>::make_shared()};
alias_bounded_string_type_descriptor->kind(TK_ALIAS);
alias_bounded_string_type_descriptor->name("MyAliasedBoundedString");
alias_bounded_string_type_descriptor->base_type(DynamicTypeBuilderFactory::get_instance()->
create_string_type(100)->build());
DynamicTypeBuilder::_ref_type alias_bounded_string_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(alias_bounded_string_type_descriptor)};
// Build the alias type for the bounded string
DynamicType::_ref_type alias_bounded_string_type = alias_bounded_string_builder->build();
// Define a recursive alias
TypeDescriptor::_ref_type recursive_alias_type_descriptor {traits<TypeDescriptor>::make_shared()};
recursive_alias_type_descriptor->kind(TK_ALIAS);
recursive_alias_type_descriptor->name("MyRecursiveAlias");
recursive_alias_type_descriptor->base_type(aliasenum_type);
DynamicTypeBuilder::_ref_type recursive_alias_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(recursive_alias_type_descriptor)};
// Build the recursive alias type
DynamicType::_ref_type recursive_alias_type = recursive_alias_builder->build();
// Add alias enum member to the structure
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_aliased_enum");
member_descriptor->type(aliasenum_type);
struct_builder->add_member(member_descriptor);
// Add alias bounded string member to the structure
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_aliased_bounded_string");
member_descriptor->type(alias_bounded_string_type);
struct_builder->add_member(member_descriptor);
// Add recursive alias member to the structure
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->name("my_recursive_alias");
member_descriptor->type(recursive_alias_type);
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for the alias enum member
MyEnum in_value {MyEnum::C};
int32_t out_value {0};
data->set_int32_value(data->get_member_id_by_name("my_alias_enum"), in_value);
data->get_int32_value(out_value, data->get_member_id_by_name("my_alias_enum"));
For a detailed explanation about the XML definition of this type, please refer to XML Alias Types.
Sequence types¶
Sequence types are one-dimensional collections of any type.
The TypeKind used to identify sequences is TK_SEQUENCE.
TypeDescriptor element_type property must be set with the collection’s type.
Additionally, bound property must also be configured with the sequence’s maximum length, or
LENGTH_UNLIMITED in case of unbounded sequences.
DynamicTypeBuilderFactory exposes the function DynamicTypeBuilderFactory::create_sequence_type to
facilitate the creation of this type.
This API requires the type stored in the collection and the collection’s bound, using LENGTH_UNLIMITED in case
of unbounded sequences.
DynamicData class provides specific get_values() and set_values() functions for each primitive
type, allowing users to easily work with sequences of primitive types.
Primitive type promotion is also applicable for these methods.
For sequences of more complex types, please refer to Managing Complex Types Data.
If a specific range of values within the sequence are to be modified, passing the starting index to
get_values() / set_values() would only manage data from that element forward until the length of the given
input.
Specific collection’s element can be also be modified using the get_value() / set_value() passing the index
of the element to be modified.
struct SequenceStruct
{
sequence<MyBitmask> bitmask_sequence;
sequence<short, 5> short_sequence;
};
<struct name="SequenceStruct">
<member name="bitmask_sequence" type="nonBasic" nonBasicTypeName="MyBitMask" sequenceMaxLength="-1"/>
<member name="short_sequence" sequenceMaxLength="5" type="int16"/>
</struct>
// Define a struct type to contain the sequence
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("SequenceStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define a member for the sequence
MemberDescriptor::_ref_type sequence_member_descriptor {traits<MemberDescriptor>::make_shared()};
sequence_member_descriptor->name("bitmask_sequence");
sequence_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_sequence_type(bitmask_type,
static_cast<uint32_t>(LENGTH_UNLIMITED))->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_SEQUENCE);
type_descriptor->element_type(bitmask_type);
type_descriptor->bound().push_back(static_cast<uint32_t>(LENGTH_UNLIMITED));
sequence_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(
type_descriptor)->build());
*/
// Add the sequence member to the struct
struct_builder->add_member(sequence_member_descriptor);
sequence_member_descriptor = traits<MemberDescriptor>::make_shared();
sequence_member_descriptor->name("short_sequence");
sequence_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_sequence_type(
DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16), 5)->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_SEQUENCE);
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16));
type_descriptor->bound().push_back(5);
sequence_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(
type_descriptor)->build());
*/
// Add the sequence member to the struct
struct_builder->add_member(sequence_member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for the sequence member
Int16Seq in_value = {1, 2};
Int16Seq out_value;
data->set_int16_values(data->get_member_id_by_name("short_sequence"), in_value);
data->get_int16_values(out_value, data->get_member_id_by_name("short_sequence"));
DynamicData::_ref_type sequence_data {data->loan_value(data->get_member_id_by_name("short_sequence"))};
// Set the two latest possible values on the sequence
sequence_data->set_int16_values(3, in_value);
// Read every sequence value from index 1 to the end
sequence_data->get_int16_values(out_value, 1);
int16_t in_simple_value = 8;
int16_t out_simple_value;
sequence_data->set_int16_value(2, in_simple_value);
sequence_data->get_int16_value(out_simple_value, 2);
data->return_loaned_value(sequence_data);
For a detailed explanation about the XML definition of this type, please refer to XML Sequence Types.
Array types¶
Array types are multi-dimensional collections of any type.
The TypeKind used to identify arrays is TK_ARRAY.
TypeDescriptor element_type property must be set with the collection’s type.
Additionally, bound property must be configured with the sequence containing the size of each dimension.
Bound sequence must have at least one dimension and it is not allowed for any dimension to have size 0.
DynamicTypeBuilderFactory exposes the function DynamicTypeBuilderFactory::create_array_type to
facilitate the creation of this type.
This API requires the type stored in the collection and the sequence with the collection’s dimensions.
DynamicData class provides specific get_values() and set_values() functions for each primitive
type, allowing users to easily work with arrays of primitives types.
For arrays of more complex types, please refer to Managing Complex Types Data.
Note
Multi-dimensional arrays flatten every dimension into a single-dimension array.
Primitive type promotion is also applicable for these methods.
If a specific range of values within the array are to be modified, passing the starting index to
get_values() / set_values() would only manage data from that element forward until the length of the given
input.
Specific collection’s element can be also be modified using the get_value() / set_value() passing the index
of the element to be modified.
struct ArrayStruct
{
long long_array[2][3][4];
};
<struct name="ArrayStruct">
<member name="long_array" type="int32" arrayDimensions="2,3,4"/>
</struct>
// Define a struct type to contain the array
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("ArrayStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define a member for the array
MemberDescriptor::_ref_type array_member_descriptor {traits<MemberDescriptor>::make_shared()};
array_member_descriptor->name("long_array");
array_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_array_type(
DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT32), { 2, 3, 4 })->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_ARRAY);
type_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT32));
type_descriptor->bound().push_back(2);
type_descriptor->bound().push_back(3);
type_descriptor->bound().push_back(4);
array_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(
type_descriptor)->build());
*/
// Add the array member to the struct
struct_builder->add_member(array_member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Set and retrieve values for the array member
Int32Seq in_value = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 23, 24};
Int32Seq out_value;
data->set_int32_values(data->get_member_id_by_name("long_array"), in_value);
data->get_int32_values(out_value, data->get_member_id_by_name("long_array"));
DynamicData::_ref_type array_data {data->loan_value(data->get_member_id_by_name("long_array"))};
// Set the two latest possible values on the array
Int32Seq small_in_value = {0, 1};
array_data->set_int32_values(22, small_in_value);
// Read every array value from index 1 to the end
array_data->get_int32_values(out_value, 1);
int32_t in_simple_value = 8;
int32_t out_simple_value;
array_data->set_int32_value(2, in_simple_value);
array_data->get_int32_value(out_simple_value, 2);
data->return_loaned_value(array_data);
For a detailed explanation about the XML definition of this type, please refer to XML Array Types.
Map Types¶
Map types are a collection of key/value pair types.
Access to the value element is done through the key which is unique within the map type.
The TypeKind used to identify maps is TK_MAP.
TypeDescriptor element_type property must be set with the map value type.
TypeDescriptor key_type property must be set with the map key type.
Allowed key types are signed and unsigned integer types and string types.
Note
Currently, wide string keys are not supported as map keys.
Additionally, bound property must also be configured with the map’s maximum length, or LENGTH_UNLIMITED
in case of unbounded maps.
DynamicTypeBuilderFactory exposes the DynamicTypeBuilderFactory::create_map_type function to
facilitate the creation of this type.
This API requires the type of both the key and the value stored in the collection, and the collection’s bound, using
LENGTH_UNLIMITED in case of unbounded maps.
Manipulating map types data is more complex.
First the MemberId corresponding to a specific key must be retrieved using
DynamicData::get_member_id_by_name API.
This API either returns the MemberId corresponding to the existing key or, if the key does not
exist yet, it creates the key and returns the memberId associated to the just created key.
In order to call this method, the correct string representation of the key value must be passed.
The map value can now be set using the API corresponding to the map value type.
For complex map values, please refer to Managing Complex Types Data.
struct MapStruct
{
map<string, MyAliasedBoundedString> string_alias_unbounded_map;
map<short, long, 2> short_long_map;
};
<struct name="MapStruct">
<member name="string_alias_unbounded_map" type="nonBasic" nonBasicTypeName="MyAliasedBoundedString" key_type="string" mapMaxLength="-1"/>
<member name="short_long_map" type="int32" key_type="int16" mapMaxLength="2"/>
</struct>
// Define a struct type to contain the map
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("MapStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Define a member for the map
MemberDescriptor::_ref_type map_member_descriptor {traits<MemberDescriptor>::make_shared()};
map_member_descriptor->name("string_long_array_unbounded_map");
map_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_map_type(
DynamicTypeBuilderFactory::get_instance()->create_string_type(static_cast<uint32_t>(
LENGTH_UNLIMITED))->build(), alias_bounded_string_type, static_cast<uint32_t>(
LENGTH_UNLIMITED))->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_MAP);
type_descriptor->key_element_type(DynamicTypeBuilderFactory::get_instance()->create_string_type(
static_cast<uint32_t>(LENGTH_UNLIMITED)->build());
type_descriptor->element_type(alias_bounded_string_type);
type_descriptor->bound().push_back(static_cast<uint32_t>(LENGTH_UNLIMITED));
map_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(
type_descriptor)->build());
*/
// Add the map member to the struct
struct_builder->add_member(map_member_descriptor);
map_member_descriptor = traits<MemberDescriptor>::make_shared();
map_member_descriptor->name("short_long_map");
map_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_map_type(
DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16),
DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT32), 2)->build());
/* Alternative
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_MAP);
type_descriptor->key_element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16));
type_descriptor->element_type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT32));
type_descriptor->bound().push_back(2);
map_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_type(
type_descriptor)->build());
*/
struct_builder->add_member(map_member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Get the data loan of the map member
DynamicData::_ref_type map_data = data->loan_value(data->get_member_id_by_name("short_long_map"));
// Set and retrieve values for the map member
int32_t key {1};
int32_t in_value {2};
int32_t out_value;
map_data->set_int32_value(map_data->get_member_id_by_name(std::to_string(key)), in_value);
map_data->get_int32_value(out_value, map_data->get_member_id_by_name(std::to_string(key)));
// Return de data loan of the map member
data->return_loaned_value(map_data);
For a detailed explanation about the XML definition of this type, please refer to XML Map Types.
Structure Types¶
Structure types are an aggregation of members of different types.
The TypeKind used to identify structures is TK_STRUCTURE.
Structure types have single inheritance support, so a structure type might extend one other already defined structure.
The structure type which is extended should be configured in the TypeDescriptor base_type property.
Structure extensibility might be configured using TypeDescriptor extensibility_kind
property.
Note
Currently, @nested builtin annotation is not supported.
Structure members must be configured using the DynamicTypeBuilder by calling the DynamicTypeBuilder::add_member
function with the corresponding MemberDescriptor.
Note
Empty structures, with no members, are allowed.
Member name is configured using MemberDescriptor name property and the member type is set using
type property.
Structure members might be keyed to create topic instances by setting the
MemberDescriptor is_key property.
The behavior is the same as setting the @key builtin annotation.
Additionally, MemberDescriptor default_value property might be set to configure the member default value,
and MemberDescriptor id property sets explicitly the member ID.
This behavior is the same as setting the @default and @id
builtin annotations.
Note
Currently, Fast DDS-Gen does not support @default builtin annotation.
Note
Currently, Dynamic Language Binding API implementation does not support the following builtin annotations:
@optional@must_understand@external@try_construct
Member data can be managed using the corresponding accessors for the underlying member type.
Member ID might be retrieved using DynamicData::get_member_id_by_name API.
For managing complex type members, please refer to Managing Complex Types Data.
struct InnerStruct
{
@id(0x10) long first;
};
struct ParentStruct
{
float first;
long long second;
};
struct ComplexStruct : ParentStruct
{
InnerStruct complex_member;
};
<struct name="InnerStruct">
<!-- XML does not support setting Member ID -->
<member name="first" type="int32"/>
</struct>
<!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
<!-- <struct name="ParentStruct">
<member name="first" type="float32"/>
<member name="second" type="int64"/>
</struct>
<struct name="ComplexStruct" baseType="ParentStruct">
<member name="complex_member" type="nonBasic" nonBasicTypeName="InnerStruct"/>
</struct> -->
// Create inner struct type
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(eprosima::fastdds::dds::TK_STRUCTURE);
type_descriptor->name("InnerStruct");
DynamicTypeBuilder::_ref_type builder {DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor)};
// Add members to the inner struct type
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(eprosima::fastdds::dds::TK_INT32));
member_descriptor->name("first");
member_descriptor->id(16);
builder->add_member(member_descriptor);
// Build the inner struct type
DynamicType::_ref_type inner_struct_type {builder->build()};
// Create parent struct type
TypeDescriptor::_ref_type parentstruct_type_descriptor {traits<TypeDescriptor>::make_shared()};
parentstruct_type_descriptor->kind(TK_STRUCTURE);
parentstruct_type_descriptor->name("ParentStruct");
DynamicTypeBuilder::_ref_type parentstruct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(parentstruct_type_descriptor)};
// Add members to the parent struct type
MemberDescriptor::_ref_type parentstruct_member {traits<MemberDescriptor>::make_shared()};
parentstruct_member->name("first");
parentstruct_member->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_FLOAT32));
parentstruct_builder->add_member(parentstruct_member);
parentstruct_member = traits<MemberDescriptor>::make_shared();
parentstruct_member->name("second");
parentstruct_member->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT64));
parentstruct_builder->add_member(parentstruct_member);
// Build the parent struct type
DynamicType::_ref_type parentstruct_type = parentstruct_builder->build();
// Create complex struct type
TypeDescriptor::_ref_type complexstruct_type_descriptor {traits<TypeDescriptor>::make_shared()};
complexstruct_type_descriptor->kind(TK_STRUCTURE);
complexstruct_type_descriptor->name("ComplexStruct");
complexstruct_type_descriptor->base_type(parentstruct_type);
DynamicTypeBuilder::_ref_type complexstruct_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(complexstruct_type_descriptor)};
// Add members to the complex struct type
MemberDescriptor::_ref_type complexstruct_member {traits<MemberDescriptor>::make_shared()};
complexstruct_member->name("complex_member");
complexstruct_member->type(inner_struct_type);
complexstruct_builder->add_member(complexstruct_member);
// Build the complex struct type
DynamicType::_ref_type complexstruct_type = complexstruct_builder->build();
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(complexstruct_type)};
// Set and retrieve values for member of type float
float in_value {3.14};
float out_value {0.0};
data->set_float32_value(data->get_member_id_by_name("first"), in_value);
data->get_float32_value(out_value, data->get_member_id_by_name("first"));
For a detailed explanation about the XML definition of this type, please refer to XML Structure Types.
Union Types¶
Union types are a special type of structure type where only one member exists.
The TypeKind used to identify unions is TK_UNION.
Member selection is performed by setting another special member called discriminator.
The discriminator type must be defined using TypeDescriptor discriminator_type property.
Supported discriminator TypeKind are the following:
TK_BOOLEANTK_BYTETK_CHAR8TK_CHAR16TK_INT8TK_UINT8TK_INT16TK_UINT16TK_INT32TK_UINT32TK_INT64TK_UINT64TK_ENUMTK_ALIASthat resolves, directly or indirectly to one of the aforementioned types.
Union extensibility might be configured using TypeDescriptor extensibility_kind
property.
Note
Currently, @nested builtin annotation is not supported.
Union members must be configured using the DynamicTypeBuilder by calling the DynamicTypeBuilder::add_member
function with the corresponding MemberDescriptor.
At least one union member must be added to the union type.
Union member name is configured using MemberDescriptor name property and the member type is set using
type property.
It is also mandatory to either set MemberDescriptor is_default_label property or configure the
label property.
This latest property indicates the discriminator values that select this specific member.
If no labels are configured, then the flag indicating the member to be the default one, must be set.
Only one union member must be configured as default.
Additionally, MemberDescriptor default_value property might be set to configure the member default value,
and MemberDescriptor id property sets explicitly the member ID.
This behavior is the same as setting the @default and @id
builtin annotations.
Note
Currently, Fast DDS-Gen does not support @default builtin annotation.
Note
Currently, Dynamic Language Binding API implementation does not support the following builtin annotations:
@optional@must_understand@external@try_construct
Member data can be managed using the corresponding accessors for the underlying member type.
Setting a member automatically changes the discriminator value selecting the set member.
When reading a member, the discriminator must be selecting the member being read.
Member ID might be retrieved using DynamicData::get_member_id_by_name API.
For managing complex type members, please refer to Managing Complex Types Data.
union InnerUnion switch (short)
{
case 0:
@id(0x10) PrimitivesStruct first;
case 1:
default:
long long second;
};
union ComplexUnion switch (long)
{
case 0:
case 1:
long third;
default:
InnerUnion fourth;
};
<union name="InnerUnion">
<discriminator type="int16"/>
<case>
<caseDiscriminator value="0"/>
<member name="first" type="nonBasic" nonBasicTypeName="PrimitivesStruct"/>
</case>
<case>
<caseDiscriminator value="1"/>
<caseDiscriminator value="default"/>
<member name="second" type="int64"/>
</case>
</union>
<union name="ComplexUnion">
<discriminator type="int32"/>
<case>
<caseDiscriminator value="0"/>
<caseDiscriminator value="1"/>
<member name="third" type="int32"/>
</case>
<case>
<caseDiscriminator value="default"/>
<member name="fourth" type="nonBasic" nonBasicTypeName="InnerUnion"/>
</case>
</union>
// Define a struct type to contain the union
// Create the inner union
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_UNION);
type_descriptor->name("InnerUnion");
type_descriptor->discriminator_type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(TK_INT16));
DynamicTypeBuilder::_ref_type builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
// Add members to the inner union type
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->type(struct_type);
member_descriptor->name("first");
member_descriptor->id(16);
member_descriptor->label({0});
builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(TK_INT64));
member_descriptor->name("second");
member_descriptor->label({1});
member_descriptor->is_default_label(true);
builder->add_member(member_descriptor);
// Build the inner union type
DynamicType::_ref_type inner_union_type {builder->build()};
// Create a complex union type
type_descriptor = traits<TypeDescriptor>::make_shared();
type_descriptor->kind(TK_UNION);
type_descriptor->name("ComplexUnion");
type_descriptor->discriminator_type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(TK_INT32));
builder = DynamicTypeBuilderFactory::get_instance()->create_type(type_descriptor);
// Add members to the complex union type
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->
get_primitive_type(TK_INT32));
member_descriptor->name("third");
member_descriptor->label({0, 1});
builder->add_member(member_descriptor);
member_descriptor = traits<MemberDescriptor>::make_shared();
member_descriptor->type(inner_union_type);
member_descriptor->name("fourth");
member_descriptor->is_default_label(true);
builder->add_member(member_descriptor);
// Build the complex union type
DynamicType::_ref_type union_type {builder->build()};
// Create dynamic data based on the union type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(union_type)};
// Get the loan for the InnerUnion member
DynamicData::_ref_type union_data = data->loan_value(data->get_member_id_by_name("InnerUnion"));
// Set and retrieve values for the long long member within InnerUnion member
int64_t in_value {2};
int64_t out_value;
union_data->set_int64_value(union_data->get_member_id_by_name("second"), in_value);
union_data->get_int64_value(out_value, union_data->get_member_id_by_name("second"));
// Return de data loan of the member
data->return_loaned_value(union_data);
For a detailed explanation about the XML definition of this type, please refer to XML Union Types.
Bitset Types¶
Bitset types are an aggregation of bitfields.
The TypeKind used to identify bitsets is TK_BITSET.
bound property contains the sequence with the bitfield’s bitcount (number of bits).
In order to be consistent, the length of the bound sequence must agree with the number of bitfields.
Bitset types have single inheritance support, so a bitset type might extend one other already defined bitset.
The bitset type which is extended should be configured in the TypeDescriptor base_type property.
Bitfields must be configured using the DynamicTypeBuilder by calling the DynamicTypeBuilder::add_member
function with the corresponding MemberDescriptor.
At least one bitfield is required for the bitset to be consistent.
Bitfield name is configured using MemberDescriptor name property, and the bitfield initial bit position
is set using MemberDescriptor id property.
Note
For derived bitsets, the first bitfield initial position must be after the bits defined by the parent bitset type.
A bitfield manages exclusively a set of bits, so no bitfield superposition is allowed.
Additionally, MemberDescriptor type property might be set to configure an integer type to access bitfield
data.
If not set, the minimum unsigned integer type is used instead:
Number of bits |
C++ holder type |
|---|---|
|
|
|
|
|
|
|
|
|
|
Each bitfield (or member) works like its primitive type with the only difference that the internal storage only modifies the involved bits instead of the full primitive value.
bitset ParentBitSet
{
bitfield<3> a;
bitfield<1> b;
bitfield<4>;
bitfield<10> c;
bitfield<12, short> d;
};
bitset ChildBitSet : ParentBitSet
{
bitfield<1> e;
bitfield<20, unsigned long> f;
};
struct BitsetStruct
{
ChildBitSet my_bitset;
};
<bitset name="ParentBitset">
<bitfield name="a" bit_bound="3"/>
<bitfield name="b" bit_bound="1"/>
<bitfield bit_bound="4"/>
<bitfield name="c" bit_bound="10"/>
<bitfield name="d" bit_bound="12" type="int16"/>
</bitset>
<!-- TODO(XTypes: Fix inheritance loading from XML profile) Fast DDS#4626 -->
<!--<bitset name="ChildBitSet" baseType="ParentBitSet">
<bitfield name="e" bit_bound="1"/>
<bitfield name="f" bit_bound="20" type="uint32"/>
</bitset>
<struct name="BitsetStruct">
<member name="my_bitset" type="nonBasic" nonBasicTypeName="ChildBitSet"/>
</struct>-->
// Define a struct type to contain the bitset
TypeDescriptor::_ref_type struct_type_descriptor {traits<TypeDescriptor>::make_shared()};
struct_type_descriptor->kind(TK_STRUCTURE);
struct_type_descriptor->name("BitsetStruct");
DynamicTypeBuilder::_ref_type struct_builder {DynamicTypeBuilderFactory::get_instance()->create_type(
struct_type_descriptor)};
// Define type for parent bitset
TypeDescriptor::_ref_type bitset_type_descriptor {traits<TypeDescriptor>::make_shared()};
bitset_type_descriptor->kind(TK_BITSET);
bitset_type_descriptor->name("ParentBitSet");
bitset_type_descriptor->bound({3, 1, 10, 12});
DynamicTypeBuilder::_ref_type bitset_builder {DynamicTypeBuilderFactory::get_instance()->create_type(
bitset_type_descriptor)};
// Add members to the bitset type
MemberDescriptor::_ref_type bitset_member_descriptor {traits<MemberDescriptor>::make_shared()};
bitset_member_descriptor->name("a");
bitset_member_descriptor->id(0);
bitset_builder->add_member(bitset_member_descriptor);
bitset_member_descriptor = traits<MemberDescriptor>::make_shared();
bitset_member_descriptor->name("b");
bitset_member_descriptor->id(3);
bitset_builder->add_member(bitset_member_descriptor);
bitset_member_descriptor = traits<MemberDescriptor>::make_shared();
bitset_member_descriptor->name("c");
bitset_member_descriptor->id(8);
bitset_builder->add_member(bitset_member_descriptor);
bitset_member_descriptor = traits<MemberDescriptor>::make_shared();
bitset_member_descriptor->name("d");
bitset_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16));
bitset_member_descriptor->id(18);
bitset_builder->add_member(bitset_member_descriptor);
// Build the bitset type
DynamicType::_ref_type parentbitset_type = bitset_builder->build();
// Create child bitset type
TypeDescriptor::_ref_type childbitset_type_descriptor {traits<TypeDescriptor>::make_shared()};
childbitset_type_descriptor->kind(TK_BITSET);
childbitset_type_descriptor->name("ChildBitSet");
childbitset_type_descriptor->base_type(parentbitset_type);
childbitset_type_descriptor->bound({1, 20});
DynamicTypeBuilder::_ref_type childbitset_builder {DynamicTypeBuilderFactory::get_instance()->create_type(
childbitset_type_descriptor)};
// Add members to the child bitset type
MemberDescriptor::_ref_type childbitset_member_descriptor {traits<MemberDescriptor>::make_shared()};
childbitset_member_descriptor->name("e");
childbitset_member_descriptor->id(30);
childbitset_builder->add_member(childbitset_member_descriptor);
childbitset_member_descriptor = traits<MemberDescriptor>::make_shared();
childbitset_member_descriptor->name("d");
childbitset_member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_UINT32));
childbitset_member_descriptor->id(31);
childbitset_builder->add_member(childbitset_member_descriptor);
// Build the child bitset type
DynamicType::_ref_type bitset_type = childbitset_builder->build();
// Add the bitset member to the struct
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("my_bitset");
member_descriptor->type(bitset_type);
struct_builder->add_member(member_descriptor);
// Build the struct type
DynamicType::_ref_type struct_type {struct_builder->build()};
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(struct_type)};
// Get the loan for the bitset member
DynamicData::_ref_type bitset_data = data->loan_value(data->get_member_id_by_name("my_bitset"));
// Set and retrieve bitfield values
int16_t in_value {2};
int16_t out_value;
bitset_data->set_int16_value(bitset_data->get_member_id_by_name("d"), in_value);
bitset_data->get_int16_value(out_value, bitset_data->get_member_id_by_name("d"));
// Return de data loan of the member
data->return_loaned_value(bitset_data);
For a detailed explanation about the XML definition of this type, please refer to XML Bitset Types.
Annotations¶
Custom annotations¶
Both types and type members might be annotated using DynamicTypeBuilder::apply_annotation and
DynamicTypeBuilder::apply_annotation_to_member API respectively.
Annotations are defined using an AnnotationDescriptor which provides two properties: type and
value.
The annotation type must be the DynamicType representing the annotation being applied.
The TypeKind used to identify annotations is TK_ANNOTATION.
The annotation name is set in TypeDescriptor name property.
The annotation type might have any number of parameters.
Annotation parameters must be configured using the DynamicTypeBuilder by calling the
DynamicTypeBuilder::add_member function with the corresponding MemberDescriptor.
Annotation parameters must define the annotation parameter name in MemberDescriptor name property,
and the parameter type using type property.
Only the following types can be used to define an annotation parameter:
Note
Currently, wide string types are not supported as annotation parameters.
Annotation parameter values are defined with AnnotationDescriptor value property using
AnnotationDescriptor::set_value().
The annotation parameter name provided to the API must coincide with the one defined with the annotation type.
The annotation parameter value must be converted to its string representation.
Note
Currently, custom annotations are not supported with XML DynamicTypes.
@annotation MyAnnotation
{
short length;
};
@MyAnnotation(length = 5)
struct AnnotatedStruct
{
@MyAnnotation(length = 10) string string_var;
};
<!-- XML Types Profiles does not support defining/setting custom annotations -->
// Create the structure to annotate
TypeDescriptor::_ref_type type_descriptor {traits<TypeDescriptor>::make_shared()};
type_descriptor->kind(TK_STRUCTURE);
type_descriptor->name("AnnotatedStruct");
DynamicTypeBuilder::_ref_type type_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(type_descriptor)};
MemberDescriptor::_ref_type member_descriptor {traits<MemberDescriptor>::make_shared()};
member_descriptor->name("string_var");
member_descriptor->type(DynamicTypeBuilderFactory::get_instance()->create_string_type(static_cast<uint32_t>(
LENGTH_UNLIMITED))->build());
type_builder->add_member(member_descriptor);
// Create the annotation type
AnnotationDescriptor::_ref_type annotation_descriptor {traits<AnnotationDescriptor>::make_shared()};
TypeDescriptor::_ref_type annotation_type {traits<TypeDescriptor>::make_shared()};
annotation_type->kind(TK_ANNOTATION);
annotation_type->name("MyAnnotation");
DynamicTypeBuilder::_ref_type annotation_builder {DynamicTypeBuilderFactory::get_instance()->
create_type(annotation_type)};
// Add members to the annotation type
MemberDescriptor::_ref_type annotation_parameter {traits<MemberDescriptor>::make_shared()};
annotation_parameter->name("length");
annotation_parameter->type(DynamicTypeBuilderFactory::get_instance()->get_primitive_type(TK_INT16));
annotation_builder->add_member(annotation_parameter);
// Set the annotation type using the annotation descriptor
annotation_descriptor->type(annotation_builder->build());
// Set the value of the annotation
annotation_descriptor->set_value("length", std::to_string(5));
// Apply the annotation to the structure
type_builder->apply_annotation(annotation_descriptor);
// Reuse annotation descriptor to annotate struct member
annotation_descriptor = traits<AnnotationDescriptor>::make_shared();
annotation_descriptor->type(annotation_builder->build());
annotation_descriptor->set_value("length", std::to_string(10));
DynamicTypeMember::_ref_type member;
type_builder->get_member_by_name(member, "string_var");
type_builder->apply_annotation_to_member(member->get_id(), annotation_descriptor);
Builtin annotations¶
Beside the user-defined custom annotations, there are a number of builtin annotations that have already mentioned throughout this section.
The table below summarizes the builtin annotations that can be applied using the Dynamic Language Binding API. Please, refer to builtin annotations for the complete list and their behavior.
Builtin annotation |
Dynamic Language Binding API |
Dynamic Language Binding support |
XML Dynamic Type profiles support |
|---|---|---|---|
|
|
✅ |
❌ |
|
|
✅ |
✅❌ (Enumeration types not configurable). |
|
|
✅ |
❌ |
|
|
✅ |
❌ |
|
|
✅ |
❌ |
|
|
❌ |
❌ |
|
|
✅ |
❌ |
|
|
✅ |
❌ |
|
|
✅ |
❌ |
|
|
✅ |
❌ |
|
|
❌ |
❌ |
|
|
❌ |
❌ |
|
|
✅ |
✅ |
|
|
❌ |
❌ |
|
|
✅ |
✅ |
|
|
❌ |
❌ |
To apply the @extensibility annotation (and its shortcuts) the TypeDescriptor provides
extensibility_kind property.
@key annotation is applied enabling MemberDescriptor is_key property.
Managing Complex Types Data¶
Some DynamicData instances manage complex types that cannot be directly modified with the primitive getters and
setters.
Dynamic Language Binding provides two possible approaches for managing complex data types:
DynamicData::get_complex_valueandDynamicData::set_complex_value: This API allows to get/set generic DynamicData. The main difference with the next approach is that this API performs always a copy.DynamicData::loan_value: this API allows to loan a reference to a DynamicData to work with preventing the data copy.DynamicData::return_loaned_valuemust be called to return the loan. CallingDynamicData::loan_valuefor an already loaned value will fail.
The following snippet includes an example of managing complex data using the same structure as the one defined in Structure types:
// Create dynamic data based on the struct type
DynamicData::_ref_type data {DynamicDataFactory::get_instance()->create_data(complexstruct_type)};
// Get/Set complex API (copy)
DynamicData::_ref_type complex_data;
data->get_complex_value(complex_data, data->get_member_id_by_name("complex_member"));
// Set data
int32_t in_value {10};
complex_data->set_int32_value(complex_data->get_member_id_by_name("first"), in_value);
data->set_complex_value(data->get_member_id_by_name("complex_member"), complex_data);
// Loan API
DynamicData::_ref_type loan_data = data->loan_value(data->get_member_id_by_name("complex_member"));
loan_data->set_int32_value(loan_data->get_member_id_by_name("first"), in_value);
int32_t out_value;
loan_data->get_int32_value(out_value, loan_data->get_member_id_by_name("first"));
data->return_loaned_value(loan_data);
Typical Use-Cases¶
Fast DDS is highly configurable, which allows for its use in a large number of scenarios. This section provides configuration examples for the following typical use cases when dealing with distributed systems:
Large Data mode and Fast DDS over TCP. Describes how to configure Fast DDS to use the
LARGE_DATAbuiltin transports mode. This mode enables efficient utilization of TCP transport without the need for constant reconfiguration during deployment changes. It optimizes communication performance for large data samples over lossy networks by employing a combination of UDP and TCP/SHM transports.Fast DDS over WIFI. Presents a case where Discovery through multicast communication is a challenge. This example shows how to:
Configure an initial list of peers with the address-port pairs of the remote participants (see Configuring Initial Peers).
Disable the multicast discovery mechanism (see Disabling multicast discovery).
Configure a SERVER discovery mechanism (see Discovery Server).
Well Known Network Deployments. Describes a situation where the entire entity network topology (Participants, Publishers, Subscribers, and their addresses and ports) are known beforehand. In these kind of environments, Fast DDS allows to completely avoid the discovery phase configuring a STATIC discovery mechanism.
Topics with many subscribers. In cases where there are many DataReaders subscribed to the same Topic, using multicast delivery can help reducing the overhead in the network and CPU.
Large Data Rates. Presents configuration options that can improve the performance in scenarios where the amount of data exchanged between a Publisher and a Subscriber is large, either because of the data size or because the message rate. The examples describe how to:
Use TCP based communications (see Large Data mode and Fast DDS over TCP).
Configure the socket buffer size (see increase the buffers size).
Limit the publication rate (see Flow Controllers).
Tune the size of the socket buffers (see Increasing socket buffers size).
Tune the Heartbeat period (see Tuning Heartbeat Period).
Configure a non-strict reliable mode (see Using Non-strict Reliability).
Real-time behavior. Describes the configuration options that allows using Fast DDS on a real-time scenario. The examples describe how to:
Configure memory management to avoid dynamic memory allocation (see Tuning allocations).
Limit the blocking time of API functions to have a predictable response time (see Non-blocking calls).
Reduce memory usage. For use cases with memory consumption constraints, Fast DDS can be configured to reduce memory footprint to a minimum by adjusting different QoS policies.
Zero-Copy communication. Under certain constraints, Fast DDS can provide application level communication between publishing and subscribing nodes avoiding any data copy during the process.
Unique network flows. This use case illustrates the APIs that allow for the request of unique network flows, and for the identification of those in use.
Dynamic network interfaces. If the network interfaces are expected to change while the application is running, Fast DDS provides an easy way of re-scanning the available interfaces and including them.
Statistics module. This use case explains how to enable the Statistics module within the monitored application, and how to create a statistics monitoring application.
ROS 2 using Fast DDS middleware. Since Fast DDS is the default middleware implementation in every OSRF Robot Operation System 2 (ROS 2) long term (LTS) releases and most of the non-LTS releases, this documentation includes a whole independent section to show the use of the library in ROS 2, and how to take full advantage of Fast DDS wide set of capabilities in a ROS 2 project.
How to use eProsima DDS Record and Replay (rosbag2 and DDS). Instructions on how to tune your application to be able to record and replay your DDS messages using ROS 2 rosbag2 package.
Request-Reply communication. Although Fast DDS provides a Publisher-Subscriber communication protocol, it offers a mechanism to use Request-Reply communications. This use case explains how to use the APIs to communicate two application using Request-Reply.
Remote type discovery and endpoint matching. This use case leverages the Remote Data Types Discovery to create endpoints and start communicating with remote discovered endpoints with previously unknown data types.
Large Data mode and Fast DDS over TCP¶
As explained in TCP Transport, Fast DDS offers the possibility to communicate nodes within distributed applications with DDS over a TCP transport layer. This has the advantage of leveraging the builtin flow control and reliability of the TCP protocol, which in the context of DDS applications is best suited for the transmission of large payloads, i.e. large data samples, over lossy networks. Examples of such cases would be transmitting video or large point clouds resulting from laser scanning over WiFi links.
The configuration of the TCP transport typically involves an a priori knowledge of the deployment in order
to set Initial peers for Discovery, which may not always be possible and creates difficulties when
reallocating nodes of the distributed applications, as the entire discovery configuration needs to be changed.
To overcome this problem, Fast DDS presents the LARGE_DATA builtin transports configuration as an approach for
leveraging the Fast DDS’ TCP transport capabilities while at the same time not requiring configuration modifications
when the deployment changes over time.
LARGE_DATA has been specifically designed to improve communication performance of large data samples over lossy
networks. When configured, UDP transport will exclusively be used during the PDP discovery phase,
taking advantage of the more reliable TCP/SHM for the remainder of the communication process. Fast DDS offers
an extremely straightforward implementation for this mode through an environment variable, XML profiles or via code.
Additionally, it is possible to use the builtin transports configuration options to customize the LARGE_DATA mode
to better suit the specific requirements of each user.
For a video demonstration showcasing a practical example of this configuration, please refer to: Large Data communication with ROS 2.
Also, it is possible to enable TCP communication while using Discovery Server to manage Discovery.
Large Data Mode¶
The following snippets show how to configure Fast DDS DomainParticipants to run the
PDP discovery phase over UDP multicast and communicate application data over a
TCP Transport or Shared Memory Transport, which is called the LARGE_DATA
configuration (See Managing the Builtin Transports).
With this approach, applications managing large samples can benefit from transmitting their data over TCP or SHM,
while at the same time have the flexibility of automatic discovery.
The LARGE_DATA mode can be set using the FASTDDS_BUILTIN_TRANSPORTS environment variable
(see FASTDDS_BUILTIN_TRANSPORTS), XML profiles or via code.
export FASTDDS_BUILTIN_TRANSPORTS=LARGE_DATA
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<!--
UDP transport for PDP and SHM/TCPv4 transport for both EDP and application data
-->
<participant profile_name="large_data_builtin_transports" is_default_profile="true">
<rtps>
<builtinTransports>LARGE_DATA</builtinTransports>
</rtps>
</participant>
</profiles>
</dds>
eprosima::fastdds::dds::DomainParticipantQos pqos = PARTICIPANT_QOS_DEFAULT;
/* Transports configuration */
// UDPv4 transport for PDP over multicast and SHM / TCPv4 transport for EDP and application data
pqos.setup_transports(eprosima::fastdds::rtps::BuiltinTransports::LARGE_DATA);
/* Create participant as usual */
eprosima::fastdds::dds::DomainParticipant* participant =
eprosima::fastdds::dds::DomainParticipantFactory::get_instance()->create_participant(0, pqos);
Note
LARGE_DATA configuration of the builtin transports will also create a SHM transport along the UDP and TCP
transports. Shared Memory will be used whenever it is possible. Manual configuration will be required if a TCP
communication is required when SHM is feasible.
eprosima::fastdds::dds::DomainParticipantQos pqos = PARTICIPANT_QOS_DEFAULT;
/* Transports configuration */
// UDPv4 transport for PDP over multicast
auto pdp_transport = std::make_shared<eprosima::fastdds::rtps::UDPv4TransportDescriptor>();
pqos.transport().user_transports.push_back(pdp_transport);
// TCPv4 transport for EDP and application data (The listening port must to be unique for
// each participant in the same host)
constexpr uint16_t tcp_listening_port = 0;
auto data_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>();
data_transport->add_listener_port(tcp_listening_port);
pqos.transport().user_transports.push_back(data_transport);
pqos.transport().use_builtin_transports = false;
/* Locators */
// Define locator for PDP over multicast
eprosima::fastrtps::rtps::Locator_t pdp_locator;
pdp_locator.kind = LOCATOR_KIND_UDPv4;
eprosima::fastrtps::rtps::IPLocator::setIPv4(pdp_locator, "239.255.0.1");
pqos.wire_protocol().builtin.metatrafficMulticastLocatorList.push_back(pdp_locator);
// Define locator for EDP and user data
eprosima::fastrtps::rtps::Locator_t tcp_locator;
tcp_locator.kind = LOCATOR_KIND_TCPv4;
eprosima::fastrtps::rtps::IPLocator::setIPv4(tcp_locator, "0.0.0.0");
eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(tcp_locator, tcp_listening_port);
eprosima::fastrtps::rtps::IPLocator::setLogicalPort(tcp_locator, tcp_listening_port);
pqos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(tcp_locator);
pqos.wire_protocol().default_unicast_locator_list.push_back(tcp_locator);
/* Create participant as usual */
eprosima::fastdds::dds::DomainParticipant* participant =
eprosima::fastdds::dds::DomainParticipantFactory::get_instance()->create_participant(0, pqos);
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<transport_descriptors>
<!--
UDP transport for PDP
-->
<transport_descriptor>
<transport_id>pdp_transport</transport_id>
<type>UDPv4</type>
</transport_descriptor>
<!--
TCP transport for both EDP and application data
-->
<transport_descriptor>
<transport_id>data_transport</transport_id>
<type>TCPv4</type>
<!--
Set listening port for the transport.
This needs to be unique for each participant in the host
-->
<listening_ports>
<port>0</port>
</listening_ports>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="udp_multicast_pdp_w_tcp_data" is_default_profile="true">
<rtps>
<!--
Set participant transports
-->
<userTransports>
<transport_id>pdp_transport</transport_id>
<transport_id>data_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<!--
Discovery configuration
-->
<builtin>
<!--
PDP over UDP multicast
-->
<metatrafficMulticastLocatorList>
<locator>
<udpv4>
<address>239.255.0.1</address>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
<!--
EDP over TCP
-->
<metatrafficUnicastLocatorList>
<locator>
<tcpv4>
<address>0.0.0.0</address>
<physical_port>12345</physical_port>
<port>12345</port>
</tcpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
<!--
Application data over TCP
-->
<defaultUnicastLocatorList>
<locator>
<tcpv4>
<address>0.0.0.0</address>
<physical_port>12345</physical_port>
<port>12345</port>
</tcpv4>
</locator>
</defaultUnicastLocatorList>
</rtps>
</participant>
</profiles>
</dds>
Large Data with configuration options¶
As it has been observed in Large Data Mode, LARGE_DATA builtin transports option offers an easy
and efficient way to improve performance when working with large data.
Nonetheless, custom configuration can help to enhance the performance even further.
Fast DDS provides configuration options to adjust the behavior of the builtin transports.
This becomes particularly relevant when using the LARGE_DATA mode, as it enables increasing the maximum message
size beyond 65500 KB and prevents fragmentation, leveraging the TCP and SHM transports.
All builtin transports can be configured by adjusting the following parameters:
max_msg_size: Message maximum size that can be sent over the transport. Sending messages larger than this size will result in fragmentation. Its maximum value is (2^32)-1 B for TCP and SHM and 65500 KB for UDP.sockets_size: Size of the send and receive socket buffers. This value must be higher or equal than themax_msg_sizeto obtain a valid configuration. It also defines the size of the shared memory segment, calculated as twice the value set. Its maximum value is (2^32)-1 B.non_blocking: If set to true, the transport will use non-blocking sockets. This can be useful to avoid blocking the application if the socket buffers are full. However, some messages will be lost. Its default value is false.tcp_negotiation_timeout: It specifies the timeout duration for logical port negotiation. This parameter is useful for ensuring the availability of the logical port before data transmission, thus preventing message loss during the negotiation process. Conversely, it can delay the discovery process. The default value is 0, implying that discovery will occur as soon as possible, but the initial messages might be lost if reliability is set toBEST_EFFORT_RELIABILITY_QOS. This parameter is only valid for theLARGE_DATAmode.
Adjusting the maximum message size and the socket buffer sizes to a large enough value to accommodate the data to be sent can help improve the performance with large messages, as well as setting the transport to non-blocking mode.
In this way, it is possible to take advantage of the TCP transport to avoid fragmentation and use the non-blocking mode to avoid blocking the application when the socket buffers are full. This configuration can be used, for example, when streaming video, which will result in a significant increase in fluidity.
Note that even when using the LARGE_DATA mode within the same machine, the configuration options
can prove useful for improving performance, as they affect the SHM transport.
It is highly recommended to set a shared memory segment size large enough to accommodate the data to be sent.
To achieve this, the sockets_size parameter must be set to a value at least half of the message size.
The following snippets show how to configure the LARGE_DATA mode:
export FASTDDS_BUILTIN_TRANSPORTS=LARGE_DATA?max_msg_size=1MB&sockets_size=1MB&non_blocking=true&tcp_negotiation_timeout=50
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<profiles>
<participant profile_name="large_data_builtin_transports_options" is_default_profile="true">
<rtps>
<builtinTransports max_msg_size="200KB" sockets_size="200KB" non_blocking="true" tcp_negotiation_timeout="50">LARGE_DATA</builtinTransports>
</rtps>
</participant>
</profiles>
</dds>
eprosima::fastdds::dds::DomainParticipantQos pqos = PARTICIPANT_QOS_DEFAULT;
/* Transports configuration */
// UDPv4 transport for PDP over multicast and SHM / TCPv4 transport for EDP and application data
// Message Size and Sockets sizes of 200 KB + Non-blocking send + 50ms negotiation timeout
eprosima::fastdds::rtps::BuiltinTransportsOptions large_data_options;
large_data_options.maxMessageSize = 200000;
large_data_options.sockets_buffer_size = 200000;
large_data_options.non_blocking_send = true;
large_data_options.tcp_negotiation_timeout = 50;
pqos.setup_transports(eprosima::fastdds::rtps::BuiltinTransports::LARGE_DATA, large_data_options);
/* Create participant as usual */
eprosima::fastdds::dds::DomainParticipant* participant =
eprosima::fastdds::dds::DomainParticipantFactory::get_instance()->create_participant(0, pqos);
Note
To learn how to check and modify the default maximum system value for the socket buffers size, please refer to Finding out system maximum values.
Warning
Setting a max_msg_size value higher than 65500 KB with the DEFAULT or UDP modes will result in an error
and the participant creation will fail.
TCP Communication with Discovery Server¶
Fast DDS Discovery Server consists on a client-server discovery mechanism, in which a server DomainParticipant operates as the central point of communication. It collects and processes the metatraffic sent by the client DomainParticipants, and then distributes the appropriate information among the rest of the clients. An extended description of the feature can be found at Discovery Server Settings.
To use TCP communication along with Discovery Server, both the server participant and the client participant need to use custom user transports. There exists several ways of configuring the server participant, being Fast DDS CLI the fastest solution:
It can be configured to work over a TCP transport layer by using the arguments -t and -q to set
up the IP address and the TCP port, respectively. After sourcing the environment, the following command
can be used to instantiate a server listening on localhost and port 12345 (see CLI).
fastdds discovery -i 0 -t 127.0.0.1 -q 12345
The following snippet can be used to instantiate a server on IP 192.168.10.57 listening on port 12345.
eprosima::fastdds::dds::DomainParticipantQos qos = PARTICIPANT_QOS_DEFAULT;
// Configure the current participant as SERVER
qos.wire_protocol().builtin.discovery_config.discoveryProtocol =
eprosima::fastrtps::rtps::DiscoveryProtocol_t::SERVER;
// Add custom user transport with TCP port 12345
auto data_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>();
data_transport->add_listener_port(12345);
qos.transport().user_transports.push_back(data_transport);
// Define the listening locator to be on interface 192.168.10.57 and port 12345
constexpr uint16_t tcp_listening_port = 12345;
eprosima::fastrtps::rtps::Locator_t listening_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(listening_locator, "192.168.10.57");
eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(listening_locator, tcp_listening_port);
eprosima::fastrtps::rtps::IPLocator::setLogicalPort(listening_locator, tcp_listening_port);
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(listening_locator);
// Set the GUID prefix to identify this server
std::istringstream("44.53.00.5f.45.50.52.4f.53.49.4d.41") >> qos.wire_protocol().prefix;
The following snippet can be used to instantiate a server on IP 192.168.10.57 listening on port 12345.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<transport_descriptors>
<transport_descriptor>
<transport_id>server_tcp_transport</transport_id>
<type>TCPv4</type>
<!--
Set listening port for the transport.
This port is where the clients will connect.
-->
<listening_ports>
<port>12345</port>
</listening_ports>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCP_SERVER" is_default_profile="true">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<tcpv4>
<address>192.168.10.57</address>
<port>12345</port>
<physical_port>12345</physical_port>
</tcpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
<prefix>44.53.00.5f.45.50.52.4f.53.49.4d.41</prefix>
<useBuiltinTransports>false</useBuiltinTransports>
<userTransports>
<transport_id>server_tcp_transport</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
</dds>
It can be configured to work over a TCP transport layer by using the argument --transport tcpv4. The IP
address and the TCP port can be set up with arguments --listening-address and --listening-port,
respectively. From the DiscoveryServerExample folder, the following command can be used to instantiate a
server listening on localhost and port 12345.
./DiscoveryServerExample server --transport tcpv4 --listening-address 127.0.0.1 --listening-port 12345
The client participant can be configured by either using the ROS_DISCOVERY_SERVER environment variable (see
ROS_DISCOVERY_SERVER) or by manually setting it.
To configure a client participant to communicate over the TCP transport layer with the
ROS_DISCOVERY_SERVER environment variable, the prefix TCPv4 needs to be used. The following command
can be used to configure the variable to set up a client using TCP communication and connecting to a
server on localhost and port 12345.
export ROS_DISCOVERY_SERVER=TCPv4:[127.0.0.1]:12345
The following snippet can be used to instantiate a client that will try to connect to a server on IP 192.168.10.57 and port 12345, that is, the server instantiated above.
eprosima::fastdds::dds::DomainParticipantQos qos = PARTICIPANT_QOS_DEFAULT;
// Configure the current participant as SERVER
qos.wire_protocol().builtin.discovery_config.discoveryProtocol =
eprosima::fastrtps::rtps::DiscoveryProtocol_t::CLIENT;
// Add custom user transport with TCP port 0 (automatic port assignation)
auto data_transport = std::make_shared<eprosima::fastdds::rtps::TCPv4TransportDescriptor>();
data_transport->add_listener_port(0);
qos.transport().user_transports.push_back(data_transport);
// Define the server locator to be on interface 192.168.10.57 and port 12345
constexpr uint16_t server_port = 12345;
eprosima::fastrtps::rtps::Locator_t server_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(server_locator, "192.168.10.57");
eprosima::fastrtps::rtps::IPLocator::setPhysicalPort(server_locator, server_port);
eprosima::fastrtps::rtps::IPLocator::setLogicalPort(server_locator, server_port);
// Define the server attributes
eprosima::fastrtps::rtps::RemoteServerAttributes remote_server_att;
remote_server_att.metatrafficUnicastLocatorList.push_back(server_locator);
// Set the GUID prefix to identify this server
std::istringstream("44.53.00.5f.45.50.52.4f.53.49.4d.41") >> remote_server_att.guidPrefix;
// Add the server
qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_att);
The following snippet can be used to instantiate a client that will try to connect to a server on IP 192.168.10.57 and port 12345, that is, the server instantiated above.
<?xml version="1.0" encoding="UTF-8" ?>
<dds xmlns="http://www.eprosima.com">
<profiles>
<transport_descriptors>
<transport_descriptor>
<transport_id>client_tcp_transport</transport_id>
<type>TCPv4</type>
<!--
Set listening port for the transport to 0.
This automatically assigns a port.
-->
<listening_ports>
<port>0</port>
</listening_ports>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCP_CLIENT" is_default_profile="true">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
<!--
Server locator specifying where it is listening
-->
<metatrafficUnicastLocatorList>
<locator>
<tcpv4>
<address>192.168.10.57</address>
<port>12345</port>
<physical_port>12345</physical_port>
</tcpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
<useBuiltinTransports>false</useBuiltinTransports>
<userTransports>
<transport_id>client_tcp_transport</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
</dds>
Fast DDS over WIFI¶
The RTPS v2.2 standard defines the SIMPLE Discovery as the default mechanism for discovering participants in the network. One of the main features of this mechanism is the use of multicast communication in the Participant Discovery Phase (PDP). This can be a problem in cases where WiFi communication is used, since multicast is not as reliable over WiFi as it is over ethernet.
The recommended solution to this challenge is to configure an initial list of remote peers on the DomainParticipant, so that it can set unicast communication with them. This way, the use of multicast is not needed to discover these initial peers. Furthermore, if all the peers are known and configured beforehand, all multicast communication can be removed.
Alternatively, Discovery Server can be used to avoid multicast discovery. A DomainParticipant with a well-know address acts as a discovery server, providing the rest of the participants the information required to connect among them. If all the peers are known and configured beforehand, STATIC discovery can be used instead, completely avoiding the discovery phase. Use-case Well Known Network Deployments provides a detailed explanation on how to configure Fast DDS for STATIC discovery.
Configuring Initial Peers¶
A complete description of the initial peers list and its configuration can be found in
Initial peers.
For convenience, this example shows how to configure an initial peers list with one peer
on host 192.168.10.13 with participant ID 1 in domain 0.
Note
Note that the port number used here is not arbitrary, as discovery ports are defined by the RTPS v2.2 standard. Refer to Well Known Ports to learn about these standard port numbers.
If the participant ID is not known, setting TransportDescriptorInterface
maxInitialPeersRange to at least the maximum expected number of DomainParticipants will ensure discovery and
communication.
C++ |
DomainParticipantQos qos;
// configure an initial peer on host 192.168.10.13.
// The port number corresponds to the well-known port for metatraffic unicast
// on participant ID `1` and domain `0`.
Locator_t initial_peer;
IPLocator::setIPv4(initial_peer, "192.168.10.13");
initial_peer.port = 7412;
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="initial_peers_example_profile" is_default_profile="true">
<rtps>
<builtin>
<initialPeersList>
<locator>
<udpv4>
<address>192.168.10.13</address>
<port>7412</port>
</udpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
|
Disabling multicast discovery¶
If all the peers are known and configured on the initial peer list beforehand, it is possible to disable the multicast meta traffic completely, as all DomainParticipants can communicate among them through unicast.
The complete description of the procedure to disable multicast discovery can be found at
Disabling all Multicast Traffic.
For convenience, however, this example shows how to disable all multicast traffic configuring one
metatraffic unicast locator.
Consideration should be given to the assignment of the ports in the metatrafficUnicastLocatorList,
avoiding the assignment of ports that are not available or do not match the address-port
listed in the intial peers list of the peer participant.
C++ |
DomainParticipantQos qos;
// configure one metatraffic unicast locator on interface 192.168.10.13.
// on participant ID `1` and domain `0`.
Locator_t meta_unicast_locator;
IPLocator::setIPv4(meta_unicast_locator, "192.168.10.13");
meta_unicast_locator.port = 7412;
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(meta_unicast_locator);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="initial_peers_multicast_avoidance" is_default_profile="true" >
<rtps>
<builtin>
<!-- Choosing a specific unicast address -->
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.13</address>
<port>7412</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
Discovery Server¶
During Discovery, the Participant Discovery Phase (PDP) relies on meta traffic announcements sent to multicast addresses so that all the DomainParticipants in the network can acknowledge each other. This phase is followed by a Endpoint Discovery Phase (EDP) where all the DomainParticipants use discovered unicast addresses to exchange information about their Publisher and Subscriber entities with the rest of the DomainParticipants, so that matching between entities of the same topic can occur.
Fast DDS provides a client-server discovery mechanism, in which a server DomainParticipant operates as the central point of communication. It collects and processes the metatraffic sent by the client DomainParticipants, and then distributes the appropriate information among the rest of the clients.
A complete description of the feature can be found at Discovery Server Settings. The following subsections present configurations for different discovery server use cases.
UDPv4 basic example setup¶
To configure the Discovery Server scenario, two types of participants are created: the server participant and the client participant. Two parameters to be configured in this type of implementation are outlined:
Server GUID Prefix: This is the unique identifier of the server.
Server Address-port pair: Specifies the IP address and port of the machine that implements the server. Any free random port can be used. However, using RTPS standard ports is discouraged.
SERVER |
|---|
C++ |
DomainParticipantQos qos;
// Configure the current participant as SERVER
qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::SERVER;
// Define the listening locator to be on interface 192.168.10.57 and port 56542
Locator_t server_locator;
IPLocator::setIPv4(server_locator, "192.168.10.57");
server_locator.port = 56542;
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(server_locator);
// Set the GUID prefix to identify this server
std::istringstream("72.61.73.70.66.61.72.6d.74.65.73.74") >> qos.wire_protocol().prefix;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP SERVER" is_default_profile="true">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
<prefix>72.61.73.70.66.61.72.6d.74.65.73.74</prefix>
</rtps>
</participant>
</profiles>
|
CLIENT |
|---|
C++ |
DomainParticipantQos qos;
// Configure the current participant as CLIENT
qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::CLIENT;
// Define a locator for the SERVER Participant on address 192.168.10.57 and port 56542
Locator_t remote_server_locator;
IPLocator::setIPv4(remote_server_locator, "192.168.10.57");
remote_server_locator.port = 56542;
RemoteServerAttributes remote_server_attr;
remote_server_attr.metatrafficUnicastLocatorList.push_back(remote_server_locator);
// Set the GUID prefix to identify the remote server
remote_server_attr.ReadguidPrefix("72.61.73.70.66.61.72.6d.74.65.73.74");
// Connect to the SERVER at the previous locator
qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP CLIENT" is_default_profile="true">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="72.61.73.70.66.61.72.6d.74.65.73.74">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<locator>
<udpv4>
<address>192.168.10.58</address>
<port>24565</port>
</udpv4>
</locator>
</metatrafficMulticastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
UDPv4 redundancy example¶
The basic setup example presents a single point of failure. That is, if the server fails the clients are not able to perform the discovery. To prevent this, several servers could be linked to each client. Then, a discovery failure only takes place if all servers fail, which is a more unlikely event.
In the example below, the values have been chosen to ensure each server has a unique GUID Prefix and unicast address-port pair. Note that several servers can share the same IP address but their port numbers should be different. Likewise, several servers can share the same port if their IP addresses are different.
Prefix |
UDPv4 address-port |
|---|---|
75.63.2D.73.76.72.63.6C.6E.74.2D.31 |
192.168.10.57:56542 |
75.63.2D.73.76.72.63.6C.6E.74.2D.32 |
192.168.10.60:56543 |
SERVER |
|---|
C++ |
// Configure first server's locator on interface 192.168.10.57 and port 56542
Locator_t server_locator_1;
IPLocator::setIPv4(server_locator_1, "192.168.10.57");
server_locator_1.port = 56542;
// Configure participant_1 as SERVER listening on the previous locator
DomainParticipantQos server_1_qos;
server_1_qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::SERVER;
std::istringstream("75.63.2D.73.76.72.63.6C.6E.74.2D.31") >> server_1_qos.wire_protocol().prefix;
server_1_qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(server_locator_1);
// Configure second server's locator on interface 192.168.10.60 and port 56543
Locator_t server_locator_2;
IPLocator::setIPv4(server_locator_2, "192.168.10.60");
server_locator_2.port = 56543;
// Configure participant_2 as SERVER listening on the previous locator
DomainParticipantQos server_2_qos;
server_2_qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::SERVER;
std::istringstream("75.63.2D.73.76.72.63.6C.6E.74.2D.32") >> server_2_qos.wire_protocol().prefix;
server_2_qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(server_locator_2);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP SERVER 1">
<rtps>
<prefix>75.63.2D.73.76.72.63.6C.6E.74.2D.31</prefix>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
<participant profile_name="UDP SERVER 2">
<rtps>
<prefix>75.63.2D.73.76.72.63.6C.6E.74.2D.32</prefix>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.60</address>
<port>56543</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
CLIENT |
|---|
C++ |
// Define a locator for the first SERVER Participant
Locator_t remote_server_locator_1;
IPLocator::setIPv4(remote_server_locator_1, "192.168.10.57");
remote_server_locator_1.port = 56542;
RemoteServerAttributes remote_server_attr_1;
remote_server_attr_1.ReadguidPrefix("75.63.2D.73.76.72.63.6C.6E.74.2D.31");
remote_server_attr_1.metatrafficUnicastLocatorList.push_back(remote_server_locator_1);
// Define a locator for the second SERVER Participant
Locator_t remote_server_locator_2;
IPLocator::setIPv4(remote_server_locator_2, "192.168.10.60");
remote_server_locator_2.port = 56543;
RemoteServerAttributes remote_server_attr_2;
remote_server_attr_2.ReadguidPrefix("75.63.2D.73.76.72.63.6C.6E.74.2D.32");
remote_server_attr_2.metatrafficUnicastLocatorList.push_back(remote_server_locator_2);
// Configure the current participant as CLIENT connecting to the SERVERS at the previous locators
DomainParticipantQos client_qos;
client_qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::CLIENT;
client_qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr_1);
client_qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr_2);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP CLIENT REDUNDANCY">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>CLIENT</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="75.63.2D.73.76.72.63.6C.6E.74.2D.31">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
<RemoteServer prefix="75.63.2D.73.76.72.63.6C.6E.74.2D.32">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.60</address>
<port>56543</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
</builtin>
</rtps>
</participant>
</profiles>
|
UDPv4 persistency example¶
On Discovery Server, servers gather and maintain the information of all connected endpoints, and distribute it to the clients. In case of a server failure, all this information is lost and the server needs to recover it on restart. In the basic setup this is done starting over the Discovery process. Given that servers usually have lots of clients associated, this is very time consuming.
Alternatively, Fast DDS allows to synchronize the server’s discovery record to a file, so that the information can be loaded back into memory during the restart. This feature is enabled specifying the Discovery Protocol as BACKUP.
The record file is located on the server’s process working directory, and named following the pattern server-<GUIDPREFIX>.db (for example: server-73-65-72-76-65-72-63-6C-69-65-6E-74.db). Once the server is created, it automatically looks for this file. If it already exists, its contents are loaded, avoiding the need of re-discovering the clients. To make a fresh restart, any such backup file must be removed or renamed before launching the server.
UDPv4 partitioning using servers¶
Server association can be seen as another isolation mechanism besides Domains and Partitions. Clients that do not share a server cannot see each other and belong to isolated server networks. For example, in the following figure, client 1 and client 2 cannot communicate even if they are on the same physical network and Domain.
Clients cannot see each other due to server isolation¶
However, it is possible to connect server isolated networks very much as physical networks can be connected through routers:
Options 1 and 2 can only be implemented by modifying QoS values or XML configuration files beforehand. In this regard they match the domain and partition strategy. Option 3, however, can be implemented at runtime, when the isolated networks are already up and running.
Option 1¶
Connect each client to both servers. This case matches the redundancy use case already introduced.
Option 2¶
Connect one server to the other. This means configuring one of the servers to act as a client of the other.
Consider two servers, each one managing an isolated network:
Network |
Prefix |
UDPv4 address |
|---|---|---|
A |
75.63.2D.73.76.72.63.6C.6E.74.2D.31 |
192.168.10.60:56543 |
B |
75.63.2D.73.76.72.63.6C.6E.74.2D.32 |
192.168.10.57:56542 |
In order to communicate both networks we can set server A to act as a client of server B:
C++ |
DomainParticipantQos qos;
// Configure current Participant as SERVER on address 192.168.10.60
Locator_t server_locator;
IPLocator::setIPv4(server_locator, "192.168.10.60");
server_locator.port = 56543;
qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::SERVER;
std::istringstream("75.63.2D.73.76.72.63.6C.6E.74.2D.31") >> qos.wire_protocol().prefix;
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(server_locator);
// Add the connection attributes to the remote server.
Locator_t remote_server_locator;
IPLocator::setIPv4(remote_server_locator, "192.168.10.57");
remote_server_locator.port = 56542;
RemoteServerAttributes remote_server_attr;
remote_server_attr.ReadguidPrefix("75.63.2D.73.76.72.63.6C.6E.74.2D.32");
remote_server_attr.metatrafficUnicastLocatorList.push_back(remote_server_locator);
qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP SERVER A">
<rtps>
<prefix>75.63.2D.73.76.72.63.6C.6E.74.2D.31</prefix>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="75.63.2D.73.76.72.63.6C.6E.74.2D.32">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.60</address>
<port>56543</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
Option 3¶
Create a new server linked to the servers to which the clients are connected.
Consider two servers (A and B), each one managing an isolated network, and a third server (C) that will be used to connect the first two:
Server |
Prefix |
UDPv4 address |
|---|---|---|
A |
75.63.2D.73.76.72.63.6C.6E.74.2D.31 |
192.168.10.60:56543 |
B |
75.63.2D.73.76.72.63.6C.6E.74.2D.32 |
192.168.10.57:56542 |
C |
75.63.2D.73.76.72.63.6C.6E.74.2D.33 |
192.168.10.54:56541 |
In order to communicate both networks we can setup server C to act as client of servers A and B as follows:
C++ |
DomainParticipantQos qos;
// Configure current Participant as SERVER on address 192.168.10.60
Locator_t server_locator;
IPLocator::setIPv4(server_locator, "192.168.10.54");
server_locator.port = 56541;
qos.wire_protocol().builtin.discovery_config.discoveryProtocol = DiscoveryProtocol_t::SERVER;
std::istringstream("75.63.2D.73.76.72.63.6C.6E.74.2D.33") >> qos.wire_protocol().prefix;
qos.wire_protocol().builtin.metatrafficUnicastLocatorList.push_back(server_locator);
// Add the connection attributes to the remote server A.
Locator_t remote_server_locator_A;
IPLocator::setIPv4(remote_server_locator_A, "192.168.10.60");
remote_server_locator_A.port = 56543;
RemoteServerAttributes remote_server_attr_A;
remote_server_attr_A.ReadguidPrefix("75.63.2D.73.76.72.63.6C.6E.74.2D.31");
remote_server_attr_A.metatrafficUnicastLocatorList.push_back(remote_server_locator_A);
qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr_A);
// Add the connection attributes to the remote server B.
Locator_t remote_server_locator_B;
IPLocator::setIPv4(remote_server_locator_B, "192.168.10.57");
remote_server_locator_B.port = 56542;
RemoteServerAttributes remote_server_attr_B;
remote_server_attr_B.ReadguidPrefix("75.63.2D.73.76.72.63.6C.6E.74.2D.32");
remote_server_attr_B.metatrafficUnicastLocatorList.push_back(remote_server_locator_B);
qos.wire_protocol().builtin.discovery_config.m_DiscoveryServers.push_back(remote_server_attr_B);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="UDP SERVER C">
<rtps>
<prefix>75.63.2D.73.76.72.63.6C.6E.74.2D.33</prefix>
<builtin>
<discovery_config>
<discoveryProtocol>SERVER</discoveryProtocol>
<discoveryServersList>
<RemoteServer prefix="75.63.2D.73.76.72.63.6C.6E.74.2D.32">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.57</address>
<port>56542</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
<RemoteServer prefix="75.63.2D.73.76.72.63.6C.6E.74.2D.31">
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.60</address>
<port>56543</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</RemoteServer>
</discoveryServersList>
</discovery_config>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<address>192.168.10.54</address>
<port>56541</port>
</udpv4>
</locator>
</metatrafficUnicastLocatorList>
</builtin>
</rtps>
</participant>
</profiles>
|
Well Known Network Deployments¶
It is often the case in industrial deployments, such as productions lines, that the entire network topology (hosts, IP addresses, etc.) is known beforehand. Such scenarios are perfect candidates for Fast DDS STATIC Discovery mechanism, which drastically reduces the middleware setup time (time until all the entities are ready for information exchange), while at the same time limits the connections to those strictly necessary.
Knowing the complete network topology allows to:
Minimize the PDP meta-traffic and avoid multicast communication with Peer-to-Peer Participant Discovery Phase.
Completely avoid the EDP with STATIC Endpoint Discovery Phase.
Peer-to-Peer Participant Discovery Phase¶
The SIMPLE PDP discovery phase entails the DomainParticipants sending periodic PDP announcements over multicast, and answering to the announcements received from remote DomainParticipants. As a result, the number of PDP connections grows quadratically with the number of DomainParticipants, resulting in a large amount of meta traffic on the network.
However, if all DomainParticipants are known beforehand, they can be configured to send their announcements only to the unicast addresses of their peers. This is done by specifying a list of peer addresses, and by disabling the participant multicast announcements. As an additional advantage, with this method only the peers configured on the list are known to the DomainParticipant, allowing to arrange which participant will communicate with which. This reduces the amount of meta traffic if not all the DomainParticipants need to be aware of all the rest of the remote participants present in the network.
Use-case Fast DDS over WIFI provides a detailed explanation on how to configure Fast DDS for such cases.
STATIC Endpoint Discovery Phase¶
Users can manually configure which Publisher and Subscriber match with each other, so they can start sharing user data right away, avoiding the EDP phase.
A complete description of the feature can be found at STATIC Discovery Settings. There is also a fully functional helloworld example implementing STATIC EDP in the examples/cpp/dds/StaticHelloWorldExample folder.
The following subsections present an example configuration where a Publisher in
Topic HelloWorldTopic from DomainParticipant HelloWorldPublisher
is matched with a Subscriber from DomainParticipant HelloWorldSubscriber.
Create STATIC discovery XML files¶
HelloWorldPublisher.xml |
|---|
<staticdiscovery>
<participant>
<name>HelloWorldPublisher</name>
<writer>
<userId>1</userId>
<entityID>2</entityID>
<topicName>HelloWorldTopic</topicName>
<topicDataType>HelloWorld</topicDataType>
</writer>
</participant>
</staticdiscovery>
|
HelloWorldSubscriber.xml |
|---|
<staticdiscovery>
<participant>
<name>HelloWorldSubscriber</name>
<reader>
<userId>3</userId>
<entityID>4</entityID>
<topicName>HelloWorldTopic</topicName>
<topicDataType>HelloWorld</topicDataType>
</reader>
</participant>
</staticdiscovery>
|
Create entities and load STATIC discovery XML files¶
When creating the entities, the local writer/reader attributes must match those defined in the STATIC discovery XML file loaded by the remote entity.
PUBLISHER |
|---|
C++ |
// Participant configuration
DomainParticipantQos participant_qos;
participant_qos.name("HelloWorldPublisher");
participant_qos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = false;
participant_qos.wire_protocol().builtin.discovery_config.use_STATIC_EndpointDiscoveryProtocol = true;
participant_qos.wire_protocol().builtin.discovery_config.static_edp_xml_config("HelloWorldSubscriber.xml");
// DataWriter configuration
DataWriterQos writer_qos;
writer_qos.endpoint().user_defined_id = 1;
writer_qos.endpoint().entity_id = 2;
// Create the DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, participant_qos);
if (nullptr == participant)
{
// Error
return;
}
// Create the Publisher
Publisher* publisher =
participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher)
{
// Error
return;
}
// Create the Topic with the appropriate name and data type
std::string topic_name = "HelloWorldTopic";
std::string data_type = "HelloWorld";
Topic* topic =
participant->create_topic(topic_name, data_type, TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create the DataWriter
DataWriter* writer =
publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == writer)
{
// Error
return;
}
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_static_pub">
<rtps>
<name>HelloWorldPublisher</name>
<builtin>
<discovery_config>
<EDP>STATIC</EDP>
<static_edp_xml_config>file://HelloWorldSubscriber.xml</static_edp_xml_config>
</discovery_config>
</builtin>
</rtps>
</participant>
<data_writer profile_name="uc_publisher_xml_conf_static_discovery">
<userDefinedID>1</userDefinedID>
<entityID>2</entityID>
</data_writer>
</profiles>
|
SUBSCRIBER |
|---|
C++ |
// Participant configuration
DomainParticipantQos participant_qos;
participant_qos.name("HelloWorldSubscriber");
participant_qos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = false;
participant_qos.wire_protocol().builtin.discovery_config.use_STATIC_EndpointDiscoveryProtocol = true;
participant_qos.wire_protocol().builtin.discovery_config.static_edp_xml_config("HelloWorldPublisher.xml");
// DataWriter configuration
DataWriterQos writer_qos;
writer_qos.endpoint().user_defined_id = 3;
writer_qos.endpoint().entity_id = 4;
// Create the DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, participant_qos);
if (nullptr == participant)
{
// Error
return;
}
// Create the Subscriber
Subscriber* subscriber =
participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
// Create the Topic with the appropriate name and data type
std::string topic_name = "HelloWorldTopic";
std::string data_type = "HelloWorld";
Topic* topic =
participant->create_topic(topic_name, data_type, TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create the DataReader
DataReader* reader =
subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == reader)
{
// Error
return;
}
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_static_sub">
<rtps>
<name>HelloWorldSubscriber</name>
<builtin>
<discovery_config>
<static_edp_xml_config>file://HelloWorldPublisher.xml</static_edp_xml_config>
</discovery_config>
</builtin>
</rtps>
</participant>
<data_reader profile_name="uc_subscriber_xml_conf_static_discovery">
<userDefinedID>3</userDefinedID>
<entityID>4</entityID>
</data_reader>
</profiles>
|
Large Data Rates¶
When the amount of data exchanged between a Publisher and a Subscriber is large, some extra configuration may be required to compensate for side effects on the network and CPU load. This large amount of data can be a result of the data types being large, a high message rate, or a combination of both.
In this scenario, several approaches can be considered depending on the problem:
For the cases in which the data samples are large (in the order of MB) such as transmitting raw video frames, point clouds, images, etc. between different hosts, TCP based communications may yield better reception rates with lower message loss, specially in the cases where a best effort transport layer is more susceptible to data loss, such as WiFi. To tackle these cases, Large Data mode and Fast DDS over TCP documents several ways to configure Fast DDS to communicate over TCP.
Network packages could be dropped because the transmitted amount of data fills the socket buffer before it can be processed. The solution is to increase the buffers size.
It is also possible to limit the rate at which the Publisher sends data using Flow Controllers, in order to limit the effect of message bursts, and avoid to flood the Subscribers faster than they can process the messages.
On
RELIABLE_RELIABILITY_QOSmode, the overall message rate can be affected due to the retransmission of lost packets. Selecting the Heartbeat period allows to tune between increased meta traffic or faster response to lost packets. See Tuning Heartbeat Period.Also on
RELIABLE_RELIABILITY_QOSmode, with high message rates, the history of the DataWriter can be filled up, blocking the publication of new messages. A non-strict reliable mode can be configured to avoid this blocking, at the cost of potentially losing some messages on some of the Subscribers.
Warning
eProsima Fast DDS defines a conservative default message size of 64kB, which roughly corresponds to TCP and UDP payload sizes. If the topic data is bigger, it will automatically be fragmented into several transport packets.
Warning
The loss of a fragment means the loss of the entire message.
This has the most impact on BEST_EFFORT_RELIABILITY_QOS mode, where the message loss
probability increases with the number of fragments
Increasing socket buffers size¶
In high rate scenarios or large data scenarios, network packages can be dropped because
the transmitted amount of data fills the socket buffer before it can be processed.
Using RELIABLE_RELIABILITY_QOS mode,
Fast DDS will try to recover lost samples, but with the penalty of
retransmission.
With BEST_EFFORT_RELIABILITY_QOS mode,
samples will be definitely lost.
By default eProsima Fast DDS creates socket buffers with the system default size. However, these sizes can be modified using the DomainParticipantQos, as shown in the example below.
C++ |
DomainParticipantQos participant_qos;
// Increase the sending buffer size
participant_qos.transport().send_socket_buffer_size = 1048576;
// Increase the receiving buffer size
participant_qos.transport().listen_socket_buffer_size = 4194304;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_xml_profile_qos_socketbuffers">
<rtps>
<sendSocketBufferSize>1048576</sendSocketBufferSize>
<listenSocketBufferSize>4194304</listenSocketBufferSize>
</rtps>
</participant>
</profiles>
|
Finding out system maximum values¶
Operating systems set a maximum value for socket buffer sizes. If the buffer sizes are tuned with DomainParticipantQos, the values set cannot exceed the maximum value of the system.
Linux¶
The maximum buffer size values can be retrieved with the command sysctl.
For socket buffers used to send data, use the following command:
$> sudo sysctl -a | grep net.core.wmem_max
net.core.wmem_max = 1048576
For socket buffers used to receive data the command is:
$> sudo sysctl -a | grep net.core.rmem_max
net.core.rmem_max = 4194304
However, these maximum values are also configurable and can be increased if needed. The following command increases the maximum buffer size of sending sockets:
$> sudo sysctl -w net.core.wmem_max=12582912
For receiving sockets, the command is:
$> sudo sysctl -w net.core.rmem_max=12582912
Windows¶
The following command changes the maximum buffer size of sending sockets:
C:\> reg add HKLM\SYSTEM\CurrentControlSet\services\AFD\Parameters /v DefaultSendWindow /t REG_DWORD /d 12582912
For receiving sockets, the command is:
C:\> reg add HKLM\SYSTEM\CurrentControlSet\services\AFD\Parameters /v DefaultReceiveWindow /t REG_DWORD /d 12582912
Increasing the Transmit Queue Length of an interface (Linux only)¶
The Transmit Queue Length (txqueuelen) is a TCP/UDP/IP stack network interface value.
This value sets the number of packets allowed per kernel transmit queue of a network interface device.
By default, the txqueuelen value for Ethernet interfaces is set to 1000 in Linux.
This value is adequate for most Gigabit network devices.
However, in some specific cases, the txqueuelen setting should be increased to avoid overflows that drop packets.
Similarly, choosing a value that is too large can cause added overhead resulting in higher network latencies.
Note that this information only applies to the sending side, and not the receiving side.
Also increasing the txqueuelen should go together with increasing the buffer sizes of the UDP and/or TCP buffers.
(this must be applied for both the sending and receiving sides).
The settings for a specific network adapter can be viewed using the one of the following commands:
ip link show ${interface}
ifconfig ${interface}
This will display the configuration of the adapter, and among the parameters the txqueuelen.
This parameter can be a value between 1000 and 20000.
Important
If the ip command is used, the Transmit Queue Length parameter is called qlen.
The txqueuelen can be modified for the current session using either the ifconfig or ip commands.
However, take into account that after rebooting the default values will be configured again.
ip link set txqueuelen ${value} dev ${interface}
ifconfig ${interface} txqueuelen ${size}
Flow Controllers¶
eProsima Fast DDS provides a mechanism to limit the rate at which the data is sent by a DataWriter. These controllers should be registered on the creation of the DomainParticipant using FlowControllersQos, and then referenced on the creation of the DataWriter using PublishModeQosPolicy.
A new thread is spawned the first time a flow controller is referenced by an asynchronous DataWriter. This thread will be responsible for arbitrating the network output of the samples being transmitted by all the DataWriters referencing the same flow controller.
Flow controllers should be given a name so they can later on be referenced by the DataWriters.
A default, unlimited, FIFO flow controller is always available with name
FASTDDS_FLOW_CONTROLLER_DEFAULT.
Scheduling policy¶
There are different kinds of flow controllers, depending on the scheduling policy used.
All of them will limit the number of bytes sent to the network to no more than
max_bytes_per_period bytes during period_ms
milliseconds.
They only differ in the way they decide the order in which the samples are sent.
FIFOwill output samples on a first come, first served order.ROUND_ROBINwill output one sample from each DataWriter in circular order.HIGH_PRIORITYwill output samples from DataWriters with the highest priority first. The priority of a DataWriter is configured using propertyfastdds.sfc.priority. Allowed values are from -10 (highest priority) to 10 (lowest priority). If the property is not present, it will be set to the lowest priority. Samples for DataWriters with the same priority are handled with FIFO order.PRIORITY_WITH_RESERVATIONworks as the previous one, but allows the DataWriters to reserve part of the output bandwidth. This is done with the propertyfastdds.sfc.bandwidth_reservation. Allowed values are from 0 to 100, and express a percentage of the total flow controller limit. If the property is not present, it will be set to 0 (no bandwidth is reserved for the DataWriter). After the reserved bandwidth has been consumed, the rest of the samples will be handled with the rules ofHIGH_PRIORITY.
Example configuration¶
// Limit to 300kb per second.
static const char* flow_controller_name = "example_flow_controller";
auto flow_control_300k_per_sec = std::make_shared<eprosima::fastdds::rtps::FlowControllerDescriptor>();
flow_control_300k_per_sec->name = flow_controller_name;
flow_control_300k_per_sec->scheduler = eprosima::fastdds::rtps::FlowControllerSchedulerPolicy::FIFO;
flow_control_300k_per_sec->max_bytes_per_period = 300 * 1000;
flow_control_300k_per_sec->period_ms = 1000;
// [OPTIONAL] Configure sender thread settings
flow_control_300k_per_sec->sender_thread = eprosima::fastdds::rtps::ThreadSettings{-1, 0, 0, -1};
// Register flow controller on participant
DomainParticipantQos participant_qos;
participant_qos.flow_controllers().push_back(flow_control_300k_per_sec);
// .... create participant and publisher
// Link writer to the registered flow controller.
// Note that ASYNCHRONOUS_PUBLISH_MODE must be used
DataWriterQos qos;
qos.publish_mode().kind = ASYNCHRONOUS_PUBLISH_MODE;
qos.publish_mode().flow_controller_name = flow_controller_name;
There is currently no way of configuring flow controllers with XML. This will be added in future releases of the product.
Warning
Specifying a flow controller with a size smaller than the transport buffer size can cause the messages to never be sent.
Tuning Heartbeat Period¶
On RELIABLE_RELIABILITY_QOS (ReliabilityQosPolicy), RTPS protocol can detect which messages have been lost
and retransmit them.
This mechanism is based on meta-traffic information exchanged between
DataWriters and DataReaders,
namely, Heartbeat and Ack/Nack messages.
A smaller Heartbeat period increases the CPU and network overhead, but speeds up the system response when a piece of data is lost. Therefore, users can customize the Heartbeat period to match their needs. This can be done with the DataWriterQos.
DataWriterQos qos;
qos.reliable_writer_qos().times.heartbeatPeriod.seconds = 0;
qos.reliable_writer_qos().times.heartbeatPeriod.nanosec = 500000000; //500 ms
Using Non-strict Reliability¶
When HistoryQosPolicyKind is set as KEEP_ALL_HISTORY_QOS, all samples have to be received
(and acknowledged) by all subscribers before they can be overridden by the DataWriter.
If the message rate is high and the network is not reliable (i.e., lots of packets get lost), the history of the
DataWriter can be filled up, blocking the publication of new messages until any
of the old messages is acknowledged by all subscribers.
If this strictness is not needed, HistoryQosPolicyKind can be set as KEEP_LAST_HISTORY_QOS.
In this case, when the history of the DataWriter is full, the oldest message that has not
been fully acknowledged yet is overridden with the new one.
If any subscriber did not receive the discarded message, the publisher
will send a GAP message to inform the subscriber that the message is lost forever.
Practical Examples¶
Example: Sending a large file¶
Consider the following scenario:
A Publisher needs to send a file with a size of 9.9 MB.
The Publisher and Subscriber are connected through a network with a bandwidth of 100 MB/s
With a fragment size of 64 kB, the Publisher has to send about 1100 fragments to send the whole file. A possible configuration for this scenario could be:
Using
RELIABLE_RELIABILITY_QOS, since a losing a single fragment would mean the loss of the complete file.Decreasing the heartbeat period, in order to increase the reactivity of the Publisher.
Limiting the data rate using a Flow Controller, to avoid this transmission cannibalizing the whole bandwidth. A reasonable rate for this application could be 5 MB/s, which represents only 5% of the total bandwidth.
Note
Using Shared Memory Transport the only limit to the fragment size is the available memory. Therefore, all fragmentation can be avoided in SHM by increasing the size of the shared buffers.
Example: Video streaming¶
In this scenario, the application transmits a video stream between a Publisher
and a Subscriber, at 50 fps. In real-time audio or video transmissions,
it is usually preferred to have a high stable datarate feed, even at the cost of losing some
samples.
Losing one or two samples per second at 50 fps is more acceptable than freezing the video waiting for the retransmission
of lost samples.
Therefore, in this case BEST_EFFORT_RELIABILITY_QOS can be appropriate.
Topics with many subscribers¶
By default, every time a DataWriter publishes a data change on a Topic, it sends a unicast message for every DataReader that is subscribed to the Topic. If there are several DataReaders subscribed, it is recommendable to use multicast instead of unicast. By doing so, only one network package will be sent for each sample. This will improve both CPU and network usage.
This solution can be implemented with UDP Transport or Shared Memory Transport (SHM). SHM transport is multicast by default, but is only available between DataWriters and DataReaders on the same machine. UDP transport needs some extra configuration. The example below shows how to set a DataReaderQos to configure a DataReader to use a multicast transport on UDP. More information about configuring local and remote locators on endpoints can be found in RTPSEndpointQos.
Note
Multicast over UDP can be problematic on some scenarios, mainly WiFi and complex networks with multiple network links.
C++ |
DataReaderQos qos;
// Add new multicast locator with IP 239.255.0.4 and port 7900
eprosima::fastrtps::rtps::Locator_t new_multicast_locator;
eprosima::fastrtps::rtps::IPLocator::setIPv4(new_multicast_locator, "239.255.0.4");
new_multicast_locator.port = 7900;
qos.endpoint().multicast_locator_list.push_back(new_multicast_locator);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_reader profile_name="reader_xml_conf_multicast_locators_profile">
<multicastLocatorList>
<locator>
<udpv4>
<address>239.255.0.4</address>
<port>7900</port>
</udpv4>
</locator>
</multicastLocatorList>
</data_reader>
</profiles>
|
Real-time behavior¶
Real-time applications have very tight constraints on data processing times. In order to comply with these constraints, Fast DDS can be configured to guarantee responses within a specified time. This is achieved with the following restraints:
Allocating all the required memory during entity initialization, so that all the data processing tasks are heap allocation free (see Tuning allocations).
Returning from blocking functions if the provided timeout is reached (see Non-blocking calls).
This section explains how to configure Fast DDS to achieve this behavior.
Tuning allocations¶
Allocating and deallocating memory implies some non-deterministic time consuming operations. Therefore, most real-time systems need to operate in a way that all dynamic memory is allocated during the application initialization, avoiding memory management operations in the main loop.
If users provide maximum sizes for the data and collections that Fast DDS keeps internally, memory for these data and collections can be preallocated during entity initialization. In order to choose the correct size values, users must be aware of the topology of the whole domain. Specifically, the number of DomainParticipants, DataWriters, and DataReaders must be known when setting their configuration.
The following sections describe how to configure allocations to be done during the initialization of the entities. Although some examples are provided on each section as reference, there is also a complete example use case.
Parameters on the participant¶
Every DomainParticipant holds an internal collection with information about every local and remote peer DomainParticipants that has been discovered. This information includes, among other things:
A nested collection with information of every DataWriter announced on the peer DomainParticipant.
A nested collection with information of every DataReader announced on the peer DomainParticipant.
Custom data configured by the user on the peer DomainParticipant, namely, UserDataQosPolicy, PartitionQosPolicy, and PropertyPolicyQos.
By default, these collections are fully dynamic, meaning that new memory is allocated when a new DomainParticipant, DataWriter, or DataReader is discovered. Likewise, the mentioned custom configuration data parameters have an arbitrary size. By default, the memory for these parameters is allocated when the peer DomainParticipant announces their value.
However, DomainParticipantQos has a member function allocation(),
of type ParticipantResourceLimitsQos, that allows configuring
maximum sizes for these collections and parameters, so that all the required memory can be preallocated during
the initialization of the DomainParticipant.
Limiting the number of discovered entities¶
ParticipantResourceLimitsQos provides three data members to configure the allocation behavior of discovered entities:
participantsconfigures the allocation of the collection of discovered DomainParticipants.readersconfigures the allocation of the collection of DataWriters within each discovered DomainParticipant.writersconfigures the allocation of the collection of DataReaders within each discovered DomainParticipant.
By default, a full dynamic behavior is used. Using these members, however, it is easy to configure the collections to be preallocated during initialization, setting them to a static maximum expected value, as shown in the example below. Please, refer to ResourceLimitedContainerConfig for a complete description of additional configuration alternatives given by these data members.
C++ |
DomainParticipantQos qos;
// Fix the size of discovered participants to 3
// This will effectively preallocate the memory during initialization
qos.allocation().participants =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
// Fix the size of discovered DataWriters to 1 per DomainParticipant
// Fix the size of discovered DataReaders to 3 per DomainParticipant
// This will effectively preallocate the memory during initialization
qos.allocation().writers =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
qos.allocation().readers =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_qos_entity_resource_limit">
<rtps>
<allocation>
<!-- Limit to 3 participants -->
<total_participants>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</total_participants>
<!-- Limit to 3 readers per participant -->
<total_readers>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</total_readers>
<!-- Limit to 1 writer per participant -->
<total_writers>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</total_writers>
</allocation>
</rtps>
</participant>
</profiles>
|
Warning
Configuring a collection as fixed in size effectively limits the number of peer entities that can be discovered. Once the configured limit is reached, any new entity will be ignored. In the given example, if a fourth peer DomainParticipant appears, it will not be discovered, as the collection of discovered DomainParticipants is already full.
Limiting the size of custom parameters¶
data_limits inside ParticipantResourceLimitsQos provides three data members
to configure the allocation behavior of custom parameters:
max_user_datalimits the size of UserDataQosPolicy to the given number of octets.max_propertieslimits the size of PartitionQosPolicy to the given number of octets.max_partitionslimits the size of PropertyPolicyQos to the given number of octets.
If these sizes are configured to something different than zero, enough memory will be allocated for them for each participant and endpoint. A value of zero implies no size limitation, and memory will be dynamically allocated as needed. By default, a full dynamic behavior is used.
content_filter inside ParticipantResourceLimitsQos provides members
to configure the allocation behavior of content filter discovery information:
expression_initial_sizesets the preallocated size of the filter expression.expression_parameterscontrols the allocation behavior for the list of expression parameters. Refer to ResourceLimitedContainerConfig for a complete description of the alternatives. Receiving information about a content filter with more parameters than the maximum configured here, will make the filtering happen on the reader side.
C++ |
DomainParticipantQos qos;
// Fix the size of the complete user data field to 256 octets
qos.allocation().data_limits.max_user_data = 256u;
// Fix the size of the complete partitions field to 256 octets
qos.allocation().data_limits.max_partitions = 256u;
// Fix the size of the complete properties field to 512 octets
qos.allocation().data_limits.max_properties = 512u;
// Set the preallocated filter expression size to 512 characters
qos.allocation().content_filter.expression_initial_size = 512u;
// Set the maximum number of expression parameters to 4 and its allocation configuration to fixed size
qos.allocation().content_filter.expression_parameters =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(4u);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_qos_parameter_resource_limit">
<rtps>
<allocation>
<max_partitions>256</max_partitions>
<max_user_data>256</max_user_data>
<max_properties>512</max_properties>
<!-- content_filter cannot be configured using XML (yet) -->
</allocation>
</rtps>
</participant>
</profiles>
|
Warning
If the data fields announced by the remote peer do not fit on the preallocated memory, an error will be triggered during the processing of the announcement message. This usually means that the discovery messages of a remote peer with too large data fields will be discarded, i.e., peers with too large data fields will not be discovered.
Parameters on the DataWriter¶
Every DataWriter holds internal collections with information about every
DataReader to which it matches.
By default, these collections are fully dynamic, meaning that new memory is allocated when a new
DataReader is matched.
However, DataWriterQos has a data member writer_resource_limits(),
of type WriterResourceLimitsQos, that allows configuring
the memory allocation behavior on the DataWriter.
WriterResourceLimitsQos provides data members matched_subscriber_allocation
and reader_filters_allocation
of type ResourceLimitedContainerConfig that allow configuring
the maximum expected size of the collection of matched DataReader,
and the collection of writer side content filters,
so they can be preallocated during the initialization of the DataWriter,
as shown in the example below.
Please, refer to ResourceLimitedContainerConfig for a complete description of additional configuration
alternatives given by these data members.
C++ |
DataWriterQos qos;
// Fix the size of matched DataReaders to 3
// This will effectively preallocate the memory during initialization
qos.writer_resource_limits().matched_subscriber_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
// Fix the size of writer side content filters to 1
// This will effectively preallocate the memory during initialization
qos.writer_resource_limits().reader_filters_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="writer_profile_qos_resource_limit">
<!-- Limit to 3 matching readers -->
<matchedSubscribersAllocation>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
<!-- reader_filters_allocation cannot be configured using XML (yet) -->
</data_writer>
</profiles>
|
Warning
Configuring the collection of matched DataReaders as fixed in size effectively limits the number of DataReaders to be matched. Once the configured limit is reached, any new DataReader will be ignored. In the given example, if a fourth (potentially matching) DataReader appears, it will not be matched, as the collection is already full.
Parameters on the DataReader¶
Every DataReader holds an internal collection with information about every
ReaderResourceLimitsQos to which it matches.
By default, this collection is fully dynamic, meaning that new memory is allocated when a new
DataWriter is matched.
However, DataReaderQos has a data member reader_resource_limits(),
of type ReaderResourceLimitsQos, that allows configuring
the memory allocation behavior on the DataReader.
ReaderResourceLimitsQos provides a data member matched_publisher_allocation
of type ResourceLimitedContainerConfig that allows configuring
the maximum expected size of the collection of matched DataWriters,
so that it can be preallocated during the initialization of the DataReader,
as shown in the example below.
Please, refer to ResourceLimitedContainerConfig for a complete description of additional configuration
alternatives given by this data member.
C++ |
DataReaderQos qos;
// Fix the size of matched DataWriters to 1
// This will effectively preallocate the memory during initialization
qos.reader_resource_limits().matched_publisher_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_reader profile_name="reader_profile_qos_resource_limit">
<!-- Limit to 1 matching writer -->
<matchedPublishersAllocation>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</matchedPublishersAllocation>
</data_reader>
</profiles>
|
Warning
Configuring the collection of matched DataWriters as fixed in size effectively limits the number of DataWriters to be matched. Once the configured limit is reached, any new DataWriter will be ignored. In the given example, if a fourth (potentially matching) DataWriter appears, it will not be matched, as the collection is already full.
Full example¶
Given a system with the following topology:
Participant P1 |
Participant P2 |
Participant P3 |
|---|---|---|
Topic 1 publisher |
Topic 1 subscriber |
Topic 2 subscriber |
Topic 1 subscriber |
Topic 2 publisher |
|
Topic 1 subscriber |
Topic 2 subscriber |
The total number of DomainParticipants is 3.
The maximum number of DataWriters per DomainParticipant is 1
The maximum number of DataReaders per DomainParticipant is 2.
The DataWriter for topic 1 matches with 3 DataReaders.
The DataWriter for topic 2 matches with 2 DataReaders.
All the DataReaders match exactly with 1 DataWriter.
We will assume that content filtering is not being used, and will also limit the size of the parameters:
Maximum PartitionQosPolicy size: 256
Maximum UserDataQosPolicy size: 256
Maximum PropertyPolicyQos size: 512
The following piece of code shows the set of parameters needed for the use case depicted in this example.
C++ |
// DomainParticipant configuration
//////////////////////////////////
DomainParticipantQos participant_qos;
// We know we have 3 participants on the domain
participant_qos.allocation().participants =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
// We know we have at most 2 readers on each participant
participant_qos.allocation().readers =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(2u);
// We know we have at most 1 writer on each participant
participant_qos.allocation().writers =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
// We know the maximum size of partition data
participant_qos.allocation().data_limits.max_partitions = 256u;
// We know the maximum size of user data
participant_qos.allocation().data_limits.max_user_data = 256u;
// We know the maximum size of properties data
participant_qos.allocation().data_limits.max_properties = 512u;
// Content filtering is not being used
participant_qos.allocation().content_filter.expression_initial_size = 0u;
participant_qos.allocation().content_filter.expression_parameters =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(0u);
// DataWriter configuration for Topic 1
///////////////////////////////////////
DataWriterQos writer1_qos;
// We know we will only have three matching subscribers, and no content filters
writer1_qos.writer_resource_limits().matched_subscriber_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
writer1_qos.writer_resource_limits().reader_filters_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(0u);
// DataWriter configuration for Topic 2
///////////////////////////////////////
DataWriterQos writer2_qos;
// We know we will only have two matching subscribers
writer2_qos.writer_resource_limits().matched_subscriber_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(2u);
writer2_qos.writer_resource_limits().reader_filters_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(0u);
// DataReader configuration for both Topics
///////////////////////////////////////////
DataReaderQos reader_qos;
// We know we will only have one matching publisher
reader_qos.reader_resource_limits().matched_publisher_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(1u);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_alloc_qos_example">
<rtps>
<allocation>
<!-- We know we have 3 participants on the domain -->
<total_participants>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</total_participants>
<!-- We know we have at most 2 readers on each participant -->
<total_readers>
<initial>2</initial>
<maximum>2</maximum>
<increment>0</increment>
</total_readers>
<!-- We know we have at most 1 writer on each participant -->
<total_writers>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</total_writers>
<max_partitions>256</max_partitions>
<max_user_data>256</max_user_data>
<max_properties>512</max_properties>
<!-- content_filter cannot be configured using XML (yet) -->
</allocation>
</rtps>
</participant>
<data_writer profile_name="allocation_qos_example_pub_for_topic_1">
<!-- we know we will have three matching subscribers and no content filter -->
<matchedSubscribersAllocation>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
<!-- reader_filters_allocation cannot be configured using XML (yet) -->
</data_writer>
<data_writer profile_name="allocation_qos_example_pub_for_topic_2">
<!-- we know we will have two matching subscribers and no content filter -->
<matchedSubscribersAllocation>
<initial>2</initial>
<maximum>2</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
<!-- reader_filters_allocation cannot be configured using XML (yet) -->
</data_writer>
<data_reader profile_name="allocation_qos_example_sub">
<!-- we know we will only have one matching publisher -->
<matchedPublishersAllocation>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</matchedPublishersAllocation>
</data_reader>
</profiles>
|
Non-blocking calls¶
Note
As OSX does not support necessary POSIX Real-time features, this feature is not fully supported on OSX. In that case, the feature is limited by the implementation of std::timed_mutex and std::condition_variable_any.
Several functions on the Fast DDS API can be blocked for an undefined period of time when operations compete for the control of a resource. The blocked function cannot continue until the operation that gained the control finishes, thus blocking the calling thread.
Real-time applications need a predictable behavior, including a predictable maximum time since a function is called until it returns control. In order to comply with this restriction, Fast DDS can be configured to limit the maximum blocking time of these functions. If the blocking time limit is exceeded, the requested operation is aborted and function terminated, returning the control to the caller.
This configuration needs two steps:
Set the CMake option
-DSTRICT_REALTIME=ONduring the compilation of the application.Configure the maximum blocking times for the functions.
Method |
Configuration attribute |
Default value |
|---|---|---|
|
|
100 milliseconds. |
|
|
100 milliseconds. |
|
|
100 milliseconds. |
|
The method accepts an argument with the maximum blocking time. |
Reduce memory usage¶
A great number of modern systems have tight constraints on available memory, making the reduction of memory usage to a minimum critical. Reducing memory consumption of a Fast DDS application can be achieved through various approaches, mainly through architectural restructuring of the application, but also by limiting the resources the middleware utilizes, and by avoiding static allocations.
Limiting Resources¶
The ResourceLimitsQosPolicy controls the resources that the service can use in order to meet the requirements imposed. It limits the amount of allocated memory per DataWriter or DataReader, as per the following parameters:
max_samples: Configures the maximum number of samples that the DataWriter or DataReader can manage across all the instances associated with it, i.e. it represents the maximum samples that the middleware can store for a DataReader or DataWriter.max_instances: Configures the maximum number of instances that the DataWriter or DataReader can manage.max_samples_per_instance: Controls the maximum number of samples within an instance that the DataWriter or DataReader can manage.allocated_samples: States the number of samples that will be allocated on initialization.
All these parameters may be lowered as much as needed to reduce memory consumption, limit the resources to the application’s needs. Below is an example of a configuration for the minimum resource limits possible.
Warning
The value of
max_samplesmust be higher or equal to the value ofmax_samples_per_instance.The value established for the HistoryQosPolicy
depthmust be lower or equal to the value stated formax_samples_per_instance.
C++ |
ResourceLimitsQosPolicy resource_limits;
// The ResourceLimitsQosPolicy is default constructed with max_samples = 5000
// Change max_samples to the minimum
resource_limits.max_samples = 1;
// The ResourceLimitsQosPolicy is default constructed with max_instances = 10
// Change max_instances to the minimum
resource_limits.max_instances = 1;
// The ResourceLimitsQosPolicy is default constructed with max_samples_per_instance = 400
// Change max_samples_per_instance to the minimum
resource_limits.max_samples_per_instance = 1;
// The ResourceLimitsQosPolicy is default constructed with allocated_samples = 100
// No allocated samples
resource_limits.allocated_samples = 0;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="data_writer_min_samples">
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
<depth>1</depth>
</historyQos>
<resourceLimitsQos>
<max_samples>1</max_samples>
<max_instances>1</max_instances>
<max_samples_per_instance>1</max_samples_per_instance>
<allocated_samples>0</allocated_samples>
</resourceLimitsQos>
</topic>
</data_writer>
<data_reader profile_name="data_reader_min_samples">
<topic>
<historyQos>
<kind>KEEP_LAST</kind>
<depth>1</depth>
</historyQos>
<resourceLimitsQos>
<max_samples>1</max_samples>
<max_instances>1</max_instances>
<max_samples_per_instance>1</max_samples_per_instance>
<allocated_samples>0</allocated_samples>
</resourceLimitsQos>
</topic>
</data_reader>
</profiles>
|
Set Dynamic Allocation¶
By default MemoryManagementPolicy is set to PREALLOCATED_WITH_REALLOC_MEMORY_MODE, meaning that the
amount of memory required by the configured ResourceLimitsQosPolicy will be allocated at initialization.
If some more memory has to be allocated at run time, it is reallocated.
Using the dynamic settings of the RTPSEndpointQos will prevent unnecessary allocations. Lowest footprint is
achieved with DYNAMIC_RESERVE_MEMORY_MODE at the cost of higher allocation counts, in this mode memory is
allocated when needed and freed as soon as it stops being used. For higher determinism at a small memory cost the
DYNAMIC_REUSABLE_MEMORY_MODE option is available, this option is similar but once more memory is allocated it is
not freed and is reused for future messages.
C++ |
RTPSEndpointQos endpoint;
endpoint.history_memory_policy = eprosima::fastrtps::rtps::DYNAMIC_REUSABLE_MEMORY_MODE;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<data_writer profile_name="data_writer_low_memory">
<!-- ... -->
<historyMemoryPolicy>DYNAMIC_REUSABLE</historyMemoryPolicy>
</data_writer>
<data_reader profile_name="data_reader_low_memory">
<!-- ... -->
<historyMemoryPolicy>DYNAMIC_REUSABLE</historyMemoryPolicy>
</data_reader>
</profiles>
|
Zero-Copy communication¶
This section explains how to configure a Zero-Copy communication in Fast DDS. The Zero-Copy communication allows the transmission of data between applications without copying data in memory, saving time and resources. In order to achieve this, it uses Data-sharing delivery between the DataWriter and the DataReader, and data buffer loans between the application and Fast DDS.
Overview¶
Data-sharing delivery provides a communication channel between a DataWriter and a DataReader using shared memory. Therefore, it does not require copying the sample data to transmit it.
DataWriter sample loaning is a Fast DDS extension that allows the application to borrow a buffer for a sample in the publishing DataWriter. The sample can be constructed directly on this buffer, eliminating the need to copy it to the DataWriter afterwards. This prevents the copying of the data between the publishing application and the DataWriter. If Data-sharing delivery is used, the loaned data buffer will be in the shared memory itself.
Reading the data on the subscriber side can also be done with loans from the DataReader. The application gets the received samples as a reference to the receive queue itself. This prevents the copying of the data from the DataReader to the receiving application. Again, if Data-sharing delivery is used, the loaned data will be in the shared memory, and will indeed be the same memory buffer used in the DataWriter history.
Combining these three features, we can achieve Zero-Copy communication between the publishing application and the subscribing application.
Getting started¶
To enable Zero-Copy perform the following steps:
Define a plain and bounded type in an IDL file and generate the corresponding source code for further processing with the Fast DDS-Gen tool.
struct LoanableHelloWorld { unsigned long index; char message[256]; };
On the DataWriter side:
Create a DataWriter for the previous type. Make sure that the DataWriter does not have DataSharing disabled.
Get a loan on a sample using
loan_sample().Write the sample using
write().
On the DataReader side:
Create a DataReader for the previous type. Make sure that the DataReader does not have DataSharing disabled.
Take/read samples using the available functions in the DataReader. Please refer to section Loaning and Returning Data and SampleInfo Sequences for further detail on how to access to loans of the received data.
Return the loaned samples using
DataReader::return_loan().
Writing and reading in Zero-Copy transfers¶
The following is an example of how to publish and receive samples with DataWriters and DataReaders respectively that implement Zero-Copy.
DataWriter¶
When the DataWriter is created, Fast DDS will pre-allocate a pool of
max_samples + extra_samples samples that reside
in a shared memory mapped file.
This pool will be used to loan samples when the loan_sample() function is called.
An application example of a DataWriter that supports Zero-Copy using the Fast DDS library is presented below. There are several points to note in the following code:
Not disabling the DataSharingQosPolicy.
AUTOkind automatically enables Zero-Copy when possible.The use of the
loan_sample()function to access and modify data samples.The writing of data samples.
// CREATE THE PARTICIPANT
DomainParticipantQos pqos;
pqos.name("Participant_pub");
DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(0, pqos);
// REGISTER THE TYPE
TypeSupport type(new LoanableHelloWorldPubSubType());
type.register_type(participant);
// CREATE THE PUBLISHER
Publisher* publisher = participant->create_publisher(PUBLISHER_QOS_DEFAULT, nullptr);
// CREATE THE TOPIC
Topic* topic = participant->create_topic(
"LoanableHelloWorldTopic",
type.get_type_name(),
TOPIC_QOS_DEFAULT);
// CREATE THE WRITER
DataWriterQos wqos = publisher->get_default_datawriter_qos();
wqos.history().depth = 10;
wqos.durability().kind = TRANSIENT_LOCAL_DURABILITY_QOS;
// DataSharingQosPolicy has to be set to AUTO (the default) or ON to enable Zero-Copy
wqos.data_sharing().on("shared_directory");
DataWriter* writer = publisher->create_datawriter(topic, wqos);
std::cout << "LoanableHelloWorld DataWriter created." << std::endl;
int msgsent = 0;
void* sample = nullptr;
// Always call loan_sample() before writing a new sample.
// This function will provide the user with a pointer to an internal buffer where the data type can be
// prepared for sending.
if (RETCODE_OK == writer->loan_sample(sample))
{
// Modify the sample data
LoanableHelloWorld* data = static_cast<LoanableHelloWorld*>(sample);
data->index() = msgsent + 1;
memcpy(data->message().data(), "LoanableHelloWorld ", 20);
std::cout << "Sending sample (count=" << msgsent
<< ") at address " << &data << std::endl
<< " index=" << data->index() << std::endl
<< " message=" << data->message().data() << std::endl;
// Write the sample.
// After this function returns, the middleware owns the sample.
writer->write(sample);
}
DataReader¶
The following is an application example of a DataReader that supports Zero-Copy using the Fast DDS library.
As shown in this code snippet, the configuration in the DataReader is similar to the DataWriter.
Be sure not to disable the DataSharingQosPolicy.
AUTO kind automatically enables Zero-Copy when possible.
// CREATE THE PARTICIPANT
DomainParticipantQos pqos;
pqos.name("Participant_sub");
DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(0, pqos);
// REGISTER THE TYPE
TypeSupport type(new LoanableHelloWorldPubSubType());
type.register_type(participant);
// CREATE THE SUBSCRIBER
Subscriber* subscriber = participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT, nullptr);
// CREATE THE TOPIC
Topic* topic = participant->create_topic(
"LoanableHelloWorldTopic",
type.get_type_name(),
TOPIC_QOS_DEFAULT);
// CREATE THE READER
DataReaderQos rqos = subscriber->get_default_datareader_qos();
rqos.history().depth = 10;
rqos.reliability().kind = RELIABLE_RELIABILITY_QOS;
rqos.durability().kind = TRANSIENT_LOCAL_DURABILITY_QOS;
// DataSharingQosPolicy has to be set to AUTO (the default) or ON to enable Zero-Copy
rqos.data_sharing().automatic();
DataReader* reader = subscriber->create_datareader(topic, rqos, &datareader_listener);
Finally, the code snippet below implements the on_data_available() DataReaderListener
callback.
The key points to be noted in this function are:
The declaration and handling of
LoanableSequence.Checking
DataReader::is_sample_valid()for verifying that the sample was not replaced. Refer to DataReader and DataWriter history coupling for further information.The use of the
DataReader::return_loan()function to indicate to the DataReader that the application has finished accessing the sequence.
void on_data_available(
eprosima::fastdds::dds::DataReader* reader) override
{
// Declare a LoanableSequence for a data type
FASTDDS_SEQUENCE(DataSeq, LoanableHelloWorld);
DataSeq data;
SampleInfoSeq infos;
// Access to the collection of data-samples and its corresponding collection of SampleInfo structures
while (RETCODE_OK == reader->take(data, infos))
{
// Iterate over each LoanableCollection in the SampleInfo sequence
for (LoanableCollection::size_type i = 0; i < infos.length(); ++i)
{
// Check whether the DataSample contains data or is only used to communicate of a
// change in the instance
if (infos[i].valid_data)
{
// Print the data.
const LoanableHelloWorld& sample = data[i];
++samples;
std::cout << "Sample received (count=" << samples
<< ") at address " << &sample
<< (reader->is_sample_valid(&sample,
&infos[i]) ? " is valid" : " was replaced" ) << std::endl
<< " index=" << sample.index() << std::endl
<< " message=" << sample.message().data() << std::endl;
}
}
// Indicate to the DataReader that the application is done accessing the collection of
// data values and SampleInfo, obtained by some earlier invocation of read or take on the
// DataReader.
reader->return_loan(data, infos);
}
}
Caveats¶
After calling
write(), Fast DDS takes ownership of the sample and therefore it is no longer safe to make changes to that sample.If function
loan_sample()is called first and the sample is never written, it is necessary to use functiondiscard_loan()to return the sample to the DataWriter. If this is not done, the subsequent calls toloan_sample()may fail if DataWriter has no moreextra_samplesto loan.The current maximum supported sample size is the maximum value of an
uint32_t.
Constraints¶
Although Zero-Copy can be used for one or several Fast DDS application processes running on the same machine, it has some constraints:
Only plain types are supported.
A plain type is a type whose CDR representation matches its in-memory representation. This requirement avoids the copy between the CDR buffer and the user buffer because the data representation is the same. Consequently, only primitive types (except
string), arrays of these primitive types, and structures with FINAL extensibility and members of these primitive types, are considered to be plain (Fast DDS also provides an API to check if a defined type is plain:TypeSupport::is_plain()).Constraints for datasharing delivery also apply.
Note
Zero-Copy transfer support for non-plain types may be implemented in future releases of Fast DDS.
Unique network flows¶
This section explains which APIs should be used on Fast DDS in order to have unique network flows on specific topics.
Background¶
IP networking is the pre-dominant inter-networking technology used nowadays. Ethernet, WiFi, 4G/5G telecommunication, all of them rely on IP networking.
Streams of IP packets from a given source to destination are called packet flows or simply flows. The network QoS of a flow can be configured when using certain networking equipment (routers, switches). Such pieces of equipment typically support 3GPP/5QI protocols to assign certain Network QoS parameters to specific flows. Requesting a specific Network QoS is usually done on the endpoint sending the data, as it is the one that usually haves complete information about the network flow.
Applications may need to use specific Network QoS parameters on different topics.
This means an application should be able to:
Identify the flows being used in the communications, so they can correctly configure the networking equipment.
Use specific flows on selected topics.
Identifying a flow¶
The 5-tuple is a traditional unique identifier for flows on 3GPP enabled equipment. The 5-tuple consists of five parameters: source IP address, source port, destination IP address, destination port, and the transport protocol (example, TCP/UDP).
Definitions¶
Network flow: A tuple of networking resources selected by the middleware for transmission of messages from a DataWriter to a DataReader, namely:
Transport protocol: UDP or TCP
Transport port
Internet protocol: IPv4 or IPv6
IP address
Network Flow Endpoint (NFE): The portion of a network flow specific to the DataWriter or the DataReader. In other words, each network flow has two NFEs; one for the DataWriter, and the other for the DataReader.
APIs¶
Fast DDS provides the APIs needed to get the list of NFEs used by a given DataWriter or a DataReader.
On the DataWriter,
get_sending_locators()allows the application to obtain the list of locators from which the writer may send data.On the DataReader,
get_listening_locators()allows the application to obtain the list of locators on which the reader is listening.
Requesting unique flows¶
A unique flow can be created by ensuring that at least one of the two NFEs are unique. On Fast DDS, there are two ways to select unique listening locators on the DataReader:
The application can specify on which locators the DataReader should be listening. This is done using RTPSEndpointQos on the DataReaderQos. In this case it is the responsibility of the application to ensure the uniqueness of the locators used.
The application can request the reader to be created with unique listening locators. This is done using a PropertyPolicyQos including the property
"fastdds.unique_network_flows". In this case, the reader will listen on a unique port outside the range of ports typically used by RTPS.
Example¶
The following snippet demonstrates all the APIs described on this page:
// Create the DataWriter
DataWriter* writer = publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == writer)
{
// Error
return;
}
// Create DataReader with unique flows
DataReaderQos drqos = DATAREADER_QOS_DEFAULT;
drqos.properties().properties().emplace_back("fastdds.unique_network_flows", "");
DataReader* reader = subscriber->create_datareader(topic, drqos);
// Print locators information
eprosima::fastdds::rtps::LocatorList locators;
writer->get_sending_locators(locators);
std::cout << "Writer is sending from the following locators:" << std::endl;
for (const auto& locator : locators)
{
std::cout << " " << locator << std::endl;
}
reader->get_listening_locators(locators);
std::cout << "Reader is listening on the following locators:" << std::endl;
for (const Locator_t& locator : locators)
{
std::cout << " " << locator << std::endl;
}
Statistics module¶
eProsima Fast DDS Statistics Module allows the user to monitor the data being exchanged by its application. In order to use this module, the user must enable it in the monitored application, and create another application that receives the data being published by the statistics DataWriters. The user can also use for the latter the eProsima Fast DDS Statistics Backend which already implements the collection and aggregation of the data coming from the statistics topics.
Enable Statistics module¶
The Statistics module has to be enabled both at build and runtime.
On the one hand, CMake option FASTDDS_STATISTICS must be enabled when building the library
(since Fast DDS v2.9.0 this CMake option is enabled by default).
On the other hand, the desired statistics DataWriters should be enabled using the Statistics Module DDS Layer.
The statistics DataWriters can be enabled automatically using the PropertyPolicyQos fastdds.statistics and
the FASTDDS_STATISTICS environment variable.
They can also be enabled manually following the next example:
// Create a DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Obtain pointer to child class
eprosima::fastdds::statistics::dds::DomainParticipant* statistics_participant =
eprosima::fastdds::statistics::dds::DomainParticipant::narrow(participant);
// Enable statistics DataWriter
if (statistics_participant->enable_statistics_datawriter(eprosima::fastdds::statistics::GAP_COUNT_TOPIC,
eprosima::fastdds::statistics::dds::STATISTICS_DATAWRITER_QOS) != RETCODE_OK)
{
// Error
return;
}
// Use the DomainParticipant to communicate
// (...)
// Disable statistics DataWriter
if (statistics_participant->disable_statistics_datawriter(eprosima::fastdds::statistics::GAP_COUNT_TOPIC) !=
RETCODE_OK)
{
// Error
return;
}
// Delete DomainParticipant
if (DomainParticipantFactory::get_instance()->delete_participant(participant) != RETCODE_OK)
{
// Error
return;
}
Create monitoring application¶
Once the monitored application is publishing the collected data within the statistics topics enabled by the user, another application should be configured to subscribe to those topics. This application is a DDS standard application where the statistics DataReaders should be created. In order to create these statistics DataReaders, the user should follow the next steps:
Using the statistics IDL provided in the public API, generate the
TopicDataTypeswith Fast DDS-Gen.Create the
DomainParticipantand register theTopicDataTypesand the corresponding statisticsTopics.Create the statistics DataReaders using the corresponding statistics topic.
Dynamic network interfaces¶
DDS Simple Discovery relies on well-known multicast addresses and ports to relay the Participant announcement messages (see Discovery phases). Such Participant announcement includes information about the unicast address-port pairs (a.k.a locators) where the Participant is expecting to receive incoming metatraffic data. The list with these unicast locators is automatically initialized taking into account the network interfaces that are available when the Fast DDS DomainParticipant is enabled. Consequently, any network interface that is added after enabling the DomainParticipant should be notified to Fast DDS in order to initialize an unicast locator in said network, so communication can be established over that new interface.
Dynamic network interface addition at run-time¶
In case that the user wants to include new network interfaces at run-time, some prerequisites have to be fulfilled. Then, once the interfaces are available, the user may notify Fast DDS so these interfaces are also used in the communication.
Prerequisites¶
This feature is intended to be used when Fast DDS automatically sets the listening unicast locators.
Consequently, both metatrafficUnicastLocatorList and
metatrafficMulticastLocatorList lists must be empty.
These attributes are set within the builtin member of wire_protocol() contained in the
DomainParticipantQos (please refer to DomainParticipantQos).
Note
Be aware of the remote locators’ collections limits set within the DomainParticipantQos (please refer to RemoteLocatorsAllocationAttributes). It is recommended to use the highest number of local addresses found on all the systems belonging to the same domain.
Notify Fast DDS¶
Once a new network interface has been enabled, Fast DDS has to be manually notified.
This is done calling DomainParticipant::set_qos().
The DomainParticipantQoS that is passed to the method can either change one of the mutable DomainParticipant QoS or
it can simply be the current DomainParticipant QoS (obtained with DomainParticipant::get_qos()).
Using DomainParticipant::set_qos() is the reason for the previous prerequisites: once the DomainParticipant is
enabled, there are several QoS policies that are immutable and cannot be changed at run-time.
WireProtocolConfigQos where the aforementioned lists are defined is among these immutable policies.
Find below a brief snippet of how to use this feature:
// Create the DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// User application
// Notify Fast DDS a new network interface is available
participant->set_qos(PARTICIPANT_QOS_DEFAULT);
Important
This feature is still under development and only officially supported for UDPv4 Transport without whitelisting.
How to use eProsima DDS Record and Replay (rosbag2 and DDS)¶
eProsima DDS Record and Replay allows the user to continuously monitor the ROS 2 traffic in real time, and to play it back at any given time. This highly contributes to facilitating simulation of real life conditions, application testing, optimizing data analysis and general troubleshooting. rosbag2 is a ROS 2 application that can be used to capture DDS messages and store them on an SQLite database which allows inspecting and replaying said messages at a later time.
rosbag2 interactions with a native Fast DDS application¶
Using rosbag2 to capture traffic between ROS 2 talkers and listeners is straightforward. However, recording and replaying messages sent by Fast DDS participants outside ROS 2 ecosystem requires some modifications.
Prerequisites¶
A Fast DDS installation, either binary or from sources is required. Fast DDS-Gen is also required for generating the examples and Fast DDS TypeSupport from the IDL file. A ROS 2 installation with the rosbag2 package is needed as well.
DDS IDL interoperability with ROS 2 messages¶
DDS uses IDLs to define the data model being exchanged by the applications.
While ROS 2 can use IDL files to define the messages, there are some rules that these IDL files must follow so
compatibility between ROS 2 and Fast DDS native applications can be achieved.
Specifically, the type definition must be nested inside the type module name and then the generator to be used.
For ROS 2 messages, the generator would be msg, whereas in this case, the idl generator must be used.
Assuming that the type module name selected is fastdds_record_typesupport the following HelloWorld.idl
file could be defined.
This IDL file will be the one used in the following steps.
module fastdds_record_typesupport
{
module idl
{
struct HelloWorld
{
unsigned long index;
string message;
};
};
};
By default, rosbag2 can only recognize those Topics which types ROS 2 has already defined in its different TypeSupport libraries. Therefore, a new ROS 2 TypeSupport module library generated with the previously defined types must be created, so rosbag2 would be able to parse the message contents coming from the Fast DDS application. First, the new ROS 2 TypeSupport package should be created. Follow the instructions below, after having sourced your ROS 2 installation:
ros2 pkg create --build-type ament_cmake fastdds_record_typesupport
This command will create a new ROS 2 package named fastdds_record_typesupport with the following folder structure:
.
└── fastdds_record_typesupport
├── include
│ └── fastdds_record_typesupport
├── src
├── CMakeLists.txt
└── package.xml
ROS 2 TypeSupport code generators expect IDL files inside their own idl folder, so the final folder structure would be like this:
.
└── fastdds_record_typesupport
├── idl
│ └── HelloWorld.idl
├── include
│ └── fastdds_record_typesupport
├── src
├── CMakeLists.txt
└── package.xml
In order to generate the TypeSupport interfaces required, the CMakeLists.txt file should be modified accordingly so the
ROS 2 TypeSupport generator is called.
Please add the following lines to the CMakeLists.txt file before calling ament_package():
find_package(rosidl_default_generators REQUIRED)
set(idl_files
"idl/HelloWorld.idl"
)
rosidl_generate_interfaces(${PROJECT_NAME}
${idl_files}
)
Similarly, the package.xml file should be modified adding the ROS 2 TypeSupport generator dependency.
Add the following lines to the package.xml file after the buildtool_depend tags:
<buildtool_depend>rosidl_default_generators</buildtool_depend>
<exec_depend>rosidl_default_runtime</exec_depend>
<member_of_group>rosidl_interface_packages</member_of_group>
The last step would be to build the package.
Run the following command within the fastdds_record_typesupport folder:
RMW_IMPLEMENTATION=rmw_fastrtps_cpp colcon build
The build process will create inside the install folder a new ROS 2 overlay with all the required libraries and scripts for the ROS 2 applications to use te type defined in the IDL file.
Fast DDS Application tuning¶
ROS 2 adds special tokens to the topic names depending on the ROS 2 subsystem the topic belongs to. More information on this topic can be found on ROS 2 design documentation .
Using the same IDL file defined earlier, Fast DDS-Gen can generate the required code to handle the new type in Fast DDS. The changes required in the Fast DDS application so rosbag2 can communicate with it are going to be illustrated via the Publisher/Subscriber example generated automatically from an IDL using Fast DDS-Gen. An in-depth guide to Fast DDS-Gen can be found here.
In the case of plain topics, the namespace “rt/” is added by ROS 2 to the DDS topic name. DataType names for ROS 2 generated types are structured concatenating the modules names. For the IDL being used in this example the data type name would be “fastdds_record_typesupport::idl::HelloWorld”.
Create a new workspace different from the ROS 2 one used previously. Copy inside the same IDL file and run Fast DDS-Gen to generate the TypeSupport and the example source files.
Note
Fast DDS-Gen -no-typeobjectsupport option is advisable to be enabled as this feature does not ensure vendor
interoperability for the moment.
mkdir HelloWorldExample
cd HelloWorldExample
cp <PATH_TO_ROS2_WORKSPACE>/fastdds_record_typesupport/idl/HelloWorld.idl .
fastddsgen -example CMake -typeros2 -no-typeobjectsupport HelloWorld.idl
This command will populate the current folder with the required header and source files to build the TypeSupport, and the Publisher and Subscriber applications.
└── HelloWorldExample
├── CMakeLists.txt
├── HelloWorldCdrAux.hpp
├── HelloWorldCdrAux.ipp
├── HelloWorld.hpp
├── HelloWorld.idl
├── HelloWorldPublisher.cxx
├── HelloWorldPublisher.h
├── HelloWorldPubSubMain.cxx
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
├── HelloWorldSubscriber.cxx
└── HelloWorldSubscriber.h
The Fast DDS-Gen example should be modified taking into account the topic and type name mangling
applied by ROS 2 so communication can be established with rosbag2.
Having used the -typeros2 Fast DDS-Gen option when generating the TypeSupport, the generated type
name would already include the ROS 2 naming rule mangling.
However, the topic name must be modified manually both in the Publisher and Subscriber applications.
Look for the create_topic command in both the HelloWorldPublisher.cxx and the HelloWorldSubscriber.cxx
files and modify the topic name:
topic_ = participant_->create_topic(
"rt/HelloWorldTopic",
type_.get_type_name(),
TOPIC_QOS_DEFAULT);
if (topic_ == nullptr)
{
return false;
}
To build this example run the following commands:
mkdir build && cd build
cmake ..
make
This will create a HelloWorld binary file inside the build directory that can be used to launch both the Publisher and the Subscriber applications. Run each application in a terminal and confirm that the communication is established.
./HelloWorld publisher|subscriber
eProsima DDS Record and Replay¶
In order to use the generated ROS 2 TypeSupport package, the ROS 2 workspace should be sourced besides the
ROS 2 installation.
This allows rosbag2 to record the data types used in this example.
To start recording the traffic being exchanged between the Publisher/Subscriber applications the corresponding
ROS 2 Topic name has to be passed to rosbag2 (not to be mistaken with the DDS Topic name).
Remember also to ensure that Fast DDS is the ROS 2 middleware being used by setting the environment variable
RMW_IMPLEMENTATION.
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp
source <PATH_TO_ROS2_WORKSPACE>/fastdds_record_typesupport/install/setup.bash
ros2 bag record /HelloWorldTopic
Having the Publisher application running already, the following rosbag2 log discovery info would be shown:
[INFO] [1644320308.422161532] [rosbag2_recorder]: Subscribed to topic '/HelloWorldTopic'
[INFO] [1644320308.422292205] [rosbag2_recorder]: All requested topics are subscribed. Stopping discovery...
rosbag2 will proceed to create a folder named rosbag2_<DATE> with an SQLite database inside (db3 extension)
where the received messages will be recorded.
Within the folder a YAML file provides metadata information about the record: type and topic name, number of
messages recorded, record duration, etc.
The path to this database file can be used to replay the recorded messages.
Having the Subscriber application running, the previously recorded traffic will be replayed.
After stopping the rosbag2 application, rerun it in replay mode running the following command.
The recorded messages will be published by rosbag2 at their original publishing rate and the Subscriber application
will receive them:
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp
source <PATH_TO_ROS2_WORKSPACE>/fastdds_record_typesupport/install/setup.bash
ros2 bag play <path-to-db-file>
Request-Reply communication¶
This section explains how to configure a Request-Reply communication in Fast DDS between two applications. A Client application will send a Request to the Server application and this one, after processing the request, will send a Reply to the Client application.
Overview¶
This kind of communication involves in the DDS paradigm the usage of two Topics: one for sending requests (Request Topic) and the other one for sending replies (Reply Topic). For managing these Topics four DDS entities are involved: a DataReader and a DataWriter for each Topic. The DDS communication schema will be:
The key for making Request-Reply work is relating the Request with the Reply in the client’s side.
Fast DDS API provides SampleIdentity to achieve this.
A full example can be found in Fast DDS repository.
Getting started¶
For Request-Reply communication perform the following steps:
Define two structures in an IDL file. One structure will be used as Request Topic’s data type and the other one as Reply Topic’s data type.
enum OperationType { ADDITION, SUBSTRACTION, MULTIPLICATION, DIVISION }; struct RequestType { OperationType operation; long x; long y; }; struct ReplyType { long long z; };
In the client application, create a DataWriter for the request and a DataReader for the reply.
participant->register_type(request_type); participant->register_type(reply_type); Topic* request_topic = participant->create_topic("CalculatorRequest", request_type.get_type_name(), TOPIC_QOS_DEFAULT); Topic* reply_topic = participant->create_topic("CalculatorReply", reply_type.get_type_name(), TOPIC_QOS_DEFAULT); DataWriter* request_writer = publisher->create_datawriter(request_topic, DATAWRITER_QOS_DEFAULT); DataReader* reply_reader = subscriber->create_datareader(reply_topic, DATAREADER_QOS_DEFAULT, &listener);
In the server application, create a DataWriter for the reply and a DataReader for the request.
participant->register_type(request_type); participant->register_type(reply_type); Topic* request_topic = participant->create_topic("CalculatorRequest", request_type.get_type_name(), TOPIC_QOS_DEFAULT); Topic* reply_topic = participant->create_topic("CalculatorReply", reply_type.get_type_name(), TOPIC_QOS_DEFAULT); DataWriter* reply_writer = publisher->create_datawriter(reply_topic, DATAWRITER_QOS_DEFAULT); DataReader* request_reader = subscriber->create_datareader(request_topic, DATAREADER_QOS_DEFAULT, &listener);
Sending the request and storing the assigned identifier¶
For sending the request, the client application should retrieve and store the internal identifier assigned to the
published sample.
Therefore the sample should be published using the overloaded write() function which second argument is
a reference to a WriteParams object.
The assigned identifier will be stored in the WriteParams’s attribute sample_identity().
eprosima::fastrtps::rtps::SampleIdentity my_request_sample_identity;
RequestType request;
// Fill the request
// Publish request
eprosima::fastrtps::rtps::WriteParams write_params;
request_writer->write(static_cast<void*>(&request), write_params);
// Store sample identity
my_request_sample_identity = write_params.sample_identity();
Receiving the request and sending a reply associated with it¶
When the server application receives the request (for example through on_data_available()),
it has to retrieve the request’s identifier using sample_identity.
void on_data_available(
eprosima::fastdds::dds::DataReader* reader) override
{
RequestType request;
eprosima::fastdds::dds::SampleInfo sample_info;
reader->take_next_sample(&request, &sample_info);
if (eprosima::fastdds::dds::InstanceStateKind::ALIVE_INSTANCE_STATE == sample_info.instance_state)
{
// Store the request identity.
eprosima::fastrtps::rtps::SampleIdentity client_request_identity = sample_info.sample_identity;
}
}
After processing the request, the server should send the reply to the client with the related request attached.
This is done assigning the stored identifier in related_sample_identity().
ReplyType reply;
// Fill reply
// Send reply associating it with the client request.
eprosima::fastrtps::rtps::WriteParams write_params;
write_params.related_sample_identity() = client_request_identity;
reply_writer->write(reinterpret_cast<void*>(&reply), write_params);
Identifying the reply for the client¶
When the client application receives a reply (for example through on_data_available()),
the client application should identify if the received reply is the one expected for its request.
For this the client application has to compare the stored SampleIdentity with the incoming
related_sample_identity.
void on_data_available(
eprosima::fastdds::dds::DataReader* reader) override
{
ReplyType reply;
eprosima::fastdds::dds::SampleInfo sample_info;
reader->take_next_sample(&reply, &sample_info);
if (eprosima::fastdds::dds::InstanceStateKind::ALIVE_INSTANCE_STATE == sample_info.instance_state)
{
if (sample_info.related_sample_identity == my_request_sample_identity)
{
// Work to do
}
}
}
Remote type discovery and endpoint matching¶
This section explains how to create an endpoint using a remotely discovered data type that was previously unknown to the local participant.
Prerequisites¶
This use case focuses on the strategy to follow in order to create an endpoint at runtime in a previously unknown topic using the information provided by the remote endpoint discovery information. Therefore, the prerequisites are:
Two participants, A and B, running in different process (type information is shared within the same DomainParticipantFactory).
Participant A must not know the data type registered in participant B.
Participant B data type must be registered using the code generated by eProsima Fast DDS-Gen without disabling the TypeObjectSupport code generation.
Participant B must create an endpoint using the data type unknown by participant A.
Participant A must be attached to a DomainParticipantListener.
Remote type discovery¶
Following the participant discovery phase, the endpoint information is exchanged.
The appropriate on_data_reader_discovery() or
on_data_writer_discovery() callback is called, depending on the kind of endpoint
created on the remote participant.
The endpoint discovery callback provides access to the remotely discovered information including the TypeInformation.
Provided the TypeInformation, ITypeObjectRegistry singleton can be queried for the corresponding
TypeObject representation calling ITypeObjectRegistry::get_type_object API.
Register remote type¶
DynamicTypeBuilderFactory provides a specific API that given a TypeObject representation returns the corresponding
DynamicTypeBuilder: DynamicTypeBuilderFactory::create_type_w_type_object.
The DynamicType can then be obtained and registered using DynamicPubSubType.
Create local endpoint¶
Once the remote type has been locally registered, a Topic can be created within the DomainParticipant and endpoints using this Topic might be also created.
Note
Endpoint matching takes into consideration QoS consistency. Consequently, for the local endpoint to match, the remote QoS has to be taken into account. The remote endpoint discovery information provided by the discovery callback includes also this data.
Example¶
The following snippet shows the previously explained steps:
class RemoteDiscoveryDomainParticipantListener : public DomainParticipantListener
{
/* Custom Callback on_data_reader_discovery */
void on_data_reader_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ReaderDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
// Get remote type information
xtypes::TypeObject remote_type_object;
if (RETCODE_OK != DomainParticipantFactory::get_instance()->type_object_registry().get_type_object(
info.info.type_information().type_information.complete().typeid_with_size().type_id(),
remote_type_object))
{
// Error
return;
}
// Register remotely discovered type
DynamicType::_ref_type remote_type = DynamicTypeBuilderFactory::get_instance()->create_type_w_type_object(
remote_type_object)->build();
TypeSupport dyn_type_support(new DynamicPubSubType(remote_type));
dyn_type_support.register_type(participant);
// Create a Topic with the remotely discovered type.
Topic* topic =
participant->create_topic(info.info.topicName().to_string(), dyn_type_support.get_type_name(),
TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create endpoint
Publisher* publisher = participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher)
{
// Error
return;
}
DataWriter* data_writer = publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == data_writer)
{
// Error
return;
}
}
/* Custom Callback on_data_writer_discovery */
void on_data_writer_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::WriterDiscoveryInfo&& info,
bool& should_be_ignored) override
{
should_be_ignored = false;
// Get remote type information
xtypes::TypeObject remote_type_object;
if (RETCODE_OK != DomainParticipantFactory::get_instance()->type_object_registry().get_type_object(
info.info.type_information().type_information.complete().typeid_with_size().type_id(),
remote_type_object))
{
// Error
return;
}
// Register remotely discovered type
DynamicType::_ref_type remote_type = DynamicTypeBuilderFactory::get_instance()->create_type_w_type_object(
remote_type_object)->build();
TypeSupport dyn_type_support(new DynamicPubSubType(remote_type));
dyn_type_support.register_type(participant);
// Create a Topic with the remotely discovered type.
Topic* topic =
participant->create_topic(info.info.topicName().to_string(), dyn_type_support.get_type_name(),
TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
// Error
return;
}
// Create endpoint
Subscriber* subscriber = participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
// Error
return;
}
// The QoS depends on the remote endpoint QoS. For simplicity, default QoS have been assumed.
DataReader* data_reader = subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == data_reader)
{
// Error
return;
}
}
};
ROS 2 using Fast DDS middleware¶
Fast DDS is the default middleware implementation in the Open Source Robotic Fundation (OSRF) Robot Operating System ROS 2 in every long term (LTS) releases and most of the non-LTS releases.
ROS 2 is a state-of-the-art software for robot engineering which consists of a set of free software libraries and tools for building robot applications. This section presents some use cases and shows how to take full advantage of Fast DDS wide set of capabilities in a ROS 2 project.
The interface between the ROS 2 stack and Fast DDS is provided by a ROS 2 package
rmw_fastrtps.
This package is available in all ROS 2 distributions, both from binaries and from sources.
rmw_fastrtps actually provides not one but two different ROS 2 middleware implementations, both of them using Fast
DDS as middleware layer: rmw_fastrtps_cpp and rmw_fastrtps_dynamic_cpp.
The main difference between the two is that rmw_fastrtps_dynamic_cpp uses introspection type support at run time to
decide on the serialization/deserialization mechanism, while rmw_fastrtps_cpp uses its own type support, which
generates the mapping for each message type at build time.
The default ROS 2 RMW implementation until Foxy is rmw_fastrtps_cpp.
For Galactic the environment variable RMW_IMPLEMENTATION has to be set to select rmw_fastrtps_cpp in order to
use Fast DDS as the middleware layer.
This environment variable can also be used to select the rmw_fastrtps_dynamic_cpp implementation:
Exporting
RMW_IMPLEMENTATIONenvironment variable:export RMW_IMPLEMENTATION=rmw_fastrtps_cpp
or
export RMW_IMPLEMENTATION=rmw_fastrtps_dynamic_cpp
When launching your ROS 2 application:
RMW_IMPLEMENTATION=rmw_fastrtps_cpp ros2 run <package> <application>
or
RMW_IMPLEMENTATION=rmw_fastrtps_dynamic_cpp ros2 run <package> <application>
Note
Since Galactic you may have to install the rmw_fastrtps_cpp package:
sudo apt install ros-galactic-rmw-fastrtps-cpp
Configuring Fast DDS in ROS 2¶
ROS 2 only allows for the configuration of certain middleware QoS (see ROS 2 QoS policies). However, rmw_fastrtps offers extended configuration capabilities to take full advantage of the features in Fast DDS. This section describes how to specify this extended configuration.
Changing publication mode¶
rmw_fastrtps in ROS 2 uses asynchronous publication by default.
This can be easily changed setting the environment variable RMW_FASTRTPS_PUBLICATION_MODE
to one of the following allowed values:
ASYNCHRONOUS: asynchronous publication mode. Setting this mode implies that when the publisher invokes the write operation, the data is copied into a queue, a background thread (asynchronous thread) is notified about the addition to the queue, and control of the thread is returned to the user before the data is actually sent. The background thread is in charge of consuming the queue and sending the data to every matched reader.
SYNCHRONOUS: synchronous publication mode. Setting this mode implies that the data is sent directly within the context of the user thread. This entails that any blocking call occurring during the write operation would block the user thread, thus preventing the application from continuing its operation. It is important to note that this mode typically yields higher throughput rates at lower latencies, since there is no notification nor context switching between threads.
AUTO: let Fast DDS select the publication mode. This implies using the publication mode set in the XML file, or otherwise, the default value set in Fast DDS (see PublishModeQosPolicy).
rmw_fastrtps defines two configurable parameters in addition to ROS 2 QoS policies. Said parameters, and their default values under ROS 2, are:
Parameter |
Description |
Default ROS 2 value |
|---|---|---|
Fast DDS preallocates memory for the publisher |
|
|
User calls to publication method add the messages |
|
XML configuration¶
To use specific Fast-DDS features within a ROS 2 application, XML configuration files can be used to configure a wide set of QoS. Please refer to XML profiles to see the whole list of configuration options available in Fast DDS.
When configuring rmw_fastrtps using XML files, there are certain points that have to be taken into account:
ROS 2 QoS contained in rmw_qos_profile_t are always honored, unless set to
*_SYSTEM_DEFAULT. In that case, XML values, or Fast DDS default values in the absences of XML ones, are applied. This means that if any QoS inrmw_qos_profile_tis set to something other than*_SYSTEM_DEFAULT, the corresponding value in the XML is ignored.By default, rmw_fastrtps overrides the values for MemoryManagementPolicy and PublishModeQosPolicy. This means that the values configured in the XML for these two parameters will be ignored. Instead,
PREALLOCATED_WITH_REALLOC_MEMORY_MODEandASYNCHRONOUS_PUBLISH_MODEare used respectively.The override of MemoryManagementPolicy and PublishModeQosPolicy can be avoided by setting the environment variable
RMW_FASTRTPS_USE_QOS_FROM_XMLto1(its default value is0). This will make rmw_fastrtps use the values defined in the XML for MemoryManagementPolicy and PublishModeQosPolicy. Bear in mind that setting this environment variable but not setting these policies in the XML results in using the default values in Fast DDS. These are different from the aforementioned rmw_fastrtps default values (see MemoryManagementPolicy and PublishModeQosPolicy).Setting
RMW_FASTRTPS_USE_QOS_FROM_XMLeffectively overrides whatever configuration was set withRMW_FASTRTPS_PUBLICATION_MODE, setting the publication mode to the value specified in the XML, or to the Fast DDS default publication mode if none is set in the XML.
The following table summarizes which values are used or ignored according to the configured variables:
RMW_FASTRTPS_USE_QOS_FROM_XML |
|
Fast DDS XML QoS |
Fast DDS XML history memory policy |
|---|---|---|---|
0 (default) |
Default values |
Overridden by |
Overridden by |
0 (default) |
Non system default |
overridden by |
Overridden by |
0 (default) |
System default |
Used |
Overridden by |
1 |
Default values |
Overridden by |
Used |
1 |
Non system default |
Overridden by |
Used |
1 |
System default |
Used |
Used |
XML configuration file location¶
There are two possibilities for providing Fast DDS with XML configuration files:
Recommended: Setting the location with environment variable
FASTDDS_DEFAULT_PROFILES_FILEto contain the path to the XML configuration file (see Environment variables).export FASTDDS_DEFAULT_PROFILES_FILE=<path_to_xml_file>
Alternative: Placing the XML file in the running application directory under the name DEFAULT_FASTDDS_PROFILES.xml.
For example:
export FASTDDS_DEFAULT_PROFILES_FILE=<path_to_xml_file>
export RMW_FASTRTPS_USE_QOS_FROM_XML=1
ros2 run <package> <application>
Applying different profiles to different entities¶
rmw_fastrtps allows for the configuration of different entities with different QoS using the same XML file. For doing so, rmw_fastrtps locates profiles in the XML based on topic names.
Creating publishers/subscribers with different profiles¶
To configure a publisher, define a
<data_writer>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the topic prepended by the node namespace (which defaults to “” if not specified), i.e. the node’s namespace followed by topic name used to create the publisher. Mind that topic names always start with/(it is added when creating the topic if not present), and that namespace and topic name are always separated by one/. If such profile is not defined, rmw_fastrtps attempts to load the<data_writer>profile with attributeis_default_profile="true".To configure a subscriber, define a
<data_reader>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the topic prepended by the node namespace (which defaults to “” if not specified), i.e. the node’s namespace followed by topic name used to create the subscriber. Mind that topic names always start with/(it is added when creating the topic if not present), and that namespace and topic name are always separated by one/. If such profile is not defined, rmw_fastrtps attempts to load the<data_reader>profile with attributeis_default_profile="true".
The following table presents different combinations of node namespaces and user specified topic names, as well as the resulting topic names and the suitable profile names:
User specified topic name |
Node namespace |
Final topic name |
Profile name |
|---|---|---|---|
chatter |
DEFAULT (“”) |
/chatter |
/chatter |
chatter |
test_namespace |
/test_namespace/chatter |
/test_namespace/chatter |
chatter |
/test_namespace |
/test_namespace/chatter |
/test_namespace/chatter |
/chatter |
test_namespace |
/chatter |
/chatter |
/chatter |
/test_namespace |
/chatter |
/chatter |
Important
Node namespaces are NOT prepended to user specified topic names starting with /, a.k.a Fully Qualified Names (FQN). For a complete description of topic name remapping please refer to Remapping Names.
Creating services with different profiles¶
ROS 2 services contain a subscriber for receiving requests, and a publisher to reply to them. rmw_fastrtps allows for configuring each of these endpoints separately in the following manner:
To configure the request subscriber, define a
<data_reader>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the service after mangling. For more information on name mangling, please refer to Topic and Service name mapping to DDS. If such profile is not defined, rmw_fastrtps attempts to load a<data_reader>profile with attributeprofile_name="service". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<data_reader>profile with attributeis_default_profile="true".To configure the reply publisher, define a
<data_writer>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the service after mangling. If such profile is not defined, rmw_fastrtps attempts to load a<data_writer>profile withattribute profile_name="service". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<data_writer>profile with attributeis_default_profile="true".
Creating clients with different profiles¶
ROS 2 clients contain a publisher to send requests, and a subscription to receive the service’s replies. rmw_fastrtps allows for configuring each of these endpoints separately in the following manner:
To configure the requests publisher, define a
<data_writer>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the service after mangling. If such profile is not defined, rmw_fastrtps attempts to load a<data_writer>profile with attributeprofile_name="client". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<data_writer>profile with attributeis_default_profile="true".To configure the reply subscription, define a
<data_reader>profile withattribute profile_name=topic_name, wheretopic_nameis the name of the service after mangling. If such profile is not defined, rmw_fastrtps attempts to load a<data_reader>profile with attributeprofile_name="client". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<data_reader>profile with attributeis_default_profile="true".
Creating ROS contexts and nodes¶
ROS context and node entities are mapped to Fast DDS Participant entity, according to the following table:
ROS entity |
Fast DDS entity since Foxy |
Fast DDS entity in Eloquent & below |
|---|---|---|
Context |
Participant |
Not DDS direct mapping |
Node |
Not DDS direct mapping |
Participant |
This means that on Foxy and later releases, contexts can be configured using a <Participant> profile
with attribute is_default_profile="true".
The same profile will be used in Eloquent and below to configure nodes.
For example, a profile for a ROS 2 context on Foxy and later releases would be specified as:
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
<participant profile_name="participant_profile_ros2" is_default_profile="true">
<rtps>
<name>profile_for_ros2_context</name>
</rtps>
</participant>
</profiles>
|
Example¶
The following example uses the ROS 2 talker/listener demo, configuring Fast DDS to publish synchronously, and to have dynamically allocated publisher and subscriber histories.
Create a XML file ros_example.xml and save it in path/to/xml/
XML
<?xml version="1.0" encoding="UTF-8" ?> <profiles xmlns="http://www.eprosima.com"> <participant profile_name="participant_profile_ros2" is_default_profile="true"> <rtps> <name>profile_for_ros2_context</name> </rtps> </participant> <!-- Default publisher profile --> <data_writer profile_name="default publisher profile" is_default_profile="true"> <qos> <publishMode> <kind>SYNCHRONOUS</kind> </publishMode> </qos> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </data_writer> <!-- Publisher profile for topic helloworld --> <data_writer profile_name="helloworld"> <qos> <publishMode> <kind>SYNCHRONOUS</kind> </publishMode> </qos> </data_writer> <!-- Request subscriber profile for services --> <data_reader profile_name="service"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </data_reader> <!-- Request publisher profile for clients --> <data_writer profile_name="client"> <qos> <publishMode> <kind>ASYNCHRONOUS</kind> </publishMode> </qos> </data_writer> <!-- Request subscriber profile for server of service "add_two_ints" --> <data_reader profile_name="rq/add_two_intsRequest"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </data_reader> <!-- Reply subscriber profile for client of service "add_two_ints" --> <data_reader profile_name="rr/add_two_intsReply"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </data_reader> </profiles>
Open one terminal and run:
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp export FASTDDS_DEFAULT_PROFILES_FILE=path/to/xml/ros_example.xml export RMW_FASTRTPS_USE_QOS_FROM_XML=1 ros2 run demo_nodes_cpp talker
Open one terminal and run:
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp export FASTDDS_DEFAULT_PROFILES_FILE=path/to/xml/ros_example.xml export RMW_FASTRTPS_USE_QOS_FROM_XML=1 ros2 run demo_nodes_cpp listener
Use ROS 2 with Fast-DDS Discovery Server¶
This section explains how to run some ROS 2 examples using the Discovery Servers as discovery communication. In order to get more information about the specific use of this configuration, please check the Discovery Server Documentation or read the common use cases for this configuration.
The following tutorial gathers the steps to check this functionality and learn how to use it with ROS 2.
The Simple Discovery Protocol is the standard protocol defined in the DDS standard. However, it has certain known disadvantages in some scenarios, mainly:
It does not Scale efficiently, as the number of exchanged packets highly increases as new nodes are added.
It requires Multicasting capabilities that may not work reliably in some scenarios, e.g. WiFi.
The Discovery Server provides a Client-Server Architecture that allows the nodes to connect with each other using an intermediate server. Each node will work as a Client, sharing its info with the Discovery Server and receiving the discovery information from it. This means that the network traffic is highly reduced in big systems, and it does not require Multicasting.
These Discovery Servers can be independent, duplicated or connected with each other in order to create redundancy over the network and avoid having a Single-Point-Of-Failure.
Discovery Server v2¶
The new version v2 of Discovery Server, available from Fast DDS v2.0.2, implements a new filter feature that allows to further reduce the number of discovery messages sent. This version uses the topic of the different nodes to decide if two nodes must be connected, or they could be left unmatched. The following schema represents the decrease of the discovery packages:
This architecture reduces the number of packages sent between the server and the different clients dramatically. In the following graph, the reduction in traffic network over the discovery phase for a RMF Clinic demo use case, is shown:
In order to use this functionality, Fast-DDS Discovery Server can be set using
the XML configuration for Participants.
Furthermore, Fast DDS provides an easier way to set a Discovery Server communication using
the fastdds CLI tool and an environment variable,
which are going to be used along this tutorial.
For a more detailed explanation about the configuration of the Discovery Server,
visit Discovery Server Settings.
Prerequisites¶
This tutorial assumes you have at least a
working Foxy ROS 2 installation.
In case your installation is using a Fast DDS version lower than v2.0.2 you could not use the fastdds tool.
You could update your repository to use a different Fast DDS version,
or set the discovery server by Fast-DDS XML QoS configuration.
Note
This tutorial can also be run in Galactic exporting the environment variable that selects Fast DDS as the middleware layer:
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp
Run the demo¶
The talker-listener ROS 2 demo allows to create a talker node that publishes a Hello World message every second,
and a listener node that listens to these messages.
By Sourcing ROS 2
you will get access to the CLI of Fast DDS: fastdds.
This CLI gives access to the discovery tool,
which allows to launch a server. This server will manage the discovery process for the nodes that connect to it.
Important
Do not forget to source ROS 2 in every new terminal opened.
Setup Discovery Server¶
Start by launching a server with id 0, with port 11811 and listening on all available interfaces.
Open a new terminal and run:
fastdds discovery -i 0
Launch node listener¶
Execute the listener demo, that will listen in /chatter topic.
In a new terminal, set the environment variable ROS_DISCOVERY_SERVER to use Discovery Server.
(Do not forget to source ROS 2 in every new terminal)
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
Afterwards, launch the listener node. Use the argument --remap __node:=listener_discovery_server
to change the node’s name for future purpose.
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener_discovery_server
This process will create a ROS 2 node, that will automatically create a client for the Discovery Server and use the server created previously to run the discovery protocol.
Launch node talker¶
Open a new terminal and set the environment variable as before, so the node raises a client for the discovery protocol.
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker_discovery_server
Now, we should see the talker publishing Hello World messages, and the listener receiving these messages.
Demonstrate Discovery Server execution¶
So far, there is not proof that this example and the standard talker-listener example run differently.
For this purpose, run another node that is not connected to our Discovery Server.
Just run a new listener (listening in /chatter topic by default) in a new terminal and check that it is
not connected to the talker already running.
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=simple_listener
In this case, we should not see the listener receiving the messages.
To finally verify that everything is running correctly, a new talker can be created using the simple discovery protocol.
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=simple_talker
Now we should see the listener simple_listener receiving the messages from simple_talker but not the other messages from talker_discovery_server.
Advance user cases¶
The following paragraphs are going to show different features of the Discovery Server that allows to hold a robust structure over the node’s network.
Server Redundancy¶
By using the Fast DDS tool, several servers can be created, and the nodes can be connected to as many servers as desired. This allows to have a safe redundancy network that will work even if some servers or nodes shut down unexpectedly. Next schema shows a simple architecture that will work with server redundancy:
In different terminals, run the next code to establish a communication over redundant servers.
fastdds discovery -i 0 -l 127.0.0.1 -p 11811
fastdds discovery -i 1 -l 127.0.0.1 -p 11888
-i N means server with id N. When referencing the servers with ROS_DISCOVERY_SERVER,
server 0 must be in first place and server 1 in second place.
export ROS_DISCOVERY_SERVER="127.0.0.1:11811;127.0.0.1:11888"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker
export ROS_DISCOVERY_SERVER="127.0.0.1:11811;127.0.0.1:11888"
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener
Now, if one of these servers fails, there would still be discovery communication between nodes.
Backup Server¶
Fast DDS Discovery Server allows to easily build a server with a backup functionality. This allows the server to retake the last state it saved in case of a shutdown.
In different terminals, run the next code to establish a communication over a backup server.
fastdds discovery -i 0 -l 127.0.0.1 -p 11811 -b
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener
Several backup files are created in the path the server has run.
Two SQLite files and two json files that contains the information required to
raise a new server in case of failure, avoiding the whole discovery process to happen again and
without losing information.
Discovery partitions¶
The Discovery Server communication could be used with different servers to split in virtual partitions the discovery info. This means that two endpoints only would know each other if there is a server or a server network between them. We are going to execute an example with two different independent servers. The following image shows a schema of the architecture desired:
With this schema Listener 1 will be connected to Talker 1 and Talker 2, as they share Server 1. Listener 2 will connect with Talker 1 as they share Server 2. But Listener 2 will not hear the messages from Talker 2 because they do not share any server or servers’ network that connect them.
Run the first server listening in localhost in default port 11811.
fastdds discovery -i 0 -l 127.0.0.1 -p 11811
In another terminal run the second server listening in localhost in port another port, in this case 11888.
fastdds discovery -i 1 -l 127.0.0.1 -p 11888
Now, run each node in a different terminal. Use the environment variable ROS_DISCOVERY_SERVER to decide which
server they are connected to. Be aware that the ids must match (Environment variables).
export ROS_DISCOVERY_SERVER="127.0.0.1:11811;127.0.0.1:11888"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker_1
export ROS_DISCOVERY_SERVER="127.0.0.1:11811;127.0.0.1:11888"
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener_1
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker_2
export ROS_DISCOVERY_SERVER=";127.0.0.1:11888"
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener_2
We should see how Listener 1 is receiving double messages, while Listener 2 is in a different partition from Talker 2 and so it does not listen to it.
Note
Once two endpoints know each other, they do not need the server network between them to listen to each other messages.
ROS 2 Introspection¶
ROS 2 Command Line Interface (CLI) implements several introspection features to analyze the behaviour of a ROS 2 execution. These features (i.e. rosbag, topic list, etc.) are very helpful to understand a ROS 2 working network.
Most of these features use the DDS capability to share any topic information with every exiting participant. However, the new Discovery Server v2 implements a traffic network reduction that limits the discovery data between nodes that do not share a topic. This means that not every node will receive every topic data unless it has a reader in that topic. As most of ROS 2 CLI Introspection is executed by adding a node into the network (some of them use ROS 2 Daemon, and some create their own nodes), using Discovery Server v2 we will find that most of these functionalities are limited and do not have all the information.
The Discovery Server v2 functionality allows every node running as a SUPER_CLIENT, a kind of Client that
connects to a SERVER, from which it receives all the available discovery information (instead of just what it needs).
In this sense, ROS 2 introspection tools can be configured as Super Client, thus being able to discover every entity
that is using the Discovery Server protocol within the network.
No Daemon commands¶
Some ROS 2 CLI tools can be executed without the ROS 2 Daemon. In order for these tools to connect with a Discovery Server and receive all the topics information they need to be instantiated as a Super Client that connects to the Server.
Following the previous configuration, build a simple system with a talker and a listener. First, run a Server:
fastdds discovery -i 0 -l 127.0.0.1 -p 11811
Then, run the talker and listener is separate terminals:
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp listener --ros-args --remap __node:=listener
export ROS_DISCOVERY_SERVER="127.0.0.1:11811"
ros2 run demo_nodes_cpp talker --ros-args --remap __node:=talker
Continue using the ROS 2 CLI with --no-daemon option with the new configuration.
New nodes will connect with the existing Server and will know every topic.
Exporting ROS_DISCOVERY_SERVER is not needed as the remote server has been configured in the xml file.
export FASTDDS_DEFAULT_PROFILES_FILE=super_client_configuration_file.xml
ros2 topic list --no-daemon
ros2 node info /talker --no-daemon --spin-time 2
Compare Discovery Server with Simple Discovery¶
In order to compare the ROS 2 execution using Simple Discovery or Discovery Server, two scripts that
execute a talker and many listeners and analyze the network traffic during this time are provided.
For this experiment, tshark is required to be installed on your system.
The configuration file is mandatory in order to avoid using intra-process mode.
Note
These scripts require a Discovery Server closure feature that is only available from Fast DDS v2.1.0 and forward. In order to use this functionality, compile ROS 2 with Fast DDS v2.1.0 or higher.
These scripts’ functionalities are references for advance purpose and their study is left to the user.
Run the bash script with the setup path to source ROS 2 as argument.
This will generate the traffic trace for simple discovery.
Executing the same script with second argument SERVER, it will generates the trace for service discovery.
Note
Depending on your configuration of tcpdump, this script may require sudo privileges to read traffic across
your network device.
After both executions are done, run the python script to generates a graph similar to the one below:
$ export FASTDDS_DEFAULT_PROFILES_FILE="no_intraprocess_configuration.xml"
$ sudo bash generate_discovery_packages.bash ~/ros2_foxy/install/local_setup.bash
$ sudo bash generate_discovery_packages.bash ~/ros2_foxy/install/local_setup.bash SERVER
$ python3 discovery_packets.py
This graph is the result of a is a specific example, the user can execute the scripts and watch their own results. It can easily be seen how the network traffic is reduced when using Discovery Service.
The reduction in traffic is a result of avoiding every node announcing itself and waiting a response from every other node in the net. This creates a huge amount of traffic in large architectures. This reduction from this method increases with the number of Nodes, making this architecture more scalable than the simple one.
Since Fast DDS v2.0.2 the new Discovery Server v2 is available, substituting the old Discovery Server. In this new version, those nodes that do not share topics will not know each other, saving the whole discovery data required to connect them and their endpoints. Notice that this is not this example case, but even though the massive reduction could be appreciate due to the hidden architecture topics of ROS 2 nodes.
Troubleshooting¶
This section offers hints and pointers to help users with navigating through the documentation while troubleshooting issues.
Although UDP/SHM default transports of Fast DDS are designed to work in most network environments, they may encounter certain limitations when operating over WiFi or within lossy network conditions. In these cases, it is advisable to set up the
LARGE_DATAconfiguration, which has been specifically optimized for these scenarios. TheLARGE_DATAprofile limits the use of UDP solely to the PDP discovery phase, employing the more reliable TCP/SHM for the remainder of the communication process. Its implementation can be accomplished by simply configuring theFASTDDS_BUILTIN_TRANSPORTSenvironment variable, or alternatively through XML profiles or via code. For more information, please refer to Large Data Mode.export FASTDDS_BUILTIN_TRANSPORTS=LARGE_DATA
<?xml version="1.0" encoding="UTF-8" ?> <dds xmlns="http://www.eprosima.com"> <profiles> <!-- UDP transport for PDP and SHM/TCPv4 transport for both EDP and application data --> <participant profile_name="large_data_builtin_transports" is_default_profile="true"> <rtps> <builtinTransports>LARGE_DATA</builtinTransports> </rtps> </participant> </profiles> </dds>
eprosima::fastdds::dds::DomainParticipantQos pqos = PARTICIPANT_QOS_DEFAULT; /* Transports configuration */ // UDPv4 transport for PDP over multicast and SHM / TCPv4 transport for EDP and application data pqos.setup_transports(eprosima::fastdds::rtps::BuiltinTransports::LARGE_DATA); /* Create participant as usual */ eprosima::fastdds::dds::DomainParticipant* participant = eprosima::fastdds::dds::DomainParticipantFactory::get_instance()->create_participant(0, pqos);
If having problems with transmitting large samples when using the
LARGE_DATAmode, try to use the builtin transports configuration options to adjustLARGE_DATAto your specific use case. Please refer to Large Data with configuration options for more information.If having problems with transmitting large samples such as video or point clouds, please refer to Large Data Rates.
C++ API Reference¶
Fast DDS, as a Data Distribution Service (DDS) standard implementation, exposes the DDS Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API, as specified in the DDS specification. Furthermore, is also gives the user the possibility to directly interact with the underlying Real-time Publish-Subscribe (RTPS) API that DDS implements for wired communications, as specified in the RTPS standard.
This section presents the most commonly used APIs provided by Fast DDS. For more information about the API reference, please refer to Fast DDS API reference.
DDS DCPS PIM¶
Data Distribution Service (DDS) Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API
Core¶
Entity¶
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DomainEntity¶
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Policy¶
DataRepresentationId¶
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DataRepresentationQosPolicy¶
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DataSharingQosPolicy¶
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DataSharingKind¶
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DeadlineQosPolicy¶
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DestinationOrderQosPolicy¶
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DestinationOrderQosPolicyKind¶
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DisablePositiveACKsQosPolicy¶
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DurabilityQosPolicy¶
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DurabilityQosPolicyKind¶
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DurabilityServiceQosPolicy¶
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EntityFactoryQosPolicy¶
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GenericDataQosPolicy¶
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GroupDataQosPolicy¶
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HistoryQosPolicy¶
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HistoryQosPolicyKind¶
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LatencyBudgetQosPolicy¶
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LifespanQosPolicy¶
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LivelinessQosPolicy¶
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LivelinessQosPolicyKind¶
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OwnershipQosPolicy¶
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OwnershipQosPolicyKind¶
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OwnershipStrengthQosPolicy¶
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ParticipantResourceLimitsQos¶
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Partition_t¶
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PartitionQosPolicy¶
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PresentationQosPolicy¶
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PresentationQosPolicyAccessScopeKind¶
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PropertyPolicyQos¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PublishModeQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PublishModeQosPolicyKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
QosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
QosPolicyId_t¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderDataLifecycleQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReliabilityQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReliabilityQosPolicyKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ResourceLimitsQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSEndpointQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TimeBasedFilterQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TopicDataQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TransportConfigQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TransportPriorityQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeConsistencyEnforcementQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeConsistencyKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
UserDataQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WireProtocolConfigQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterDataLifecycleQosPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterResourceLimitsQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Status¶
BaseStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DeadlineMissedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IncompatibleQosStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InconsistentTopicStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LivelinessChangedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
MatchedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
OfferedDeadlineMissedStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
OfferedIncompatibleQosStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PublicationMatchedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
QosPolicyCount¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
QosPolicyCountSeq¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RequestedDeadlineMissedStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RequestedIncompatibleQosStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LivelinessLostStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleLostStatus¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleRejectedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleRejectedStatusKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
StatusMask¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SubscriptionMatchedStatus¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Condition¶
Condition¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ConditionSeq¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GuardCondition¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
StatusCondition¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Wait-set¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LoanableArray¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LoanableCollection¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LoanableSequence¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
StackAllocatedSequence¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Domain¶
DomainParticipant¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DomainParticipantFactory¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DomainParticipantFactoryQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DomainParticipantListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DomainParticipantQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Publisher¶
DataWriter¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataWriterListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataWriterQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Publisher¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PublisherListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PublisherQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSReliableWriterQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Subscriber¶
DataReader¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataReaderListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataReaderQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InstanceStateKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReadCondition¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderResourceLimitsQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSReliableReaderQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleInfo¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleStateKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Subscriber¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SubscriberListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SubscriberQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeConsistencyQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ViewStateKind¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Topic¶
TopicDataType¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeSupport¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TopicDescription¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Topic¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ContentFilteredTopic¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IContentFilter¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IContentFilterFactory¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TopicListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TopicQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeInformationParameter¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
XTypes¶
Dynamic Language Binding¶
AnnotationDescriptor¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicData¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicDataFactory¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicPubSubType¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicType¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicTypeBuilder¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicTypeBuilderFactory¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DynamicTypeMember¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
MemberDescriptor¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeDescriptor¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
VerbatimTextDescriptor¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InvalidArgumentError¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Type Representation¶
TypeObjectRegistry¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TypeObjectUtils¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPS¶
eProsima Fast DDS Real-Time Publish-Subscribe (RTPS) layer API.
Attributes¶
BuiltinAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
c_default_RTPSParticipantAllocationAttributes¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DiscoveryProtocol¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DiscoverySettings¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EndpointAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ExternalLocators¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
HistoryAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InitialAnnouncementConfig¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ParticipantFilteringFlags¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PropertyPolicy¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PropertyPolicyHelper¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderTimes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RemoteLocatorsAllocationAttributes¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RemoteServerAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RemoteServerList_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSParticipantAllocationAttributes¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSParticipantAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSWriterPublishMode¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SendBuffersAllocationAttributes¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SimpleEDPAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ThreadSettings¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
VariableLengthDataLimits¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterAttributes¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterTimes¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Builtin data¶
ContentFilterProperty¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Common¶
BinaryProperty¶
BinaryProperty¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
BinaryPropertyHelper¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
BinaryPropertySeq¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
CacheChange¶
CacheChange_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ChangeForReader_t¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ChangeForReaderCmp¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ChangeForReaderStatus_t¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ChangeKind_t¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
CDRMessage¶
CDRMessage_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
CDRSerialization¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EntityId¶
Const values¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EntityId_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EntityId_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
FragmentNumber¶
FragmentNumber_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
FragmentNumberSet_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Guid¶
c_Guid_Unknown¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GUID_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GUID_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GuidPrefix¶
c_GuidPrefix_Unknown¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GuidPrefix_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
GuidPrefix_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InstanceHandle¶
c_InstanceHandle_Unknown¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InstanceHandle_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
InstanceHandle_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Locator¶
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IsAddressDefined¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IsLocatorValid¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Locator_t¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorList¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorListConstIterator¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorListIterator¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorsIterator¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Locators¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Locator Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorSelectorEntry¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorSelector¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LocatorWithMask¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
MatchingInfo¶
MatchingInfo¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
MatchingStatus¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PortParameters¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Property¶
Property¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PropertyHelper¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PropertySeq¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RemoteLocators¶
RemoteLocators Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RemoteLocatorList¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SampleIdentity¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumber¶
c_SequenceNumber_Unknown¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumber_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumber_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumberDiff¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumberHash¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SequenceNumberSet_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
sort_seqNum¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SerializedPayload¶
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SerializedPayload_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Time_t¶
Const values¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
eprosima::fastrtps::Duration_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
eprosima::fastrtps::Time_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Time_t Operators¶
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Time_t¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Token¶
AuthenticatedPeerCredentialToken¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataHolder¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataHolderHelper¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataHolderSeq¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IdentityStatusToken¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IdentityToken¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PermissionsCredentialToken¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PermissionsToken¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Token¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Types¶
BuiltinEndpointSet_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Const values¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Count_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Macro definitions (#define)¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DurabilityKind_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Endianness_t¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EndpointKind_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
octet¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ProtocolVersion_t¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReliabilityKind_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SubmessageFlag¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TopicKind_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
VendorId_t¶
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriteParams¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Endpoint¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Exceptions¶
Exception¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Flow control¶
FlowControllerDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
FlowControllerSchedulerPolicy¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
History¶
History¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IChangePool¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
IPayloadPool¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderHistory¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterHistory¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSParticipant¶
ParticipantDiscoveryInfo¶
ParticipantAuthenticationInfo¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenfunction: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ParticipantDiscoveryInfo¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ParticipantProxyData¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderDiscoveryInfo¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ReaderProxyData¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterDiscoveryInfo¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterProxyData¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSParticipant¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSParticipantListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSReader¶
ReaderListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSReader¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Resources¶
MemoryManagementPolicy¶
Warning
doxygenenum: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSDomain¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
RTPSWriter¶
RTPSWriter¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
WriterListener¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Transport¶
eProsima Fast DDS Transport Layer API.
Transport Generic Interfaces¶
TransportDescriptorInterface¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TransportInterface¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygentypedef: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TransportReceiverInterface¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
PortBasedTransportDescriptor¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
SocketTransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Chaining of transports¶
ChainingTransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
ChainingTransport¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
UDP Transport¶
UDPTransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
UDPv4TransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
UDPv6TransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
test_UDPv4TransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TCP Transport¶
TCPTransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TCPv4TransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
TCPv6TransportDescriptor¶
Warning
doxygenstruct: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LOG¶
eProsima Fast DDS Logging Module API
Colors¶
A collection of macros for ease the stream coloring.
Color Blue¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Blue¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Cyan¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Green¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Magenta¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Red¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright White¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Bright Yellow¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Cyan¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Def¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Green¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Magenta¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Red¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color White¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Color Yellow¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
FileConsumer¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Log¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
LogConsumer¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EPROSIMA_LOG_ERROR¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EPROSIMA_LOG_INFO¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
EPROSIMA_LOG_WARNING¶
Warning
doxygendefine: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
OStreamConsumer¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
StdoutConsumer¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
StdoutErrConsumer¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Statistics¶
eProsima Fast DDS Statistics Module extension API.
DomainParticipant¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataWriterQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
DataReaderQos¶
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenclass: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Topic names¶
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
doxygenvariable: Cannot find file: /home/docs/checkouts/readthedocs.org/user_builds/eprosima-fast-rtps/checkouts/3.0.x-devel/build/doxygen/xml/index.xml
Warning
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Python API Reference¶
This section presents the most commonly used Python APIs provided by Fast DDS.
DDS DCPS PIM¶
Data Distribution Service (DDS) Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API
Core¶
Entity¶
- class fastdds.Entity(*args, **kwargs)¶
The Entity class is the abstract base class for all the objects that support QoS policies, a listener and a status condition.
- close()¶
This operation disables the Entity before closing it
- enable()¶
This operation enables the Entity
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_instance_handle()¶
Retrieves the instance handler that represents the Entity
- Return type
InstanceHandle_t- Returns
Reference to the InstanceHandle
- get_status_changes()¶
Retrieves the set of triggered statuses in the Entity
Triggered statuses are the ones whose value has changed since the last time the application read the status. When the entity is first created or if the entity is not enabled, all communication statuses are in the non-triggered state, so the list returned by the get_status_changes operation will be empty. The list of statuses returned by the get_status_changes operation refers to the status that are triggered on the Entity itself and does not include statuses that apply to contained entities.
- Return type
- Returns
const reference to the StatusMask with the triggered statuses set to 1
- get_status_mask()¶
Retrieves the set of relevant statuses for the Entity
- Return type
- Returns
Reference to the StatusMask with the relevant statuses set to 1
- get_statuscondition()¶
Allows access to the StatusCondition associated with the Entity
- Return type
StatusCondition- Returns
Reference to StatusCondition object
- is_enabled()¶
Checks if the Entity is enabled
- Return type
boolean
- Returns
true if enabled, false if not
- property thisown¶
The membership flag
DomainEntity¶
Policy¶
DataRepresentationId¶
- class fastdds.XCDR_DATA_REPRESENTATION(*args: Any, **kwargs: Any)¶
- class fastdds.XML_DATA_REPRESENTATION(*args: Any, **kwargs: Any)¶
- class fastdds.XCDR2_DATA_REPRESENTATION(*args: Any, **kwargs: Any)¶
- class fastdds.DEFAULT_DATA_REPRESENTATION(*args: Any, **kwargs: Any)¶
DataRepresentationQosPolicy¶
- class fastdds.DataRepresentationQosPolicy¶
With multiple standard data Representations available, and vendor-specific extensions possible, DataWriters and DataReaders must be able to negotiate which data representation(s) to use. This negotiation shall occur based on DataRepresentationQosPolicy.
Warning: If a writer’s offered representation is contained within a reader’s sequence, the offer satisfies the request and the policies are compatible. Otherwise, they are incompatible.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property m_value¶
- List of ‘DataRepresentationId’.
By default, empty list.
- property thisown¶
The membership flag
DataSharingQosPolicy¶
- class fastdds.DataSharingQosPolicy(*args)¶
Qos Policy to configure the data sharing
Notes: Immutable Qos Policy
- add_domain_id(*args)¶
- automatic(*args)¶
Overload 1:
Configures the DataSharing in automatic mode
The default shared memory directory of the OS is used. A default domain ID is automatically computed.
Overload 2:
Configures the DataSharing in automatic mode
The default shared memory directory of the OS is used.
- Parameters
domain_ids (std::vector< uint16_t,std::allocator< uint16_t > >) – the user configured DataSharing domain IDs (16 bits).
Overload 3:
Configures the DataSharing in automatic mode
A default domain ID is automatically computed.
- Parameters
directory (string) – The shared memory directory to use.
Overload 4:
Configures the DataSharing in automatic mode
- Parameters
directory (string) – The shared memory directory to use.
domain_ids (std::vector< uint16_t,std::allocator< uint16_t > >) – the user configured DataSharing domain IDs (16 bits).
- clear()¶
Clears the QosPolicy object
- data_sharing_listener_thread(*args)¶
Overload 1:
Getter for DataSharing listener thread ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for DataSharing listener thread ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the DataSharing listener thread ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- domain_ids()¶
Gets the set of DataSharing domain IDs.
Each domain ID is 64 bit long. However, user-defined domain IDs are only 16 bit long, while the rest of the 48 bits are used for the automatically generated domain ID (if any).
Automatic domain IDs use the 48 MSB and leave the 16 LSB as zero.
User defined domain IDs use the 16 LSB and leave the 48 MSB as zero.
- Return type
std::vector< uint64_t,std::allocator< uint64_t > >
- Returns
the current DataSharing domain IDs
- kind()¶
- Return type
int
- Returns
the current DataSharing configuration mode
- max_domains()¶
- Return type
int
- Returns
the current configured maximum number of domain IDs
- off()¶
Configures the DataSharing in disabled mode
- on(*args)¶
Overload 1:
Configures the DataSharing in active mode
A default domain ID is automatically computed.
- Parameters
directory (string) – The shared memory directory to use. It is mandatory to provide a non-empty name or the creation of endpoints will fail.
Overload 2:
Configures the DataSharing in active mode
- Parameters
directory (string) – The shared memory directory to use. It is mandatory to provide a non-empty name or the creation of endpoints will fail.
domain_ids (std::vector< uint16_t,std::allocator< uint16_t > >) – the user configured DataSharing domain IDs (16 bits).
- set_max_domains(size)¶
- Parameters
size (int) – the new maximum number of domain IDs
- shm_directory()¶
- Return type
string
- Returns
the current DataSharing shared memory directory
- property thisown¶
The membership flag
DataSharingKind¶
- class fastdds.AUTO(*args: Any, **kwargs: Any)¶
- class fastdds.ON(*args: Any, **kwargs: Any)¶
- class fastdds.OFF(*args: Any, **kwargs: Any)¶
DeadlineQosPolicy¶
- class fastdds.DeadlineQosPolicy¶
DataReader expects a new sample updating the value of each instance at least once every deadline period. DataWriter indicates that the application commits to write a new value (using the DataWriter) for each instance managed by the DataWriter at least once every deadline period.
Notes: Mutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property period¶
Maximum time expected between samples. It is inconsistent for a DataReader to have a DEADLINE period less than its TimeBasedFilterQosPolicy minimum_separation.
By default, c_TimeInifinite.
- property thisown¶
The membership flag
DestinationOrderQosPolicy¶
- class fastdds.DestinationOrderQosPolicy¶
Controls the criteria used to determine the logical order among changes made by Publisher entities to the same instance of data (i.e., matching Topic and key).
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property kind¶
- DestinationOrderQosPolicyKind.
By default, BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS.
- property thisown¶
The membership flag
DestinationOrderQosPolicyKind¶
- class fastdds.BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS(*args: Any, **kwargs: Any)¶
DisablePositiveACKsQosPolicy¶
- class fastdds.DisablePositiveACKsQosPolicy¶
Class DisablePositiveACKsQosPolicy to disable sending of positive ACKs
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property duration¶
The duration to keep samples for (not serialized as not needed by reader). By default, c_TimeInfinite
- property enabled¶
True if this QoS is enabled. By default, false
- property thisown¶
The membership flag
DurabilityQosPolicy¶
- class fastdds.DurabilityQosPolicy¶
This policy expresses if the data should ‘outlive’ their writing time.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- durabilityKind(*args)¶
Overload 1:
Translates kind to rtps layer equivalent
- Return type
int
- Returns
fastrtps::rtps::DurabilityKind_t
Overload 2:
Set kind passing the rtps layer equivalent kind
- Parameters
new_kind (int) – fastrtps::rtps::DurabilityKind_t
- property kind¶
DurabilityQosPolicyKind.
By default the value for DataReaders: VOLATILE_DURABILITY_QOS, for DataWriters TRANSIENT_LOCAL_DURABILITY_QOS
- property thisown¶
The membership flag
DurabilityQosPolicyKind¶
- class fastdds.VOLATILE_DURABILITY_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.TRANSIENT_LOCAL_DURABILITY_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.TRANSIENT_DURABILITY_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.PERSISTENT_DURABILITY_QOS(*args: Any, **kwargs: Any)¶
DurabilityServiceQosPolicy¶
- class fastdds.DurabilityServiceQosPolicy¶
Specifies the configuration of the durability service. That is, the service that implements the DurabilityQosPolicy kind of TRANSIENT and PERSISTENT.
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property history_depth¶
Number of most recent values that should be maintained on the History. It only have effect if the history_kind is KEEP_LAST_HISTORY_QOS.
By default, 1.
- property history_kind¶
Controls the HistoryQosPolicy of the fictitious DataReader that stores the data within the durability service.
By default, KEEP_LAST_HISTORY_QOS.
- property max_instances¶
Control the ResourceLimitsQos of the implied DataReader that stores the data within the durability service. Represents the maximum number of instances DataWriter (or DataReader) can manage.
By default, LENGTH_UNLIMITED.
- property max_samples¶
Control the ResourceLimitsQos of the implied DataReader that stores the data within the durability service. Specifies the maximum number of data-samples the DataWriter (or DataReader) can manage across all the instances associated with it. Represents the maximum samples the middleware can store for any one DataWriter (or DataReader). It is inconsistent for this value to be less than max_samples_per_instance.
By default, LENGTH_UNLIMITED.
- property max_samples_per_instance¶
Control the ResourceLimitsQos of the implied DataReader that stores the data within the durability service. Represents the maximum number of samples of any one instance a DataWriter(or DataReader) can manage. It is inconsistent for this value to be greater than max_samples.
By default, LENGTH_UNLIMITED.
- property service_cleanup_delay¶
Control when the service is able to remove all information regarding a data-instance.
By default, c_TimeZero.
- property thisown¶
The membership flag
EntityFactoryQosPolicy¶
- class fastdds.EntityFactoryQosPolicy(*args)¶
Controls the behavior of the entity when acting as a factory for other entities. In other words, configures the side-effects of the create_* and delete_* operations.
Notes: Mutable Qos Policy
- property autoenable_created_entities¶
Specifies whether the entity acting as a factory automatically enables the instances it creates. If True the factory will automatically enable each created Entity otherwise it will not.
By default, True.
- clear()¶
- property thisown¶
The membership flag
GenericDataQosPolicy¶
- class fastdds.GenericDataQosPolicy(*args)¶
Class GenericDataQosPolicy, base class to transmit user data during the discovery phase.
- clear()¶
Clears the QosPolicy object
- dataVec()¶
- Return type
eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type
- Returns
const reference to the internal raw data.
- data_vec(*args)¶
Overload 1:
Returns raw data vector.
- Return type
eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type
- Returns
raw data as vector of octets.
Overload 2:
Returns raw data vector.
- Return type
eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type
- Returns
raw data as vector of octets.
Overload 3:
Sets raw data vector.
- Parameters
vec (eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type) – raw data to set.
- getValue()¶
Returns raw data vector.
- Return type
eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type
- Returns
raw data as vector of octets.
- resize(new_size)¶
- setValue(vec)¶
Sets raw data vector.
- Parameters
vec (eprosima::fastrtps::ResourceLimitedVector< unsigned char >::collection_type) – raw data to set.
- set_max_size(size)¶
Set the maximum size of the user data and reserves memory for that much.
- Parameters
size (int) – new maximum size of the user data. Zero for unlimited size
- property thisown¶
The membership flag
HistoryQosPolicy¶
- class fastdds.HistoryQosPolicy¶
Specifies the behavior of the Service in the case where the value of a sample changes (one or more times) before it can be successfully communicated to one or more existing subscribers. This QoS policy controls whether the Service should deliver only the most recent value, attempt to deliver all intermediate values, or do something in between. On the publishing side this policy controls the samples that should be maintained by the DataWriter on behalf of existing DataReader entities. The behavior with regards to a DataReaderentities discovered after a sample is written is controlled by the DURABILITY QoS policy. On the subscribing side it controls the samples that should be maintained until the application “takes” them from the Service.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property depth¶
History depth. By default, 1. If a value other than 1 is specified, it should be consistent with the settings of the ResourceLimitsQosPolicy.
Warning: Only takes effect if the kind is KEEP_LAST_HISTORY_QOS.
- property kind¶
- HistoryQosPolicyKind.
By default, KEEP_LAST_HISTORY_QOS.
- property thisown¶
The membership flag
HistoryQosPolicyKind¶
- class fastdds.KEEP_LAST_HISTORY_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.KEEP_ALL_HISTORY_QOS(*args: Any, **kwargs: Any)¶
LatencyBudgetQosPolicy¶
- class fastdds.LatencyBudgetQosPolicy¶
Specifies the maximum acceptable delay from the time the data is written until the data is inserted in the receiver’s application-cache and the receiving application is notified of the fact.This policy is a hint to the Service, not something that must be monitored or enforced. The Service is not required to track or alert the user of any violation.
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Mutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property duration¶
- Maximum acceptable delay from the time data is written until it is received.
By default, c_TimeZero.
- property thisown¶
The membership flag
LifespanQosPolicy¶
LivelinessQosPolicy¶
- class fastdds.LivelinessQosPolicy¶
Determines the mechanism and parameters used by the application to determine whether an Entity is “active” (alive). The “liveliness” status of an Entity is used to maintain instance ownership in combination with the setting of the OwnershipQosPolicy. The application is also informed via listener when an Entity is no longer alive.
The DataReader requests that liveliness of the writers is maintained by the requested means and loss of liveliness is detected with delay not to exceed the lease_duration.
The DataWriter commits to signaling its liveliness using the stated means at intervals not to exceed the lease_duration. Listeners are used to notify the DataReaderof loss of liveliness and DataWriter of violations to the liveliness contract.
- property announcement_period¶
The period for automatic assertion of liveliness. Only used for DataWriters with AUTOMATIC liveliness. By default, c_TimeInfinite.
Warning: When not infinite, must be < lease_duration, and it is advisable to be less than 0.7*lease_duration.
- clear()¶
Clears the QosPolicy object
- property kind¶
Liveliness kind By default, AUTOMATIC_LIVELINESS.
- property lease_duration¶
Period within which liveliness should be asserted. On a DataWriter it represents the period it commits to signal its liveliness. On a DataReader it represents the period without assertion after which a DataWriter is considered inactive. By default, c_TimeInfinite.
- property thisown¶
The membership flag
LivelinessQosPolicyKind¶
- class fastdds.AUTOMATIC_LIVELINESS_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.MANUAL_BY_PARTICIPANT_LIVELINESS_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.MANUAL_BY_TOPIC_LIVELINESS_QOS(*args: Any, **kwargs: Any)¶
OwnershipQosPolicy¶
- class fastdds.OwnershipQosPolicy¶
Specifies whether it is allowed for multiple DataWriters to write the same instance of the data and if so, how these modifications should be arbitrated
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property kind¶
OwnershipQosPolicyKind
- property thisown¶
The membership flag
OwnershipQosPolicyKind¶
- class fastdds.SHARED_OWNERSHIP_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.EXCLUSIVE_OWNERSHIP_QOS(*args: Any, **kwargs: Any)¶
OwnershipStrengthQosPolicy¶
- class fastdds.OwnershipStrengthQosPolicy¶
Specifies the value of the “strength” used to arbitrate among multiple DataWriter objects that attempt to modify the same instance of a data-object (identified by Topic + key).This policy only applies if the OWNERSHIP QoS policy is of kind EXCLUSIVE.
Notes: Mutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property thisown¶
The membership flag
- property value¶
Strength By default, 0.
ParticipantResourceLimitsQos¶
Partition_t¶
PartitionQosPolicy¶
- class fastdds.PartitionQosPolicy(*args)¶
Set of strings that introduces a logical partition among the topics visible by the Publisher and Subscriber. A DataWriter within a Publisher only communicates with a DataReader in a Subscriber if (in addition to matching the Topic and having compatible QoS) the Publisher and Subscriber have a common partition name string.
The empty string (“”) is considered a valid partition that is matched with other partition names using the same rules of string matching and regular-expression matching used for any other partition name.
Notes: Mutable Qos Policy
- begin()¶
Getter for the first position of the partition list
- Return type
eprosima::fastdds::dds::PartitionQosPolicy::const_iterator
- Returns
const_iterator
- clear()¶
Clears list of partition names
- empty()¶
Check if the set is empty
- Return type
int
- Returns
true if it is empty, false otherwise
- end()¶
Getter for the end of the partition list
- Return type
eprosima::fastdds::dds::PartitionQosPolicy::const_iterator
- Returns
const_iterator
- getNames()¶
Returns partition names.
- Return type
std::vector< std::string,std::allocator< std::string > >
- Returns
Vector of partition name strings.
- max_size()¶
Getter for the maximum size (in bytes)
- Return type
int
- Returns
uint32_t with the maximum size
- names(*args)¶
Overload 1:
Returns partition names.
- Return type
std::vector< std::string,std::allocator< std::string > >
- Returns
Vector of partition name strings.
Overload 2:
Overrides partition names
- Parameters
nam (std::vector< std::string,std::allocator< std::string > >) – Vector of partition name strings.
- push_back(name)¶
Appends a name to the list of partition names.
- Parameters
name (string) – Name to append.
- setNames(nam)¶
Overrides partition names
- Parameters
nam (std::vector< std::string,std::allocator< std::string > >) – Vector of partition name strings.
- set_max_size(size)¶
Setter for the maximum size reserved for partitions (in bytes)
- Parameters
size (int) – Size to be set
- size()¶
Getter for the number of partitions
- Return type
int
- Returns
uint32_t with the size
- property thisown¶
The membership flag
PresentationQosPolicy¶
- class fastdds.PresentationQosPolicy¶
Specifies how the samples representing changes to data instances are presented to the subscribing application. This policy affects the application’s ability to specify and receive coherent changes and to see the relative order of changes.access_scope determines the largest scope spanning the entities for which the order and coherency of changes can be preserved. The two booleans control whether coherent access and ordered access are supported within the scope access_scope.
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Immutable Qos Policy
- property access_scope¶
- Access Scope Kind
By default, INSTANCE_PRESENTATION_QOS.
- clear()¶
Clears the QosPolicy object
- property coherent_access¶
Specifies support coherent access. That is, the ability to group a set of changes as a unit on the publishing end such that they are received as a unit at the subscribing end. by default, false.
- property ordered_access¶
Specifies support for ordered access to the samples received at the subscription end. That is, the ability of the subscriber to see changes in the same order as they occurred on the publishing end. By default, false.
- property thisown¶
The membership flag
PresentationQosPolicyAccessScopeKind¶
- class fastdds.INSTANCE_PRESENTATION_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.TOPIC_PRESENTATION_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.GROUP_PRESENTATION_QOS(*args: Any, **kwargs: Any)¶
PropertyPolicyQos¶
PublishModeQosPolicy¶
- class fastdds.PublishModeQosPolicy¶
Class PublishModeQosPolicy, defines the publication mode for a specific writer.
- clear()¶
Clears the QosPolicy object
- property flow_controller_name¶
Name of the flow controller used when publish mode kind is ASYNCHRONOUS_PUBLISH_MODE.
Since: 2.4.0
- property kind¶
- PublishModeQosPolicyKind
By default, SYNCHRONOUS_PUBLISH_MODE.
- property thisown¶
The membership flag
PublishModeQosPolicyKind¶
- class fastdds.SYNCHRONOUS_PUBLISH_MODE(*args: Any, **kwargs: Any)¶
- class fastdds.ASYNCHRONOUS_PUBLISH_MODE(*args: Any, **kwargs: Any)¶
QosPolicy¶
- class fastdds.QosPolicy(*args, **kwargs)¶
Class QosPolicy, base for all QoS policies defined for Writers and Readers.
- clear()¶
Clears the QosPolicy object
- property hasChanged¶
Boolean that indicates if the Qos has been changed with respect to the default Qos.
- send_always()¶
Whether it should always be sent.
- Return type
boolean
- Returns
True if it should always be sent.
- property thisown¶
The membership flag
QosPolicyId_t¶
- class fastdds.INVALID_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.USERDATA_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DURABILITY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.PRESENTATION_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DEADLINE_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.LATENCYBUDGET_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.OWNERSHIP_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.OWNERSHIPSTRENGTH_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.LIVELINESS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TIMEBASEDFILTER_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.PARTITION_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.RELIABILITY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DESTINATIONORDER_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.HISTORY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.RESOURCELIMITS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.ENTITYFACTORY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.WRITERDATALIFECYCLE_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.READERDATALIFECYCLE_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TOPICDATA_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.GROUPDATA_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TRANSPORTPRIORITY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.LIFESPAN_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DURABILITYSERVICE_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DATAREPRESENTATION_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TYPECONSISTENCYENFORCEMENT_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.DISABLEPOSITIVEACKS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.PARTICIPANTRESOURCELIMITS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.PROPERTYPOLICY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.PUBLISHMODE_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.READERRESOURCELIMITS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.RTPSENDPOINT_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.RTPSRELIABLEREADER_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.RTPSRELIABLEWRITER_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TRANSPORTCONFIG_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.TYPECONSISTENCY_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.WIREPROTOCOLCONFIG_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.WRITERRESOURCELIMITS_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
- class fastdds.NEXT_QOS_POLICY_ID(*args: Any, **kwargs: Any)¶
ReaderDataLifecycleQosPolicy¶
- class fastdds.ReaderDataLifecycleQosPolicy¶
Specifies the behavior of the DataReader with regards to the lifecycle of the data-instances it manages. Warning: This Qos Policy will be implemented in future releases. Notes: Mutable Qos Policy
- property autopurge_disposed_samples_delay¶
Indicates the duration the DataReader must retain information regarding instances that have the instance_state NOT_ALIVE_DISPOSED.
By default, c_TimeInfinite.
- property autopurge_no_writer_samples_delay¶
Indicates the duration the DataReader must retain information regarding instances that have the instance_state NOT_ALIVE_NO_WRITERS.
By default, c_TimeInfinite.
- clear()¶
- property thisown¶
The membership flag
ReliabilityQosPolicy¶
- class fastdds.ReliabilityQosPolicy¶
Indicates the reliability of the endpoint.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property kind¶
Defines the reliability kind of the endpoint.
By default, BEST_EFFORT_RELIABILITY_QOS for DataReaders and RELIABLE_RELIABILITY_QOS for DataWriters.
- property max_blocking_time¶
Defines the maximum period of time certain methods will be blocked.
Methods affected by this property are: - DataWriter::write - DataReader::takeNextData - DataReader::readNextData
By default, 100 ms.
- property thisown¶
The membership flag
ReliabilityQosPolicyKind¶
- class fastdds.BEST_EFFORT_RELIABILITY_QOS(*args: Any, **kwargs: Any)¶
- class fastdds.RELIABLE_RELIABILITY_QOS(*args: Any, **kwargs: Any)¶
ResourceLimitsQosPolicy¶
- class fastdds.ResourceLimitsQosPolicy¶
Specifies the resources that the Service can consume in order to meet the requested QoS
Notes: Immutable Qos Policy
- property allocated_samples¶
Number of samples currently allocated.
By default, 100.
- clear()¶
Clears the QosPolicy object
- property extra_samples¶
Represents the extra number of samples available once the max_samples have been reached in the history. This makes it possible, for example, to loan samples even with a full history. By default, 1.
- property max_instances¶
Represents the maximum number of instances DataWriter (or DataReader) can manage.
Value less or equal to 0 means infinite resources. By default, 10.
Warning: It is inconsistent if (max_instances * max_samples_per_instance) > max_samples.
- property max_samples¶
Specifies the maximum number of data-samples the DataWriter (or DataReader) can manage across all the instances associated with it. Represents the maximum samples the middleware can store for any one DataWriter (or DataReader).
Value less or equal to 0 means infinite resources. By default, 5000.
Warning: It is inconsistent if max_samples < (max_instances * max_samples_per_instance).
- property max_samples_per_instance¶
Represents the maximum number of samples of any one instance a DataWriter(or DataReader) can manage.
Value less or equal to 0 means infinite resources. By default, 400.
Warning: It is inconsistent if (max_instances * max_samples_per_instance) > max_samples.
- property thisown¶
The membership flag
RTPSEndpointQos¶
- class fastdds.RTPSEndpointQos¶
Qos Policy to configure the endpoint
- property entity_id¶
Entity ID, if the user wants to specify the EntityID of the endpoint. By default, -1.
- property external_unicast_locators¶
The collection of external locators to use for communication.
- property history_memory_policy¶
Underlying History memory policy. By default, PREALLOCATED_WITH_REALLOC_MEMORY_MODE.
- property ignore_non_matching_locators¶
Whether locators that don’t match with the announced locators should be kept.
- property multicast_locator_list¶
Multicast locator list
- property remote_locator_list¶
Remote locator list
- property thisown¶
The membership flag
- property unicast_locator_list¶
Unicast locator list
- property user_defined_id¶
User Defined ID, used for StaticEndpointDiscovery. By default, -1.
TimeBasedFilterQosPolicy¶
- class fastdds.TimeBasedFilterQosPolicy¶
Filter that allows a DataReader to specify that it is interested only in (potentially) a subset of the values of the data. The filter states that the DataReader does not want to receive more than one value each minimum_separation, regardless of how fast the changes occur. It is inconsistent for a DataReader to have a minimum_separation longer than its Deadline period.
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Mutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property minimum_separation¶
Minimum interval between samples. By default, c_TimeZero (the DataReader is interested in all values)
- property thisown¶
The membership flag
TransportConfigQos¶
- class fastdds.TransportConfigQos¶
Qos Policy to configure the transport layer
- property builtin_transports_reception_threads_¶
Thread settings for the builtin transports reception threads
- clear()¶
Clears the QosPolicy object
- property listen_socket_buffer_size¶
Listen socket buffer for all listen resources. Zero value indicates to use default system buffer size.
By default, 0.
- property max_msg_size_no_frag¶
Maximum message size used to avoid fragmentation, set ONLY in LARGE_DATA. If this value is
not zero, the network factory will allow the initialization of UDP transports with maxMessageSize higher than 65500K.
- property netmask_filter¶
Netmask filter configuration
- property send_socket_buffer_size¶
Send socket buffer size for the send resource. Zero value indicates to use default system buffer size.
By default, 0.
- property thisown¶
The membership flag
- property use_builtin_transports¶
- Set as false to disable the default UDPv4 implementation.
By default, true.
- property user_transports¶
User defined transports to use alongside or in place of builtins.
TransportPriorityQosPolicy¶
- class fastdds.TransportPriorityQosPolicy¶
This policy is a hint to the infrastructure as to how to set the priority of the underlying transport used to send the data.
Warning: This QosPolicy can be defined and is transmitted to the rest of the network but is not implemented in this version.
Notes: Mutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property thisown¶
The membership flag
- property value¶
- Priority
By default, 0.
TypeConsistencyEnforcementQosPolicy¶
- class fastdds.TypeConsistencyEnforcementQosPolicy¶
The TypeConsistencyEnforcementQosPolicy defines the rules for determining whether the type used to publish a given data stream is consistent with that used to subscribe to it. It applies to DataReaders.
Notes: Immutable Qos Policy
- clear()¶
Clears the QosPolicy object
- property m_force_type_validation¶
This option requires type information to be available in order to complete matching between a DataWriter and DataReader when set to TRUE, otherwise matching can occur without complete type information when set to FALSE.
By default, false.
- property m_ignore_member_names¶
This option controls whether member names are taken into consideration for type assignability. If the option is set to TRUE, member names are considered as part of assignability in addition to member IDs (so that members with the same ID also have the same name). If the option is set to FALSE, then member names are not ignored.
By default, false.
- property m_ignore_sequence_bounds¶
This option controls whether sequence bounds are taken into consideration for type assignability. If the option is set to TRUE, sequence bounds (maximum lengths) are not considered as part of the type assignability. This means that a T2 sequence type with maximum length L2 would be assignable to a T1 sequence type with maximum length L1, even if L2 is greater than L1. If the option is set to false, then sequence bounds are taken into consideration for type assignability and in order for T1 to be assignable from T2 it is required that L1>= L2.
By default, true.
- property m_ignore_string_bounds¶
This option controls whether string bounds are taken into consideration for type assignability. If the option is set to TRUE, string bounds (maximum lengths) are not considered as part of the type assignability. This means that a T2 string type with maximum length L2 would be assignable to a T1 string type with maximum length L1, even if L2 is greater than L1. If the option is set to false, then string bounds are taken into consideration for type assignability and in order for T1 to be assignable from T2 it is required that L1>= L2.
By default, true.
- property m_kind¶
- TypeConsistencyKind.
By default, ALLOW_TYPE_COERCION.
- property m_prevent_type_widening¶
This option controls whether type widening is allowed. If the option is set to FALSE, type widening is permitted. If the option is set to TRUE,it shall cause a wider type to not be assignable to a narrower type.
By default, false.
- property thisown¶
The membership flag
TypeConsistencyKind¶
- class fastdds.DISALLOW_TYPE_COERCION(*args: Any, **kwargs: Any)¶
- class fastdds.ALLOW_TYPE_COERCION(*args: Any, **kwargs: Any)¶
UserDataQosPolicy¶
WireProtocolConfigQos¶
- class fastdds.WireProtocolConfigQos¶
Qos Policy that configures the wire protocol
- property builtin¶
Builtin parameters.
- clear()¶
Clears the QosPolicy object
- property default_external_unicast_locators¶
The collection of external locators to use for communication on user created topics.
- property default_multicast_locator_list¶
Default list of Multicast Locators to be used for any Endpoint defined inside this RTPSParticipant in the case that it was defined with NO MulticastLocators. This is usually left empty.
- property default_unicast_locator_list¶
Default list of Unicast Locators to be used for any Endpoint defined inside this RTPSParticipant in the case that it was defined with NO UnicastLocators. At least ONE locator should be included in this list.
- property ignore_non_matching_locators¶
Whether locators that don’t match with the announced locators should be kept.
- property participant_id¶
Participant ID By default, -1.
- property port¶
Port Parameters
- property prefix¶
Optionally allows user to define the GuidPrefix_t
- property thisown¶
The membership flag
WriterDataLifecycleQosPolicy¶
- class fastdds.WriterDataLifecycleQosPolicy¶
Specifies the behavior of the DataWriter with regards to the lifecycle of the data-instances it manages. Warning: This Qos Policy will be implemented in future releases. Notes: Mutable Qos Policy
- property autodispose_unregistered_instances¶
Controls whether a DataWriter will automatically dispose instances each time they are unregistered. The setting autodispose_unregistered_instances = TRUE indicates that unregistered instances will also be considered disposed.
By default, true.
- property thisown¶
The membership flag
WriterResourceLimitsQos¶
Status¶
BaseStatus¶
DeadlineMissedStatus¶
- class fastdds.DeadlineMissedStatus¶
A struct storing the deadline status
- property last_instance_handle¶
Handle to the last instance missing the deadline
- property thisown¶
The membership flag
- property total_count¶
Total cumulative number of offered deadline periods elapsed during which a writer failed to provide data Missed deadlines accumulate, that is, each deadline period the total_count will be incremented by 1
- property total_count_change¶
The change in total_count since the last time the listener was called or the status was read
IncompatibleQosStatus¶
- class fastdds.IncompatibleQosStatus¶
A struct storing the requested incompatible QoS status
- property last_policy_id¶
The id of the policy that was found to be incompatible the last time an incompatibility is detected
- property policies¶
A list of QosPolicyCount
- property thisown¶
The membership flag
- property total_count¶
Total cumulative number of times the concerned writer discovered a reader for the same topic The requested QoS is incompatible with the one offered by the writer
- property total_count_change¶
The change in total_count since the last time the listener was called or the status was read
InconsistentTopicStatus¶
LivelinessChangedStatus¶
- class fastdds.LivelinessChangedStatus¶
A struct storing the liveliness changed status
- property alive_count¶
The total number of currently active publishers that write the topic read by the subscriber This count increases when a newly matched publisher asserts its liveliness for the first time or when a publisher previously considered to be not alive reasserts its liveliness. The count decreases when a publisher considered alive fails to assert its liveliness and becomes not alive, whether because it was deleted normally or for some other reason
- property alive_count_change¶
The change in the alive_count since the last time the listener was called or the status was read
- property last_publication_handle¶
Handle to the last publisher whose change in liveliness caused this status to change
- property not_alive_count¶
The total count of current publishers that write the topic read by the subscriber that are no longer asserting their liveliness This count increases when a publisher considered alive fails to assert its liveliness and becomes not alive for some reason other than the normal deletion of that publisher. It decreases when a previously not alive publisher either reasserts its liveliness or is deleted normally
- property not_alive_count_change¶
The change in the not_alive_count since the last time the listener was called or the status was read
- property thisown¶
The membership flag
MatchedStatus¶
- class fastdds.MatchedStatus¶
A structure storing a matching status
- property current_count¶
The number of writers currently matched to the concerned reader
- property current_count_change¶
The change in current_count since the last time the listener was called or the status was read
- property thisown¶
The membership flag
- property total_count¶
Total cumulative count the concerned reader discovered a match with a writer It found a writer for the same topic with a requested QoS that is compatible with that offered by the reader
- property total_count_change¶
The change in total_count since the last time the listener was called or the status was read
OfferedDeadlineMissedStatus¶
OfferedIncompatibleQosStatus¶
PublicationMatchedStatus¶
QosPolicyCount¶
- class fastdds.QosPolicyCount(*args)¶
A struct storing the id of the incompatible QoS Policy and the number of times it fails
- property count¶
Total number of times that the concerned writer discovered a reader for the same topic The requested QoS is incompatible with the one offered by the writer
- property policy_id¶
The id of the policy
- property thisown¶
The membership flag
QosPolicyCountSeq¶
RequestedDeadlineMissedStatus¶
RequestedIncompatibleQosStatus¶
LivelinessLostStatus¶
SampleLostStatus¶
SampleRejectedStatus¶
- class fastdds.SampleRejectedStatus¶
A struct storing the sample rejected status
- property last_instance_handle¶
Handle to the instance being updated by the last sample that was rejected.
- property last_reason¶
Reason for rejecting the last sample rejected. If no samples have been rejected, the reason is the special value NOT_REJECTED.
- property thisown¶
The membership flag
- property total_count¶
Total cumulative count of samples rejected by the DataReader.
- property total_count_change¶
The incremental number of samples rejected since the last time the listener was called or the status was read.
SampleRejectedStatusKind¶
- class fastdds.NOT_REJECTED(*args: Any, **kwargs: Any)¶
- class fastdds.REJECTED_BY_INSTANCES_LIMIT(*args: Any, **kwargs: Any)¶
- class fastdds.REJECTED_BY_SAMPLES_LIMIT(*args: Any, **kwargs: Any)¶
- class fastdds.REJECTED_BY_SAMPLES_PER_INSTANCE_LIMIT(*args: Any, **kwargs: Any)¶
StatusMask¶
- class fastdds.StatusMask(*args)¶
StatusMask is a bitmap or bitset field.
This bitset is used to: - determine which listener functions to call - set conditions in dds::core::cond::StatusCondition - indicate status changes when calling dds::core::Entity::status_changes
- static all()¶
Get all StatusMasks
- Return type
- Returns
StatusMask all
- static data_available()¶
get the statusmask associated with dds::core::status::data_available
- Return type
- Returns
statusmask data_available
- static data_on_readers()¶
Get the StatusMask associated with dds::core::status::data_on_readers
- Return type
- Returns
StatusMask data_on_readers
- static inconsistent_topic()¶
Get the StatusMask associated with dds::core::status::InconsistentTopicStatus
- Return type
- Returns
StatusMask inconsistent_topic
- is_active(status)¶
Checks if the status passed as parameter is 1 in the actual StatusMask :type status:
StatusMask:param status: Status that need to be checked :rtype: boolean :return: true if the status is active and false if not
- static liveliness_changed()¶
Get the StatusMask associated with dds::core::status::LivelinessChangedStatus
- Return type
- Returns
StatusMask liveliness_changed
- static liveliness_lost()¶
Get the StatusMask associated with dds::core::status::LivelinessLostStatus
- Return type
- Returns
StatusMask liveliness_lost
- static none()¶
Get no StatusMasks
- Return type
- Returns
StatusMask none
- static offered_deadline_missed()¶
Get the StatusMask associated with dds::core::status::OfferedDeadlineMissedStatus
- Return type
- Returns
StatusMask offered_deadline_missed
- static offered_incompatible_qos()¶
Get the StatusMask associated with dds::core::status::OfferedIncompatibleQosStatus
- Return type
- Returns
StatusMask offered_incompatible_qos
- static publication_matched()¶
Get the statusmask associated with dds::core::status::PublicationMatchedStatus
- Return type
- Returns
StatusMask publication_matched
- static requested_deadline_missed()¶
Get the StatusMask associated with dds::core::status::RequestedDeadlineMissedStatus
- Return type
- Returns
StatusMask requested_deadline_missed
- static requested_incompatible_qos()¶
Get the StatusMask associated with dds::core::status::RequestedIncompatibleQosStatus
- Return type
- Returns
StatusMask requested_incompatible_qos
- static sample_lost()¶
Get the StatusMask associated with dds::core::status::SampleLostStatus
- Return type
- Returns
StatusMask sample_lost
- static sample_rejected()¶
Get the StatusMask associated with dds::core::status::SampleRejectedStatus
- Return type
- Returns
StatusMask sample_rejected
- static subscription_matched()¶
Get the statusmask associated with dds::core::status::SubscriptionMatchedStatus
- Return type
- Returns
StatusMask subscription_matched
- property thisown¶
The membership flag
LoanableArray¶
LoanableCollection¶
- class fastdds.LoanableCollection(*args, **kwargs)¶
A collection of generic opaque pointers that can receive the buffer from outside (loan).
This is an abstract class. See ‘LoanableSequence’ for details.
- buffer()¶
Get the pointer to the elements buffer.
The returned value may be nullptr if maximum() is 0. Otherwise it is guaranteed that up to maximum() elements can be accessed.
- Return type
void
- Returns
the pointer to the elements buffer.
- has_ownership()¶
Get the ownership flag.
- Return type
boolean
- Returns
whether the collection has ownership of the buffer.
- length(*args)¶
Overload 1:
Get the number of elements currently accessible.
- Return type
int
- Returns
the number of elements currently accessible.
Overload 2:
Set the number of elements currently accessible.
This method tells the collection that a certain number of elements should be accessible. If the new length is greater than the current ‘maximum()’ the collection should allocate space for the new elements. If this is the case and the collection does not own the buffer (i.e. ‘has_ownership()’ is false) then no allocation will be performed, the length will remain unchanged, and false will be returned.
- Parameters
[in] – new_length New number of elements to be accessible.
- Return type
boolean
- Returns
true if the new length was correctly set.
- loan(buffer, new_maximum, new_length)¶
Loan a buffer to the collection.
- Parameters
[in] – buffer pointer to the buffer to be loaned.
[in] – new_maximum number of allocated elements in buffer.
[in] – new_length number of accessible elements in buffer.
- Return type
boolean
- Returns
false if preconditions are not met.
- Return type
boolean
- Returns
true if operation succeeds.
- maximum()¶
Get the maximum number of elements currently allocated.
- Return type
int
- Returns
the maximum number of elements currently allocated.
- property thisown¶
The membership flag
- unloan(*args)¶
Overload 1:
Remove the loan from the collection.
- Parameters
[out] – maximum number of allocated elements on the returned buffer.
[out] – length number of accessible elements on the returned buffer.
- Return type
void
- Returns
nullptr if preconditions are not met.
- Return type
void
- Returns
pointer to the previously loaned buffer of elements.
Overload 2:
Remove the loan from the collection.
- Return type
void
- Returns
nullptr if preconditions are not met.
- Return type
void
- Returns
pointer to the previously loaned buffer of elements.
LoanableSequence¶
StackAllocatedSequence¶
Domain¶
DomainParticipant¶
- class fastdds.DomainParticipant(*args, **kwargs)¶
Class DomainParticipant used to group Publishers and Subscribers into a single working unit.
- assert_liveliness()¶
This operation manually asserts the liveliness of the DomainParticipant. This is used in combination with the LIVELINESS QoS policy to indicate to the Service that the entity remains active.
This operation needs to only be used if the DomainParticipant contains DataWriter entities with the LIVELINESS set to MANUAL_BY_PARTICIPANT and it only affects the liveliness of those DataWriter entities. Otherwise, it has no effect.
Notes: Writing data via the write operation on a DataWriter asserts liveliness on the DataWriter itself and its DomainParticipant. Consequently the use of assert_liveliness is only needed if the application is not writing data regularly.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the liveliness was asserted, RETCODE_ERROR otherwise.
- contains_entity(a_handle, recursive=True)¶
This operation checks whether or not the given handle represents an Entity that was created from the DomainParticipant.
- Parameters
a_handle (
InstanceHandle_t) – InstanceHandle of the entity to look for.recursive (boolean) – The containment applies recursively. That is, it applies both to entities (TopicDescription, Publisher, or Subscriber) created directly using the DomainParticipant as well as entities created using a contained Publisher, or Subscriber as the factory, and so forth. (default: true)
- Return type
boolean
- Returns
True if entity is contained. False otherwise.
- create_contentfilteredtopic(*args)¶
Overload 1:
Create a ContentFilteredTopic in this Participant.
- Parameters
name (string) – Name of the ContentFilteredTopic
related_topic (
Topic) – Related Topic to being subscribedfilter_expression (string) – Logic expression to create filter
expression_parameters (std::vector< std::string,std::allocator< std::string > >) – Parameters to filter content
- Return type
ContentFilteredTopic- Returns
Pointer to the created ContentFilteredTopic.
- Return type
ContentFilteredTopic- Returns
nullptr if
related_topicdoes not belong to this participant.- Return type
ContentFilteredTopic- Returns
nullptr if a topic with the specified
namehas already been created.- Return type
ContentFilteredTopic- Returns
nullptr if a filter cannot be created with the specified
filter_expressionandexpression_parameters.
Overload 2:
Create a ContentFilteredTopic in this Participant using a custom filter.
- Parameters
name (string) – Name of the ContentFilteredTopic
related_topic (
Topic) – Related Topic to being subscribedfilter_expression (string) – Logic expression to create filter
expression_parameters (std::vector< std::string,std::allocator< std::string > >) – Parameters to filter content
filter_class_name (string) – Name of the filter class to use
- Return type
ContentFilteredTopic- Returns
Pointer to the created ContentFilteredTopic.
- Return type
ContentFilteredTopic- Returns
nullptr if
related_topicdoes not belong to this participant.- Return type
ContentFilteredTopic- Returns
nullptr if a topic with the specified
namehas already been created.- Return type
ContentFilteredTopic- Returns
nullptr if a filter cannot be created with the specified
filter_expressionandexpression_parameters.- Return type
ContentFilteredTopic- Returns
nullptr if the specified
filter_class_namehas not been registered.
- create_multitopic(name, type_name, subscription_expression, expression_parameters)¶
Create a MultiTopic in this Participant.
- Parameters
name (string) – Name of the MultiTopic
type_name (string) – Result type of the MultiTopic
subscription_expression (string) – Logic expression to combine filter
expression_parameters (std::vector< std::string,std::allocator< std::string > >) – Parameters to subscription content
- Return type
eprosima::fastdds::dds::MultiTopic
- Returns
Pointer to the created ContentFilteredTopic, nullptr in error case
- create_publisher(*args)¶
Create a Publisher in this Participant.
- Parameters
qos (
PublisherQos) – QoS of the Publisher.listener (
PublisherListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Publisher.
- create_publisher_with_profile(*args)¶
Create a Publisher in this Participant.
- Parameters
profile_name (string) – Publisher profile name.
listener (
PublisherListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Publisher.
- create_subscriber(*args)¶
Create a Subscriber in this Participant.
- Parameters
qos (
SubscriberQos) – QoS of the Subscriber.listener (
SubscriberListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Subscriber.
- create_subscriber_with_profile(*args)¶
Create a Subscriber in this Participant.
- Parameters
profile_name (string) – Subscriber profile name.
listener (
SubscriberListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Subscriber.
- create_topic(*args)¶
Create a Topic in this Participant.
- Parameters
topic_name (string) – Name of the Topic.
type_name (string) – Data type of the Topic.
qos (
TopicQos) – QoS of the Topic.listener (
TopicListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Topic.
- create_topic_with_profile(*args)¶
Create a Topic in this Participant.
- Parameters
topic_name (string) – Name of the Topic.
type_name (string) – Data type of the Topic.
profile_name (string) – Topic profile name.
listener (
TopicListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all)
- Return type
- Returns
Pointer to the created Topic.
- delete_contained_entities()¶
Deletes all the entities that were created by means of the “create” methods
- Return type
ReturnCode_t- Returns
RETURN_OK code if everything correct, error code otherwise
- delete_contentfilteredtopic(a_contentfilteredtopic)¶
Deletes an existing ContentFilteredTopic.
- Parameters
a_contentfilteredtopic (
ContentFilteredTopic) – ContentFilteredTopic to be deleted- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the topic passed is a nullptr, RETCODE_PRECONDITION_NOT_MET if the topic does not belong to this participant or if it is referenced by any entity and RETCODE_OK if the ContentFilteredTopic was deleted.
- delete_multitopic(a_multitopic)¶
Deletes an existing MultiTopic.
- Parameters
a_multitopic (eprosima::fastdds::dds::MultiTopic) – MultiTopic to be deleted
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the topic passed is a nullptr, RETCODE_PRECONDITION_NOT_MET if the topic does not belong to this participant or if it is referenced by any entity and RETCODE_OK if the Topic was deleted.
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- delete_publisher(publisher)¶
Deletes an existing Publisher.
- Parameters
publisher (
Publisher) – to be deleted.- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the publisher does not belong to this participant or if it has active DataWriters, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- delete_subscriber(subscriber)¶
Deletes an existing Subscriber.
- Parameters
subscriber (
Subscriber) – to be deleted.- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the subscriber does not belong to this participant or if it has active DataReaders, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- delete_topic(topic)¶
Deletes an existing Topic.
- Parameters
topic (
Topic) – to be deleted.- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the topic passed is a nullptr, RETCODE_PRECONDITION_NOT_MET if the topic does not belong to this participant or if it is referenced by any entity and RETCODE_OK if the Topic was deleted.
- enable()¶
This operation enables the DomainParticipant
- Return type
ReturnCode_t- Returns
RETCODE_OK
- find_topic(topic_name, timeout)¶
Gives access to an existing (or ready to exist) enabled Topic. It should be noted that the returned Topic is a local object that acts as a proxy to designate the global concept of topic. Topics obtained by means of find_topic, must also be deleted by means of delete_topic so that the local resources can be released. If a Topic is obtained multiple times by means of find_topic or create_topic, it must also be deleted that same number of times using delete_topic.
- Parameters
topic_name (string) – Topic name
timeout (
Duration_t) – Maximum time to wait for the Topic
- Return type
- Returns
Pointer to the existing Topic, nullptr in case of error or timeout
- find_type(type_name)¶
This method gives access to a registered type based on its name.
- Parameters
type_name (string) – Name of the type
- Return type
- Returns
TypeSupport corresponding to the type_name
- get_builtin_subscriber()¶
Allows access to the builtin Subscriber.
- Return type
- Returns
Pointer to the builtin Subscriber, nullptr in error case
- get_current_time(current_time)¶
This operation returns the current value of the time that the service uses to time-stamp data-writes and to set the reception-timestamp for the data-updates it receives.
- Parameters
current_time (
Time_t) – Time_t reference where the current time is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_default_publisher_qos(*args)¶
Overload 1:
This operation retrieves the default value of the Publisher QoS, that is, the QoS policies which will be used for newly created Publisher entities in the case where the QoS policies are defaulted in the create_publisher operation.
The values retrieved get_default_publisher_qos will match the set of values specified on the last successful call to set_default_publisher_qos, or else, if the call was never made, the default values.
- Return type
- Returns
Current default publisher qos.
Overload 2:
This operation retrieves the default value of the Publisher QoS, that is, the QoS policies which will be used for newly created Publisher entities in the case where the QoS policies are defaulted in the create_publisher operation.
The values retrieved get_default_publisher_qos will match the set of values specified on the last successful call to set_default_publisher_qos, or else, if the call was never made, the default values.
- Parameters
qos (
PublisherQos) – PublisherQos reference where the default_publisher_qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_default_subscriber_qos(*args)¶
Overload 1:
This operation retrieves the default value of the Subscriber QoS, that is, the QoS policies which will be used for newly created Subscriber entities in the case where the QoS policies are defaulted in the create_subscriber operation.
The values retrieved get_default_subscriber_qos will match the set of values specified on the last successful call to set_default_subscriber_qos, or else, if the call was never made, the default values.
- Return type
- Returns
Current default subscriber qos.
Overload 2:
This operation retrieves the default value of the Subscriber QoS, that is, the QoS policies which will be used for newly created Subscriber entities in the case where the QoS policies are defaulted in the create_subscriber operation.
The values retrieved get_default_subscriber_qos will match the set of values specified on the last successful call to set_default_subscriber_qos, or else, if the call was never made, the default values.
- Parameters
qos (
SubscriberQos) – SubscriberQos reference where the default_subscriber_qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_default_topic_qos(*args)¶
Overload 1:
This operation retrieves the default value of the Topic QoS, that is, the QoS policies that will be used for newly created Topic entities in the case where the QoS policies are defaulted in the create_topic operation.
The values retrieved get_default_topic_qos will match the set of values specified on the last successful call to set_default_topic_qos, or else, TOPIC_QOS_DEFAULT if the call was never made.
- Return type
- Returns
Current default topic qos.
Overload 2:
This operation retrieves the default value of the Topic QoS, that is, the QoS policies that will be used for newly created Topic entities in the case where the QoS policies are defaulted in the create_topic operation.
The values retrieved get_default_topic_qos will match the set of values specified on the last successful call to set_default_topic_qos, or else, TOPIC_QOS_DEFAULT if the call was never made.
- Parameters
qos (
TopicQos) – TopicQos reference where the default_topic_qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_discovered_participant_data(participant_data, participant_handle)¶
Retrieves the DomainParticipant data of a discovered not ignored participant.
participant_data Reference to the ParticipantBuiltinTopicData object to return the data :type participant_handle:
InstanceHandle_t:param participant_handle: InstanceHandle of DomainParticipant to retrieve the data from :rtype:ReturnCode_t:return: RETCODE_OK if everything correct, PRECONDITION_NOT_MET if participant does not exist Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_discovered_participants(participant_handles)¶
Retrieves the list of DomainParticipants that have been discovered in the domain and are not “ignored”.
participant_handles Reference to the vector where discovered participants will be returned :rtype:
ReturnCode_t:return: RETCODE_OK if everything correct, error code otherwise Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_discovered_topic_data(topic_data, topic_handle)¶
Retrieves the Topic data of a discovered not ignored topic.
topic_data Reference to the TopicBuiltinTopicData object to return the data :type topic_handle:
InstanceHandle_t:param topic_handle: InstanceHandle of Topic to retrieve the data from :rtype:ReturnCode_t:return: RETCODE_OK if everything correct, PRECONDITION_NOT_MET if topic does not existWarning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_discovered_topics(topic_handles)¶
Retrieves the list of topics that have been discovered in the domain and are not “ignored”.
topic_handles Reference to the vector where discovered topics will be returned :rtype:
ReturnCode_t:return: RETCODE_OK if everything correct, error code otherwise Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_domain_id()¶
This operation retrieves the domain_id used to create the DomainParticipant. The domain_id identifies the DDS domain to which the DomainParticipant belongs.
- Return type
int
- Returns
The Participant’s domain_id
- get_instance_handle()¶
Returns the DomainParticipant’s handle.
- Return type
InstanceHandle_t- Returns
InstanceHandle of this DomainParticipant.
- get_listener()¶
Allows accessing the DomainParticipantListener.
- Return type
- Returns
DomainParticipantListener pointer
- get_participant_names()¶
Getter for the participant names
- Return type
std::vector< std::string,std::allocator< std::string > >
- Returns
Vector with the names
- get_publisher_qos_from_profile(profile_name, qos)¶
Fills the PublisherQos with the values of the XML profile.
- Parameters
profile_name (string) – Publisher profile name.
qos (
PublisherQos) – PublisherQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_qos(*args)¶
Overload 1:
This operation returns the value of the DomainParticipant QoS policies
- Parameters
qos (
DomainParticipantQos) – DomainParticipantQos reference where the qos is going to be returned- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
This operation returns the value of the DomainParticipant QoS policies
- Return type
- Returns
A reference to the DomainParticipantQos
- get_resource_event()¶
Getter for the resource event
- Return type
eprosima::fastrtps::rtps::ResourceEvent
- Returns
A reference to the resource event
- get_subscriber_qos_from_profile(profile_name, qos)¶
Fills the SubscriberQos with the values of the XML profile.
- Parameters
profile_name (string) – Subscriber profile name.
qos (
SubscriberQos) – SubscriberQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_topic_qos_from_profile(profile_name, qos)¶
Fills the TopicQos with the values of the XML profile.
- Parameters
profile_name (string) – Topic profile name.
qos (
TopicQos) – TopicQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_type_dependencies(_in)¶
When a DomainParticipant receives an incomplete list of TypeIdentifiers in a PublicationBuiltinTopicData or SubscriptionBuiltinTopicData, it may request the additional type dependencies by invoking the getTypeDependencies operation.
- Parameters
in (eprosima::fastrtps::types::TypeIdentifierSeq) – TypeIdentifier sequence
- Return type
SampleIdentity- Returns
SampleIdentity
- get_types(_in)¶
A DomainParticipant may invoke the operation getTypes to retrieve the TypeObjects associated with a list of TypeIdentifiers.
- Parameters
in (eprosima::fastrtps::types::TypeIdentifierSeq) – TypeIdentifier sequence
- Return type
SampleIdentity- Returns
SampleIdentity
- guid()¶
Getter for the Participant GUID
- Return type
GUID_t- Returns
A reference to the GUID
- ignore_participant(handle)¶
Locally ignore a remote domain participant.
Notes: This action is not reversible.
- Parameters
handle (
InstanceHandle_t) – Identifier of the remote participant to ignore- Return type
ReturnCode_t- Returns
RETURN_OK code if everything correct, RETCODE_BAD_PARAMENTER otherwise
- ignore_publication(handle)¶
Locally ignore a remote datawriter.
Notes: This action is not reversible.
- Parameters
handle (
InstanceHandle_t) – Identifier of the datawriter to ignore- Return type
ReturnCode_t- Returns
RETURN_OK code if everything correct, error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- ignore_subscription(handle)¶
Locally ignore a remote datareader.
Notes: This action is not reversible.
- Parameters
handle (
InstanceHandle_t) – Identifier of the datareader to ignore- Return type
ReturnCode_t- Returns
RETURN_OK code if everything correct, error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- ignore_topic(handle)¶
Locally ignore a topic.
Notes: This action is not reversible.
- Parameters
handle (
InstanceHandle_t) – Identifier of the topic to ignore- Return type
ReturnCode_t- Returns
RETURN_OK code if everything correct, error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- lookup_content_filter_factory(filter_class_name)¶
Lookup a custom content filter factory previously registered with register_content_filter_factory.
- Parameters
filter_class_name (string) – Name of the filter class. Cannot be nullptr.
- Return type
IContentFilterFactory- Returns
nullptr if the given filter_class_name has not been previously registered on this DomainParticipant. Otherwise, the content filter factory previously registered with the given filter_class_name.
- lookup_topicdescription(topic_name)¶
Looks up an existing, locally created ‘TopicDescription’, based on its name. May be called on a disabled participant.
- Parameters
topic_name (string) – Name of the ‘TopicDescription’ to search for.
- Return type
- Returns
Pointer to the topic description, if it has been created locally. Otherwise, nullptr is returned.
Remarks: UNSAFE. It is unsafe to lookup a topic description while another thread is creating a topic.
- new_remote_endpoint_discovered(partguid, userId, kind)¶
This method can be used when using a StaticEndpointDiscovery mechanism different that the one included in FastRTPS, for example when communicating with other implementations. It indicates the Participant that an Endpoint from the XML has been discovered and should be activated.
- Parameters
partguid (
GUID_t) – Participant GUID_t.userId (int) – User defined ID as shown in the XML file.
kind (int) – EndpointKind (WRITER or READER)
- Return type
boolean
- Returns
True if correctly found and activated.
- register_content_filter_factory(filter_class_name, filter_factory)¶
Register a custom content filter factory, which can be used to create a ContentFilteredTopic.
DDS specifies a SQL-like content filter to be used by content filtered topics. If this filter does not meet your filtering requirements, you can register a custom filter factory.
To use a custom filter, a factory for it must be registered in the following places:
In any application that uses the custom filter factory to create a ContentFilteredTopic and the corresponding DataReader.
In each application that writes the data to the applications mentioned above.
For example, suppose Application A on the subscription side creates a Topic named X and a ContentFilteredTopic named filteredX (and a corresponding DataReader), using a previously registered content filter factory, myFilterFactory. With only that, you will have filtering at the subscription side. If you also want to perform filtering in any application that publishes Topic X, then you also need to register the same definition of the ContentFilterFactory myFilterFactory in that application.
Each
filter_class_namecan only be used to register a content filter factory once per DomainParticipant.- Parameters
filter_class_name (string) – Name of the filter class. Cannot be nullptr, must not exceed 255 characters, and must be unique within this DomainParticipant.
filter_factory (
IContentFilterFactory) – Factory of content filters to be registered. Cannot be nullptr.
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if any parameter is nullptr, or the filter_class_name exceeds 255 characters.
- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the filter_class_name has been already registered.
- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if filter_class_name is FASTDDS_SQLFILTER_NAME.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the filter is correctly registered.
- register_remote_type(type_information, type_name, callback)¶
Helps the user to solve all dependencies calling internally to the type lookup service and registers the resulting dynamic type. The registration may be perform asynchronously, case in which the user will be notified through the given callback, which receives the type_name as unique argument.
- Parameters
type_information (eprosima::fastrtps::types::TypeInformation) –
type_name (string) –
callback (std::function< void (std::string const &,eprosima::fastrtps::types::DynamicType_ptr const) >) –
- Return type
ReturnCode_t- Returns
RETCODE_OK If the given type_information is enough to build the type without using the typelookup service (callback will not be called).
- Return type
ReturnCode_t- Returns
RETCODE_OK if the given type is already available (callback will not be called).
- Return type
ReturnCode_t- Returns
RETCODE_NO_DATA if type is not available yet (the callback will be called if negotiation is success, and ignored in other case).
- Return type
ReturnCode_t- Returns
RETCODE_NOT_ENABLED if the DomainParticipant is not enabled.
- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the DomainParticipant type lookup service is disabled.
- register_type(*args)¶
Overload 1:
Register a type in this participant.
- Parameters
type (
TypeSupport) – TypeSupport.type_name (string) – The name that will be used to identify the Type.
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the size of the name is 0, RERCODE_PRECONDITION_NOT_MET if there is another TypeSupport with the same name and RETCODE_OK if it is correctly registered.
Overload 2:
Register a type in this participant.
- Parameters
type (
TypeSupport) – TypeSupport.- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the size of the name is 0, RERCODE_PRECONDITION_NOT_MET if there is another TypeSupport with the same name and RETCODE_OK if it is correctly registered.
- set_default_publisher_qos(qos)¶
This operation sets a default value of the Publisher QoS policies which will be used for newly created Publisher entities in the case where the QoS policies are defaulted in the create_publisher operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return false.
The special value PUBLISHER_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_publisher_qos operation had never been called.
- Parameters
qos (
PublisherQos) – PublisherQos to be set- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_default_subscriber_qos(qos)¶
This operation sets a default value of the Subscriber QoS policies that will be used for newly created Subscriber entities in the case where the QoS policies are defaulted in the create_subscriber operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return false.
The special value SUBSCRIBER_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_subscriber_qos operation had never been called.
- Parameters
qos (
SubscriberQos) – SubscriberQos to be set- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_default_topic_qos(qos)¶
This operation sets a default value of the Topic QoS policies which will be used for newly created Topic entities in the case where the QoS policies are defaulted in the create_topic operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return INCONSISTENT_POLICY.
The special value TOPIC_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_topic_qos operation had never been called.
- Parameters
qos (
TopicQos) – TopicQos to be set- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_listener(*args)¶
Overload 1:
Modifies the DomainParticipantListener, sets the mask to StatusMask::all()
- Parameters
listener (
DomainParticipantListener) – new value for the DomainParticipantListener- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
Modifies the DomainParticipantListener.
- Parameters
listener (
DomainParticipantListener) – new value for the DomainParticipantListenermask (
StatusMask) – StatusMask that holds statuses the listener responds to
- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_qos(qos)¶
This operation sets the value of the DomainParticipant QoS policies.
- Parameters
qos (
DomainParticipantQos) – DomainParticipantQos to be set- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- property thisown¶
The membership flag
- unregister_content_filter_factory(filter_class_name)¶
Unregister a custom content filter factory previously registered with register_content_filter_factory.
A filter_class_name can be unregistered only if it has been previously registered to the DomainParticipant with register_content_filter_factory.
The unregistration of filter is not allowed if there are any existing ContentFilteredTopic objects that are using the filter.
If there is any existing discovered DataReader with the same filter_class_name, filtering on the writer side will be stopped, but this operation will not fail.
- Parameters
filter_class_name (string) – Name of the filter class. Cannot be nullptr.
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the filter_class_name is nullptr.
- Return type
ReturnCode_t- Returns
RERCODE_PRECONDITION_NOT_MET if the filter_class_name has not been previously registered.
- Return type
ReturnCode_t- Returns
RERCODE_PRECONDITION_NOT_MET if there is any ContentFilteredTopic referencing the filter.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the filter is correctly unregistered.
- unregister_type(typeName)¶
Unregister a type in this participant.
- Parameters
typeName (string) – Name of the type
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the size of the name is 0, RERCODE_PRECONDITION_NOT_MET if there are entities using that TypeSupport and RETCODE_OK if it is correctly unregistered.
DomainParticipantFactory¶
- class fastdds.DomainParticipantFactory(*args, **kwargs)¶
Class DomainParticipantFactory
- check_xml_static_discovery(xml_file)¶
Check the validity of the provided static discovery XML file
- Parameters
xml_file (string) – xml file path
- Return type
ReturnCode_t- Returns
RETCODE_OK if the validation is successful, RETCODE_ERROR otherwise.
- create_participant(*args)¶
Create a Participant.
- Parameters
domain_id (int) – Domain Id.
qos (
DomainParticipantQos) – DomainParticipantQos Reference.listener (
DomainParticipantListener) – DomainParticipantListener Pointer (default: nullptr)mask (
StatusMask) – StatusMask Reference (default: all)
- Return type
- Returns
DomainParticipant pointer. (nullptr if not created.)
- create_participant_with_profile(*args)¶
Overload 1:
Create a Participant.
- Parameters
domain_id (int) – Domain Id.
profile_name (string) – Participant profile name.
listener (
DomainParticipantListener) – DomainParticipantListener Pointer (default: nullptr)mask (
StatusMask) – StatusMask Reference (default: all)
- Return type
- Returns
DomainParticipant pointer. (nullptr if not created.)
Overload 2:
Create a Participant.
- Parameters
profile_name (string) – Participant profile name.
listener (
DomainParticipantListener) – DomainParticipantListener Pointer (default: nullptr)mask (
StatusMask) – StatusMask Reference (default: all)
- Return type
- Returns
DomainParticipant pointer. (nullptr if not created.)
Overload 3:
Create a Participant.
- Parameters
profile_name (string) – Participant profile name.
listener (
DomainParticipantListener) – DomainParticipantListener Pointer (default: nullptr)mask – StatusMask Reference (default: all)
- Return type
- Returns
DomainParticipant pointer. (nullptr if not created.)
Overload 4:
Create a Participant.
- Parameters
profile_name (string) – Participant profile name.
listener – DomainParticipantListener Pointer (default: nullptr)
mask – StatusMask Reference (default: all)
- Return type
- Returns
DomainParticipant pointer. (nullptr if not created.)
- delete_participant(part)¶
Remove a Participant and all associated publishers and subscribers.
- Parameters
part (
DomainParticipant) – Pointer to the participant.- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the participant has active entities, RETCODE_OK if the participant is correctly deleted and RETCODE_ERROR otherwise.
- get_default_participant_qos(*args)¶
Overload 1:
This operation retrieves the default value of the DomainParticipant QoS, that is, the QoS policies which will be used for newly created DomainParticipant entities in the case where the QoS policies are defaulted in the create_participant operation. The values retrieved get_default_participant_qos will match the set of values specified on the last successful call to set_default_participant_qos, or else, if the call was never made, the default values.
- Parameters
qos (
DomainParticipantQos) – DomainParticipantQos where the qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
This operation retrieves the default value of the DomainParticipant QoS, that is, the QoS policies which will be used for newly created DomainParticipant entities in the case where the QoS policies are defaulted in the create_participant operation. The values retrieved get_default_participant_qos will match the set of values specified on the last successful call to set_default_participant_qos, or else, if the call was never made, the default values.
- Return type
- Returns
A reference to the default DomainParticipantQos
- static get_instance()¶
Returns the DomainParticipantFactory singleton instance.
- Return type
- Returns
A raw pointer to the DomainParticipantFactory singleton instance.
- get_participant_qos_from_profile(profile_name, qos)¶
Fills the DomainParticipantQos with the values of the XML profile.
- Parameters
profile_name (string) – DomainParticipant profile name.
qos (
DomainParticipantQos) – DomainParticipantQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_qos(qos)¶
This operation returns the value of the DomainParticipantFactory QoS policies.
- Parameters
qos (
DomainParticipantFactoryQos) – DomaParticipantFactoryQos reference where the qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
Returns the DomainParticipantFactory singleton instance.
- Return type
std::shared_ptr< eprosima::fastdds::dds::DomainParticipantFactory >
- Returns
A shared pointer to the DomainParticipantFactory singleton instance.
- load_XML_profiles_file(xml_profile_file)¶
Load profiles from XML file.
- Parameters
xml_profile_file (string) – XML profile file.
- Return type
ReturnCode_t- Returns
RETCODE_OK if it is correctly loaded, RETCODE_ERROR otherwise.
- load_XML_profiles_string(data, length)¶
Load profiles from XML string.
- Parameters
data (string) – buffer containing xml data.
length (int) – length of data
- Return type
ReturnCode_t- Returns
RETCODE_OK if it is correctly loaded, RETCODE_ERROR otherwise.
- load_profiles()¶
Load profiles from default XML file.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- lookup_participant(domain_id)¶
This operation retrieves a previously created DomainParticipant belonging to specified domain_id. If no such DomainParticipant exists, the operation will return ‘nullptr’. If multiple DomainParticipant entities belonging to that domain_id exist, then the operation will return one of them. It is not specified which one.
- Parameters
domain_id (int) –
- Return type
- Returns
previously created DomainParticipant within the specified domain
- lookup_participants(domain_id)¶
Returns all participants that belongs to the specified domain_id.
- Parameters
domain_id (int) –
- Return type
std::vector< eprosima::fastdds::dds::DomainParticipant *,std::allocator< eprosima::fastdds::dds::DomainParticipant * > >
- Returns
previously created DomainParticipants within the specified domain
- set_default_participant_qos(qos)¶
This operation sets a default value of the DomainParticipant QoS policies which will be used for newly created DomainParticipant entities in the case where the QoS policies are defaulted in the create_participant operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return INCONSISTENT_POLICY.
The special value PARTICIPANT_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_participant_qos operation had never been called.
- Parameters
qos (
DomainParticipantQos) – DomainParticipantQos to be set- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_qos(qos)¶
This operation sets the value of the DomainParticipantFactory QoS policies. These policies control the behavior of the object a factory for entities.
Note that despite having QoS, the DomainParticipantFactory is not an Entity.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return INCONSISTENT_POLICY.
- Parameters
qos (
DomainParticipantFactoryQos) – DomainParticipantFactoryQos to be set.- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- property thisown¶
The membership flag
DomainParticipantFactoryQos¶
- class fastdds.DomainParticipantFactoryQos¶
Class DomainParticipantFactoryQos, contains all the possible Qos that can be set for a determined participant. Please consult each of them to check for implementation details and default values.
- entity_factory(*args)¶
Overload 1:
Getter for EntityFactoryQosPolicy :rtype:
EntityFactoryQosPolicy:return: EntityFactoryQosPolicy referenceOverload 2:
Getter for EntityFactoryQosPolicy :rtype:
EntityFactoryQosPolicy:return: EntityFactoryQosPolicy referenceOverload 3:
Setter for EntityFactoryQosPolicy :type entity_factory:
EntityFactoryQosPolicy:param entity_factory: EntityFactoryQosPolicy
- file_watch_threads(*args)¶
Overload 1:
Getter for file watch related ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for file watch related ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the file watch related ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- shm_watchdog_thread(*args)¶
Overload 1:
Getter for SHM watchdog ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for SHM watchdog ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the SHM watchdog ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- property thisown¶
The membership flag
DomainParticipantListener¶
- class fastdds.DomainParticipantListener¶
Class DomainParticipantListener, overrides behaviour towards certain events.
- on_participant_discovery(*args)¶
This method is called when a new Participant is discovered, or a previously discovered participant changes its QOS or is removed.
participant Pointer to the Participant which discovered the remote participant. info Remote participant information. User can take ownership of the object. should_be_ignored Flag to indicate the library to automatically ignore the discovered Participant.
- on_publisher_discovery(*args)¶
Overload 1:
This method is called when a new DataWriter is discovered, or a previously discovered DataWriter changes its QOS or is removed.
participant Pointer to the Participant which discovered the remote DataWriter. info Remote DataWriter information. User can take ownership of the object.
Overload 2:
This method is called when a new DataWriter is discovered, or a previously discovered DataWriter changes its QOS or is removed.
Warning: Not Supported. This callback will never be called in the current version.
participant Pointer to the Participant which discovered the remote DataWriter. info Remote DataWriter information. User can take ownership of the object. should_be_ignored Flag to indicate the library to automatically ignore the discovered DataWriter.
- on_subscriber_discovery(*args)¶
Overload 1:
This method is called when a new DataReader is discovered, or a previously discovered DataReader changes its QOS or is removed.
participant Pointer to the Participant which discovered the remote DataReader. info Remote DataReader information. User can take ownership of the object.
Overload 2:
This method is called when a new DataReader is discovered, or a previously discovered DataReader changes its QOS or is removed.
Warning: Not Supported. This callback will never be called in the current version.
participant Pointer to the Participant which discovered the remote DataReader. info Remote DataReader information. User can take ownership of the object. should_be_ignored Flag to indicate the library to automatically ignore the discovered DataReader.
- on_type_dependencies_reply(participant, request_sample_id, dependencies)¶
This method is called when the typelookup client received a reply to a getTypeDependencies request. The user may want to retrieve these new types using the getTypes request and create a new DynamicType using the retrieved TypeObject.
- on_type_discovery(participant, request_sample_id, topic, identifier, object, dyn_type)¶
This method is called when a participant discovers a new Type The ownership of all object belongs to the caller so if needs to be used after the method ends, a full copy should be perform (except for dyn_type due to its shared_ptr nature. For example: fastrtps::types::TypeIdentifier new_type_id = *identifier;
- on_type_information_received(participant, topic_name, type_name, type_information)¶
This method is called when a participant receives a TypeInformation while discovering another participant.
- property thisown¶
The membership flag
DomainParticipantQos¶
- class fastdds.DomainParticipantQos¶
Class DomainParticipantQos, contains all the possible Qos that can be set for a determined participant. Please consult each of them to check for implementation details and default values.
- allocation(*args)¶
Overload 1:
Getter for ParticipantResourceLimitsQos
- Return type
ParticipantResourceLimitsQos- Returns
ParticipantResourceLimitsQos reference
Overload 2:
Getter for ParticipantResourceLimitsQos
- Return type
ParticipantResourceLimitsQos- Returns
ParticipantResourceLimitsQos reference
Overload 3:
Setter for ParticipantResourceLimitsQos
- Parameters
allocation (
ParticipantResourceLimitsQos) – ParticipantResourceLimitsQos
- builtin_controllers_sender_thread(*args)¶
Overload 1:
Getter for builtin flow controllers sender threads ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for builtin flow controllers sender threads ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the builtin flow controllers sender threads ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- discovery_server_thread(*args)¶
Overload 1:
Getter for discovery server ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for discovery server ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the discovery server ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- entity_factory(*args)¶
Overload 1:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 2:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 3:
Setter for EntityFactoryQosPolicy
- Parameters
value (
EntityFactoryQosPolicy) – EntityFactoryQosPolicy
- flow_controllers(*args)¶
Overload 1:
Getter for FlowControllerDescriptorList
- Return type
FlowControllerDescriptorList- Returns
FlowControllerDescriptorList reference
Overload 2:
Getter for FlowControllerDescriptorList
- Return type
FlowControllerDescriptorList- Returns
FlowControllerDescriptorList reference
- name(*args)¶
Overload 1:
Getter for the Participant name
- Return type
string
- Returns
name
Overload 2:
Setter for the Participant name
- Parameters
value (string) – New name to be set.
- properties(*args)¶
Overload 1:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos reference
Overload 2:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos reference
Overload 3:
Setter for PropertyPolicyQos
- Parameters
properties (
PropertyPolicyQos) – PropertyPolicyQos
- setup_transports(*args)¶
Provides a way of easily configuring transport related configuration on certain pre-defined scenarios with certain options.
- Parameters
transports (eprosima::fastdds::rtps::BuiltinTransports) – Defines the transport configuration scenario to setup.
options (eprosima::fastdds::rtps::BuiltinTransportsOptions) – Defines the options to be used in the transport configuration.
- property thisown¶
The membership flag
- timed_events_thread(*args)¶
Overload 1:
Getter for timed event ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 2:
Getter for timed event ThreadSettings
- Return type
ThreadSettings- Returns
rtps::ThreadSettings reference
Overload 3:
Setter for the timed event ThreadSettings
- Parameters
value (
ThreadSettings) – New ThreadSettings to be set
- transport(*args)¶
Overload 1:
Getter for TransportConfigQos
- Return type
- Returns
TransportConfigQos reference
Overload 2:
Getter for TransportConfigQos
- Return type
- Returns
TransportConfigQos reference
Overload 3:
Setter for TransportConfigQos
- Parameters
transport (
TransportConfigQos) – TransportConfigQos
- user_data(*args)¶
Overload 1:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy reference
Overload 2:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy reference
Overload 3:
Setter for UserDataQosPolicy
- Parameters
value (
UserDataQosPolicy) – UserDataQosPolicy
- wire_protocol(*args)¶
Overload 1:
Getter for WireProtocolConfigQos
- Return type
- Returns
WireProtocolConfigQos reference
Overload 2:
Getter for WireProtocolConfigQos
- Return type
- Returns
WireProtocolConfigQos reference
Overload 3:
Setter for WireProtocolConfigQos
- Parameters
wire_protocol (
WireProtocolConfigQos) – WireProtocolConfigQos
Publisher¶
DataWriter¶
- class fastdds.DataWriter(*args, **kwargs)¶
Class DataWriter, contains the actual implementation of the behaviour of the DataWriter.
- assert_liveliness()¶
This operation manually asserts the liveliness of the DataWriter. This is used in combination with the LivelinessQosPolicy to indicate to the Service that the entity remains active. This operation need only be used if the LIVELINESS setting is either MANUAL_BY_PARTICIPANT or MANUAL_BY_TOPIC. Otherwise, it has no effect.
Notes: Writing data via the write operation on a DataWriter asserts liveliness on the DataWriter itself and its DomainParticipant. Consequently the use of assert_liveliness is only needed if the application is not writing data regularly.
- Return type
ReturnCode_t- Returns
RETCODE_OK if asserted, RETCODE_ERROR otherwise
- clear_history()¶
- dispose(data, handle)¶
This operation requests the middleware to delete the data (the actual deletion is postponed until there is no more use for that data in the whole system). In general, applications are made aware of the deletion by means of operations on the DataReader objects that already knew that instance. This operation does not modify the value of the instance. The instance parameter is passed just for the purposes of identifying the instance. When this operation is used, the Service will automatically supply the value of the source_timestamp that is made available to DataReader objects by means of the source_timestamp attribute inside the SampleInfo. The constraints on the values of the handle parameter and the corresponding error behavior are the same specified for the unregister_instance operation.
data Sample used to deduce instance’s key in case of handle parameter is HANDLE_NIL. handle InstanceHandle of the data :rtype:
ReturnCode_t:return: RETCODE_PRECONDITION_NOT_MET if the handle introduced does not match with the one associated to the data,RETCODE_OK if the data is correctly sent and RETCODE_ERROR otherwise.
- dispose_w_timestamp(instance, handle, timestamp)¶
This operation performs the same functions as ‘dispose’ except that the application provides the value for the ‘source_timestamp’ that is made available to DataReader objects by means of the ‘source_timestamp’ attribute inside the SampleInfo.
The constraints on the values of the
handleparameter and the corresponding error behavior are the same specified for the ‘dispose’ operation.This operation may return RETCODE_PRECONDITION_NOT_MET and RETCODE_BAD_PARAMETER under the same circumstances described for the ‘dispose’ operation.
This operation may return RETCODE_TIMEOUT and RETCODE_OUT_OF_RESOURCES under the same circumstances described for the ‘write’ operation.
- Parameters
instance (void) – Sample used to deduce instance’s key in case of handle parameter is HANDLE_NIL.
handle (
InstanceHandle_t) – Instance’s key to be disposed.timestamp (
Time_t) – Time_t used to set the source_timestamp.
- Return type
ReturnCode_t- Returns
RTPS_DllAPI
- enable()¶
This operation enables the DataWriter
- Return type
ReturnCode_t- Returns
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the Publisher creating this DataWriter is not enabled.
- get_instance_handle()¶
Returns the DataWriter’s InstanceHandle
- Return type
InstanceHandle_t- Returns
Copy of the DataWriter InstanceHandle
- get_key_value(key_holder, handle)¶
This operation can be used to retrieve the instance key that corresponds to an ‘instance_handle’. The operation will only fill the fields that form the key inside the key_holder instance.
This operation may return BAD_PARAMETER if the InstanceHandle_t handle does not correspond to an existing data-object known to the DataWriter. If the implementation is not able to check invalid handles then the result in this situation is unspecified.
,out] key_holder Sample where the key fields will be returned. handle Handle to the instance to retrieve the key values from.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- get_listener()¶
Retrieves the listener for this DataWriter.
- Return type
- Returns
Pointer to the DataWriterListener
- get_liveliness_lost_status(status)¶
Returns the liveliness lost status
- Parameters
status (
LivelinessLostStatus) – Liveliness lost status struct- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_matched_subscription_data(subscription_data, subscription_handle)¶
Retrieves in a subscription associated with the DataWriter
subscription_data subscription data struct :type subscription_handle:
InstanceHandle_t:param subscription_handle: InstanceHandle_t of the subscription :rtype:ReturnCode_t:return: RETCODE_OK Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_matched_subscriptions(subscription_handles)¶
Fills the given vector with the InstanceHandle_t of matched DataReaders
subscription_handles Vector where the InstanceHandle_t are returned :rtype:
ReturnCode_t:return: RETCODE_OK Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_offered_deadline_missed_status(status)¶
Returns the offered deadline missed status
status Deadline missed status struct :rtype:
ReturnCode_t:return: RETCODE_OK
- get_offered_incompatible_qos_status(status)¶
Returns the offered incompatible qos status
status Offered incompatible qos status struct :rtype:
ReturnCode_t:return: RETCODE_OK
- get_publication_matched_status(status)¶
Returns the publication matched status
status publication matched status struct :rtype:
ReturnCode_t:return: RETCODE_OK
- get_publisher()¶
Getter for the Publisher that creates this DataWriter
- Return type
- Returns
Pointer to the Publisher
- get_qos(*args)¶
Overload 1:
Retrieves the DataWriterQos for this DataWriter.
- Return type
- Returns
Reference to the current DataWriterQos
Overload 2:
Fills the DataWriterQos with the values of this DataWriter.
- Parameters
qos (
DataWriterQos) – DataWriterQos object where the qos is returned.- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_sending_locators(locators)¶
Get the list of locators from which this DataWriter may send data.
- Parameters
[out] – locators LocatorList where the list of locators will be stored.
- Return type
ReturnCode_t- Returns
NOT_ENABLED if the reader has not been enabled.
- Return type
ReturnCode_t- Returns
OK if a list of locators is returned.
- get_topic()¶
Retrieves the topic for this DataWriter.
- Return type
- Returns
Pointer to the associated Topic
- get_type()¶
Get data type associated to the DataWriter
- Return type
- Returns
Copy of the TypeSupport
- guid()¶
Returns the DataWriter’s GUID
- Return type
GUID_t- Returns
Reference to the DataWriter GUID
- loan_sample(*args)¶
Get a pointer to the internal pool where the user could directly write.
This method can only be used on a DataWriter for a plain data type. It will provide the user with a pointer to an internal buffer where the data type can be prepared for sending.
When using NO_LOAN_INITIALIZATION on the initialization parameter, which is the default, no assumptions should be made on the contents where the pointer points to, as it may be an old pointer being reused. See ‘LoanInitializationKind’ for more details.
Once the sample has been prepared, it can then be published by calling ‘write’. After a successful call to ‘write’, the middleware takes ownership of the loaned pointer again, and the user should not access that memory again.
If, for whatever reason, the sample is not published, the loan can be returned by calling ‘discard_loan’.
- Parameters
[out] – sample Pointer to the sample on the internal pool.
[in] – initialization How to initialize the loaned sample.
- Return type
ReturnCode_t- Returns
ReturnCode_t::RETCODE_ILLEGAL_OPERATION when the data type does not support loans.
- Return type
ReturnCode_t- Returns
ReturnCode_t::RETCODE_NOT_ENABLED if the writer has not been enabled.
- Return type
ReturnCode_t- Returns
ReturnCode_t::RETCODE_OUT_OF_RESOURCES if the pool has been exhausted.
- Return type
ReturnCode_t- Returns
ReturnCode_t::RETCODE_OK if a pointer to a sample is successfully obtained.
- lookup_instance(instance)¶
NOT YET IMPLEMENTED
Takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument. The instance parameter is only used for the purpose of examining the fields that define the key.
instance Data pointer to the sample
- Return type
InstanceHandle_t- Returns
handle of the given instance
- register_instance(instance)¶
Informs that the application will be modifying a particular instance. It gives an opportunity to the middleware to pre-configure itself to improve performance.
instance Sample used to get the instance’s key. :rtype:
InstanceHandle_t:return: Handle containing the instance’s key.This handle could be used in successive write or dispose operations. In case of error, HANDLE_NIL will be returned.
- register_instance_w_timestamp(instance, timestamp)¶
This operation performs the same function as register_instance and can be used instead of ‘register_instance’ in the cases where the application desires to specify the value for the ‘source_timestamp’. The ‘source_timestamp’ potentially affects the relative order in which readers observe events from multiple writers. See the QoS policy ‘DESTINATION_ORDER’.
This operation may block and return RETCODE_TIMEOUT under the same circumstances described for the ‘write’ operation.
This operation may return RETCODE_OUT_OF_RESOURCES under the same circumstances described for the ‘write’ operation.
- Parameters
instance (void) – Sample used to get the instance’s key.
timestamp (
Time_t) – Time_t used to set the source_timestamp.
- Return type
InstanceHandle_t- Returns
Handle containing the instance’s key.
- set_listener(*args)¶
- set_qos(qos)¶
Establishes the DataWriterQos for this DataWriter.
- Parameters
qos (
DataWriterQos) – DataWriterQos to be set- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- property thisown¶
The membership flag
- unregister_instance(instance, handle)¶
This operation reverses the action of register_instance. It should only be called on an instance that is currently registered. Informs the middleware that the DataWriter is not intending to modify any more of that data instance. Also indicates that the middleware can locally remove all information regarding that instance.
instance Sample used to deduce instance’s key in case of handle parameter is HANDLE_NIL. handle Instance’s key to be unregistered. :rtype:
ReturnCode_t:return: Returns the operation’s result.If the operation finishes successfully, ReturnCode_t::RETCODE_OK is returned.
- unregister_instance_w_timestamp(instance, handle, timestamp)¶
This operation performs the same function as ‘unregister_instance’ and can be used instead of ‘unregister_instance’ in the cases where the application desires to specify the value for the ‘source_timestamp’. The ‘source_timestamp’ potentially affects the relative order in which readers observe events from multiple writers. See the QoS policy ‘DESTINATION_ORDER’.
The constraints on the values of the
handleparameter and the corresponding error behavior are the same specified for the ‘unregister_instance’ operation.This operation may block and return RETCODE_TIMEOUT under the same circumstances described for the write operation
- Parameters
instance (void) – Sample used to deduce instance’s key in case of handle parameter is HANDLE_NIL.
handle (
InstanceHandle_t) – Instance’s key to be unregistered.timestamp (
Time_t) – Time_t used to set the source_timestamp.
- Return type
ReturnCode_t- Returns
Handle containing the instance’s key.
- wait_for_acknowledgments(*args)¶
Overload 1:
Waits the current thread until all writers have received their acknowledgments.
- Parameters
max_wait (
Duration_t) – Maximum blocking time for this operation- Return type
ReturnCode_t- Returns
RETCODE_OK if the DataWriter receive the acknowledgments before the time expires and RETCODE_ERROR otherwise
Overload 2:
Block the current thread until the writer has received the acknowledgment corresponding to the given instance. Operations performed on the same instance while the current thread is waiting will not be taken into consideration, i.e. this method may return RETCODE_OK with those operations unacknowledged.
- Parameters
instance (void) – Sample used to deduce instance’s key in case of handle parameter is HANDLE_NIL.
handle (
InstanceHandle_t) – Instance handle of the data.max_wait (
Duration_t) – Maximum blocking time for this operation.
- Return type
ReturnCode_t- Returns
RETCODE_NOT_ENABLED if the writer has not been enabled.
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if instance is not a valid pointer.
- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the topic does not have a key, the key is unknown to the writer, or the key is not consistent with handle.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the DataWriter received the acknowledgments before the time expired.
- Return type
ReturnCode_t- Returns
RETCODE_TIMEOUT otherwise.
- write(*args)¶
Overload 1:
Write data to the topic.
- Parameters
data (void) – Pointer to the data
- Return type
boolean
- Returns
True if correct, false otherwise
Overload 2:
Write data with params to the topic.
- Parameters
data (void) – Pointer to the data
params (
WriteParams) – Extra write parameters.
- Return type
boolean
- Returns
True if correct, false otherwise
Overload 3:
Write data with handle.
The special value HANDLE_NIL can be used for the parameter handle.This indicates that the identity of the instance should be automatically deduced from the instance_data (by means of the key).
- Parameters
data (void) – Pointer to the data
handle (
InstanceHandle_t) – InstanceHandle_t.
- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the handle introduced does not match with the one associated to the data, RETCODE_OK if the data is correctly sent and RETCODE_ERROR otherwise.
- write_w_timestamp(data, handle, timestamp)¶
This operation performs the same function as write except that it also provides the value for the ‘source_timestamp’ that is made available to DataReader objects by means of the ‘eprosima::fastdds::dds::SampleInfo::source_timestamp’ attribute “source_timestamp” inside the SampleInfo. The constraints on the values of the
handleparameter and the corresponding error behavior are the same specified for the ‘write’ operation. This operation may block and return RETCODE_TIMEOUT under the same circumstances described for the ‘write’ operation. This operation may return RETCODE_OUT_OF_RESOURCES, RETCODE_PRECONDITION_NOT_MET or RETCODE_BAD_PARAMETER under the same circumstances described for the write operation.- Parameters
data (void) – Pointer to the data
handle (
InstanceHandle_t) – InstanceHandle_ttimestamp (
Time_t) – Time_t used to set the source_timestamp.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
DataWriterListener¶
- class fastdds.DataWriterListener¶
Class DataWriterListener, allows the end user to implement callbacks triggered by certain events.
- on_liveliness_lost(writer, status)¶
Method called when the liveliness of a DataWriter is lost
- Parameters
writer (
DataWriter) – Pointer to the associated DataWriterstatus (
LivelinessLostStatus) – The liveliness lost status
- on_offered_deadline_missed(writer, status)¶
A method called when a deadline is missed
- Parameters
writer (
DataWriter) – Pointer to the associated DataWriterstatus (
OfferedDeadlineMissedStatus) – The deadline missed status
- on_offered_incompatible_qos(writer, status)¶
A method called when an incompatible QoS is offered
- Parameters
writer (
DataWriter) – Pointer to the associated DataWriterstatus (
OfferedIncompatibleQosStatus) – The deadline missed status
- on_publication_matched(writer, info)¶
This method is called when the DataWriter is matched (or unmatched) against an endpoint.
- Parameters
writer (
DataWriter) – Pointer to the associated DataWriterinfo (
PublicationMatchedStatus) – Information regarding the matched DataReader
- on_unacknowledged_sample_removed(writer, instance)¶
Method called when a sample has been removed unacknowledged
- Parameters
writer (
DataWriter) – Pointer to the associated DataWriterinstance (
InstanceHandle_t) – Handle to the instance the sample was removed from
- property thisown¶
The membership flag
DataWriterQos¶
- class fastdds.DataWriterQos¶
Class DataWriterQos, containing all the possible Qos that can be set for a determined DataWriter. Although these values can be and are transmitted during the Endpoint Discovery Protocol, not all of the behaviour associated with them has been implemented in the library. Please consult each of them to check for implementation details and default values.
- data_sharing(*args)¶
Overload 1:
Getter for DataSharingQosPolicy
- Return type
- Returns
DataSharingQosPolicy reference
Overload 2:
Getter for DataSharingQosPolicy
- Return type
- Returns
DataSharingQosPolicy reference
Overload 3:
Setter for DataSharingQosPolicy
- Parameters
data_sharing (
DataSharingQosPolicy) – new value for the DataSharingQosPolicy
- deadline(*args)¶
Overload 1:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQosPolicy reference
Overload 2:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQosPolicy reference
Overload 3:
Setter for DeadlineQosPolicy
- Parameters
deadline (
DeadlineQosPolicy) – new value for the DeadlineQosPolicy
- destination_order(*args)¶
Overload 1:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQosPolicy reference
Overload 2:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQosPolicy reference
Overload 3:
Setter for DestinationOrderQosPolicy
- Parameters
destination_order (
DestinationOrderQosPolicy) – new value for the DestinationOrderQosPolicy
- durability(*args)¶
Overload 1:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQosPolicy reference
Overload 2:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQosPolicy reference
Overload 3:
Setter for DurabilityQosPolicy
- Parameters
durability (
DurabilityQosPolicy) – new value for the DurabilityQosPolicy
- durability_service(*args)¶
Overload 1:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQosPolicy reference
Overload 2:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQosPolicy reference
Overload 3:
Setter for DurabilityServiceQosPolicy
- Parameters
durability_service (
DurabilityServiceQosPolicy) – new value for the DurabilityServiceQosPolicy
- endpoint(*args)¶
Overload 1:
Getter for RTPSEndpointQos
- Return type
- Returns
RTPSEndpointQos reference
Overload 2:
Getter for RTPSEndpointQos :rtype:
RTPSEndpointQos:return: RTPSEndpointQos referenceOverload 3:
Setter for RTPSEndpointQos
- Parameters
endpoint (
RTPSEndpointQos) – new value for the RTPSEndpointQos
- get_writerqos(pqos, tqos)¶
- history(*args)¶
Overload 1:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQosPolicy reference
Overload 2:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQosPolicy reference
Overload 3:
Setter for HistoryQosPolicy
- Parameters
history (
HistoryQosPolicy) – new value for the HistoryQosPolicy
- latency_budget(*args)¶
Overload 1:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQosPolicy reference
Overload 2:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQosPolicy reference
Overload 3:
Setter for LatencyBudgetQosPolicy
- Parameters
latency_budget (
LatencyBudgetQosPolicy) – new value for the LatencyBudgetQosPolicy
- lifespan(*args)¶
Overload 1:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQosPolicy reference
Overload 2:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQosPolicy reference
Overload 3:
Setter for LifespanQosPolicy
- Parameters
lifespan (
LifespanQosPolicy) – new value for the LifespanQosPolicy
- liveliness(*args)¶
Overload 1:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQosPolicy reference
Overload 2:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQosPolicy reference
Overload 3:
Setter for LivelinessQosPolicy
- Parameters
liveliness (
LivelinessQosPolicy) – new value for the LivelinessQosPolicy
- ownership(*args)¶
Overload 1:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQosPolicy reference
Overload 2:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQosPolicy reference
Overload 3:
Setter for OwnershipQosPolicy
- Parameters
ownership (
OwnershipQosPolicy) – new value for the OwnershipQosPolicy
- ownership_strength(*args)¶
Overload 1:
Getter for OwnershipStrengthQosPolicy
- Return type
- Returns
OwnershipStrengthQosPolicy reference
Overload 2:
Getter for OwnershipStrengthQosPolicy
- Return type
- Returns
OwnershipStrengthQosPolicy reference
Overload 3:
Setter for OwnershipStrengthQosPolicy
- Parameters
ownership_strength (
OwnershipStrengthQosPolicy) – new value for the OwnershipStrengthQosPolicy
- properties(*args)¶
Overload 1:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos reference
Overload 2:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos reference
Overload 3:
Setter for PropertyPolicyQos
- Parameters
properties (
PropertyPolicyQos) – new value for the PropertyPolicyQos
- publish_mode(*args)¶
Overload 1:
Getter for PublishModeQosPolicy
- Return type
- Returns
PublishModeQosPolicy reference
Overload 2:
Getter for PublishModeQosPolicy
- Return type
- Returns
PublishModeQosPolicy reference
Overload 3:
Setter for PublishModeQosPolicy
- Parameters
publish_mode (
PublishModeQosPolicy) – new value for the PublishModeQosPolicy
- reliability(*args)¶
Overload 1:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQosPolicy reference
Overload 2:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQosPolicy reference
Overload 3:
Setter for ReliabilityQosPolicy
- Parameters
reliability (
ReliabilityQosPolicy) – new value for the ReliabilityQosPolicy
- reliable_writer_qos(*args)¶
Overload 1:
Getter for RTPSReliableWriterQos
- Return type
- Returns
RTPSReliableWriterQos reference
Overload 2:
Getter for RTPSReliableWriterQos
- Return type
- Returns
RTPSReliableWriterQos reference
Overload 3:
Setter for RTPSReliableWriterQos
- Parameters
reliable_writer_qos (
RTPSReliableWriterQos) – new value for the RTPSReliableWriterQos
- resource_limits(*args)¶
Overload 1:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQosPolicy reference
Overload 2:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQosPolicy reference
Overload 3:
Setter for ResourceLimitsQosPolicy
- Parameters
resource_limits (
ResourceLimitsQosPolicy) – new value for the ResourceLimitsQosPolicy
- property thisown¶
The membership flag
- transport_priority(*args)¶
Overload 1:
Getter for TransportPriorityQosPolicy
- Return type
- Returns
TransportPriorityQosPolicy reference
Overload 2:
Getter for TransportPriorityQosPolicy
- Return type
- Returns
TransportPriorityQosPolicy reference
Overload 3:
Setter for TransportPriorityQosPolicy
- Parameters
transport_priority (
TransportPriorityQosPolicy) – new value for the TransportPriorityQosPolicy
- user_data(*args)¶
Overload 1:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy reference
Overload 2:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy reference
Overload 3:
Setter for UserDataQosPolicy
- Parameters
user_data (
UserDataQosPolicy) – new value for the UserDataQosPolicy
- writer_data_lifecycle(*args)¶
Overload 1:
Getter for WriterDataLifecycleQosPolicy
- Return type
- Returns
WriterDataLifecycleQosPolicy reference
Overload 2:
Getter for WriterDataLifecycleQosPolicy
- Return type
- Returns
WriterDataLifecycleQosPolicy reference
Overload 3:
Setter for WriterDataLifecycleQosPolicy
- Parameters
writer_data_lifecycle (
WriterDataLifecycleQosPolicy) – new value for the WriterDataLifecycleQosPolicy
- writer_resource_limits(*args)¶
Overload 1:
Getter for WriterResourceLimitsQos
- Return type
- Returns
WriterResourceLimitsQos reference
Overload 2:
Getter for WriterResourceLimitsQos
- Return type
- Returns
WriterResourceLimitsQos reference
Overload 3:
Setter for WriterResourceLimitsQos
- Parameters
writer_resource_limits (
WriterResourceLimitsQos) – new value for the WriterResourceLimitsQos
- class fastdds.DATAWRITER_QOS_DEFAULT(*args: Any, **kwargs: Any)¶
Publisher¶
- class fastdds.Publisher(*args, **kwargs)¶
Class Publisher, used to send data to associated subscribers.
- begin_coherent_changes()¶
Signals the beginning of a set of coherent cache changes using the Datawriters attached to the publisher
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- copy_from_topic_qos(writer_qos, topic_qos)¶
Copies TopicQos into the corresponding DataWriterQos
writer_qos topic_qos :rtype:
ReturnCode_t:return: RETCODE_OK if successful, an error code otherwise Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- create_datawriter(*args)¶
This operation creates a DataWriter. The returned DataWriter will be attached and belongs to the Publisher.
- Parameters
topic (
Topic) – Topic the DataWriter will be listeningqos – QoS of the DataWriter.
listener (
DataWriterListener) – Pointer to the listener (default: nullptr).mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all).
- Return type
- Returns
Pointer to the created DataWriter. nullptr if failed.
- create_datawriter_with_profile(*args)¶
This operation creates a DataWriter. The returned DataWriter will be attached and belongs to the Publisher.
- Parameters
topic (
Topic) – Topic the DataWriter will be listeningprofile_name (string) – DataWriter profile name.
listener (
DataWriterListener) – Pointer to the listener (default: nullptr).mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all).
- Return type
- Returns
Pointer to the created DataWriter. nullptr if failed.
- delete_contained_entities()¶
Deletes all contained DataWriters
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
- delete_datawriter(writer)¶
This operation deletes a DataWriter that belongs to the Publisher.
The delete_datawriter operation must be called on the same Publisher object used to create the DataWriter. If delete_datawriter is called on a different Publisher, the operation will have no effect and it will return false.
The deletion of the DataWriter will automatically unregister all instances. Depending on the settings of the WRITER_DATA_LIFECYCLE QosPolicy, the deletion of the DataWriter may also dispose all instances.
- Parameters
writer (
DataWriter) – DataWriter to delete- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if it does not belong to this Publisher, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- enable()¶
This operation enables the Publisher
- Return type
ReturnCode_t- Returns
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the participant creating this Publisher is not enabled.
- end_coherent_changes()¶
Signals the end of a set of coherent cache changes
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_datawriter_qos_from_profile(profile_name, qos)¶
Fills the DataWriterQos with the values of the XML profile.
- Parameters
profile_name (string) – DataWriter profile name.
qos (
DataWriterQos) – DataWriterQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_datawriters(writers)¶
Fills the given vector with all the datawriters of this publisher.
- Parameters
writers (std::vector< eprosima::fastdds::dds::DataWriter *,std::allocator< eprosima::fastdds::dds::DataWriter * > >) – Vector where the DataWriters are returned
- Return type
boolean
- Returns
true
- get_default_datawriter_qos(*args)¶
Overload 1:
This operation returns the default value of the DataWriter QoS, that is, the QoS policies which will be used for newly created DataWriter entities in the case where the QoS policies are defaulted in the create_datawriter operation.
The values retrieved by get_default_datawriter_qos will match the set of values specified on the last successful call to set_default_datawriter_qos, or else, if the call was never made, the default values.
- Return type
- Returns
Current default WriterQos
Overload 2:
This operation retrieves the default value of the DataWriter QoS, that is, the QoS policies which will be used for newly created DataWriter entities in the case where the QoS policies are defaulted in the create_datawriter operation.
The values retrieved by get_default_datawriter_qos will match the set of values specified on the last successful call to set_default_datawriter_qos, or else, if the call was never made, the default values.
- Parameters
qos (
DataWriterQos) – Reference to the current default WriterQos.- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_instance_handle()¶
Returns the Publisher’s handle.
- Return type
InstanceHandle_t- Returns
InstanceHandle of this Publisher.
- get_listener()¶
Retrieves the attached PublisherListener.
- Return type
- Returns
PublisherListener pointer
- get_participant()¶
This operation returns the DomainParticipant to which the Publisher belongs.
- Return type
- Returns
Pointer to the DomainParticipant
- get_qos(*args)¶
Overload 1:
Allows accessing the Publisher Qos.
- Return type
- Returns
PublisherQos reference
Overload 2:
Retrieves the Publisher Qos.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- has_datawriters()¶
This operation checks if the publisher has DataWriters
- Return type
boolean
- Returns
true if the publisher has one or several DataWriters, false otherwise
- lookup_datawriter(topic_name)¶
This operation retrieves a previously created DataWriter belonging to the Publisher that is attached to a Topic with a matching topic_name. If no such DataWriter exists, the operation will return nullptr.
If multiple DataWriter attached to the Publisher satisfy this condition, then the operation will return one of them. It is not specified which one.
- Parameters
topic_name (string) – Name of the Topic
- Return type
- Returns
Pointer to a previously created DataWriter associated to a Topic with the requested topic_name
- resume_publications()¶
Indicates to FastDDS that the modifications to the DataWriters are complete.
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- set_default_datawriter_qos(qos)¶
This operation sets a default value of the DataWriter QoS policies which will be used for newly created DataWriter entities in the case where the QoS policies are defaulted in the create_datawriter operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return false.
The special value DATAWRITER_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_datawriter_qos operation had never been called.
- Parameters
qos (
DataWriterQos) – DataWriterQos to be set- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_listener(*args)¶
Overload 1:
Modifies the PublisherListener, sets the mask to StatusMask::all()
- Parameters
listener (
PublisherListener) – new value for the PublisherListener- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
Modifies the PublisherListener.
- Parameters
listener (
PublisherListener) – new value for the PublisherListenermask (
StatusMask) – StatusMask that holds statuses the listener responds to
- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_qos(qos)¶
Allows modifying the Publisher Qos. The given Qos must be supported by the PublisherQos.
- Parameters
qos (
PublisherQos) – PublisherQos to be set- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- suspend_publications()¶
Indicates to FastDDS that the contained DataWriters are about to be modified
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- property thisown¶
The membership flag
- wait_for_acknowledgments(max_wait)¶
This operation blocks the calling thread until either all data written by the reliable DataWriter entities is acknowledged by all matched reliable DataReader entities, or else the duration specified by the max_wait parameter elapses, whichever happens first. A return value of true indicates that all the samples written have been acknowledged by all reliable matched data readers; a return value of false indicates that max_wait elapsed before all the data was acknowledged.
- Parameters
max_wait (
Duration_t) – Maximum blocking time for this operation- Return type
ReturnCode_t- Returns
RETCODE_TIMEOUT if the function takes more than the maximum blocking time established, RETCODE_OK if the Publisher receives the acknowledgments and RETCODE_ERROR otherwise.
PublisherListener¶
PublisherQos¶
- class fastdds.PublisherQos¶
Class PublisherQos, containing all the possible Qos that can be set for a determined Publisher. Although these values can be set and are transmitted during the Endpoint Discovery Protocol, not all of the behaviour associated with them has been implemented in the library. Please consult each of them to check for implementation details and default values.
- entity_factory(*args)¶
Overload 1:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 2:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 3:
Setter for EntityFactoryQosPolicy
- Parameters
entity_factory (
EntityFactoryQosPolicy) – EntityFactoryQosPolicy
- group_data(*args)¶
Overload 1:
Getter for GroupDataQosPolicy
- Return type
- Returns
GroupDataQosPolicy reference
Overload 2:
Getter for GroupDataQosPolicy
- Return type
- Returns
GroupDataQosPolicy reference
Overload 3:
Setter for GroupDataQosPolicy
- Parameters
group_data (
GroupDataQosPolicy) – GroupDataQosPolicy
- partition(*args)¶
Overload 1:
Getter for PartitionQosPolicy
- Return type
- Returns
PartitionQosPolicy reference
Overload 2:
Getter for PartitionQosPolicy
- Return type
- Returns
PartitionQosPolicy reference
Overload 3:
Setter for PartitionQosPolicy
- Parameters
partition (
PartitionQosPolicy) – PartitionQosPolicy
- presentation(*args)¶
Overload 1:
Getter for PresentationQosPolicy
- Return type
- Returns
PresentationQosPolicy reference
Overload 2:
Getter for PresentationQosPolicy
- Return type
- Returns
PresentationQosPolicy reference
Overload 3:
Setter for PresentationQosPolicy
- Parameters
presentation (
PresentationQosPolicy) – PresentationQosPolicy
- property thisown¶
The membership flag
- class fastdds.PUBLISHER_QOS_DEFAULT(*args: Any, **kwargs: Any)¶
RTPSReliableWriterQos¶
- class fastdds.RTPSReliableWriterQos¶
Qos Policy to configure the DisablePositiveACKsQos and the writer timing attributes
- property disable_heartbeat_piggyback¶
Disable heartbeat piggyback mechanism.
- property disable_positive_acks¶
Disable positive acks QoS, implemented in the library.
- property thisown¶
The membership flag
- property times¶
Writer Timing Attributes
Subscriber¶
DataReader¶
- class fastdds.DataReader(*args, **kwargs)¶
Class DataReader, contains the actual implementation of the behaviour of the Subscriber.
- create_querycondition(sample_states, view_states, instance_states, query_expression, query_parameters)¶
This operation creates a QueryCondition. The returned QueryCondition will be attached and belong to the DataReader.
- Parameters
[in] – sample_states Only data samples with
sample_statematching one of these will trigger the created condition.[in] – view_states Only data samples with
view_statematching one of these will trigger the created condition.[in] – instance_states Only data samples with
instance_statematching one of these will trigger the created condition.[in] – query_expression Only data samples matching this query will trigger the created condition.
[in] – query_parameters Value of the parameters on the query expression.
- Return type
eprosima::fastdds::dds::QueryCondition
- Returns
pointer to the created QueryCondition, nullptr in case of error.
- create_readcondition(sample_states, view_states, instance_states)¶
This operation creates a ReadCondition. The returned ReadCondition will be attached and belong to the DataReader.
- Parameters
[in] – sample_states Only data samples with
sample_statematching one of these will trigger the created condition.[in] – view_states Only data samples with
view_statematching one of these will trigger the created condition.[in] – instance_states Only data samples with
instance_statematching one of these will trigger the created condition.
- Return type
ReadCondition- Returns
pointer to the created ReadCondition, nullptr in case of error.
- delete_contained_entities()¶
This operation deletes all the entities that were created by means of the “create” operations on the DataReader. That is, it deletes all contained ReadCondition and QueryCondition objects.
The operation will return PRECONDITION_NOT_MET if the any of the contained entities is in a state where it cannot be deleted.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- delete_readcondition(a_condition)¶
This operation deletes a ReadCondition attached to the DataReader.
- Parameters
a_condition (
ReadCondition) – pointer to a ReadCondition belonging to the DataReader- Return type
ReturnCode_t- Returns
RETCODE_OK
- enable()¶
This operation enables the DataReader.
- Return type
ReturnCode_t- Returns
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the Subscriber creating this DataReader is not enabled.
- get_first_untaken_info(info)¶
Returns information about the first untaken sample. This method is meant to be called prior to a read() or take() operation as it does not modify the status condition of the entity.
- Parameters
[out] – info Pointer to a SampleInfo_t structure to store first untaken sample information.
- Return type
ReturnCode_t- Returns
RETCODE_OK if sample info was returned. RETCODE_NO_DATA if there is no sample to take.
- get_instance_handle()¶
Getter for the associated InstanceHandle.
- Return type
InstanceHandle_t- Returns
Copy of the InstanceHandle
- get_key_value(key_holder, handle)¶
NOT YET IMPLEMENTED
This operation can be used to retrieve the instance key that corresponds to an
instance_handle. The operation will only fill the fields that form the key inside the key_holder instance.This operation may return BAD_PARAMETER if the InstanceHandle_t a_handle does not correspond to an existing data-object known to the DataReader. If the implementation is not able to check invalid handles then the result in this situation is unspecified.
,out] key_holder handle
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_listener()¶
Getter for the DataReaderListener
- Return type
- Returns
Pointer to the DataReaderListener
- get_listening_locators(locators)¶
Get the list of locators on which this DataReader is listening.
- Parameters
[out] – locators LocatorList where the list of locators will be stored.
- Return type
ReturnCode_t- Returns
NOT_ENABLED if the reader has not been enabled.
- Return type
ReturnCode_t- Returns
OK if a list of locators is returned.
- get_liveliness_changed_status(status)¶
Get the liveliness changed status.
- Parameters
[out] – status LivelinessChangedStatus object where the status is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_matched_publication_data(publication_data, publication_handle)¶
Retrieves in a publication associated with the DataWriter
publication_data publication data struct :type publication_handle:
InstanceHandle_t:param publication_handle: InstanceHandle_t of the publication :rtype:ReturnCode_t:return: RETCODE_OK Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_matched_publications(publication_handles)¶
Fills the given vector with the InstanceHandle_t of matched DataReaders
publication_handles Vector where the InstanceHandle_t are returned :rtype:
ReturnCode_t:return: RETCODE_OK Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_qos(*args)¶
Overload 1:
Getter for the DataReaderQos.
- Return type
- Returns
Pointer to the DataReaderQos.
Overload 2:
Getter for the DataReaderQos.
- Parameters
[in] – qos DataReaderQos where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_requested_deadline_missed_status(status)¶
Get the requested deadline missed status.
- Return type
ReturnCode_t- Returns
The deadline missed status.
- get_requested_incompatible_qos_status(status)¶
Get the requested incompatible qos status.
- Parameters
[out] – status Requested incompatible qos status.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_sample_lost_status(status)¶
Get the SAMPLE_LOST communication status
status SampleLostStatus object where the status is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_sample_rejected_status(status)¶
Get the SAMPLE_REJECTED communication status
status SampleRejectedStatus object where the status is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_subscriber()¶
Getter for the Subscriber :rtype:
Subscriber:return: Subscriber pointer
- get_subscription_matched_status(status)¶
Returns the subscription matched status
status subscription matched status struct :rtype:
ReturnCode_t:return: RETCODE_OK
- get_topicdescription()¶
Get TopicDescription.
- Return type
- Returns
TopicDescription pointer.
- get_unread_count(*args)¶
Overload 1:
Get the number of samples pending to be read. The number includes samples that may not yet be available to be read or taken by the user, due to samples being received out of order.
- Return type
int
- Returns
the number of samples on the reader history that have never been read.
Overload 2:
Get the number of samples pending to be read.
- Parameters
mark_as_read (boolean) – Whether the unread samples should be marked as read or not.
- Return type
int
- Returns
the number of samples on the reader history that have never been read.
- guid(*args)¶
Overload 1:
Get associated GUID.
- Return type
GUID_t- Returns
Associated GUID
Overload 2:
Get associated GUID.
- Return type
GUID_t- Returns
Associated GUID
- is_sample_valid(data, info)¶
Checks whether a loaned sample is still valid or is corrupted. Calling this method on a sample which has not been loaned, or one for which the loan has been returned yields undefined behavior.
- Parameters
data (void) – Pointer to the sample data to check
info (
SampleInfo) – Pointer to the SampleInfo related todata
- Return type
boolean
- Returns
true if the sample is valid
- lookup_instance(instance)¶
Takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument. The instance parameter is only used for the purpose of examining the fields that define the key.
- Parameters
[in] – instance Data pointer to the sample
- Return type
InstanceHandle_t- Returns
handle of the given
instance.- Return type
InstanceHandle_t- Returns
HANDLE_NIL if
instanceis nullptr.- Return type
InstanceHandle_t- Returns
HANDLE_NIL if there is no instance on the DataReader’s history with the same key as
instance.
- read(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of Data values from the DataReader. The caller can limit the size of the returned collection with the
max_samplesparameter.The properties of the
data_valuescollection and the setting of the ‘PresentationQosPolicy’ may impose further limits on the size of the returned ‘list.’If ‘PresentationQosPolicy::access_scope’ is ‘INSTANCE_PRESENTATION_QOS’, then the returned collection is a ‘list’ where samples belonging to the same data-instance are consecutive.
If ‘PresentationQosPolicy::access_scope’ is ‘TOPIC_PRESENTATION_QOS’ and ‘PresentationQosPolicy::ordered_access’ is set to
false, then the returned collection is a ‘list’ where samples belonging to the same data-instance are consecutive.If ‘PresentationQosPolicy::access_scope’ is ‘TOPIC_PRESENTATION_QOS’ and ‘PresentationQosPolicy::ordered_access’ is set to
true, then the returned collection is a ‘list’ where samples belonging to the same instance may or may not be consecutive. This is because to preserve order it may be necessary to mix samples from different instances.If ‘PresentationQosPolicy::access_scope’ is ‘GROUP_PRESENTATION_QOS’ and ‘PresentationQosPolicy::ordered_access’ is set to
false, then the returned collection is a ‘list’ where samples belonging to the same data instance are consecutive.If ‘PresentationQosPolicy::access_scope’ is ‘GROUP_PRESENTATION_QOS’ and ‘PresentationQosPolicy::ordered_access’ is set to
true, then the returned collection contains at most one sample. The difference in this case is due to the fact that it is required that the application is able to read samples belonging to different DataReader objects in a specific order.
In any case, the relative order between the samples of one instance is consistent with the ‘DestinationOrderQosPolicy’:
If ‘DestinationOrderQosPolicy::kind’ is ‘BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS’, samples belonging to the same instances will appear in the relative order in which there were received (FIFO, earlier samples ahead of the later samples).
If ‘DestinationOrderQosPolicy::kind’ is ‘BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS’, samples belonging to the same instances will appear in the relative order implied by the source_timestamp (FIFO, smaller values of source_timestamp ahead of the larger values).
The actual number of samples returned depends on the information that has been received by the middleware as well as the ‘HistoryQosPolicy’, ‘ResourceLimitsQosPolicy’, and ‘ReaderResourceLimitsQos’:
In the case where the ‘HistoryQosPolicy::kind’ is KEEP_LAST_HISTORY_QOS, the call will return at most ‘HistoryQosPolicy::depth’ samples per instance.
The maximum number of samples returned is limited by ‘ResourceLimitsQosPolicy::max_samples’, and by ‘ReaderResourceLimitsQos::max_samples_per_read’.
For multiple instances, the number of samples returned is additionally limited by the product (‘ResourceLimitsQosPolicy::max_samples_per_instance’ * ‘ResourceLimitsQosPolicy::max_instances)’.
If ReaderResourceLimitsQos::sample_infos_allocation has a maximum limit, the number of samples returned may also be limited if insufficient ‘SampleInfo’ resources are available.
If the operation succeeds and the number of samples returned has been limited (by means of a maximum limit, as listed above, or insufficient ‘SampleInfo’ resources), the call will complete successfully and provide those samples the reader is able to return. The user may need to make additional calls, or return outstanding loaned buffers in the case of insufficient resources, in order to access remaining samples.
In addition to the collection of samples, the read operation also uses a collection of ‘SampleInfo’ structures (
sample_infos).The initial (input) properties of the
data_valuesandsample_infoscollections will determine the precise behavior of this operation. For the purposes of this description the collections are modeled as having three properties:the current length (
len, see ‘LoanableCollection::length())’the maximum length (
max_len, see ‘LoanableCollection::maximum())’whether the collection container owns the memory of the elements within (
owns, see ‘LoanableCollection::has_ownership())’
The initial (input) values of the
len,max_len, andownsproperties for thedata_valuesandsample_infoscollections govern the behavior of the read operation as specified by the following rules:The values of
len,max_len, andownsfor the two collections must be identical. Otherwise read will fail with RETCODE_PRECONDITION_NOT_MET.On successful output, the values of
len,max_len, andownswill be the same for both collections.If the input max_len == 0 , then the
data_valuesandsample_infoscollections will be filled with elements that are ‘loaned’ by the DataReader. On output,ownswill befalse,lenwill be set to the number of values returned, andmax_lenwill be set to a value verifying max_len >= len . The use of this variant allows for zero-copy access to the data and the application will need to return the loan to the DataReader using the ‘return_loan’ operation.If the input max_len > 0 and the input owns == false , then the read operation will fail with RETCODE_PRECONDITION_NOT_MET. This avoids the potential hard-to-detect memory leaks caused by an application forgetting to return the loan.
If input max_len > 0 and the input owns == true , then the read operation will copy the Data values and SampleInfo values into the elements already inside the collections. On output,
ownswill betrue,lenwill be set to the number of values copied, andmax_lenwill remain unchanged. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to return the loan. The number of samples copied depends on the values ofmax_lenandmax_samples:If max_samples == LENGTH_UNLIMITED , then at most
max_lenvalues will be copied. The use of this variant lets the application limit the number of samples returned to what the sequence can accommodate.If max_samples <= max_len , then at most
max_samplesvalues will be copied. The use of this variant lets the application limit the number of samples returned to fewer that what the sequence can accommodate.If max_samples > max_len , then the read operation will fail with RETCODE_PRECONDITION_NOT_MET. This avoids the potential confusion where the application expects to be able to access up to
max_samples, but that number can never be returned, even if they are available in the DataReader, because the output sequence cannot accommodate them.
As described above, upon return the
data_valuesandsample_infoscollections may contain elements ‘loaned’ from the DataReader. If this is the case, the application will need to use the ‘return_loan’ operation to return the loan once it is no longer using the Data in the collection. Upon return from ‘return_loan’, the collection will have max_len == 0 and owns == false .The application can determine whether it is necessary to return the loan or not based on the state of the collections when the read operation was called, or by accessing the
ownsproperty. However, in many cases it may be simpler to always call ‘return_loan’, as this operation is harmless (i.e., leaves all elements unchanged) if the collection does not have a loan.On output, the collection of Data values and the collection of SampleInfo structures are of the same length and are in a one-to-one correspondence. Each SampleInfo provides information, such as the
source_timestamp, thesample_state,view_state, andinstance_state, etc., about the corresponding sample.Some elements in the returned collection may not have valid data. If the
instance_statein the SampleInfo is ‘NOT_ALIVE_DISPOSED_INSTANCE_STATE’ or ‘NOT_ALIVE_NO_WRITERS_INSTANCE_STATE’, then the last sample for that instance in the collection, that is, the one whose SampleInfo has sample_rank == 0 does not contain valid data. Samples that contain no data do not count towards the limits imposed by the ‘ResourceLimitsQosPolicy’.The act of reading a sample changes its
sample_stateto ‘READ_SAMPLE_STATE’. If the sample belongs to the most recent generation of the instance, it will also set theview_stateof the instance to be ‘NOT_NEW_VIEW_STATE’. It will not affect theinstance_stateof the instance.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
Important: If the samples “returned” by this method are loaned from the middleware (see ‘take’ for more information on memory loaning), it is important that their contents not be changed. Because the memory in which the data is stored belongs to the middleware, any modifications made to the data will be seen the next time the same samples are read or taken; the samples will no longer reflect the state that was received from the network.
- Parameters
[in,out] – data_values A LoanableCollection object where the received data samples will be returned.
[in,out] – sample_infos A SampleInfoSeq object where the received sample info will be returned.
[in] – max_samples The maximum number of samples to be returned. If the special value ‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described above.
[in] – sample_states Only data samples with
sample_statematching one of these will be returned.[in] – view_states Only data samples with
view_statematching one of these will be returned.[in] – instance_states Only data samples with
instance_statematching one of these will be returned.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- read_instance(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of data values from the DataReader. The behavior is identical to ‘read’, except that all samples returned belong to the single specified instance whose handle is
a_handle.Upon successful completion, the data collection will contain samples all belonging to the same instance. The corresponding ‘SampleInfo’ verifies ‘SampleInfo::instance_handle’ ==
a_handle.This operation is semantically equivalent to the ‘read’ operation, except in building the collection. The DataReader will check that the sample belongs to the specified instance and otherwise it will not place the sample in the returned collection.
The behavior of this operation follows the same rules as the ‘read’ operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infos. Similar to ‘read’, this operation may ‘loan’ elements to the output collections, which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
- Parameters
[in,out] – data_values A LoanableCollection object where the received data samples will be returned.
[in,out] – sample_infos A SampleInfoSeq object where the received sample info will be returned.
[in] – max_samples The maximum number of samples to be returned. If the special value ‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
[in] – a_handle The specified instance to return samples for. The method will fail with RETCODE_BAD_PARAMETER if the handle does not correspond to an existing data-object known to the DataReader.
[in] – sample_states Only data samples with
sample_statematching one of these will be returned.[in] – view_states Only data samples with
view_statematching one of these will be returned.[in] – instance_states Only data samples with
instance_statematching one of these will be returned.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- read_next_instance(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of data values from the DataReader where all the samples belong to a single instance. The behavior is similar to ‘read_instance’, except that the actual instance is not directly specified. Rather, the samples will all belong to the ‘next’ instance with
instance_handle‘greater’ than the specified ‘previous_handle’ that has available samples.This operation implies the existence of a total order ‘greater-than’ relationship between the instance handles. The specifics of this relationship are not all important and are implementation specific. The important thing is that, according to the middleware, all instances are ordered relative to each other. This ordering is between the instance handles, and should not depend on the state of the instance (e.g. whether it has data or not) and must be defined even for instance handles that do not correspond to instances currently managed by the DataReader. For the purposes of the ordering, it should be ‘as if’ each instance handle was represented as an integer.
The behavior of this operation is ‘as if’ the DataReader invoked ‘read_instance’, passing the smallest
instance_handleamong all the ones that: (a) are greater thanprevious_handle, and (b) have available samples (i.e. samples that meet the constraints imposed by the specified states).The special value ‘HANDLE_NIL’ is guaranteed to be ‘less than’ any valid
instance_handle. So the use of the parameter valueprevious_handle== ‘HANDLE_NIL’ will return the samples for the instance which has the smallestinstance_handleamong all the instances that contain available samples.This operation is intended to be used in an application-driven iteration, where the application starts by passing
previous_handle== ‘HANDLE_NIL’, examines the samples returned, and then uses theinstance_handlereturned in the ‘SampleInfo’ as the value of theprevious_handleargument to the next call to ‘read_next_instance’. The iteration continues until ‘read_next_instance’ fails with RETCODE_NO_DATA.Note that it is possible to call the ‘read_next_instance’ operation with a
previous_handlethat does not correspond to an instance currently managed by the DataReader. This is because as stated earlier the ‘greater-than’ relationship is defined even for handles not managed by the DataReader. One practical situation where this may occur is when an application is iterating through all the instances, takes all the samples of a ‘NOT_ALIVE_NO_WRITERS_INSTANCE_STATE’ instance, returns the loan (at which point the instance information may be removed, and thus the handle becomes invalid), and tries to read the next instance.The behavior of this operation follows the same rules as the ‘read’ operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infos. Similar to ‘read’, this operation may ‘loan’ elements to the output collections, which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
- Parameters
[in,out] – data_values A LoanableCollection object where the received data samples will be returned.
[in,out] – sample_infos A SampleInfoSeq object where the received sample info will be returned.
[in] – max_samples The maximum number of samples to be returned. If the special value ‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
[in] – previous_handle The ‘next smallest’ instance with a value greater than this value that has available samples will be returned.
[in] – sample_states Only data samples with
sample_statematching one of these will be returned.[in] – view_states Only data samples with
view_statematching one of these will be returned.[in] – instance_states Only data samples with
instance_statematching one of these will be returned.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- read_next_instance_w_condition(data_values, sample_infos, max_samples, previous_handle, a_condition)¶
This operation accesses a collection of Data values from the DataReader. The behavior is identical to ‘read_next_instance’ except that all samples returned satisfy the specified condition. In other words, on success all returned samples belong to the same instance, and the instance is the instance with ‘smallest’
instance_handleamong the ones that verify (a)instance_handle>=previous_handleand (b) have samples for which the specified ReadCondition evaluates to TRUE.Similar to the operation ‘read_next_instance’ it is possible to call ‘read_next_instance_w_condition’ with a
previous_handlethat does not correspond to an instance currently managed by the DataReader.The behavior of the ‘read_next_instance_w_condition’ operation follows the same rules than the read operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infoscollections. Similar to read, the ‘read_next_instance_w_condition’ operation may ‘loan’ elements to the output collections which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the return value will be RETCODE_NO_DATA.
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. If the special value
‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
- previous_handle The ‘next smallest’ instance with a value greater than this value that has
available samples will be returned.
a_condition A ReadCondition that returned
data_valuesmust pass- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- read_next_sample(data, info)¶
This operation copies the next, non-previously accessed Data value from the DataReader; the operation also copies the corresponding SampleInfo. The implied order among the samples stored in the DataReader is the same as for the read operation.
The read_next_sample operation is semantically equivalent to the read operation where the input Data sequence has max_length = 1 , the sample_states = NOT_READ_SAMPLE_STATE , the view_states = ANY_VIEW_STATE , and the instance_states = ANY_INSTANCE_STATE .
The read_next_sample operation provides a simplified API to ‘read’ samples avoiding the need for the application to manage sequences and specify states.
If there is no unread data in the DataReader, the operation will return RETCODE_NO_DATA and nothing is copied
- Parameters
[out] – data Data pointer to store the sample
[out] – info SampleInfo pointer to store the sample information
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- read_w_condition(data_values, sample_infos, max_samples, a_condition)¶
This operation accesses via ‘read’ the samples that match the criteria specified in the ReadCondition. This operation is especially useful in combination with QueryCondition to filter data samples based on the content.
The specified ReadCondition must be attached to the DataReader; otherwise the operation will fail and return RETCODE_PRECONDITION_NOT_MET.
In case the ReadCondition is a ‘plain’ ReadCondition and not the specialized QueryCondition, the operation is equivalent to calling read and passing as
sample_states,view_statesandinstance_statesthe value of the corresponding attributes ina_condition. Using this operation the application can avoid repeating the same parameters specified when creating the ReadCondition.The samples are accessed with the same semantics as the read operation. If the DataReader has no samples that meet the constraints, the return value will be RETCODE_NO_DATA.
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. a_condition A ReadCondition that returned
data_valuesmust pass- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- return_loan(data_values, sample_infos)¶
This operation indicates to the DataReader that the application is done accessing the collection of
data_valuesandsample_infosobtained by some earlier invocation of ‘read’ or ‘take’ on the DataReader.The
data_valuesandsample_infosmust belong to a single related ‘pair’; that is, they should correspond to a pair returned from a single call to read or take. Thedata_valuesandsample_infosmust also have been obtained from the same DataReader to which they are returned. If either of these conditions is not met, the operation will fail and return RETCODE_PRECONDITION_NOT_MET.This operation allows implementations of the ‘read’ and ‘take’ operations to “loan” buffers from the DataReader to the application and in this manner provide “zero-copy” access to the data. During the loan, the DataReader will guarantee that the data and sample-information are not modified.
It is not necessary for an application to return the loans immediately after the read or take calls. However, as these buffers correspond to internal resources inside the DataReader, the application should not retain them indefinitely.
The use of the ‘return_loan’ operation is only necessary if the read or take calls “loaned” buffers to the application. This only occurs if the
data_valuesandsample_infoscollections had max_len == 0 at the time read or take was called. The application may also examine theownsproperty of the collection to determine if there is an outstanding loan. However, calling ‘return_loan’ on a collection that does not have a loan is safe and has no side effects.If the collections had a loan, upon return from return_loan the collections will have max_len == 0 .
- Parameters
[in,out] – data_values A LoanableCollection object where the received data samples were obtained from an earlier invocation of read or take on this DataReader.
[in,out] – sample_infos A SampleInfoSeq object where the received sample infos were obtained from an earlier invocation of read or take on this DataReader.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- set_listener(*args)¶
- set_qos(qos)¶
Setter for the DataReaderQos.
- Parameters
[in] – qos new value for the DataReaderQos.
- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- take(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of data-samples from the DataReader and a corresponding collection of SampleInfo structures, and ‘removes’ them from the DataReader. The operation will return either a ‘list’ of samples or else a single sample. This is controlled by the ‘PresentationQosPolicy’ using the same logic as for the ‘read’ operation.
The act of taking a sample removes it from the DataReader so it cannot be ‘read’ or ‘taken’ again. If the sample belongs to the most recent generation of the instance, it will also set the
view_stateof the instance to NOT_NEW. It will not affect theinstance_stateof the instance.The behavior of the take operation follows the same rules than the ‘read’ operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infoscollections. Similar to ‘read’, the take operation may ‘loan’ elements to the output collections which must then be returned by means of ‘return_loan’. The only difference with ‘read’ is that, as stated, the samples returned by take will no longer be accessible to successive calls to read or take.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
- Parameters
[in,out] – data_values A LoanableCollection object where the received data samples will be returned.
[in,out] – sample_infos A SampleInfoSeq object where the received sample info will be returned.
[in] – max_samples The maximum number of samples to be returned. If the special value ‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
[in] – sample_states Only data samples with
sample_statematching one of these will be returned.[in] – view_states Only data samples with
view_statematching one of these will be returned.[in] – instance_states Only data samples with
instance_statematching one of these will be returned.
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- take_instance(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of data values from the DataReader and ‘removes’ them from the DataReader.
This operation has the same behavior as ‘read_instance’, except that the samples are ‘taken’ from the DataReader such that they are no longer accessible via subsequent ‘read’ or ‘take’ operations.
The behavior of this operation follows the same rules as the ‘read’ operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infos. Similar to ‘read’, this operation may ‘loan’ elements to the output collections, which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. If the special value
‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
- a_handle The specified instance to return samples for. The method will fail with
RETCODE_BAD_PARAMETER if the handle does not correspond to an existing data-object known to the DataReader.
sample_states Only data samples with
sample_statematching one of these will be returned. view_states Only data samples withview_statematching one of these will be returned. instance_states Only data samples withinstance_statematching one of these will be returned.- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- take_next_instance(*args)¶
Access a collection of data samples from the DataReader.
This operation accesses a collection of data values from the DataReader and ‘removes’ them from the DataReader.
This operation has the same behavior as ‘read_next_instance’, except that the samples are ‘taken’ from the DataReader such that they are no longer accessible via subsequent ‘read’ or ‘take’ operations.
Similar to the operation ‘read_next_instance’, it is possible to call this operation with a
previous_handlethat does not correspond to an instance currently managed by the DataReader.The behavior of this operation follows the same rules as the ‘read’ operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infos. Similar to ‘read’, this operation may ‘loan’ elements to the output collections, which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the operations fails with RETCODE_NO_DATA.
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. If the special value
‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
- previous_handle The ‘next smallest’ instance with a value greater than this value that has
available samples will be returned.
sample_states Only data samples with
sample_statematching one of these will be returned. view_states Only data samples withview_statematching one of these will be returned. instance_states Only data samples withinstance_statematching one of these will be returned.- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- take_next_instance_w_condition(data_values, sample_infos, max_samples, previous_handle, a_condition)¶
This operation accesses a collection of Data values from the DataReader. The behavior is identical to ‘read_next_instance’ except that all samples returned satisfy the specified condition. In other words, on success all returned samples belong to the same instance, and the instance is the instance with ‘smallest’
instance_handleamong the ones that verify (a)instance_handle>=previous_handleand (b) have samples for which the specified ReadCondition evaluates to TRUE.Similar to the operation ‘read_next_instance’ it is possible to call ‘read_next_instance_w_condition’ with a
previous_handlethat does not correspond to an instance currently managed by the DataReader.The behavior of the ‘read_next_instance_w_condition’ operation follows the same rules than the read operation regarding the pre-conditions and post-conditions for the
data_valuesandsample_infoscollections. Similar to read, the ‘read_next_instance_w_condition’ operation may ‘loan’ elements to the output collections which must then be returned by means of ‘return_loan’.If the DataReader has no samples that meet the constraints, the return value will be RETCODE_NO_DATA
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. If the special value
‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are available, up to the limits described in the documentation for ‘read()’.
- previous_handle The ‘next smallest’ instance with a value greater than this value that has
available samples will be returned.
a_condition A ReadCondition that returned
data_valuesmust pass- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- take_next_sample(data, info)¶
This operation copies the next, non-previously accessed Data value from the DataReader and ‘removes’ it from the DataReader so it is no longer accessible. The operation also copies the corresponding SampleInfo.
This operation is analogous to ‘read_next_sample’ except for the fact that the sample is ‘removed’ from the DataReader.
- This operation is semantically equivalent to the ‘take’ operation where the input sequence has
max_length = 1 , the sample_states = NOT_READ_SAMPLE_STATE , the view_states = ANY_VIEW_STATE , and the instance_states = ANY_INSTANCE_STATE .
This operation provides a simplified API to ’take’ samples avoiding the need for the application to manage sequences and specify states.
If there is no unread data in the DataReader, the operation will return RETCODE_NO_DATA and nothing is copied.
- Parameters
[out] – data Data pointer to store the sample
[out] – info SampleInfo pointer to store the sample information
- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- take_w_condition(data_values, sample_infos, max_samples, a_condition)¶
This operation is analogous to ‘read_w_condition’ except it accesses samples via the ‘take’ operation.
The specified ReadCondition must be attached to the DataReader; otherwise the operation will fail and return RETCODE_PRECONDITION_NOT_MET.
The samples are accessed with the same semantics as the ‘take’ operation.
This operation is especially useful in combination with QueryCondition to filter data samples based on the content.
If the DataReader has no samples that meet the constraints, the return value will be RETCODE_NO_DATA.
,out] data_values A LoanableCollection object where the received data samples will be returned. ,out] sample_infos A SampleInfoSeq object where the received sample info will be returned. max_samples The maximum number of samples to be returned. If the special value
‘LENGTH_UNLIMITED’ is provided, as many samples will be returned as are.
a_condition A ReadCondition that returned
data_valuesmust pass- Return type
ReturnCode_t- Returns
Any of the standard return codes.
- property thisown¶
The membership flag
- type()¶
Getter for the data type.
- Return type
- Returns
TypeSupport associated to the DataReader.
- wait_for_historical_data(max_wait)¶
NOT YET IMPLEMENTED
Method to block the current thread until an unread message is available.
max_wait Max blocking time for this operation. :rtype:
ReturnCode_t:return: RETCODE_OK if there is new unread message, ReturnCode_t::RETCODE_TIMEOUT if timeout Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- wait_for_unread_message(timeout)¶
Method to block the current thread until an unread message is available.
- Parameters
[in] – timeout Max blocking time for this operation.
- Return type
boolean
- Returns
true if there is new unread message, false if timeout
DataReaderListener¶
- class fastdds.DataReaderListener¶
Class DataReaderListener, it should be used by the end user to implement specific callbacks to certain actions.
- on_data_available(reader)¶
Virtual function to be implemented by the user containing the actions to be performed when new Data Messages are received.
- Parameters
reader (
DataReader) – DataReader
- on_liveliness_changed(reader, status)¶
Method called when the liveliness status associated to a subscriber changes
- Parameters
reader (
DataReader) – The DataReaderstatus (eprosima::fastrtps::LivelinessChangedStatus) – The liveliness changed status
- on_requested_deadline_missed(reader, status)¶
Virtual method to be called when a topic misses the deadline period
- Parameters
reader (
DataReader) – DataReaderstatus (eprosima::fastrtps::RequestedDeadlineMissedStatus) – The requested deadline missed status
- on_requested_incompatible_qos(reader, status)¶
Method called an incompatible QoS was requested.
- Parameters
reader (
DataReader) – The DataReaderstatus (
RequestedIncompatibleQosStatus) – The requested incompatible QoS status
- on_sample_lost(reader, status)¶
Method called when a sample was lost.
- Parameters
reader (
DataReader) – The DataReaderstatus (
SampleLostStatus) – The sample lost status
- on_sample_rejected(reader, status)¶
Method called when a sample was rejected.
- Parameters
reader (
DataReader) – The DataReaderstatus (eprosima::fastrtps::SampleRejectedStatus) – The rejected status
- on_subscription_matched(reader, info)¶
Virtual method to be called when the subscriber is matched with a new Writer (or unmatched); i.e., when a writer publishing in the same topic is discovered.
- Parameters
reader (
DataReader) – DataReaderinfo (
SubscriptionMatchedStatus) – The subscription matched status
- property thisown¶
The membership flag
DataReaderQos¶
- class fastdds.DataReaderQos¶
Class DataReaderQos, containing all the possible Qos that can be set for a determined DataReader. Although these values can be set and are transmitted during the Endpoint Discovery Protocol, not all of the behaviour associated with them has been implemented in the library. Please consult each of them to check for implementation details and default values.
- data_sharing(*args)¶
Overload 1:
Getter for DataSharingQosPolicy
- Return type
- Returns
DataSharingQosPolicy reference
Overload 2:
Getter for DataSharingQosPolicy
- Return type
- Returns
DataSharingQosPolicy reference
Overload 3:
Setter for DataSharingQosPolicy
- Parameters
data_sharing (
DataSharingQosPolicy) – new value for the DataSharingQosPolicy
- deadline(*args)¶
Overload 1:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQosPolicy reference
Overload 2:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQosPolicy const reference
Overload 3:
Setter for DeadlineQosPolicy
- Parameters
new_value (
DeadlineQosPolicy) – new value for the DeadlineQosPolicy
- destination_order(*args)¶
Overload 1:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQosPolicy reference
Overload 2:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQosPolicy const reference
Overload 3:
Setter for DestinationOrderQosPolicy
- Parameters
new_value (
DestinationOrderQosPolicy) – new value for the DestinationOrderQosPolicy
- durability(*args)¶
Overload 1:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQosPolicy reference
Overload 2:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQosPolicy const reference
Overload 3:
Setter for DurabilityQosPolicy
- Parameters
new_value (
DurabilityQosPolicy) – new value for the DurabilityQosPolicy
- durability_service(*args)¶
Overload 1:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQosPolicy reference
Overload 2:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQosPolicy const reference
Overload 3:
Setter for DurabilityServiceQosPolicy
- Parameters
new_value (
DurabilityServiceQosPolicy) – new value for the DurabilityServiceQosPolicy
- endpoint(*args)¶
Overload 1:
Getter for RTPSEndpointQos
- Return type
- Returns
RTPSEndpointQos reference
Overload 2:
Getter for RTPSEndpointQos
- Return type
- Returns
RTPSEndpointQos const reference
Overload 3:
Setter for RTPSEndpointQos
- Parameters
new_value (
RTPSEndpointQos) – new value for the RTPSEndpointQos
- expects_inline_qos(*args)¶
Overload 1:
Getter for expectsInlineQos
- Return type
boolean
- Returns
expectsInlineQos
Overload 2:
Setter for expectsInlineQos
- Parameters
new_value (boolean) – new value for the expectsInlineQos
- get_readerqos(sqos)¶
- history(*args)¶
Overload 1:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQosPolicy reference
Overload 2:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQosPolicy const reference
Overload 3:
Setter for HistoryQosPolicy
- Parameters
new_value (
HistoryQosPolicy) – new value for the HistoryQosPolicy
- latency_budget(*args)¶
Overload 1:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQosPolicy reference
Overload 2:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQosPolicy const reference
Overload 3:
Setter for LatencyBudgetQosPolicy
- Parameters
new_value (
LatencyBudgetQosPolicy) – new value for the LatencyBudgetQosPolicy
- lifespan(*args)¶
Overload 1:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQosPolicy reference
Overload 2:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQosPolicy const reference
Overload 3:
Setter for LifespanQosPolicy
- Parameters
new_value (
LifespanQosPolicy) – new value for the LifespanQosPolicy
- liveliness(*args)¶
Overload 1:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQosPolicy reference
Overload 2:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQosPolicy const reference
Overload 3:
Setter for LivelinessQosPolicy
- Parameters
new_value (
LivelinessQosPolicy) – new value for the LivelinessQosPolicy
- ownership(*args)¶
Overload 1:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQosPolicy reference
Overload 2:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQosPolicy const reference
Overload 3:
Setter for OwnershipQosPolicy
- Parameters
new_value (
OwnershipQosPolicy) – new value for the OwnershipQosPolicy
- properties(*args)¶
Overload 1:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos reference
Overload 2:
Getter for PropertyPolicyQos
- Return type
PropertyPolicyQos- Returns
PropertyPolicyQos const reference
Overload 3:
Setter for PropertyPolicyQos
- Parameters
new_value (
PropertyPolicyQos) – new value for the PropertyPolicyQos
- reader_data_lifecycle(*args)¶
Overload 1:
Getter for ReaderDataLifecycleQosPolicy
- Return type
- Returns
ReaderDataLifecycleQosPolicy reference
Overload 2:
Getter for ReaderDataLifecycleQosPolicy
- Return type
- Returns
ReaderDataLifecycleQosPolicy const reference
Overload 3:
Setter for ReaderDataLifecycleQosPolicy
- Parameters
new_value (
ReaderDataLifecycleQosPolicy) – new value for the ReaderDataLifecycleQosPolicy
- reader_resource_limits(*args)¶
Overload 1:
Getter for ReaderResourceLimitsQos
- Return type
- Returns
ReaderResourceLimitsQos reference
Overload 2:
Getter for ReaderResourceLimitsQos
- Return type
- Returns
ReaderResourceLimitsQos const reference
Overload 3:
Setter for ReaderResourceLimitsQos
- Parameters
new_value (
ReaderResourceLimitsQos) – new value for the ReaderResourceLimitsQos
- reliability(*args)¶
Overload 1:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQosPolicy reference
Overload 2:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQosPolicy const reference
Overload 3:
Setter for ReliabilityQosPolicy
- Parameters
new_value (
ReliabilityQosPolicy) – new value for the ReliabilityQosPolicy
- reliable_reader_qos(*args)¶
Overload 1:
Getter for RTPSReliableReaderQos
- Return type
- Returns
RTPSReliableReaderQos reference
Overload 2:
Getter for RTPSReliableReaderQos
- Return type
- Returns
RTPSReliableReaderQos const reference
Overload 3:
Setter for RTPSReliableReaderQos
- Parameters
new_value (
RTPSReliableReaderQos) – new value for the RTPSReliableReaderQos
- resource_limits(*args)¶
Overload 1:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQosPolicy reference
Overload 2:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQosPolicy const reference
Overload 3:
Setter for ResourceLimitsQosPolicy
- Parameters
new_value (
ResourceLimitsQosPolicy) – new value for the ResourceLimitsQosPolicy
- property thisown¶
The membership flag
- time_based_filter(*args)¶
Overload 1:
Getter for TimeBasedFilterQosPolicy
- Return type
- Returns
TimeBasedFilterQosPolicy reference
Overload 2:
Getter for TimeBasedFilterQosPolicy
- Return type
- Returns
TimeBasedFilterQosPolicy const reference
Overload 3:
Setter for TimeBasedFilterQosPolicy
- Parameters
new_value (
TimeBasedFilterQosPolicy) – new value for the TimeBasedFilterQosPolicy
- type_consistency(*args)¶
Overload 1:
Getter for TypeConsistencyQos
- Return type
- Returns
TypeConsistencyQos reference
Overload 2:
Getter for TypeConsistencyQos
- Return type
- Returns
TypeConsistencyQos const reference
Overload 3:
Setter for TypeConsistencyQos
- Parameters
new_value (
TypeConsistencyQos) – new value for the TypeConsistencyQos
- user_data(*args)¶
Overload 1:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy reference
Overload 2:
Getter for UserDataQosPolicy
- Return type
- Returns
UserDataQosPolicy const reference
Overload 3:
Setter for UserDataQosPolicy
- Parameters
new_value (
UserDataQosPolicy) – new value for the UserDataQosPolicy
- class fastdds.DATAREADER_QOS_DEFAULT(*args: Any, **kwargs: Any)¶
InstanceStateKind¶
- class fastdds.ALIVE_INSTANCE_STATE(*args: Any, **kwargs: Any)¶
- class fastdds.NOT_ALIVE_DISPOSED_INSTANCE_STATE(*args: Any, **kwargs: Any)¶
- class fastdds.NOT_ALIVE_NO_WRITERS_INSTANCE_STATE(*args: Any, **kwargs: Any)¶
ReaderResourceLimitsQos¶
- class fastdds.ReaderResourceLimitsQos¶
Qos Policy to configure the limit of the reader resources
- clear()¶
- property matched_publisher_allocation¶
Matched publishers allocation limits.
- property max_samples_per_read¶
Maximum number of samples to return on a single call to read / take.
This attribute is a signed integer to be consistent with the
max_samplesargument of ‘DataReader’ methods, but should always have a strict positive value. Bear in mind that a big number here may cause the creation of the DataReader to fail due to pre-allocation of internal resources.Default value: 32.
- property outstanding_reads_allocation¶
Loaned collections allocation limits.
- property sample_infos_allocation¶
SampleInfo allocation limits.
- property thisown¶
The membership flag
RTPSReliableReaderQos¶
SampleInfo¶
- class fastdds.SampleInfo¶
SampleInfo is the information that accompanies each sample that is ‘read’ or ‘taken.’
- property absolute_generation_rank¶
the generation difference between the time the sample was received, and the time the most recent sample was received. The most recent sample used for the calculation may or may not be in the returned collection
- property disposed_generation_count¶
number of times the instance had become alive after it was disposed
- property generation_rank¶
the generation difference between the time the sample was received, and the time the most recent sample in the collection was received.
- property instance_handle¶
identifies locally the corresponding instance
- property instance_state¶
indicates whether the instance is currently in existence or, if it has been disposed, the reason why it was disposed.
- property no_writers_generation_count¶
number of times the instance had become alive after it was disposed because no writers
- property publication_handle¶
identifies locally the DataWriter that modified the instance Is the same InstanceHandle_t that is returned by the operation get_matched_publications on the DataReader
- property reception_timestamp¶
time provided by the DataReader when the sample was added to its history
Related Sample Identity (Extension for RPC)
- property sample_identity¶
Sample Identity (Extension for RPC)
- property sample_rank¶
number of samples related to the same instance that follow in the collection
- property sample_state¶
indicates whether or not the corresponding data sample has already been read
- property source_timestamp¶
time provided by the DataWriter when the sample was written
- property thisown¶
The membership flag
- property valid_data¶
whether the DataSample contains data or is only used to communicate of a change in the instance
- property view_state¶
indicates whether the DataReader has already seen samples for the most-current generation of the related instance.
SampleStateKind¶
- class fastdds.READ_SAMPLE_STATE(*args: Any, **kwargs: Any)¶
- class fastdds.NOT_READ_SAMPLE_STATE(*args: Any, **kwargs: Any)¶
Subscriber¶
- class fastdds.Subscriber(*args, **kwargs)¶
Class Subscriber, contains the public API that allows the user to control the reception of messages. This class should not be instantiated directly. DomainRTPSParticipant class should be used to correctly create this element.
- begin_access()¶
Indicates that the application is about to access the data samples in any of the DataReader objects attached to the Subscriber.
- Return type
ReturnCode_t- Returns
RETCODE_OK
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- static copy_from_topic_qos(reader_qos, topic_qos)¶
Copies TopicQos into the corresponding DataReaderQos
, out] reader_qos topic_qos :rtype:
ReturnCode_t:return: RETCODE_OK if successful, an error code otherwise Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- create_datareader(*args)¶
This operation creates a DataReader. The returned DataReader will be attached and belong to the Subscriber.
- Parameters
topic (
TopicDescription) – Topic the DataReader will be listening.reader_qos (
DataReaderQos) – QoS of the DataReader.listener (
DataReaderListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all).
- Return type
- Returns
Pointer to the created DataReader. nullptr if failed.
- create_datareader_with_profile(*args)¶
This operation creates a DataReader. The returned DataReader will be attached and belongs to the Subscriber.
- Parameters
topic (
TopicDescription) – Topic the DataReader will be listening.profile_name (string) – DataReader profile name.
listener (
DataReaderListener) – Pointer to the listener (default: nullptr)mask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all).
- Return type
- Returns
Pointer to the created DataReader. nullptr if failed.
- delete_contained_entities()¶
Deletes all contained DataReaders. If the DataReaders have any QueryCondition or ReadCondition, they are deleted before the DataReader itself.
- Return type
ReturnCode_t- Returns
RETCODE_OK if successful, an error code otherwise
- delete_datareader(reader)¶
This operation deletes a DataReader that belongs to the Subscriber.
The delete_datareader operation must be called on the same Subscriber object used to create the DataReader. If delete_datareader is called on a different Subscriber, the operation will have no effect and it will return an error.
- Parameters
reader (
DataReader) – DataReader to delete- Return type
ReturnCode_t- Returns
RETCODE_PRECONDITION_NOT_MET if the datareader does not belong to this subscriber, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- enable()¶
This operation enables the Subscriber
- Return type
ReturnCode_t- Returns
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the participant creating this Subscriber is not enabled.
- end_access()¶
Indicates that the application has finished accessing the data samples in DataReader objects managed by the Subscriber.
- Return type
ReturnCode_t- Returns
RETCODE_OK
Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_datareader_qos_from_profile(profile_name, qos)¶
Fills the DataReaderQos with the values of the XML profile.
- Parameters
profile_name (string) – DataReader profile name.
qos (
DataReaderQos) – DataReaderQos object where the qos is returned.
- Return type
ReturnCode_t- Returns
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- get_datareaders(*args)¶
Overload 1:
This operation allows the application to access the DataReader objects.
- Parameters
readers (std::vector< eprosima::fastdds::dds::DataReader *,std::allocator< eprosima::fastdds::dds::DataReader * > >) – Vector of DataReader where the list of existing readers is returned
- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
This operation allows the application to access the DataReader objects that contain samples with the specified sample_states, view_states, and instance_states.
readers Vector of DataReader where the list of existing readers is returned :type sample_states: std::vector< eprosima::fastdds::dds::SampleStateKind,std::allocator< eprosima::fastdds::dds::SampleStateKind > > :param sample_states: Vector of SampleStateKind :type view_states: std::vector< eprosima::fastdds::dds::ViewStateKind,std::allocator< eprosima::fastdds::dds::ViewStateKind > > :param view_states: Vector of ViewStateKind :type instance_states: std::vector< eprosima::fastdds::dds::InstanceStateKind,std::allocator< eprosima::fastdds::dds::InstanceStateKind > > :param instance_states: Vector of InstanceStateKind :rtype:
ReturnCode_t:return: RETCODE_OK Warning: Not supported yet. Currently returns RETCODE_UNSUPPORTED
- get_default_datareader_qos(*args)¶
Overload 1:
This operation returns the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.
The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.
- Return type
- Returns
Current default DataReaderQos.
Overload 2:
This operation returns the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.
The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.
- Return type
- Returns
Current default DataReaderQos.
Overload 3:
This operation retrieves the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.
The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.
- Parameters
qos (
DataReaderQos) – DataReaderQos where the default_qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- get_instance_handle()¶
Returns the Subscriber’s handle.
- Return type
InstanceHandle_t- Returns
InstanceHandle of this Subscriber.
- get_listener()¶
Retrieves the attached SubscriberListener.
- Return type
- Returns
Pointer to the SubscriberListener
- get_participant()¶
This operation returns the DomainParticipant to which the Subscriber belongs.
- Return type
- Returns
DomainParticipant Pointer
- get_qos(*args)¶
Overload 1:
Allows accessing the Subscriber Qos.
- Return type
- Returns
SubscriberQos reference
Overload 2:
Retrieves the Subscriber Qos.
- Parameters
qos (
SubscriberQos) – SubscriberQos where the qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- has_datareaders()¶
This operation checks if the subscriber has DataReaders
- Return type
boolean
- Returns
true if the subscriber has one or several DataReaders, false in other case
- lookup_datareader(topic_name)¶
This operation retrieves a previously-created DataReader belonging to the Subscriber that is attached to a Topic with a matching topic_name. If no such DataReader exists, the operation will return nullptr.
If multiple DataReaders attached to the Subscriber satisfy this condition, then the operation will return one of them. It is not specified which one.
- Parameters
topic_name (string) – Name of the topic associated to the DataReader
- Return type
- Returns
Pointer to a previously created DataReader created on a Topic with that topic_name
- notify_datareaders()¶
This operation invokes the operation on_data_available on the DataReaderListener objects attached to contained DataReader entities.
This operation is typically invoked from the on_data_on_readers operation in the SubscriberListener. That way the SubscriberListener can delegate to the DataReaderListener objects the handling of the data.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_default_datareader_qos(qos)¶
This operation sets a default value of the DataReader QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.
This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return false.
The special value DATAREADER_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_datareader_qos operation had never been called.
- Parameters
qos (
DataReaderQos) – new value for DataReaderQos to set as default- Return type
ReturnCode_t- Returns
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- set_listener(*args)¶
Overload 1:
Modifies the SubscriberListener, sets the mask to StatusMask::all()
- Parameters
listener (
SubscriberListener) – new value for SubscriberListener- Return type
ReturnCode_t- Returns
RETCODE_OK
Overload 2:
Modifies the SubscriberListener.
- Parameters
listener (
SubscriberListener) – new value for the SubscriberListenermask (
StatusMask) – StatusMask that holds statuses the listener responds to.
- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_qos(qos)¶
Allows modifying the Subscriber Qos. The given Qos must be supported by the SubscriberQos.
- Parameters
qos (
SubscriberQos) – new value for SubscriberQos- Return type
ReturnCode_t- Returns
RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- property thisown¶
The membership flag
SubscriberListener¶
- class fastdds.SubscriberListener¶
Class SubscriberListener, it should be used by the end user to implement specific callbacks to certain actions. It also inherits all DataReaderListener callbacks.
- on_data_on_readers(sub)¶
Virtual function to be implemented by the user containing the actions to be performed when a new Data Message is available on any reader.
- Parameters
sub (
Subscriber) – Subscriber
- property thisown¶
The membership flag
SubscriberQos¶
- class fastdds.SubscriberQos¶
Class SubscriberQos, contains all the possible Qos that can be set for a determined Subscriber. Although these values can be set and are transmitted during the Endpoint Discovery Protocol, not all of the behaviour associated with them has been implemented in the library. Please consult each of them to check for implementation details and default values.
- entity_factory(*args)¶
Overload 1:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 2:
Getter for EntityFactoryQosPolicy
- Return type
- Returns
EntityFactoryQosPolicy reference
Overload 3:
Setter for EntityFactoryQosPolicy
- Parameters
entity_factory (
EntityFactoryQosPolicy) – new value for the EntityFactoryQosPolicy
- group_data(*args)¶
Overload 1:
Getter for GroupDataQosPolicy
- Return type
- Returns
GroupDataQosPolicy reference
Overload 2:
Getter for GroupDataQosPolicy
- Return type
- Returns
GroupDataQosPolicy reference
Overload 3:
Setter for GroupDataQosPolicy
- Parameters
group_data (
GroupDataQosPolicy) – new value for the GroupDataQosPolicy
- partition(*args)¶
Overload 1:
Getter for PartitionQosPolicy
- Return type
- Returns
PartitionQosPolicy reference
Overload 2:
Getter for PartitionQosPolicy
- Return type
- Returns
PartitionQosPolicy reference
Overload 3:
Setter for PartitionQosPolicy
- Parameters
partition (
PartitionQosPolicy) – new value for the PartitionQosPolicy
- presentation(*args)¶
Overload 1:
Getter for PresentationQosPolicy
- Return type
- Returns
PresentationQosPolicy reference
Overload 2:
Getter for PresentationQosPolicy
- Return type
- Returns
PresentationQosPolicy reference
Overload 3:
Setter for PresentationQosPolicy
- Parameters
presentation (
PresentationQosPolicy) – new value for the PresentationQosPolicy
- property thisown¶
The membership flag
- class fastdds.SUBSCRIBER_QOS_DEFAULT(*args: Any, **kwargs: Any)¶
TypeConsistencyQos¶
Topic¶
Topic¶
- class fastdds.Topic(*args, **kwargs)¶
Class Topic, represents the fact that both publications and subscriptions are tied to a single data-type
- get_impl()¶
- get_listener()¶
Retrieves the attached TopicListener.
- Return type
- Returns
pointer to TopicListener
- get_participant()¶
Getter for the DomainParticipant
- Return type
- Returns
DomainParticipant pointer
- get_qos(*args)¶
Overload 1:
Allows accessing the Topic Qos.
- Return type
- Returns
reference to TopicQos
Overload 2:
Retrieves the Topic Qos.
- Parameters
qos (
TopicQos) – TopicQos where the qos is returned- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_listener(*args)¶
Modifies the TopicListener.
- Parameters
listener (
TopicListener) – new value for the TopicListenermask (
StatusMask) – StatusMask that holds statuses the listener responds to (default: all).
- Return type
ReturnCode_t- Returns
RETCODE_OK
- set_qos(qos)¶
Allows modifying the Topic Qos. The given Qos must be supported by the Topic.
- Parameters
qos (
TopicQos) – new TopicQos value to set for the Topic.
- property thisown¶
The membership flag
TopicDataType¶
- class fastdds.TopicDataType(*args, **kwargs)¶
Class TopicDataType used to provide the DomainRTPSParticipant with the methods to serialize, deserialize and get the key of a specific data type. The user should created a class that inherits from this one, where Serialize and deserialize methods MUST be implemented.
- auto_fill_type_information(*args)¶
Overload 1:
Get the type information auto-fill configuration
- Return type
boolean
- Returns
true if the type information should be auto-filled
Overload 2:
Set type information auto-fill configuration
- Parameters
auto_fill_type_information (boolean) – new value to set
- auto_fill_type_object(*args)¶
Overload 1:
Get the type object auto-fill configuration
- Return type
boolean
- Returns
true if the type object should be auto-filled
Overload 2:
Set the type object auto-fill configuration
- Parameters
auto_fill_type_object (boolean) – new value to set
- construct_sample(memory)¶
Construct a sample on a memory location.
- Parameters
memory (void) – Pointer to the memory location where the sample should be constructed.
- Return type
boolean
- Returns
whether this type supports in-place construction or not.
- createData()¶
Create a Data Type.
- Return type
void
- Returns
Void pointer to the created object.
- deleteData(data)¶
Remove a previously created object.
- Parameters
data (void) – Pointer to the created Data.
- deserialize(payload, data)¶
Deserialize method, it should be implemented by the user, since it is abstract.
payload Pointer to the payload data Pointer to the data :rtype: boolean :return: True if correct.
- getKey(data, ihandle, force_md5=False)¶
Get the key associated with the data.
data Pointer to the data. ihandle Pointer to the Handle. force_md5 Force MD5 checking. :rtype: boolean :return: True if correct.
- getName()¶
Get topic data type name
- Return type
string
- Returns
Topic data type name
- getSerializedSizeProvider(*args)¶
Overload 1:
Returns a function which can be used to calculate the serialized size of the provided data.
data Pointer to data. :rtype: std::function< uint32_t () > :return: Functor which calculates the serialized size of the data.
Overload 2:
Returns a function which can be used to calculate the serialized size of the provided data.
data Pointer to data. data_representation Representation that should be used for calculating the serialized size. :rtype: std::function< uint32_t () > :return: Functor which calculates the serialized size of the data.
- is_bounded()¶
Checks if the type is bounded.
- is_plain(*args)¶
Overload 1:
Checks if the type is plain when using default encoding.
Overload 2:
Checks if the type is plain when using a specific encoding.
- property m_isGetKeyDefined¶
Indicates whether the method to obtain the key has been implemented.
- property m_typeSize¶
Maximum serialized size of the type in bytes. If the type has unbounded fields, and therefore cannot have a maximum size, use 0.
- serialize(*args)¶
Overload 1:
Serialize method, it should be implemented by the user, since it is abstract. It is VERY IMPORTANT that the user sets the SerializedPayload length correctly.
data Pointer to the data payload Pointer to the payload :rtype: boolean :return: True if correct.
Overload 2:
Serialize method, it should be implemented by the user, since it is abstract. If not implemented, this method will call the serialize method in which the topic data representation is not considered. It is VERY IMPORTANT that the user sets the SerializedPayload length correctly.
data Pointer to the data payload Pointer to the payload data_representation Representation that should be used to encode the data into the payload. :rtype: boolean :return: True if correct.
- setName(nam)¶
Set topic data type name
- Parameters
nam (string) – Topic data type name
- property thisown¶
The membership flag
- type_identifier(*args)¶
Overload 1:
Get the type identifier
- Return type
std::shared_ptr< eprosima::fastdds::dds::TypeIdV1 >
- Returns
TypeIdV1
Overload 2:
Set type identifier
- Parameters
id (
TypeIdV1) – new value for TypeIdV1
Overload 3:
Set type identifier
- Parameters
id (std::shared_ptr< eprosima::fastdds::dds::TypeIdV1 >) – shared pointer to TypeIdV1
- type_information(*args)¶
Overload 1:
Get the type information
- Return type
std::shared_ptr< eprosima::fastdds::dds::xtypes::TypeInformation >
- Returns
TypeInformation
Overload 2:
Set type information
- Parameters
info (
TypeInformation) – new value for TypeInformation
Overload 3:
Set type information
- Parameters
info (std::shared_ptr< eprosima::fastdds::dds::xtypes::TypeInformation >) – shared pointer to TypeInformation
- type_object(*args)¶
Overload 1:
Get the type object
- Return type
std::shared_ptr< eprosima::fastdds::dds::TypeObjectV1 >
- Returns
TypeObjectV1
Overload 2:
Set type object
- Parameters
object (
TypeObjectV1) – new value for TypeObjectV1
Overload 3:
Set type object
- Parameters
object (std::shared_ptr< eprosima::fastdds::dds::TypeObjectV1 >) – shared pointer to TypeObjectV1
TopicDescription¶
- class fastdds.TopicDescription(*args, **kwargs)¶
Class TopicDescription, represents the fact that both publications and subscriptions are tied to a single data-type
- get_impl()¶
- get_name()¶
Get the name used to create this TopicDescription.
- Return type
string
- Returns
the name used to create this TopicDescription.
- get_participant()¶
Get the DomainParticipant to which the TopicDescription belongs.
- Return type
- Returns
The DomainParticipant to which the TopicDescription belongs.
- get_type_name()¶
Get the associated type name.
- Return type
string
- Returns
the type name.
- property thisown¶
The membership flag
TopicListener¶
- class fastdds.TopicListener¶
Class TopicListener, it should be used by the end user to implement specific callbacks to certain actions.
- on_inconsistent_topic(topic, status)¶
Virtual function to be implemented by the user containing the actions to be performed when another topic exists with the same name but different characteristics.
- Parameters
topic (
Topic) – Topicstatus (
InconsistentTopicStatus) – The inconsistent topic status
- property thisown¶
The membership flag
TopicQos¶
- class fastdds.TopicQos¶
Class TopicQos, containing all the possible Qos that can be set for a determined Topic. Although these values can be set and are transmitted during the Endpoint Discovery Protocol, not all of the behaviour associated with them has been implemented in the library. Please consult each of them to check for implementation details and default values.
- deadline(*args)¶
Overload 1:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQos reference
Overload 2:
Getter for DeadlineQosPolicy
- Return type
- Returns
DeadlineQos reference
Overload 3:
Setter for DeadlineQosPolicy
- Parameters
deadline (
DeadlineQosPolicy) – new value for the DeadlineQosPolicy
- destination_order(*args)¶
Overload 1:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQos reference
Overload 2:
Getter for DestinationOrderQosPolicy
- Return type
- Returns
DestinationOrderQos reference
Overload 3:
Setter for DestinationOrderQosPolicy
- Parameters
destination_order (
DestinationOrderQosPolicy) – new value for the DestinationOrderQosPolicy
- durability(*args)¶
Overload 1:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQos reference
Overload 2:
Getter for DurabilityQosPolicy
- Return type
- Returns
DurabilityQos reference
Overload 3:
Setter for DurabilityQosPolicy
- Parameters
durability (
DurabilityQosPolicy) – new value for the DurabilityQosPolicy
- durability_service(*args)¶
Overload 1:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQos reference
Overload 2:
Getter for DurabilityServiceQosPolicy
- Return type
- Returns
DurabilityServiceQos reference
Overload 3:
Setter for DurabilityServiceQosPolicy
- Parameters
durability_service (
DurabilityServiceQosPolicy) – new value for the DurabilityServiceQosPolicy
- history(*args)¶
Overload 1:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQos reference
Overload 2:
Getter for HistoryQosPolicy
- Return type
- Returns
HistoryQos reference
Overload 3:
Setter for HistoryQosPolicy
- Parameters
history (
HistoryQosPolicy) – new value for the HistoryQosPolicy
- latency_budget(*args)¶
Overload 1:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQos reference
Overload 2:
Getter for LatencyBudgetQosPolicy
- Return type
- Returns
LatencyBudgetQos reference
Overload 3:
Setter for LatencyBudgetQosPolicy
- Parameters
latency_budget (
LatencyBudgetQosPolicy) – new value for the LatencyBudgetQosPolicy
- lifespan(*args)¶
Overload 1:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQos reference
Overload 2:
Getter for LifespanQosPolicy
- Return type
- Returns
LifespanQos reference
Overload 3:
Setter for LifespanQosPolicy
- Parameters
lifespan (
LifespanQosPolicy) – new value for the LifespanQosPolicy
- liveliness(*args)¶
Overload 1:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQos reference
Overload 2:
Getter for LivelinessQosPolicy
- Return type
- Returns
LivelinessQos reference
Overload 3:
Setter for LivelinessQosPolicy
- Parameters
liveliness (
LivelinessQosPolicy) – new value for the LivelinessQosPolicy
- ownership(*args)¶
Overload 1:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQos reference
Overload 2:
Getter for OwnershipQosPolicy
- Return type
- Returns
OwnershipQos reference
Overload 3:
Setter for OwnershipQosPolicy
- Parameters
ownership (
OwnershipQosPolicy) – new value for the OwnershipQosPolicy
- reliability(*args)¶
Overload 1:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQos reference
Overload 2:
Getter for ReliabilityQosPolicy
- Return type
- Returns
ReliabilityQos reference
Overload 3:
Setter for ReliabilityQosPolicy
- Parameters
reliability (
ReliabilityQosPolicy) – new value for the ReliabilityQosPolicy
- resource_limits(*args)¶
Overload 1:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQos reference
Overload 2:
Getter for ResourceLimitsQosPolicy
- Return type
- Returns
ResourceLimitsQos reference
Overload 3:
Setter for ResourceLimitsQosPolicy
- Parameters
resource_limits (
ResourceLimitsQosPolicy) – new value for the ResourceLimitsQosPolicy
- property thisown¶
The membership flag
- topic_data(*args)¶
Overload 1:
Getter for TopicDataQosPolicy
- Return type
- Returns
TopicDataQos reference
Overload 2:
Getter for TopicDataQosPolicy
- Return type
- Returns
TopicDataQos reference
Overload 3:
Setter for TopicDataQosPolicy
- Parameters
value (
TopicDataQosPolicy) – new value for the TopicDataQosPolicy
- transport_priority(*args)¶
Overload 1:
Getter for TransportPriorityQosPolicy
- Return type
- Returns
TransportPriorityQos reference
Overload 2:
Getter for TransportPriorityQosPolicy
- Return type
- Returns
TransportPriorityQos reference
Overload 3:
Setter for TransportPriorityQosPolicy
- Parameters
transport_priority (
TransportPriorityQosPolicy) – new value for the TransportPriorityQosPolicy
- class fastdds.TOPIC_QOS_DEFAULT(*args: Any, **kwargs: Any)¶
TypeIdV1¶
TypeInformation¶
- class fastdds.TypeInformation(*args)¶
Class xtypes::TypeInformation
- assigned(*args)¶
Overload 1:
Check if it is assigned
- Return type
boolean
- Returns
true if assigned, false if not
Overload 2:
Setter for assigned boolean
- Parameters
value (boolean) – Boolean to be set
- clear()¶
Clears the QosPolicy object
- property thisown¶
The membership flag
- property type_information¶
Type Information
TypeObjectV1¶
TypeSupport¶
- class fastdds.TypeSupport(*args)¶
Notes: This class inherits from std::shared_ptr<TopicDataType>. Class TypeSupport used to provide the DomainRTPSParticipant with the methods to serialize, deserialize and get the key of a specific data type. The user should created a class that inherits from this one, where Serialize and deserialize methods MUST be implemented.
- create_data()¶
Creates new data
- Return type
void
- Returns
Pointer to the data
- delete_data(data)¶
Deletes data
- Parameters
data (void) – Pointer to the data to delete
- deserialize(payload, data)¶
Deserializes the data
- Parameters
payload (eprosima::fastrtps::rtps::SerializedPayload_t) – Pointer to payload
data (void) – Pointer to data
- Return type
boolean
- Returns
true if it is deserialized correctly, false if not
- empty()¶
Check if the TypeSupport is empty
- Return type
boolean
- Returns
true if empty, false if not
- get_key(data, i_handle, force_md5=False)¶
Getter for the data key
- Parameters
data (void) – Pointer to data
i_handle (
InstanceHandle_t) – InstanceHandle pointer to store the keyforce_md5 (boolean) – boolean to force md5 (default: false)
- Return type
boolean
- Returns
true if the key is returned, false if not
- get_serialized_size_provider(*args)¶
Overload 1:
Returns a function which can be used to calculate the serialized size of the provided data.
data Pointer to data. :rtype: std::function< uint32_t () > :return: Functor which calculates the serialized size of the data.
Overload 2:
Returns a function which can be used to calculate the serialized size of the provided data.
data Pointer to data. data_representation Representation that should be used for calculating the serialized size. :rtype: std::function< uint32_t () > :return: Functor which calculates the serialized size of the data.
- get_type_name()¶
Getter for the type name
- Return type
string
- Returns
name of the data type
- is_bounded()¶
Checks if the type is bounded.
- is_plain(*args)¶
Overload 1:
Checks if the type is plain when using default encoding.
Overload 2:
Checks if the type is plain when using a specific encoding.
- register_type(*args)¶
Overload 1:
Registers the type on a participant
- Parameters
participant (
DomainParticipant) – DomainParticipant where the type is going to be registered- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the type name is empty, RETCODE_PRECONDITION_NOT_MET if there is another type with the same name registered on the DomainParticipant and RETCODE_OK if it is registered correctly
Overload 2:
Registers the type on a participant
- Parameters
participant (
DomainParticipant) – DomainParticipant where the type is going to be registeredtype_name (string) – Name of the type to register
- Return type
ReturnCode_t- Returns
RETCODE_BAD_PARAMETER if the type name is empty, RETCODE_PRECONDITION_NOT_MET if there is another type with the same name registered on the DomainParticipant and RETCODE_OK if it is registered correctly
- serialize(*args)¶
Overload 1:
Serializes the data
- Parameters
data (void) – Pointer to data
payload (eprosima::fastrtps::rtps::SerializedPayload_t) – Pointer to payload
- Return type
boolean
- Returns
true if it is serialized correctly, false if not
Overload 2:
Serializes the data
- Parameters
data (void) – Pointer to data
payload (eprosima::fastrtps::rtps::SerializedPayload_t) – Pointer to payload data_representation Representation that should be used to encode the data into the payload.
- Return type
boolean
- Returns
true if it is serialized correctly, false if not
- set(ptr)¶
- property thisown¶
The membership flag
Introduction¶
eProsima Fast DDS-Gen is a Java application that generates eProsima Fast DDS source code using the data types
defined in an IDL (Interface Definition Language) file.
This generated source code can be used in any Fast DDS application in order to define the data type of a topic,
which will later be used to publish or subscribe.
eProsima Fast DDS defines the data type exchanged in a Topic through two classes: the TypeSupport and the
TopicDataType. TopicDataType describes the data type exchanged between a publication and a subscription, i.e.
the data corresponding to a Topic; while TypeSupport encapsulates an instance of TopicDataType, providing
the functions needed to register the type and interact with the publication and subscription.
Please refer to Definition of data types for more information on data types.
To declare the structured data, the IDL format must be used. IDL is a specification language, made by OMG (Object Management Group), which describes an interface in a language independent manner, allowing communication between software components that do not share the same language. The eProsima Fast DDS-Gen tool reads the IDL files and parses a subset of the OMG IDL specification to generate source code for data serialization. This subset includes the data type descriptions included in Defining a data type via IDL. The rest of the file content is ignored.
eProsima Fast DDS-Gen generated source code uses Fast CDR, a C++11 library that provides the data serialization and codification mechanisms. Therefore, as stated in the RTPS standard, when the data are sent, they are serialized and encoded using the corresponding Common Data Representation (CDR). The CDR transfer syntax is a low-level representation for inter-agents transfer, mapping from OMG IDL data types to byte streams. Please refer to the official CDR specification for more information on the CDR transfer syntax (see PDF section 15.3).
The main feature of eProsima Fast DDS-Gen is to facilitate the implementation of DDS applications without the knowledge of serialization or deserialization mechanisms. With Fast DDS-Gen it is also possible to generate the C++ source code of a DDS application with a publisher and a subscriber that uses the eProsima Fast DDS library (see Building a publish/subscribe application). Fast DDS-Gen can also generate Python bindings for the data types in order to use them within a Python-based Fast DDS application (see Building Python auxiliary libraries).
For installing Fast DDS-Gen, please refer to Linux installation of Fast DDS-Gen or to Windows installation of Fast DDS-Gen.
Usage¶
This section explains the usage of Fast DDS-Gen tool and briefly describes the generated files.
Running the Fast DDS-Gen Java application¶
First, the steps outlined in Linux installation of Fast DDS-Gen or
Window installation of Fast DDS-Gen must be accomplished for the installation of Fast DDS-Gen.
According to this section, an executable file for Linux and Windows that runs the Java Fast DDS-Gen application is
available in the scripts folder.
If the scripts folder path is added to the PATH environment variable, Fast DDS-Gen can be executed running
the following commands:
Linux:
$ fastddsgenWindows:
> fastddsgen.bat
Note
In case the PATH has not been modified, these scripts can be found in the <fastddsgen_directory>/scripts
directory.
Supported options¶
The expected argument list of the application is:
fastddsgen [<options>] <IDL file> [<IDL file> ...]
Where the options are:
Option |
Description |
|---|---|
-cs |
Enables case sensitivity in variable names. |
-d <directory> |
Sets the output directory for the generated files. |
-default-container-prealloc-size |
Sets the default preallocated size for unbounded collections (sequences and maps) |
-default_extensibility <extensibility> |
Sets the default extensibility for types without the @extensibility annotation. |
-example <platform> |
Generates an example and a solution to compile the generated source code for a specific |
-extrastg <template> <output> |
Specifies a custom template used for generating source code. |
-flat-output-dir |
Ignores input files relative paths and place all generated files in the specified output directory. |
-help |
Shows the help information |
-I <directory> |
Adds directory to preprocessor include paths. |
-no-typesupport |
Avoids generating the type support files. |
-no-typeobjectsupport |
Avoids generating the TypeObject support specific files. |
-no-dependencies |
Avoids processing the dependent IDL files. |
-ppDisable |
Disables the preprocessor. |
-ppPath |
Specifies the preprocessor path. |
-python |
Generates source code and a CMake solution to compile a library containing the data types |
-replace |
Replaces the generated source code files even if they exist. |
-t <directory> |
Sets a specific directory as a temporary directory. |
-typeros2 |
Generates type naming compatible with ROS 2. |
-version |
Shows the current version of eProsima Fast DDS-Gen. |
Please refer to XTypes for more information on TypeObject representation.
Building a publish/subscribe application¶
Fast DDS-Gen can be used to build a fully functional publication/subscription application from an IDL file that defines the Topic under which messages are published and received. The application generated allows for the creation of as many publishers and subscribers as desired, all belonging to the same Domain and communicating using the same Topic.
Background¶
eProsima Fast DDS-Gen is a Java application that generates eProsima Fast DDS source code using the data types defined in an IDL (Interface Definition Language) file. This generated source code can be used in any Fast DDS application in order to define the data type of a topic, which will later be used to publish or subscribe. Please refer to Fast DDS-Gen introduction for more information.
Prerequisites¶
First of all, follow the steps outlined in the Installation Manual for the installation of eProsima Fast DDS and all its dependencies. Moreover, perform the steps outlined in Linux installation of Fast DDS-Gen or in Window installation of Fast DDS-Gen, depending on the operating system, for the installation of the eProsima Fast DDS-Gen tool.
Create the application workspace¶
The application workspace will have the following structure at the end of the project.
The file build/HelloWorld is the generated Fast DDS application.
.
└── FastDDSGenHelloWorld
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── HelloWorld
│ ├── libHelloWorld_lib.a
│ └── Makefile
├── CMakeLists.txt
├── HelloWorld.hpp
├── HelloWorld.idl
├── HelloWorldCdrAux.hpp
├── HelloWorldCdrAux.ipp
├── HelloWorldPublisher.cxx
├── HelloWorldPublisher.h
├── HelloWorldPubSubMain.cxx
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
├── HelloWorldSubscriber.cxx
├── HelloWorldSubscriber.h
├── HelloWorldTypeObjecSupport.cxx
└── HelloWorldTypeObjecSupport.h
Execute the following command to create the directory in which the files generated by Fast DDS-Gen will be saved.
mkdir FastDDSGenHelloWorld && cd FastDDSGenHelloWorld
mkdir build
Import linked libraries and its dependencies¶
The DDS application requires the Fast DDS and Fast CDR libraries. The way of making these accessible from the workspace depends on the installation procedure followed in the Installation Manual.
Installation from binaries¶
If the installation from binaries has been followed, these libraries are already accessible from the workspace.
On Linux: The header files can be found in directories
/usr/include/fastdds/and/usr/include/fastcdr/for Fast DDS and Fast CDR respectively. The compiled libraries of both can be found in the directory/usr/lib/.On Windows: The header files can be found in directories
C:\Program Files\eProsima\fastdds <major>.<minor>.<patch>\include\fastddsandC:\Program Files\eProsima\fastdds <major>.<minor>.<patch>\include\fastcdr\for Fast DDS and Fast CDR respectively. The compiled libraries of both can be found in the directoryC:\Program Files\eProsima\fastdds <major>.<minor>.<patch>\lib\.
Colcon installation¶
If the Colcon installation has been followed, there are several ways to import the libraries. To make these accessible only from the current shell session, run one of the following two commands.
On Linux:
source <path/to/Fast-DDS/workspace>/install/setup.bash
On Windows:
<path/to/Fast-DDS/workspace>/install/setup.bat
However, to make these accessible from any session, add the Fast DDS installation directory to the $PATH
variable in the shell configuration files running the following command.
On Linux:
echo 'source <path/to/Fast-DDS/workspace>/install/setup.bash' >> ~/.bashrc
On Windows: Open the Edit the system environment variables control panel and add
<path/to/Fast-DDS/workspace>/install/setup.batto thePATH.
Creating the IDL file with the data type¶
To build a minimal application, the Topic must be defined by means of an IDL file.
For this example the Topic data type defined by IDL is just a string message.
Topics are explained in more detail in Topic, while the Topic data types to be defined using IDL are
presented in Definition of data types.
In the preferred text editor, create the HelloWorld.idl file with the following content and save it in the
FastDDSGenHelloWorld directory.
// HelloWorld.idl
struct HelloWorld
{
string message;
};
Then, this file is translated to something Fast DDS understands. For this, use the Fast DDS-Gen code generation tool, which can do two different things:
Generate C++ definitions for a custom topic.
Generate a functional example that uses the topic data.
The second option is the one used to create this publish/subscribe application, while the first option is applied in this other tutorial: Writing a simple C++ publisher and subscriber application.
Generating a minimal functional example¶
If the steps outlined in the Installation Manual have been followed, then Fast DDS, Fast CDR, and Fast-RTPS-Gen should be installed in the system.
Generate the Fast DDS source code¶
The application files are generated using the following command.
The -example option creates an example application, and the CMake files needed to build it.
In the workspace directory (FastDDSGenHelloWorld directory), execute one of the following commands according to the
installation followed and the operating system.
On Linux:
For an installation from binaries or a colcon installation:
<path-to-Fast-DDS-workspace>/src/fastddsgen/scripts/fastddsgen -example CMake HelloWorld.idl
For a stand-alone installation, run:
<path-to-Fast-DDS-Gen>/scripts/fastddsgen -example CMake HelloWorld.idl
On Windows:
For a colcon installation:
<path-to-Fast-DDS-workspace>/src/fastddsgen/scripts/fastddsgen.bat -example CMake HelloWorld.idl
For a stand-alone installation, run:
<path-to-Fast-DDS-Gen>/scripts/fastddsgen.bat -example CMake HelloWorld.idl
For an installation from binaries, run:
fastddsgen.bat -example CMake HelloWorld.idl
Warning
The colcon installation does not build the fastddsgen.jar file although it does download the Fast DDS-Gen
repository. The following commands must be executed to build the Java executable:
cd <path-to-Fast-DDS-workspace>/src/fastddsgen
gradle assemble
Build the Fast DDS application¶
Then, compile the generated code executing the following commands from the FastDDSGenHelloWorld directory.
On Linux:
cd build
cmake ..
make
On Windows:
cd build
cmake -G "Visual Studio 15 2017 Win64" ..
cmake --build .
Run the Fast DDS application¶
The application build can be used to spawn any number of publishers and subscribers associated with the topic.
On Linux:
./HelloWorld publisher
./HelloWorld subscriber
On Windows:
HelloWorld.exe publisher
HelloWorld.exe subscriber
Each time <Enter> is pressed on the Publisher, a new datagram is generated, sent over the network and received by Subscribers currently online. If more than one subscriber is available, it can be seen that the message is equally received on all listening nodes.
The values on the custom IDL-generated data type can also be modified as indicated below.
HelloWorld sample; //Auto-generated container class for topic data from Fast DDS-Gen
sample.msg("Hello there!"); // Add contents to the message
data_writer->write(&sample); //Publish
Warning
It may be necessary to set up a special rule in the Firewall for eprosima Fast DDS to work correctly on Windows.
Summary and next steps¶
In this tutorial, a publisher/subscriber DDS application using Fast DDS-Gen has been built. The tutorial also describes how to generate IDL files that contain the description of the Topic data type.
To continue developing DDS applications please take a look at the eProsima Fast DDS examples on github for ideas on how to improve this basic application through different configuration options, and also for examples of advanced Fast DDS features.
Building Python auxiliary libraries¶
eProsima Fast DDS-Gen can generate the required source files and CMake project to build the Python modules that allow the use of the IDL defined data types within a Fast DDS Python-based application. Each IDL file will result in a new Python module that will contain all the data types defined in the file. The Python binding is generated building the provided solution using SWIG.
Calling eProsima Fast DDS-Gen with the option -python will generate these files. eProsima Fast DDS-Gen will generate a .i file which will be processed by SWIG and a CMake project to call SWIG first generating C++ files (for connecting C++ and Python) and Python files (Python module for your type) and then compiling the C++ sources.
Before calling CMake, the Building process needs several Dependencies to be met.
Dependencies¶
SWIG¶
SWIG is a development tool that allows connecting programs written in C/C++ with a variety of other programming languages, among them Python. SWIG 4.0 is required in order to build Fast DDS Python bindings.
Note
More recent SWIG releases are not yet supported. Please, ensure to be using SWIG 4.0.
SWIG can be installed directly from the package manager of the appropriate Linux distribution. For Ubuntu, please run:
sudo apt install swig
Building¶
Call CMake:
mkdir build
cd build
cmake ..
cmake --build .
This will create the Python files (.py) with the modules (one per each IDL file) that have to be imported within the Python script.
Defining a data type via IDL¶
This section describes the data types that can be defined using IDL files, as well as other mechanisms for building data types using IDL files.
Supported IDL types¶
Be aware that Fast DDS-Gen is not case sensitive as it is specified in the
IDL specification.
To activate case sensitivity use option -cs when running Fast DDS-Gen (see
Supported options).
Primitive types¶
The following table shows the basic IDL types supported by Fast DDS-Gen and how they are mapped to C++11.
IDL |
C++11 |
|---|---|
char |
|
octet |
|
short |
|
unsigned short |
|
long |
|
unsigned long |
|
long long |
|
unsigned long long |
|
float |
|
double |
|
long double |
|
boolean |
|
string |
|
Arrays¶
Fast DDS-Gen supports unidimensional and multidimensional arrays.
Arrays are always mapped to std::array containers.
The following table shows the array types supported and their mapping.
IDL |
C++11 |
|---|---|
char a[5] |
|
octet a[5] |
|
short a[5] |
|
unsigned short a[5] |
|
long a[5] |
|
unsigned long a[5] |
|
long long a[5] |
|
unsigned long long a[5] |
|
float a[5] |
|
double a[5] |
|
Sequences¶
Fast DDS-Gen supports sequences, which map into the std::vector container.
The following table represents how the map between IDL and C++11 is handled.
IDL |
C++11 |
|---|---|
sequence<char> |
|
sequence<octet> |
|
sequence<short> |
|
sequence<unsigned short> |
|
sequence<long> |
|
sequence<unsigned long> |
|
sequence<long long> |
|
sequence<unsigned long long> |
|
sequence<float> |
|
sequence<double> |
|
Maps¶
Fast DDS-Gen supports maps, which are equivalent to the std::map container.
The equivalence between types is handled in the same way as for sequences.
IDL |
C++11 |
|---|---|
map<char, unsigned long long> |
|
Note
Only Primitive types are currently supported.
Structures¶
You can define an IDL structure with a set of members with multiple types.
It will be converted into a C++ class in which the members of the structure defined via IDL are mapped to private data
members of the class.
Furthermore, set() and get() member functions are created to access these private data members.
The following IDL structure:
struct Structure
{
octet octet_value;
long long_value;
string string_value;
};
Would be converted to:
class Structure
{
public:
Structure();
~Structure();
Structure(
const Structure& x);
Structure(
Structure&& x);
Structure& operator =(
const Structure& x);
Structure& operator =(
Structure&& x);
void octet_value(
uint8_t _octet_value);
uint8_t octet_value() const;
uint8_t& octet_value();
void long_value(
int64_t _long_value);
int64_t long_value() const;
int64_t& long_value();
void string_value(
const std::string
& _string_value);
void string_value(
std::string&& _string_value);
const std::string& string_value() const;
std::string& string_value();
private:
uint8_t m_octet_value;
int64_t m_long_value;
std::string m_string_value;
};
Structures can inherit from other structures, extending their member set.
struct ParentStruct
{
octet parent_member;
};
struct ChildStruct : ParentStruct
{
long child_member;
};
In this case, the resulting C++ code will be:
class ParentStruct
{
octet parent_member;
};
class ChildStruct : public ParentStruct
{
long child_member;
};
Optional members¶
A member of a structure can be optional.
This is achieved by writing the @optional annotation before the member.
struct StructWithOptionalMember
{
@optional octet octet_opt;
};
An optional member is converted into a template class eprosima::fastcdr::optional<T>, where T is the member’s
type.
class StructWithOptionalMember
{
eprosima::fastcdr::optional<octet> octet_opt;
};
Before reading the value of the optional member, it should be checked the optional contains a value using
has_value() function.
Accessing a null optional throws a eprosima::fastcdr::exception::BadOptionalAccessException exception.
if (octet_opt.has_value())
{
octet oc = octet_opt.value();
}
Extensibility¶
In order to support evolving types without breaking interoperability, the concept of type extensibility is supported by Fast DDS-Gen. There are three extensibility kinds: final, appendable and mutable.
FINAL extensibility indicates that the type is strictly defined. It is not possible to add members while maintaining type assignability.
APPENDABLE extensibility indicates that two types, where one contains all of the members of the other plus additional members appended to the end, may remain assignable.
MUTABLE extensibility indicates that two types may differ from one another in the additional, removal, and/or transposition of members while remaining assignable.
@extensibility(FINAL)
struct FinalStruct
{
octet octet_opt;
};
@extensibility(APPENDABLE)
struct AppendableStruct
{
octet octet_opt;
};
@extensibility(MUTABLE)
struct MutableStruct
{
octet octet_opt;
};
Note
XCDRv1 encoding algorithm is not able to manage correctly the deserialization of an appendable structure when it is used as a member of another one.
Unions¶
In IDL, a union is defined as a sequence of members with their own types and a discriminant that specifies which member is in use. An IDL union type is mapped as a C++ class with member functions to access the union members and the discriminant.
The following IDL union:
union Union switch(long)
{
case 1:
octet octet_value;
case 2:
long long_value;
case 3:
string string_value;
};
Would be converted to:
class Union
{
public:
Union();
~Union();
Union(
const Union& x);
Union(
Union&& x);
Union& operator =(
const Union& x);
Union& operator =(
Union&& x);
void d(
int32_t __d);
int32_t _d() const;
int32_t& _d();
void octet_value(
uint8_t _octet_value);
uint8_t octet_value() const;
uint8_t& octet_value();
void long_value(
int64_t _long_value);
int64_t long_value() const;
int64_t& long_value();
void string_value(
const std::string
& _string_value);
void string_value(
std:: string&& _string_value);
const std::string& string_value() const;
std::string& string_value();
private:
int32_t m__d;
uint8_t m_octet_value;
int64_t m_long_value;
std::string m_string_value;
};
Bitsets¶
Bitsets are a special kind of structure, which encloses a set of bits. A bitset can represent up to 64 bits. Each member is defined as bitfield and eases the access to a part of the bitset.
For example:
bitset MyBitset
{
bitfield<3> a;
bitfield<10> b;
bitfield<12, long> c;
};
The type MyBitset will store a total of 25 bits (3 + 10 + 12) and will require 32 bits in memory
(lowest primitive type to store the bitset’s size).
The bitfield ‘a’ allows us to access to the first 3 bits (0..2).
The bitfield ‘b’ allows us to access to the next 10 bits (3..12).
The bitfield ‘c’ allows us to access to the next 12 bits (13..24).
The resulting C++ code will be similar to:
class MyBitset
{
public:
void a(
char _a);
char a() const;
void b(
uint16_t _b);
uint16_t b() const;
void c(
int32_t _c);
int32_t c() const;
private:
std::bitset<25> m_bitset;
};
Internally, it is stored as a std::bitset.
For each bitfield, get() and set() member functions are generated with the smaller possible primitive
unsigned type to access it.
In the case of bitfield ‘c’, the user has established that this accessing type will be long, so the generated code
uses int32_t instead of automatically use uint16_t.
Bitsets can inherit from other bitsets, extending their member set.
bitset ParentBitset
{
bitfield<3> parent_member;
};
bitset ChildBitset : ParentBitset
{
bitfield<10> child_member;
};
In this case, the resulting C++ code will be:
class ParentBitset
{
std::bitset<3> parent_member;
};
class ChildBitset : public ParentBitset
{
std::bitset<10> child_member;
};
Note that in this case, ChildBitset will have two std::bitset data members, one belonging to
ParentBitset and the other belonging to ChildBitset.
Enumerations¶
An enumeration in IDL format is a collection of identifiers that have an associated numeric value. An IDL enumeration type is mapped directly to the corresponding C++11 enumeration definition.
The following IDL enumeration:
enum Enumeration
{
RED,
GREEN,
BLUE
};
Would be converted to:
enum Enumeration : uint32_t
{
RED,
GREEN,
BLUE
};
Bitmasks¶
Bitmasks are a special kind of Enumeration to manage masks of bits. It allows defining bit masks based on their position.
The following IDL bitmask:
@bit_bound(8)
bitmask MyBitMask
{
@position(0) flag0,
@position(1) flag1,
@position(4) flag4,
@position(6) flag6,
flag7
};
Would be converted to:
enum MyBitMask : uint8_t
{
flag0 = 0x01 << 0,
flag1 = 0x01 << 1,
flag4 = 0x01 << 4,
flag6 = 0x01 << 6,
flag7 = 0x01 << 7
};
The annotation bit_bound defines the width of the associated enumeration.
It must be a positive number between 1 and 64.
If omitted, it will be 32 bits.
For each flag, the user can use the annotation position to define the position of the flag.
If omitted, it will be auto incremented from the last defined flag, starting at 0.
Modules¶
In order to avoid collision between variable names, modules can be defined within the IDL file. A module would be converted into a namespace in C++.
Data types with a key¶
In order to use keyed topics, the user should define some key members inside the structure.
This is achieved by writing the @key annotation before the members of the structure that are used as keys.
For example in the following IDL file the id and type field would be the keys:
struct MyType
{
@key long id;
@key string type;
long positionX;
long positionY;
};
Fast DDS-Gen automatically detects these tags and correctly generates the serialization methods for the key generation
function in TopicDataType (getKey()).
This function will obtain the 128-bit MD5 digest of the big-endian serialization of the Key Members.
Including other IDL files¶
Other IDL files can be included in addition to the current IDL file.
Fast DDS-Gen uses a C/C++ preprocessor for this purpose, and #include directive can be used to include an IDL
file.
Preprocessor directives guarding against multiple inclusion of the same IDL file are also advisable.
#include "OtherFile.idl"
#include <AnotherFile.idl>
If Fast DDS-Gen does not find a C/C++ preprocessor in default system paths, the preprocessor path can be specified
using parameter -ppPath.
The parameter -ppDisable can be used to disable the usage of the C/C++ preprocessor.
Annotations¶
The application allows the user to define and use their own annotations as defined in the OMG IDL specification.
@annotation MyAnnotation
{
long value;
string name;
};
Additionally, the following standard annotations are defined by the specification and considered builtin (these annotations might be applied without the need of defining them).
Builtin Annotation |
Behavior |
Supported |
|---|---|---|
|
Asynchronous interface or operation. |
❌ |
|
Shortcut for |
✅ |
|
Member ID algorithm configuration if there is no member ID explicitly set using |
✅ |
|
Set number of bits on bitmasks and enumerations underlying primitive type. |
✅❌ |
|
Specify the |
❌ |
|
Set constant default value to a member. |
❌ |
|
Mark an enumerations literal as default. |
❌ |
|
Use in module declaration to mark as |
❌ |
|
Applicable to any constructed element.
Specify how the element is allowed to evolve. |
✅ |
|
Member is stored in external storage. |
✅ |
|
Shortcut for |
✅ |
|
Calculate the member ID with the string provided or, if empty, with the member name. |
✅ |
|
Assign member ID to a structure or union member. |
✅ |
|
When checking evolved type compatibility, take or not into account member names. |
❌ |
|
Mark a structure member as part of the key. |
✅ |
|
Set a maximum constant value to the member. |
❌ |
|
Set a minimum constant value to the member. |
❌ |
|
Mark a structure member as essential for the structure cohesion. |
❌ |
|
Shortcut for |
✅ |
|
Type is always used within another one. |
❌ |
|
Omit member during serialization. |
❌ |
|
One-way operation, flowing the information only on one direction. |
❌ |
|
Configure a structure member as optional. Please refer to Optional Members for more information. |
✅ |
|
Set a bitflag position in bitmasks. |
✅ |
|
Set a range of allowed values for the member. |
❌ |
|
Interface is to be treated as a service. |
❌ |
|
Structure or union is meant to be used as Topic Data Type. |
❌ |
|
When checking evolved type compatibility, configure the behavior for |
❌ |
|
Specify a unit of measurement for the member. |
❌ |
|
Set constant value to enumerations literal. |
❌ |
|
Add comment or text to the element. |
❌ |
Forward declaration¶
Fast DDS-Gen supports forward declarations. This allows declaring inter-dependant structures, unions, etc.
struct ForwardStruct;
union ForwardUnion;
struct ForwardStruct
{
ForwardUnion fw_union;
};
union ForwardUnion switch (long)
{
case 0:
ForwardStruct fw_struct;
default:
string empty;
};
IDL 4.2 aliases¶
IDL 4.2 allows using the following names for primitive types:
int8 |
uint8 |
int16 |
uint16 |
int32 |
uint32 |
int64 |
uint64 |
IDL 4.2 comments¶
There are two ways to write IDL comments:
The characters
/*start a comment, which terminates with the characters*/.The characters
//start a comment, which terminates at the end of the line on which they occur.
Please refer to the IDL 4.2 specification (Section 7.2 Lexical Conventions) for more information on IDL conventions.
/* MyStruct definition */
struct MyStruc
{
string mymessage; // mymessage data member.
};
CLI¶
The Fast DDS command line interface provides a set commands and sub-commands to perform, Fast DDS related, maintenance and configuration tasks.
An executable file for Linux and Windows that runs the Fast DDS CLI application is
available in the tools folder.
If the tools/fastdds folder path is added to the PATH, or by sourcing the <path/to/fastdds>/install/setup.bash
configuration file, Fast DDS CLI can be executed running the following commands:
Linux:
$ fastdds <command> [<command-args>]
Windows:
> fastdds.bat <command> [<command-args>]
There are three verbs whose functionality is described in the following table:
Verbs |
Description |
|---|---|
|
Launches a server for Discovery Server. |
|
Allows manual cleaning of garbage files that may be generated by Shared Memory Transport |
|
Checks if a xml profile is well formed. |
discovery¶
This command launches a SERVER (or BACKUP) for Discovery Server. This server will manage
the discovery phases of the CLIENTS which are connected to it.
Clients must know how to reach the server, which is accomplished by specifying an IP address, the servers GUID
prefix, and a transport protocol like UDP or TCP.
Servers do not need any prior knowledge of their clients, but require a GUID prefix, and the listening IP address
where they may be reached.
For more information on the different Fast DDS discovery mechanisms and how to configure them, please refer to
Discovery.
Important
It is possible to interconnect servers (or backup servers) instantiated with fastdds discovery using
environment variable ROS_DISCOVERY_SERVER (see ROS_DISCOVERY_SERVER) or a XML configuration
file.
How to run¶
On a shell, execute:
fastdds discovery -i {0-255} [optional parameters]
Where the parameters are:
Option |
Description |
|---|---|
|
Produce help message. |
|
Unique server identifier. Specifies zero based server position in |
|
IPv4/IPv6 address chosen to listen the clients using UDP transport. Defaults to any |
|
UDP port chosen to listen the clients. Defaults to ‘11811’. |
|
IPv4/IPv6 address chosen to listen the clients using TCP transport. Instead of an |
|
TCP port chosen to listen the clients. Defaults to ‘42100’. Only one server can be |
|
Creates a BACKUP server (see Discovery Protocol) |
|
XML configuration file (see XML profiles). In this case, the default |
The output is:
### Server is running ###
Participant Type: <SERVER|BACKUP>
Security: <YES|NO>
Server ID: <server-id>
Server GUID prefix: 44.53.<server-id-in-hex>.5f.45.50.52.4f.53.49.4d.41
Server Addresses: UDPv4:[<ip-address>]:<port>
UDPv6:[<ip-address>]:<port>
TCPv4:[<ip-address>]:<physical-port>-<logical-port>
TCPv6:[<ip-address>]:<physical-port>-<logical-port>
Once the server is instantiated, the clients can be configured either programmatically or by XML (see
Discovery Server Settings), or using environment variable ROS_DISCOVERY_SERVER (see
ROS_DISCOVERY_SERVER)
Note
The Security configuration of the discovery server should be done through XML. See example below.
Examples¶
Launch a default server with id 0 (first on
ROS_DISCOVERY_SERVER) listening on all available interfaces on UDP port ‘11811’. Only one server can use default values per machine.fastdds discovery -i 0
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[0.0.0.0]:11811
Launch a default server with id 1 (second on
ROS_DISCOVERY_SERVER) listening on localhost with UDP port 14520. Only localhost clients can reach the server defining as ROS_DISCOVERY_SERVER=;127.0.0.1:14520 .fastdds discovery -i 1 -l 127.0.0.1 -p 14520
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 1 Server GUID prefix: 44.53.01.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[127.0.0.1]:14520
This same output can be obtained loading the following XML configuration file
DiscoveryServerCLI.xml:<participant profile_name="participant_profile_discovery_server_cli" is_default_profile="true"> <rtps> <prefix>44.53.01.5f.45.50.52.4f.53.49.4d.41</prefix> <builtin> <discovery_config> <discoveryProtocol>SERVER</discoveryProtocol> </discovery_config> <metatrafficUnicastLocatorList> <locator> <udpv4> <address>localhost</address> <port>14520</port> </udpv4> </locator> </metatrafficUnicastLocatorList> </builtin> </rtps> </participant> <participant profile_name="second_participant_profile_discovery_server_cli"> <rtps> <prefix>44.53.02.5f.45.50.52.4f.53.49.4d.41</prefix> <builtin> <discovery_config> <discoveryProtocol>SERVER</discoveryProtocol> </discovery_config> <metatrafficUnicastLocatorList> <locator> <udpv4> <address>192.168.36.34</address> <port>8783</port> </udpv4> </locator> <locator> <udpv4> <address>172.20.96.1</address> <port>51083</port> </udpv4> </locator> </metatrafficUnicastLocatorList> </builtin> </rtps> </participant> <participant profile_name="secure_discovery_server_cli"> <rtps> <prefix>44.53.00.5f.45.50.52.4f.53.49.4d.41</prefix> <builtin> <discovery_config> <discoveryProtocol>SERVER</discoveryProtocol> </discovery_config> <metatrafficUnicastLocatorList> <locator> <udpv4> <address>0.0.0.0</address> <port>11811</port> </udpv4> </locator> </metatrafficUnicastLocatorList> </builtin> <propertiesPolicy> <properties> <!-- Activate Auth:PKI-DH plugin --> <property> <name>dds.sec.auth.plugin</name> <value>builtin.PKI-DH</value> </property> <!-- Configure Auth:PKI-DH plugin --> <property> <name>dds.sec.auth.builtin.PKI-DH.identity_ca</name> <value>file://maincacert.pem</value> </property> <property> <name>dds.sec.auth.builtin.PKI-DH.identity_certificate</name> <value>file://appcert.pem</value> </property> <property> <name>dds.sec.auth.builtin.PKI-DH.private_key</name> <value>file://appkey.pem</value> </property> <!-- Activate Access:Permissions plugin --> <property> <name>dds.sec.access.plugin</name> <value>builtin.Access-Permissions</value> </property> <!-- Configure Access:Permissions plugin --> <property> <name>dds.sec.access.builtin.Access-Permissions.permissions_ca</name> <value>file://maincacet.pem</value> </property> <property> <name>dds.sec.access.builtin.Access-Permissions.governance</name> <value>file://governance.smime</value> </property> <property> <name>dds.sec.access.builtin.Access-Permissions.permissions</name> <value>file://permissions.smime</value> </property> <!-- Activate Crypto:AES-GCM-GMAC plugin --> <property> <name>dds.sec.crypto.plugin</name> <value>builtin.AES-GCM-GMAC</value> </property> </properties> </propertiesPolicy> </rtps> </participant>
fastdds discovery -x [PATH_TO_FILE]/DiscoveryServerCLI.xml
Launch a default server with id 1 (second on
ROS_DISCOVERY_SERVER) listening on IPv6 address2a02:ec80:600:ed1a::3with UDP port 14520.fast-discovery-serverd-1.0.1.exe -i 1 -l 2a02:ec80:600:ed1a::3 -p 14520
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 1 Server GUID prefix: 44.53.01.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv6:[2a02:ec80:600:ed1a::3]:14520
Launch a default server with id 2 (third on
ROS_DISCOVERY_SERVER) listening on WiFi (192.168.36.34) and Ethernet (172.20.96.1) local interfaces with UDP ports 8783 and 51083 respectively (addresses and ports are made up for the example).fastdds discovery -i 2 -l 192.168.36.34 -p 8783 -l 172.20.96.1 -p 51083
Output:
### Server is running ### Participant Type SERVER Security: NO Server ID: 2 Server GUID prefix: 44.53.02.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[192.168.36.34]:8783 UDPv4:[172.20.96.1]:51083
Using the same XML configuration file from the second example, the same output can be obtained loading a specific profile: second_participant_profile_discovery_server_cli.
fastdds discovery -x second_participant_profile_discovery_server_cli@[PATH_TO_FILE]/DiscoveryServerCLI.xml
Launch a default server with id 3 (fourth on
ROS_DISCOVERY_SERVER) listening on 172.30.144.1 with UDP port 12345 and provided with a backup file. If the server crashes it will automatically restore its previous state when re-enacted.fastdds discovery -i 3 -l 172.30.144.1 -p 12345 -b
Output:
### Server is running ### Participant Type BACKUP Security: NO Server ID: 3 Server GUID prefix: 44.53.03.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[172.30.144.1]:12345
Launch a default server with id 0 (first on
ROS_DISCOVERY_SERVER) listening on localhost with UDP port 14520. Only localhost clients can reach the server defining as ROS_DISCOVERY_SERVER=localhost:14520.fastdds discovery -i 0 -l localhost -p 14520
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[127.0.0.1]:14520
Launch a secure server with id 0 (first on
ROS_DISCOVERY_SERVER) listening on all available interfaces on UDP port ‘11811’.fastdds discovery -x secure_discovery_server_cli@[PATH_TO_FILE]/DiscoveryServerCLI.xml
Output:
### Server is running ### Participant Type: SERVER Security: YES Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[0.0.0.0]:11811
Launch a server with id 0 (first on
ROS_DISCOVERY_SERVER) reading specific profile_name configuration from XML file.fastdds discovery -i 0 -x profile_name@[PATH_TO_FILE]/config.xml
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: UDPv4:[127.0.0.1]:56542
Launch a server with id 0 (first on
ROS_DISCOVERY_SERVER) listening on localhost on default TCP port ‘42100’.fastdds discovery -i 0 -t 127.0.0.1
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: TCPv4:[127.0.0.1]:42100-42100
Launch a server with id 0 (first on
ROS_DISCOVERY_SERVER) listening on localhost and WiFi (192.163.6.34). Two TCP ports need to be specified because TCP transports cannot share ports.fastdds discovery -i 0 -t 127.0.0.1 -q 42100 -t 192.163.6.34 -q 42101
Output:
### Server is running ### Participant Type: SERVER Security: NO Server ID: 0 Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41 Server Addresses: TCPv4:[127.0.0.1]:42100-42100 TCPv4:[192.163.6.34]:42101-42101
Note
When using Discovery Server over TCP, the first port shown in the output refers to the TCP Physical port and the second one to the TCP Logical port (see TCP Transport).
Note
A server can be instantiated just by passing the port arguments -p
and -q. Fast DDS CLI will use the default values of the IP addresses,
that is, 0.0.0.0 for UDP and 127.0.0.1 for TCP.
shm¶
Provides maintenance tasks related with Shared Memory Transport. Shared Memory transport creates Segments, blocks of memory accessible from different processes. Zombie files are memory blocks that were reserved by shared memory and are no longer in use which take up valuable memory resources. This tool finds and frees those memory allocations.
fastdds shm [<shm-command>]
Sub-command |
Description |
|---|---|
|
Cleans SHM zombie files. |
Option |
Description |
|---|---|
|
Produce help message. |
xml¶
Checks if a given xml profile is well formed, by matching it against a XSD schema. If the given input to the command is a path to a folder instead of a path to a file,all xml files contained in the folder will be validated.
This validation consists in checking the lack of parameters, values bounds, expected values data types and main profile structure. For further information see Creating an XML profiles file.
fastdds xml [<xml-command>]
Sub-command |
Description |
|---|---|
|
Checks a xml profile by matching it against a XSD schema. |
Option |
Description |
|---|---|
|
Produce help message. |
|
Print debug information (disabled by default) |
|
XSD schema for validation (not required, Fast DDS schema is used by default) |
Example
fastdds xml validate my_profile.xml
Docker Images¶
eProsima provides the Fast DDS and the Fast DDS Suite Docker images for those who want a quick demonstration of Fast DDS running on an Ubuntu platform. They can be downloaded from eProsima’s downloads page.
This Docker images were built for Ubuntu 22.04 (Jammy Jellyfish).
To run a container you need Docker installed. From a terminal, run:
sudo apt install docker.io
Leveraging Fast DDS SHM in Docker deployments¶
By default, Fast DDS enables both a Shared Memory Transport and Data-sharing delivery (when the configuration allows it, see Constraints). The way Fast DDS utilizes to find out whether a remote DomainParticipant is running on the same host as the local one is through a hashing of the network interfaces, which entails that two Docker container which are not sharing the same network stack will be detected as two different hosts, and therefore Fast DDS will defer to communicating through the UDP Transport instead.
To enable the use of both the Shared Memory Transport and Data-sharing in Docker deployments, two additional options need to be passed to the docker run command, those are:
–network=host: This option shares the host’s network stack with the containers, and therefore Fast DDS will be able to identify them as the same host.
–ipc=host: This option shares the host’s shared memory mechanism with the containers. Without it, Fast DDS will identify both containers as the same host, but since they will have separate shared memory spaces, they will not be able to communicate with one another. The use of this option is the Docker recommended way of sharing shared memory between containers, in opposition of for instance sharing the /dev/shm volume in Linux machines. A more advanced user could set the flag to shared, thus sharing the shared memory mechanism of one of the container with the others.
docker run -it --rm --network=host --ipc=host [OPTIONS] <docker-image>
Fast DDS Image¶
This Docker image contains the Fast DDS library and its dependencies, ready to be used in a final user application. This includes:
eProsima Fast DDS libraries and examples: Fast DDS libraries bundled with several examples that showcase a variety of capabilities of eProsima’s Fast DDS implementation.
To load this image into your Docker repository, from a terminal, run:
docker load -i "ubuntu-fastdds <FastDDS-Version>.tar"
You can run this Docker container as follows:
docker run -it ubuntu-fastdds:<FastDDS-Version>
From the resulting Bash Shell you can run each feature.
Fast DDS Examples¶
Included in this Docker container is a set of binary examples that showcase several functionalities of the Fast DDS libraries. These examples’ path can be accessed from a terminal by typing:
goToExamples
From this folder, you can access all examples, both for DDS and RTPS layers.
Hello World Example¶
This is a minimal example that will perform a Publisher/Subscriber match and start sending samples.
goToExamples
cd dds/HelloWorldExample/bin
tmux new-session "./DDSHelloWorldExample publisher 0 1000" \; \
split-window "./DDSHelloWorldExample subscriber" \; \
select-layout even-vertical
This example is not constrained to the current instance. It’s possible to run several instances of this container to check the communication between them by running the following from each container.
goToExamples
cd dds/HelloWorldExample/bin
./DDSHelloWorldExample publisher
or
goToExamples
cd dds/HelloWorldExample/bin
./DDSHelloWorldExample subscriber
Benchmark Example¶
This example creates either a Publisher or a Subscriber and on a successful match starts sending samples. After a few seconds the process that launched the Publisher will show a report with the number of samples transmitted.
On the subscriber side, run:
goToExamples
cd dds/Benchmark/bin
./DDSBenchmark subscriber udp
On the publisher side, run:
goToExamples
cd dds/Benchmark/bin
./DDSBenchmark publisher udp
Fast DDS Suite Image¶
This Docker image contains the complete Fast DDS suite. This includes:
eProsima Fast DDS libraries and examples: Fast DDS libraries bundled with several examples that showcase a variety of capabilities of eProsima’s Fast DDS implementation.
Shapes Demo: eProsima Shapes Demo is an application in which Publishers and Subscribers are shapes of different colors and sizes moving on a board. Each shape refers to its own topic: Square, Triangle or Circle. A single instance of the eProsima Shapes Demo can publish on or subscribe to several topics at a time.
You can read more about this application on the Shapes Demo documentation page.
Fast DDS Monitor: eProsima Fast DDS Monitor is a graphical desktop application aimed at monitoring DDS environments deployed using the eProsima Fast DDS library. Thus, the user can monitor in real time the status of publication/subscription communications between DDS entities. They can also choose from a wide variety of communication parameters to be measured (latency, throughput, packet loss, etc.), as well as record and compute in real time statistical measurements on these parameters (mean, variance, standard deviation, etc.).
You can read more about this application on the Fast DDS Monitor documentation page.
DDS Router: eProsima DDS Router is an end-user software application that enables the connection of distributed DDS networks. That is, DDS entities such as publishers and subscribers deployed in one geographic location and using a dedicated local network will be able to communicate with other DDS entities deployed in different geographic areas on their own dedicated local networks as if they were all on the same network through the use of eProsima DDS Router. This is achieved by deploying a DDS Router on an edge device of each local network so that the DDS Router routes DDS traffic from one network to the other through WAN communication.
You can read more about this application on the DDS Router documentation website.
Plotjuggler eProsima Edition: eProsima Fast DDS Visualizer Plugin is a plugin for the PlotJuggler application. PlotJuggler is a graphical desktop application providing visualization features of data series, time series, X-Y plots. It also adds data management features, such as data import and export, custom and built-in data manipulation functions, data series merges, etc. Also, this software supports many different layouts, with dynamic, rich and user-friendly customization.
You can read more about this application on the Plotjuggler eProsima Edition documentation website.
To load this image into your Docker repository, from a terminal run
docker load -i "ubuntu-fastdds-suite <FastDDS-Version>.tar"
You can run this Docker container as follows
xhost local:root
docker run -it --privileged -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix \
ubuntu-fastdds-suite:<FastDDS-Version>
From the resulting Bash Shell you can run each feature.
Fast DDS Examples¶
Included in this Docker container is a set of binary examples that showcase several functionalities of the Fast DDS libraries. These examples’ path can be accessed from a terminal by typing
goToExamples
From this folder you can access all examples, both for DDS and RTPS. We detail the steps to launch two such examples below.
Hello World Example¶
This is a minimal example that will perform a Publisher/Subscriber match and start sending samples.
goToExamples
cd dds/HelloWorldExample/bin
tmux new-session "./DDSHelloWorldExample publisher 0 1000" \; \
split-window "./DDSHelloWorldExample subscriber" \; \
select-layout even-vertical
This example is not constrained to the current instance. It’s possible to run several instances of this container to check the communication between them by running the following from each container.
goToExamples
cd dds/HelloWorldExample/bin
./DDSHelloWorldExample publisher
or
goToExamples
cd dds/HelloWorldExample/bin
./DDSHelloWorldExample subscriber
Benchmark Example¶
This example creates either a Publisher or a Subscriber and on a successful match starts sending samples. After a few seconds the process that launched the Publisher will show a report with the number of samples transmitted.
On the subscriber side, run:
goToExamples
cd dds/Benchmark/bin
./DDSBenchmark subscriber udp
On the publisher side, run:
goToExamples
cd dds/Benchmark/bin
./DDSBenchmark publisher udp
Shapes Demo¶
To launch the Shapes Demo, from a terminal run
ShapesDemo
eProsima Shapes Demo usage information can be found on the Shapes Demo documentation.
Fast DDS Monitor¶
To launch the Fast DDS Monitor, from a terminal run
fastdds_monitor
eProsima Fast DDS Monitor user manual can be found on the Fast DDS Monitor documentation.
DDS Router¶
This example configures a DDS Router to communicate a publisher and subscriber running in different DDS Domains.
Run the following command to create the DDS Router yaml configuration file (/config.yml).
echo "version: v2.0
participants:
- name: simple_dds_participant_0
kind: local
domain: 0
- name: simple_dds_participant_1
kind: local
domain: 1" > /config.yml
Then execute the following command to run the Publisher in Domain 0, the Subscriber in Domain 1, and the DDS Router communicating both Domains.
goToExamples
cd dds/BasicConfigurationExample/bin
tmux new-session \
"ddsrouter --config-path /config.yml" \; \
split-window -h "./BasicConfigurationExample publisher --domain 0 --interval 1000 --transport udp" \; \
split-window -v "./BasicConfigurationExample subscriber --domain 1 --transport udp"
eProsima DDS Router usage information can be found on the DDS Router documentation.
PlotJuggler eProsima Edition¶
To launch the PlotJuggler eProsima Edition, from a terminal run
plotjuggler
eProsima PlotJuggler eProsima Edition usage information can be located on the PlotJuggler eProsima Edition User Manual.
Dependencies and compatibilities¶
Fast DDS is continuously evolving and improving. This means that the different software products that are part of the Fast DDS ecosystem are evolving and improving together with Fast DDS. This section provides information about the required dependencies for building Fast DDS, as well as about the versions of the eProsima software products related to Fast DDS.
Platform support¶
This following definitions reflects the level of support offered by eprosima Fast DDS on different platforms:
Tier 1: these platforms are subjected to our unit test suite and other testing tools on a frequent basis including continuous integration jobs, nightly jobs, packaging jobs, and performance testing. Errors or bugs discovered in these platforms are prioritized for correction by the development team. Significant errors discovered in Tier 1 platforms can impact release dates and we strive to resolve all known high priority errors in Tier 1 platforms prior to new version releases.
Tier 2: these platforms are subject to periodic CI testing which runs both builds and tests with publicly accessible results. The CI is expected to be run at least within a week of relevant changes for the current release of Fast DDS. Installation instructions should be available and up-to-date in order for a platform to be listed in this category. Package-level binary packages may not be provided but providing a downloadable archive of the built workspace is encouraged. Errors may be present in released product versions for Tier 2 platforms. Known errors in Tier 2 platforms will be addressed subject to resource availability on a best effort basis and may or may not be corrected prior to new version releases. One or more entities should be committed to continuing support of the platform.
Tier 3: these platforms are those for which community reports indicate that the release is functional. The development team does not run the unit test suite or perform any other tests on platforms in Tier 3. Community members may provide assistance with these platforms.
Build system dependencies¶
The following table shows the minimum version required of the Fast DDS build system dependencies.
CMake |
3.20 |
OS Architecture |
amd64 |
amd32 |
arm64 |
|---|---|---|---|
Ubuntu Jammy (22.04) |
Tier 1: GCC 11.4 |
─── |
Tier 1: GCC 11.4 |
Ubuntu Focal (20.04) |
Tier 3: GCC 9 |
─── |
Tier 3: GCC 9 |
MacOS Mojave (10.14) |
Tier 1: Clang 15 |
─── |
─── |
Windows 10 |
Tier 1: MSVC v142 (Visual Studio 2019) |
Tier 2: MSVC v142 (Visual Studio 2019) |
─── |
Windows 11 |
Tier 3: MSVC v143 (Visual Studio 2022) |
Tier 3: MSVC v143 (Visual Studio 2022) |
─── |
Debian Buster (10) |
Tier 3: GCC 8 |
─── |
Tier 3: GCC 8 |
Android 12 |
Tier 3: SDK 31 |
─── |
Tier 3: SDK 31 |
Android 13 |
Tier 3: SDK 33 |
─── |
Tier 3: SDK 33 |
QNX 7.1 |
Tier 3: QCC (over GCC 8.3) |
─── |
Tier 3: QCC (over GCC 8.3) |
CMake |
3.20 |
OS Architecture |
amd64 |
amd32 |
arm64 |
|---|---|---|---|
Ubuntu Jammy (22.04) |
Tier 1: GCC 11.4 |
─── |
Tier 1: GCC 11.4 |
Ubuntu Focal (20.04) |
Tier 3: GCC 9 |
─── |
Tier 3: GCC 9 |
MacOS Mojave (10.14) |
Tier 1: Clang 15 |
─── |
─── |
Windows 10 |
Tier 1: MSVC v142 (Visual Studio 2019) |
Tier 2: MSVC v142 (Visual Studio 2019) |
─── |
Windows 11 |
Tier 3: MSVC v143 (Visual Studio 2022) |
Tier 3: MSVC v143 (Visual Studio 2022) |
─── |
Debian Buster (10) |
Tier 3: GCC 8 |
─── |
Tier 3: GCC 8 |
Android 12 |
Tier 3: SDK 31 |
─── |
Tier 3: SDK 31 |
Android 13 |
Tier 3: SDK 33 |
─── |
Tier 3: SDK 33 |
QNX 7.1 |
Tier 3: QCC (over GCC 8.3) |
─── |
Tier 3: QCC (over GCC 8.3) |
CMake |
3.16 |
OS Architecture |
amd64 |
amd32 |
arm64 |
|---|---|---|---|
Ubuntu Jammy (22.04) |
Tier 1: GCC 9 |
─── |
Tier 1: GCC 9 |
Ubuntu Focal (20.04) |
Tier 1: GCC 9 |
─── |
Tier 1: GCC 9 |
MacOS Mojave (10.14) |
Tier 1: Clang 12 |
─── |
─── |
Windows 10 |
Tier 1: MSVC v142 (Visual Studio 2019) |
Tier 2: MSVC v142 (Visual Studio 2019) |
─── |
Debian Buster (10) |
Tier 3: GCC 8 |
─── |
Tier 3: GCC 8 |
Android 11 |
Tier 3: SDK 30 |
─── |
Tier 3: SDK 30 |
QNX 7.1 |
Tier 3: QCC (over GCC 8.3) |
─── |
Tier 3: QCC (over GCC 8.3) |
CMake |
3.16 |
OS Architecture |
amd64 |
amd32 |
arm64 |
|---|---|---|---|
Ubuntu Focal (20.04) |
Tier 1: GCC 9 |
─── |
Tier 1: GCC 9 |
MacOS Mojave (10.14) |
Tier 1: Clang 12 |
─── |
─── |
Windows 10 |
Tier 1: MSVC v142 (Visual Studio 2019) |
Tier 2: MSVC v142 (Visual Studio 2019) |
─── |
Debian Buster (10) |
Tier 3: GCC 8 |
─── |
Tier 3: GCC 8 |
Library dependencies¶
The following table shows the corresponding versions of the Fast DDS library dependencies.
Product |
Related version |
|---|---|
Product |
Related version |
|---|---|
Product |
Related version |
|---|---|
eProsima products compatibility¶
The following table shows the compatibility between the different versions of the eProsima software products that use Fast DDS as the core middleware.
Product |
Related version |
|---|---|
Product |
Related version |
|---|---|
Product |
Related version |
|---|---|
Product |
Related version |
|---|---|
Information about the release lifecycle can be found here.
Version 2.14.0 (latest)¶
Important
Fast DDS v2.14 will be the last minor version of Fast DDS v2, the next major release will be Fast DDS v3.0.0, stay tuned!
This release includes the following new features:
Add netmask filter transport configuration
Expose Security Authentication plugin Handshake Properties
Extend
LARGE_DATAconfiguration optionsOpenOutputChannels / CloseOutputChannels that receive a LocatorSelectorEntry
Support GTest v1.14.0
Update Fast CDR submodule to v2.2.0
Update roadmap and release support
This release includes the following improvements:
Ignore custom PIDs defined in Fast DDS when they are received from other vendors
Add catch of out-of-range exception for thread settings port
Explicitly pass vendor ID to
readFromCdrMessageTCP transport improvements:
TCPSendResourcescleanupTCP
non_blocking_sendmoved to TCPTransportDescriptor
Various repository improvements and housekeeping:
Migrate communication tests to the DDS API
Migrate TCPReqRepHelloWorldReplier/Requester to the DDS API
Update APIs in video performance tests to the DDS API
Remove
FASTDDS_TODO_BEFORE2.14Remove use of deprecated FindPythonInterp
Remove idl parser from .repos file
Force usage of semicolon in
FASTDDS_TODO_BEFOREmacroUbuntu example testing automation infrastructure
Multiple Github CI improvements:
Add nightly Ubuntu Github CI
Improve CI version management
Avoid running GitHub CI if PR has conflicts
Migrate apt package installation to eProsima-CI action
Include missing nightly for 3.0.x branch
Adapt nightly jobs for all supported versions
Pin CMake version and vm.mmap_rnd_bits in sanitizer workflows
Select reusable workflow version depending on target branch in nightly jobs
This release includes the following fixes:
Fix warnings when compiling for Windows x86
TCP first message loss (see TCPTransportDescriptor)
Fix warnings on tests on Windows 32bits
Protect asio exception hotfix
Fix CVE-2024-28231
Github CI fixes:
Fix CI documentation workflow label triggering
Fix nightly jobs
Fix input branch on reusable windows CI
Use correct version of GTest on DS ASan tests
Note
When upgrading to version 2.14.0 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.3.0.
See also
For further information about the corresponding versions of other products related to this Fast DDS version, please refer to the eProsima products compatibility section.
Supported versions¶
Version 2.14¶
Version 2.14.0 (latest)¶
Important
Fast DDS v2.14 will be the last minor version of Fast DDS v2, the next major release will be Fast DDS v3.0.0, stay tuned!
This release includes the following new features:
Add netmask filter transport configuration
Expose Security Authentication plugin Handshake Properties
Extend
LARGE_DATAconfiguration optionsOpenOutputChannels / CloseOutputChannels that receive a LocatorSelectorEntry
Support GTest v1.14.0
Update Fast CDR submodule to v2.2.0
Update roadmap and release support
This release includes the following improvements:
Ignore custom PIDs defined in Fast DDS when they are received from other vendors
Add catch of out-of-range exception for thread settings port
Explicitly pass vendor ID to
readFromCdrMessageTCP transport improvements:
TCPSendResourcescleanupTCP
non_blocking_sendmoved to TCPTransportDescriptor
Various repository improvements and housekeeping:
Migrate communication tests to the DDS API
Migrate TCPReqRepHelloWorldReplier/Requester to the DDS API
Update APIs in video performance tests to the DDS API
Remove
FASTDDS_TODO_BEFORE2.14Remove use of deprecated FindPythonInterp
Remove idl parser from .repos file
Force usage of semicolon in
FASTDDS_TODO_BEFOREmacroUbuntu example testing automation infrastructure
Multiple Github CI improvements:
Add nightly Ubuntu Github CI
Improve CI version management
Avoid running GitHub CI if PR has conflicts
Migrate apt package installation to eProsima-CI action
Include missing nightly for 3.0.x branch
Adapt nightly jobs for all supported versions
Pin CMake version and vm.mmap_rnd_bits in sanitizer workflows
Select reusable workflow version depending on target branch in nightly jobs
This release includes the following fixes:
Fix warnings when compiling for Windows x86
TCP first message loss (see TCPTransportDescriptor)
Fix warnings on tests on Windows 32bits
Protect asio exception hotfix
Fix CVE-2024-28231
Github CI fixes:
Fix CI documentation workflow label triggering
Fix nightly jobs
Fix input branch on reusable windows CI
Use correct version of GTest on DS ASan tests
Note
When upgrading to version 2.14.0 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.3.0.
Version 2.13¶
Version 2.13.3¶
This patch release includes the following improvements:
Enabling multiple interfaces through whitelist in TCP servers
Set LARGE_DATA Participants logic with the same listening ports
Check History QoS inconsistencies
This patch release includes the following fixes:
Prevent index overflow and correctly assert the end iterator in DataSharing
Fix the shared memory cleaning script
Fix TCP reconnection after open logical port failure
Fix data race on PDP
Fix doxygen docs warnings. Prepare for compiling with Doxygen 1.10.0
Add missing TypeLookup listeners
Restore Blackbox tests names
Add macOS Github CI
Set 2.11.x as EOL
Note
When upgrading to version 2.13.3 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.2.1.
Version 2.13.2¶
This patch release includes the following fixes and improvements:
Improve environment variable substitution algorithm
Add large data to the Advanced Configuration example
Discard already processed samples on
PDPListenerIgnore
0x8007if coming from other vendorTCP unique client announced local port
TCP non-blocking send
TCP Client&Server Participant Decision-Making
Add non-throwing getters for socket info
Add a keyed fragmented change to the reader data instance only when it is completed
Include a variety of terminate process signals handlers in the discovery server
Make DataWriters always send the key hash on keyed topics
Update Fast DDS types with Fast DDS Gen to include
<cstdint>in v1 typesAdd serialization for Log::Kind to ostream
Fix wrong log info messages on TCP
Return const reference in
get_log_resourcesRemove unnecessary warning
Avoid a maybe-uninitialized warning
Add static cast to an unused variable
Prepare for v3.0.0 branch out
Windows CI fixes
Note
When upgrading to version 2.13.2 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.2.1.
Version 2.13.1¶
This release includes the following improvements:
Downgrade CMake minimum required version to 3.20.
Update PR template to include check for PR description, title and backports.
Update Fast CDR submodule to v2.1.3.
This patch release includes the following fixes:
Revert wrong fix for TCP deadlock on channel reuse.
Fix wrong history selection when removing PDP samples.
Fix data race when processing incoming PDP samples on different threads.
Fix DNS test filter in CMakeLists.
Fix deserialization of unions in generated code.
Note
When upgrading to version 2.13.1 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.2.1.
Version 2.13.0¶
This release includes the following features:
Support Monitor Service.
Enable configuration of thread settings for all threads (both through the C++ API and XML configuration files).
Support Autofill port (automatic assignment of a port) for TCP Transport listening port.
Support TCP for Discovery Server CLI and environment variable.
Usage of gtest_discover_tests.
Define a super client by environment variable.
Support adding interfaces to the interface whitelist by the name.
Add new methods to configure Builtin Transport.
Support DataRepresentationQos.
Change serialize function default behavior to omit the data representation.
Upgrade Fast CDR submodule to v2.1.2.
Update roadmap & platforms support.
This release includes the following improvements:
Rerun failed tests with ctest option instead of colcon’s.
Add CCache to all CI jobs.
This release includes the following fixes:
Fast DDS bugfixes
Fix compilation of XMLProfileParserTests when building without security.
Improve IgnoreNonExistentSegment test for Windows.
Add missing thread includes.
Fix warning in Mac rewarding unnecessary lambda capture.
Use SO_EXCLUSIVEADDRUSE for Win32 unicast listening sockets.
Fix gtest discovery timeout.
Mark on_participant_discovery overload removal.
Fix uninitialized member in BuiltinAttributes class.
Fix set affinity directive for Android.
Fix Monitor Service types & test without security.
Fix TCP deadlock on channel reuse.
Fix DNS filter in CMakeLists file for tests.
Fix memory issues related to ciphering payload.
Fix a bad-free when receiving a malformed DATA_FRAG submessage.
Fix CVE-2023-50257.
Fix compilation of Fast DDS Python tests.
Fix data race on writer destruction while sending heartbeat.
Fix build with TLS, when SECURITY=OFF and NO_TLS=OFF.
CI fixes:
Fix colcon on github CI.
Better handling of trigger events in docs CI.
Note
When upgrading to version 2.13.0 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.2.0.
Version 2.10¶
Version 2.10.3¶
This release includes the following features in an ABI compatible manner:
Support
Autofill port(automatically set a port) for TCP Transport.Define a super client by environment variable
Support TCP Discovery server CLI and environment variable
Define methods (environment variable, rtps layer, xml) to configure transport scenarios
Custom pools on DDS layer (DataWriter and DataReader)
This release includes the following improvements:
Log warning upon receiver resource creation failure
Simplify code in
CDRMessageBackport workflows from master
Rerun failed tests with ctest option instead of colcon’s
Use foonathan memory manager for reducing allocations in
SharedMemManager.hppAdd CCache to all CI jobs
This release includes the following bugfixes:
Fix
RemoteBuiltinEndpointHonoringblackbox testFix bad-free when receiving malformed DATA submessage
Fix clang warnings
Use STL implementation of
Timed/RecursiveTimedMutexwhenMSVC >= 19.36Notify data-sharing listener at the end of a successful matching in intraprocess
Fix the clang build for clang 14
Fix
HelloWorldData-Sharing example idlFix the behaviour of
disable_positive_acksperiodFix
DomainParticipant::register_remote_typereturn when negotiating typeFix Data Race when updating liveliness changed in WLP
Fix TCP sender resources creation
Fix flow controllers unit tests compilation when using
Fast CDRfrom thirdpartyAdd XML parser
bit_boundbounds checkAdd tests for reconnection with same GUID
Fix Github Windows CI
Fix PubSubAsReliable test
Use
FASTRTPS_NO_LIBon unittest root folderFix missing mandatory attribute check in XML parser struct type
Fix mac address overflow on windows
Use
SO_EXCLUSIVEADDRUSEfor Win32 unicast listening socketsFix FileWatchTest for Github windows CI
Add missing thread include
Update TLS unit test certificates
Select correct .repos file on push events
Fix documentation CI branch
Fix TCP deadlock on channel reuse
Fix DNS filter in CMakeLists file for tests
Fix bad-free when receiving malformed DATA_FRAG submessage
Fix memory problem when ciphering payload
Fix build with TLS, but not security
Fix CVE-2023-50257
Fix data race on writer destruction while sending heartbeat
Fix comparison in
remove_from_pdp_reader_historyFix data race in PDPListener and SecurityManager
Update PR template to include check for PR description, title and backports
Fix std::move warning
Revert “TCP deadlock on channel reuse”
Fix max clash with Windows CI
Remove unnecessary TCP warning
Discard already processed samples on
PDPListenerTCP unique client announced local port
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.10.2¶
This release includes the following improvements:
Fix Data-Sharing delivery when data_count is zero
Improve performance of intraprocess plus data-sharing
Improve content filter expression parameters checks and verbosity
Improve validation on PID_PROPERTY_LIST deserialization
Participant ignore local endpoints
Pick smallest available participant ID for new participants
Improve endpoint QoS XML tags
Forward compatibility with boost interprocess 1.74+
Cap Thread Sanitizer memory usage to prevent runner shutdown
Allow participant XML profile with no <rtps> tag
Add unsupported note in API documentation to new ignore DomainParticipantListener callbacks
Add documentation version fallback
This release includes the following bugfixes:
Fixed long-standing reconnection issue on SHM transport
Fix null dereference when fuzzing
Fix segfault when creating two participant with same fixed id
Fix UBSan (Undefined Behavior Sanitizer) issues
Fix listener selection for on_requested_deadline_missed
Fix build on msvc 19.36.32528
Fix XML schema to set Transport descriptor kind as NOT mandatory
Fix missing includes
Fix overhead time unit
Fix request reply example spelling typo
Fix topic deletion after endpoint in examples
Fix Data-Sharing delivery when data_count is zero
Wait for log background thread initialization on the first queued entry
Fix alias resolve in DDSSQLFilter
Fix partition copy in QoS
Fix StatelessWriter locators filtering
Fix XMLParser null-dereference in parseLogConfig
Fix encapsulation format in WLP
Replace uint64_t by 8 in alignas specifier
Capture all Fast CDR exceptions
Security module: Honor allow_unauthenticated_participants flag
Explicitly register type object in ContentFilteredTopicExample
Avoid double definition of FASTDDS_ENFORCE_LOG_INFO
Fix API Fast DDS v2.10.0 API break calling correctly on_participant_discovery callbacks
Remove mutex from TimedEventImpl
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.10.1¶
This release includes the following feature in an ABI compatible way:
ignore_participant()implementation
This release includes the following bugfixes:
Fix repeated matched event notification.
Fix regression introduced by #3396.
Initial acknack backoff.
Fix regular expression in XML schema.
Correctly assign multicast port to multicast initial peers.
This release includes the following CI improvements:
Update runner and GCC version for Thread Sanitizer job.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.10.0¶
This minor release includes several new features, improvements and bugfixes.
Note
Mind that, even though this release is API compatible with previous v2.x versions, it is NOT ABI compatible with previous versions. This means that applications upgrading Fast DDS to v2.10.0 will require recompilation, though not source code modification.
Note
It is also advisable to regenerate the type support from the IDL files using Fast DDS-Gen v2.4.0. Furthermore, if upgrading to v2.10.0, it is also recommended to upgrade Fast CDR to v1.0.27.
This release includes the following features:
New on_unacknowledged_sample_removed callback in
DataWriterListener.DomainParticipant ignore empty API.
RTPS
ReaderListener::on_incompatible_typeandWriterListener::on_incompatible_typeempty API.
This release includes the following improvements:
- Fast DDS improvements
Improve behavior when
STRICT_REALTIMECMake option is not enabled.Using functors for
for_matched_readersparameter.Improve auto GAPs in Data Sharing.
Use standard value for
PID_RELATED_SAMPLE_IDENTITY.
- Contributions and repository quality
Update Pull Request template.
Update foonathan_memory quality declaration.
Update XSD schema.
Make network headers private avoiding exposing non-public API.
Improve Doxygen documentation for
ResourceLimitsQosPolicy.
- Examples
- CI improvements
New workflow to check documentation build.
ASAN workflow updated to use Ubuntu 22.04.
- Dependencies
Upgrade internal type supports using latest Fast DDS-Gen release v2.4.0.
Upgrade Fast CDR submodule to v1.0.27.
- Fast DDS CLI
Handle
SIGTERMsignal.
- Community supported platforms
This release includes the following fixes:
- Security vulnerability
Fix chain of trust issues with a single CA certificate.
- Bugfixes
Fix RTPS StatelessWriter ACK check.
ASAN (Address Sanitizer) fixes.
UBSan (Undefined Behavior Sanitizer) fixes.
Export public API correctly in Windows.
Correctly handle builtin endpoints mask.
Fix backwards compatibility using SHM communication.
Protect against uncaught exception in SHM segment creation.
Fix build for GCC 5.
Validity check for first sequence number.
Fix crash when enabling DisablePositiveACKsQoSPolicy with remote best-effort readers.
- Synchronization fixes
Take mutex when removing local reader in WLP.
Fix data races in SecurityManager authentication process.
- CI fixes
Fix test building when using
GTEST_INDIVIDUALCMake option.Fix overflow in received samples in performance tests.
- Example fixes
Avoid creating entities within callbacks in DynamicHelloWorldExample.
Remove Asio dependency from DeadlineQoSExample.
- Repository fixes
Remove 2.7.x as active branch.
- Community supported platforms
Include right header when building for iOS.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6¶
Version 2.6.7¶
This release includes the following features:
Support
Autofill port(automatically set a port) for TCP Transport.Define a super client by environment variable
Support TCP Discovery server CLI and environment variable
Define methods (environment variable, rtps layer, xml) to configure transport scenarios
This release includes the following improvements:
Log warning message upon receiver resource creation failure.
Add tests for reconnection with same GUID
Use foonathan memory manager for reducing allocations in
SharedMemManager.hppSimplify code in
CDRMessage.Rerun failed tests with ctest option instead of colcon’s.
Several improvements on CI jobs.
Upgrade CMake minimum requirement to 3.16.3
Update PR checklist template. Backports and Description
This release includes the following bugfixes:
Fix
DomainParticipant::register_remote_typereturn when negotiating type.Fix
RemoteBuiltinEndpointHonoringblackbox test.Allow participant profiles with no rtps tag.
Fix bad-free when receiving malformed DATA submessage.
Fix clang warnings
Use STL implementation of
Timed/RecursiveTimedMutexwhenMSVC >= 19.36.Fix encapsulation format in WLP.
Fix the clang build for clang 14.
Notify data-sharing listener at the end of a successful matching in intraprocess.
Updatable disable_positive_acks period.
Fix Data Race when updating liveliness changed in WLP.
Fix TCP sender resources creation.
Fix flow controllers unit tests compilation when using Fast CDR from thirdparty.
Add XML parser bit_bound bounds check.
Use
FASTRTPS_NO_LIBon unittest root folder.Use
SO_EXCLUSIVEADDRUSEfor Win32 unicast listening sockets.Fix mac address overflow on windows.
Fix
PubSubAsReliabletest.Fix
FileWatchTest.Add missing thread include.
Fix missing mandatory attribute check in XML parser struct type.
Better handling of trigger events in docs CI.
Fix memory problem when ciphering payload
Select correct .repos file on push events
Update TLS unit test certificates
Fix bad-free when receiving malformed DATA_FRAG submessage
Fix data race on writer destruction while sending heartbeat
Fix DiscoveryServer list access deadlock
Fix c++11 support for fast discovery server tool
Fix CVE-2023-50257
Fix std::move warning
Fix Github Windows CI
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.6¶
This release includes the following improvements:
Improve validation on PID_PROPERTY_LIST deserialization.
Improved CPU usage of timed events thread.
Improved performance on intraprocess + data-sharing.
Explicitly register type object in ContentFilteredTopicExample.
Improve installer generation with documentation version fallback.
Improve content filter expression parameters checks and verbosity.
This release includes the following bugfixes:
Fixed long-standing reconnection issues on SHM transport.
Correctly resolve alias in DDSQLFilter.
Fixed partition copy in QoS.
Added length checks to prevent nullptr memory copy calls.
Fixed XMLParser null-dereference when parsing log configuration.
Fixed SHM in 32-bit architectures.
Added missing include.
Avoid double definition of FASTDDS_ENFORCE_LOG_INFO.
Fixed statistics data_count with data-sharing.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.5¶
This release includes the following improvements:
Improve behavior when
STRICT_REALTIMECMake option is not enabled.Using functors for
for_matched_readersparameter.Improve auto GAPs in Data Sharing.
This release includes the following bugfixes:
Fix RTPS StatelessWriter ACK check.
Fix
total_read_to be consistent with Reader’s History afterDataReader::get_first_untaken_info().Add deprecation notice to
ThroughputControllerDescriptor.UBSan (Undefined Behavior Sanitizer) fixes.
Several dependencies fixes upgrading to Ubuntu 22.04.
Fix chain of trust issues with a single CA certificate.
Correctly handle builtin endpoints mask.
Take mutex when removing local reader in WLP.
Handle
SIGTERMsignal in Fast DDS CLI.Fix data races in SecurityManager authentication process.
Avoid creating entities within callbacks in DynamicHelloWorldExample.
Remove Asio dependency from DeadlineQoSExample.
Validity check for first sequence number.
Include right header when building for iOS.
Fix build on MSVC 19.
Correctly assign multicast port to multicast initial peers.
Select correct listener for
on_requested_deadline_missed().Forward compatibility with boost inter-process 1.74+.
Fix missing includes when building with GCC 13.
Honor
allow_unauthenticated_participantsflag.Capture all Fast CDR exceptions.
Fix example to delete Topic after deleting the corresponding Endpoint.
Protect against uncaught exception in SHM segment creation.
Initial acknack backoff.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.4¶
This release includes the following bugfixes:
Fix communication with asymmetric Ignore Participant flags.
Fix deadlock in Writer Liveliness Protocol when using intraprocess.
Fix notification lost.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.3¶
This release includes the following improvements:
Upgrade CMake minimum requirement to 3.13.
Improve
Guid_toperator<performance.
This release includes the following bugfixes:
Add python3 dependency to package.xml.
Fix complex member printing for DynamicDataHelper.
Fix selection of output locators.
Fix null references on XML parser.
Fix data races when creating DataWriters.
Send GAPs correctly when using separate sending.
Install Statistics IDL file.
Fixes for building in older compilers.
Fix deadlock when removing DomainParticipant when using SECURITY.
Ensure
shared_muteximplementation is consistent throughout supported platforms.Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.2¶
This release includes the following improvements:
Support for GCC 12.
Overload
DataReader::get_unread_count().Improve read/take performance when using topic with a great number of keys.
Improve rediscovery on lossy environments.
This release includes the following bugfixes:
Fixed several deadlocks and data races.
Fixed validation on
ParameterPropertyList_t.Fixed wrong usage of
std::remove_if.Fixed acknowledgement in DataSharing.
Other minor fixes.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.1¶
This release includes the following improvements:
Support for writer side content filtering
Support hexadecimal values on SQL filter
Support for
DataWriter::get_key_value()Support for
DataReader::lookup_instance()Support for SampleLostStatus on DataReader
Improved doxygen documentation
Some bugfixes are also included:
Fixed several lock order inversion issues
Fixed data race when closing UDP channels
Fixed empty partition validation checks
Fixed corner case with reliable writers and samples with a huge number of fragments
Other minor fixes and improvements
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.6.0¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed. Some API is also being deprecated.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
This minor release includes the following features:
Add statistics physical information to DATA[p] using properties
Endpoint discovery RTPS API
on_sample_lostRTPS APITransport layer API extension
It also includes the following improvements:
Support lowercase keywords on SQL filter
Separate initialization and enabling of BuiltinProtocols
Add
disable_positive_acksto Static Discovery XMLSeveral updates in the DDS-PIM API
Support for octet vectors on XML parser
Update README and roadmap
Update Fast-CDR submodule to v1.0.24
Add new CMake option
APPEND_PROJECT_NAME_TO_INCLUDEDIR
Some bugfixes are also included:
Fix MatchedStatus
last_*_handleFix recommended statistics DataReaderQos to enable backwards compatibility
Fixes for supporting Python bindings in Windows platforms
Fix publishing physical data on statistics topic
Other minor fixes and improvements
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Previous end-of-life versions¶
Version 2.12 (EOL)¶
Version 2.12.2 (EOL)¶
This release includes the following features:
Methods to configure transport scenarios
Support
Autofill port(automatically set the port) for TCP TransportSupport TCP for Discovery Server CLI and environment variable
Define a super client by environment variable
Change serialize function default behaviour to omit the data representation
LARGE_DATAParticipants logic with same listening portsTCP Client&Server Participant Decision-Making logic
Enabling multiple interfaces through whitelist in TCP servers
Add macOS and Ubuntu Github CI
This release includes the following improvements:
Improve environment variable substitution algorithm
Upgrade dependency version to last patch version in .repos file
Rerun failed tests with ctest option instead of colcon’s
Remove unnecessary TCP warning
Update PR template to include check for PR description, title and backports
Improvements in GitHub CI
This release includes the following fixes:
Fix TCP reconnection after open logical port failure
TCP unique client announced local port
TCP non-blocking send
Fix wrong log info messages on TCP
Improve
IgnoreNonExistentSegmenttestUse
SO_EXCLUSIVEADDRUSEfor Win32 unicast listening socketsFix DNS filter in CMakeLists file for tests
Fix bad-free when receiving malformed DATA_FRAG submessage
Fix memory problem related to ciphering payload
Fix CVE-2023-50257
Fix build with TLS, but not security
Fix comparison in
remove_from_pdp_reader_historyFix data race in
PDPListenerandSecurityManagerDiscard already processed samples on
PDPListenerFix .repos versions
Fix the shared memory cleaning script
Fix data race on writer destruction while sending heartbeat
Return
constreference to the shared pointer instead of a copy inget_log_resourcesIgnore
0x8007if coming from other vendorFix Doxygen docs warnings and prepare for compiling with Doxygen 1.10.0
Include variety of terminate process signals handler in discovery server
Add missing
TypeLookuplistenersAdd a keyed fragmented change to the reader data instance only when its completed
Fix data race on PDP
Check History QoS inconsistencies
Make DataWriters always send the key hash on keyed topics
Prevent index overflow and correctly assert the end iterator in DataSharing
Fix uninitialized member in
RTPSParticipantAttributesRemove unnecessary
std::moveinFileWatch.hppcausing warningAdd missing thread include
Add missing virtual destructor for
StatisticsAncillaryProtect asio exception
TCPSendResourcescleanupDowngrade CMake version to 3.20
Version 2.12.1 (EOL)¶
This release includes the following improvements:
Support for linking with Fast CDR v1.
The period for the timer within the DisablePositiveACKsQosPolicy is now updatable.
Log error message upon receiver resource creation failure.
CI and repository improvements.
Simplify code in CDRMessage.
This release includes the following fixes:
Fast DDS bugfixes
Fix transient local durability for reliable readers using intra-process and data-sharing.
Use STL implementation of Timed/RecursiveTimedMutex when MSVC >= 19.36.
Fix updatability of immutable DataWriterQos.
Fix the clang build for clang 14.
Fix remote locators filtering when whitelist provided.
Fix Data Race when updating liveliness changed in WLP.
Add XML parser bit_bound bounds check.
Fix missing mandatory attribute check in XML parser struct type.
SHM transport: ignore non-existing segment on pop.
Fix: mac address overflow on Windows.
CI fixes:
Fix flow controllers unit tests compilation when using Fast CDR from thirdparty.
PubSubAsReliable test fix.
FileWatchTest fix for github windows CI.
Note
When upgrading to version 2.12.1 it is advisable to regenerate generated source from IDL files using Fast DDS-Gen v3.1.0.
Version 2.12.0 (EOL)¶
Note
This release upgrades the following Fast DDS dependencies:
Please, read also the release notes of Fast DDS-Gen v3.0.0 to be aware of every possible break in the application code.
As Fast DDS dependencies have been upgraded to new major releases, depending on the types defined in the IDL files, it might be required to modify the user application source code besides recompiling it (more information can be found in the corresponding release notes).
Note
There is a minor API break with previous v2.x versions: MEMBER_INVALID identifier was declared using #define.
In order to prevent polluting the user workspace, it has been transformed into a constexpr within
eprosima::fastrtps::types namespace.
This release includes the following features:
New participant property to configure SHM transport metatraffic behavior.
Exposed custom payload pool on DDS DataWriter and DataReader declaration.
Feature example.
Dependencies
Upgrade internal type supports using latest Fast DDS-Gen release v3.0.0. This release introduces the following features:
Support for @optional builtin annotation <optional_members>.
Support for @extensibility builtin annotation <extensibility>.
Upgrade Fast CDR submodule to v2.0.0 introducing XCDR encoding version 2.
This release includes the following improvements:
fixed_stringcomparison operators.Remove mutex from TimedEventImpl (#3745, #3760)
Performance improvements on intraprocess and datasharing.
Improve Shared Memory resilience to crashing participants.
Improve scripts shebang portability.
Use
foonathan_memoryto reduce allocations in SharedMemManager.
This release includes the following fixes:
- Fast DDS bugfixes
Fixed XMLParser null-dereference when parsing log configuration.
Allow participant XML profiles with no
<rtps>tag.Fix encapsulation format in Writer Liveliness Protocol.
Fix
DomainParticipant::register_remote_typereturn when negotiating type.Fix strict real-time feature when using Flow Controller feature.
Fix ParameterPropertyList increment operators.
Fix bad-free when receiving malformed DATA submessage.
Fix asymmetric whitelist matching.
Fix heap-use-after-free on XMLElementParser.
Fix History remove change return statement.
- CI fixes
Fix RemoteBuiltinEndpointHonoring blackbox test.
Improve repository workflows.
Use FASTRTPS_NO_LIB on unittest root folder.
Fix Windows workflow.
- Tools
Remove C++11 check in
fastdds-discovery-serverCLI tool.
- Examples
Fix HelloWorldDataSharing data type.
- Documentation
Doxygen typos.
- Repository
Remove 2.9.x as active branch.
- Non Tier 1 support
Fixed SHM in 32-bit architectures.
Fix warning on Win32 architecture.
Note
Upgrading to version 2.12.0 requires to regenerate generated source from IDL files using Fast DDS-Gen v3.0.1.
Version 2.11 (EOL)¶
Version 2.11.3 (EOL)¶
This release includes the following features in an ABI compatible manner:
Support
Autofill port(automatically set a port) for TCP Transport.Define a super client by environment variable
Support TCP Discovery server CLI and environment variable
Define methods (environment variable, rtps layer, xml) to configure transport scenarios
Custom pools on DDS layer (DataWriter and DataReader)
This release includes the following improvements:
Allow participant profiles with no rtps tag
Add Log warning message upon receiver resource creation failure, instead of an error
Updatable disable_positive_acks period
Backport workflows from master
Update GitUtils.cmake
Use foonathan memory manager for reducing allocations in
SharedMemManager.hppRerun failed tests with ctest option instead of colcon’s
Add CCache to all CI jobs
Simplify code in
CDRMessageTCP unique client announced local port
Make DataWriters always send the key hash on keyed topics
Include terminate process signals handler in discovery server
This release includes the following fixes:
Fix encapsulation format in WLP used for the
ParticipantMessageDataFix
DomainParticipant::register_remote_typereturn when negotiating typeFix
RemoteBuiltinEndpointHonoringblackbox testFix .repos branches
Fix bad-free when receiving malformed DATA submessages
Fix clang warnings
Use STL implementation of
Timed/RecursiveTimedMutexwhenMSVC >= 19.36Fix the clang build for clang 14
Fix
HelloWorldDataSharingexample idlUse
FASTRTPS_NO_LIBon unittest root folderFix
Data Racewhen updating liveliness changed in WLPFix TCP sender resources creation
Fix flow controllers unit tests compilation when using
Fast CDRfrom thirdpartyAdd XML parser
bit_boundbounds checkFix branch selection on Github CI
Better handling of trigger events in docs CI
Use
SO_EXCLUSIVEADDRUSEfor Win32 unicast listening socketsFix
PubSubAsReliabletestFix
FileWatchTestfor Github windows CIFix mac address overflow on windows
Fix missing mandatory attribute check in XML parser struct type
Update TLS unit test certificates
Add missing thread include
Add tests for reconnection with same
GUIDNotify data-sharing listener at the end of a successful matching in intraprocess
Fix TCP deadlock on channel reuse
TCP non-blocking send
Fix DNS filter in CMakeLists file for tests
Fix bad-free when receiving malformed DATA_FRAG submessage
Fix memory problem when ciphering payload
Fix CVE-2023-50257
Fix build with TLS, but not security
Fix std::move warning
Update PR template to include check for PR description, title and backports
Fix data race on writer destruction while sending heartbeat
Fix comparison in
remove_from_pdp_reader_historyFix data race in PDPListener and SecurityManager
Fix an uninitialized value when building with GCC 13.2.0
Fix max clash with Windows CI
Discard already processed samples on PDPListener
Remove unnecessary TCP warning
Fix wrong log info messages on TCP
Revert “TCP deadlock on channel reuse”
Return const reference in
get_log_resourcesAdd a keyed fragmented change to the reader data instance only when it is completed
Fix and refactor Windows Github CI
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.11.2 (EOL)¶
This release includes the following improvements:
Improve Shared Memory resilience to crashing participants
User configuration for Shared Memory metatraffic
Performance improvements on intraprocess and data-sharing
This release includes the following fixes:
Remove Mutex from TimedEventImpl
Replace uint64_t by 8 in
alignasspecifierFix XMLParser null-dereference in
parseLogConfig
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.11.1 (EOL)¶
This release includes the following improvements:
Correct CONTRIBUTING.md typo
Improve validation on PID_PROPERTY_LIST deserialization
Apply eProsima brand style to Fast DDS repository
Fix spelling mistake: SUBSTRACTION to SUBTRACTION
This release includes the following fixes:
Fixed long-standing reconnection issue on SHM transport
Added missing include
Fixed Boost handle usage regression
Fix StatelessWriter locators filtering
Avoid double definition of FASTDDS_ENFORCE_LOG_INFO
Explicitly register type object in ContentFilteredTopicExample
Properly handle zero-sized payloads on dynamic memory payload pools
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.11.0 (EOL)¶
This release includes the following features:
Ignore every local endpoint within the DomainParticipant preventing local matching.
Extend DynamicDataHelper API providing a
printoverload withstd::ostreamas parameter.TypeLookup Service settings.
Static Discovery XSD Schema.
This release includes the following improvements:
- Fast DDS improvements
Assign minimum available participant ID to new participants.
Export symbols correctly on ContentFilteredTopic.
Improve content filter expression parameters check and verbosity.
Check TCP headers endianness.
Security module: distinguished names (DN) comparison.
- Fast DDS deprecation
DDS:Crypto:AES-GCM-GMAC configuration using Property Policy QoS (security vulnerability).
- CI improvements
Include BitmapRange unit tests.
Support for running some tests in parallel.
Windows workflow.
- Build system
Improve CMake target loading. Removal of
FASTDDS_STATICCMake option.Avoid auto-linkage using CMake.
- Dependencies
Upgrade internal type supports using latest Fast DDS-Gen release v2.5.1.
Upgrade Fast CDR submodule to v1.1.0.
- Examples
Admit XML configuration files in AdvanceConfigurationExample.
New Discovery Server example.
This release includes the following fixes:
- Fast DDS bugfixes
Fix crash when creating two participants with the same fixed participant ID.
Fix crash when calling
on_requested_deadline_missed()callback.Fix crashes caused by not capturing every Fast CDR exception.
Correctly resolve aliases in DDSSQLFilter.
Wait for log background thread initialization on the first queued entry.
Fix data race when accessing
WRITE_PARAM_DEFAULTstatic variable.Fix partition copy in QoS.
Fix Data-Sharing delivery when data_count is zero.
Fix API Fast DDS v2.10.0 API break calling correctly.
on_participant_discovery()callbacks.Security module: Honor Allow Unauthenticated Participants flag.
Fix concurrent access to
load_profiles().Fix UBSan (Undefined Behavior Sanitizer) issues.
Improve Doxygen documentation about DomainParticipantListener discovery callbacks.
- XSD fixes
Set TransportDescriptor kind parameter as optional.
Correctly assign QoS to the proper endpoint.
Add missing tags.
- CI fixes
Fix null dereference in fuzzer code.
Limit Thread Sanitizer memory usage to prevent runner shutdown.
Use correct time unit in latency tests.
Run communication tests.
- Examples
Correct DDS entity deletion order.
- Installer generation
Add documentation fallback when the documentation tag is not found.
- Repository
Remove 2.1.x as active branch.
Remove 2.8.x as active branch.
- Non Tier 1 support
Fix build on MSVC 19.36.
Forward compatibility with Boost inter-process 1.74+.
Include missing header files required for compiling with GCC 13.
QNX build fixes.
Fix build issues in RPM systems.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.9 (EOL)¶
Version 2.9.2 (EOL)¶
This release includes the following ABI compatible improvements:
- Library improvements
Improve behavior when
STRICT_REALTIMECMake option is not enabled.Using functors for
for_matched_readersparameter.Improve auto GAPs in Data Sharing.
Improve content filter expression parameters check and verbosity.
Improve validation on
PID_PROPERTY_LISTdeserialization.
- Fast DDS CLI
Handle
SIGTERMsignal.
This release includes the following bugfixes:
- Security vulnerability
Fix chain of trust issues with a single CA certificate.
- Library bugfixes
Fix RTPS StatelessWriter ACK check.
UBSan (Undefined Behavior Sanitizer) fixes.
Fix backwards compatibility using SHM communication.
Correctly handle builtin endpoint mask.
Fix crash when enabling DisablePositiveACKsQosPolicy with remote best-effort readers.
Validity check for first sequence number.
ASAN (Address Sanitizer) fixes.
Correctly assign multicast port to multicast initial peers.
Protect against uncaught exception in SHM segment creation.
Initial acknack backoff.
Fix crash when calling
on_requested_deadline_missed()callback.Security module: Honor
allow_unauthenticated_participantsflag.Fix crashes caused by not capturing every Fast CDR exception.
Correctly resolve aliases in DDSSQLFilter.
Wait for log background thread initialization on the first queued entry.
Fix partition copy in QoS.
Fix Data-Sharing delivery when
data_countis zero.Fix StatelessWriter locators filtering.
Avoid double definition of
FASTDDS_ENFORCE_LOG_INFO.Fixed long-standing reconnection issue on SHM transport.
- CI fixes
Fix test building when using
GTEST_INDIVIDUALCMake option.Use correct time unit in latency tests.
- Synchronization fixes
Take mutex when removing local reader in WLP.
Fix data races in SecurityManager authentication process.
- Example fixes
Avoid creating entities within callbacks in DynamicHelloWorldExample.
Remove Asio dependency from DeadlineQosExample.
Correct DDS entity deletion order.
Explicitly register TypeObject in ContentFilteredTopicExample.
- Installer generation
Add documentation fallback when the documentation tag is not found.
- Non Tier 1 Support
Fix build for GCC5.
Fix build on MSVC 19.36.
Include right header when building for iOS.
Forward compatibility with Boost inter-process 1.74+.
Include missing header files required for compiling with GCC13.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.9.1 (EOL)¶
This release includes the following bugfixes:
- Synchronization fixes:
Fix deadlock in Writer Liveliness Protocol (WLP) using intraprocess.
Fix data race in
DomainParticipant::set_listener().Fix deadlock on TLS closure.
- Other fixes:
Fix notification lost.
Fix
total_read_to be consistent with Reader’s History afterDataReader::get_first_untaken_info().Use shared pointers for internal singletons.
Support CCache on Windows.
Avoid null dereference on fuzzer.
Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.9.0 (EOL)¶
This minor release includes several new features (new log macros to avoid conflicts with external libraries), behavior
change (default memory management policy is no longer
PREALLOCATED_MEMORY_MODE,
enable by default Fast DDS Statistics module but only taking statistics metrics if the corresponding Statistics
DataWriter is enabled), performance improvements, CI improvements (including address sanitizer jobs), and several bug
fixes.
Note
Mind that, even though this release is API compatible with previous v2.x versions, it is NOT ABI compatible with previous versions. This means that applications upgrading Fast DDS to v2.9.0 will require recompilation, though not source code modification.
Note
It is also advisable to regenerate the type support from the IDL files using Fast DDS-Gen v2.3.0. Furthermore, if upgrading to v2.9.0, it is also recommended to upgrade Fast CDR to v1.0.26.
This release includes the following features:
New log macros
EPROSIMA_LOG_INFO,EPROSIMA_LOG_WARNINGandEPROSIMA_LOG_ERROR.Add
ENABLE_OLD_LOG_MACROSCMake option to support disabling the compilation of previous log macros.
This release includes the following behavior changes:
Default memory management policy set to
PREALLOCATED_WITH_REALLOC_MEMORY_MODE.Statistics metrics are only calculated/accumulated when their corresponding DataWriter is enabled in Fast DDS Statistics Module.
Enable
FASTDDS_STATISTICSCMake option by default.
This release includes the following improvements:
- CI improvements:
Add address sanitizer job for Fast DDS library.
Add address sanitizer job for Discovery Server test suite.
Upgrade Fast CDR submodule.
This release includes the following bugfixes:
- Synchronization fixes:
Fix deadlock when removing remote DomainParticipants by expired liveliness when using Security.
Protect
DomainParticipant::set_listener()avoiding null reference.Fix data race on
WriterProxy::stopwhile TimedEvent is being triggered.Protect creation/destruction of Boost’s
named_mutex.
- CI fixes:
Fix Statistics Module test suite.
Fix recurring data races in test suite.
Fix thread sanitizer job keeping Ubuntu 20.04.
- Other:
Fix Topic creation when registering a type name different from the internal TypeSupport name.
Fix communication with asymmetric Ignore Participant flags.
Several dependencies fixes upgrading to Ubuntu 22.04.
Disable error logged when DomainParticipant profile is not found.
Fix CMake for Fast DDS use as submodule.
Upgrade internal type supports generated with Fast DDS-Gen v2.3.0.
Other minor fixes.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.8 (EOL)¶
Version 2.8.2 (EOL)¶
This release includes the following improvements:
Add ASAN CI tests for Fast DDS and Discovery Server
Mirror master onto both 2.8.x & 2.9.x
Doxygen documentation: add deprecation notice to ThroughputControllerDescriptor
Several fixes to remove warnings in Ubuntu Jammy (22.04)
Improve behavior when HAVE_STRICT_REALTIME is not set
Using functors in StatefulWriter.cpp for_matched_readers
Fix build on old compilers
Avoid creation of DynamicTypes on example
Implement a validity check for firstSN
This release includes the following bugfixes:
Fix bug in Topic creation with different Type Name
Fix tests failing with subprocess aborted error
Fix communication with asymmetric ignoreParticipantFlags
Added ignore_participant_flags() to Blackbox_FastRTPS PubSubReader.
Fix Deadlock in remove_participant (ResourceEvent thread) when compiled WITH_SECURITY
Fix failed tests when compiling with statistics enabled
Fix Windows StatistisQosTests.cpp linkage and Failed test
Fixing deadlock in WLP
Fix notification lost
Fix StatelessWriter ACK check
Fix total_unread_ consistent with reader’s history upon get_first_untaken_info()
Fix chain of trust issues
Fixed StatisticsSubmessageData unaligned access
Fix build error when GTEST_INDIVIDUAL is OFF
Correctly handle builtin endpoints mask
Added missing mutex to WLP::remove_local_reader
Handle SIGTERM in fast discovery server
Improve auto gaps in data sharing
Replaced SecurityManager temporary ProxyDatas with ProxyPools
Fix crash when disable_positive_acks is enable and the remote reader is best-effort
Protect from uncaught exception during SHM Segment creation
Fix asio dependency
Include the right header when building for iOS
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.8.1 (EOL)¶
This release includes the following bugfixes:
- Statistics module fixes:
Increase statistics DataWriter history.
Fix Statistics module CI.
Install Statistics IDL file.
Fix for building in old compilers.
Fix core dumped in
delete_contained_entities().
- Address sanitizer fixes:
Add ASAN CI job and
SANITIZECMake option.Fixes reported by address sanitizer.
- Synchronization fixes:
Fix data races when creating DataWriters.
Ensure
shared_muteximplementation is consistent throughout supported platforms.
- Other fixes:
Include missing ReadCondition header.
Fix selection of output locators.
Fix null-dereference on
parseXMLEnumDynamicType.Include
2.8.xbranch release support.Send GAPs correctly when using separate sending.
Fixes for building in old compilers.
Fix
DataReader::read_next_instance()andDataReader::take_next_instance()implementation.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.8.0 (EOL)¶
This minor release includes several new features, performance improvements (especially in the case of topics with many instances), CI improvements (including the ability to run the CI in Android emulators or devices), and several bug fixes.
Note
Mind that, even though this release is API compatible with previous v2.x versions, it is NOT ABI compatible with previous versions. This means that applications upgrading Fast DDS to v2.8.0 will require recompilation, though not source code modification.
Note
It is also advisable to regenerate the type support from the IDL files using Fast DDS-Gen v2.2.0. Furthermore, if upgrading to v2.8.0, it is also recommended to upgrade Fast CDR to v1.0.25.
This release includes the following features:
Full Ownership and OwnershipStrength QoS support
UDPv6 support for fast-discovery-server tool and ROS_DISCOVERY_SERVER
Add API to createRTPSWriter with a custom pool
Add
std::string::compareAPI tofixed_stringGet WAN address API in TCPv4 transport descriptors
Adding
DomainParticipantFactory::get_shared_instance()API
This release includes the following improvements:
- Performance improvements:
Skip writer_removed processing for unaccounted instances
Improve GUID_t operator< performance
- CI improvements:
Add optional parameters to thread-sanitizer job
Enable Android testing on device
- Examples:
Update BasicConfigurationExample to allow set up TTL
Add Guid info to BasicConfiguration Example
cout
- Internal implementation improvements:
Add script to generate idl files
Group set_qos_from_attributes free functions into a separate file
Update script for generating idl files
Set
last_heartbeat_count_private member of WriterProxy as atomic
Android Improvements
Upgrade Fast CDR submodule
This release includes the following bugfixes:
- Synchronization fixes:
Fix datarace using writer’s locator selectors
Add lock guard at changing SHM port listener status members
Add atomic variable to prevent datarace in FlowController
Disable RTPSParticipantImpl after removing it from RTPSDomain participants list
Fixing datarace on listener callbacks
Protect access to reader listeners
Use thread-safe localtime function in unix distributions
Fixed usage of uninitialised ifreq
Adding protection to id_counter access
- Repository fixes:
Fix spelling mistake
Add python3 dependency to package.xml
- Other:
Fix null dereference on parseXMLBitsetDynamicType
Change internal include path of nlohmann/json header file
Instance allocation consistency
Fix complex member printing for DynamicDataHelper
Fix initialization order in mock
Upgraded internal type supports
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.7 (EOL)¶
Version 2.7.2 (EOL)¶
This release includes the following improvements:
Skip
writer_removedprocessing for unaccounted instances.Improve
GUID_toperator<performance.
This release also includes the following bugfixes:
Fix complex member printing for DynamicDataHelper.
Add python3 dependency.
Fix selection of output locators.
Fix data races when creating DataWriters.
Fix null dereferences on XML parser.
Send GAPs correctly when using separate sending.
Install Statistics IDL file.
Fixes for building in old compilers.
Fix several deadlocks.
Fix communication with asymmetric Ignore Participant flags.
Fix notification lost.
Fix StatelessWriter ACK check.
Fix
total_read_to be consistent with Reader’s History afterDataReader::get_first_untaken_info().Fix doxygen documentation adding deprecated to
ThroughputControllerDescriptor.Several dependencies fixes upgrading to Ubuntu 22.04.
Ensure
shared_muteximplementation is consistent throughout supported platforms.Fix StatisticsSubmessageData unaligned access.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.7.1 (EOL)¶
This release includes the following features in an ABI compatible way:
Checking STATIC EDP XML Files by means of
DomainParticipantFactory::check_xml_static_discovery().ReadCondition implementation.
This release includes the following improvements:
Thread sanitizer CI.
Overload
get_unread_count().Improve read/take performance when using topic with a great number of keys.
Improve rediscovery on lossy environments.
New CMake option USE_THIRDPARTY_SHARED_MUTEX.
Notify changes in bulk in RTPS readers.
This release includes the following bugfixes:
Fix Fast CDR submodule update to v1.0.24.
Fix access to some pointers.
Fixed validation on
ParameterPropertyList_t.Fixed acknowledgement in DataSharing.
Fixed wrong usage of
std::remove_if.Suppress OpenSSL 3.0 warnings.
Fixed race condition in Logging module.
Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.7.0 (EOL)¶
This release includes the following improvements:
Support for DDS SampleRejectedStatus API
Support for DDS DataWriter methods:
DataWriter::write_w_timestamp()
DataWriter::register_instance_w_timestamp()
DataWriter::unregister_instance_w_timestamp()
DataWriter::dispose_w_timestamp()
Support for DDS
find_topic()Support for GCC 12
Upgrade CMake minimum requirement to 3.16.3
Add Windows DLL support to Dynamic Types API
Some bugfixes are also included:
Deadlocks and data races
Move deprecated OpenSSL cleanup function to match the right version
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.5 (EOL)¶
Version 2.5.2 (EOL)¶
This release includes the following improvements:
Support lowercase keywords and hexadecimal values on SQL filter.
Support for GCC 12.
This release includes the following bugfixes:
Fix MatchedStatus last_*_handle.
Fix recommended statistics DataReaderQos to enable backwards compatibility.
Fix deadlocks and data races.
Fix empty partition validation checks.
Fix corner case with reliable writers and samples with a huge number of fragments.
Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.5.1 (EOL)¶
This release includes the following improvements:
Release lifecycle.
This release includes the following bugfixes:
XML parser fixes.
Discovery Server fixes.
Fix DataSharing sample validation.
PKCS#11 support fixes.
Test fixes.
Doxygen documentation fixes.
GAP message fix.
Enable memory protection on DataSharing readers.
TCP reconnection issues.
Fix dynamic network interfaces feature.
Several Security module fixes.
STRICT_REALTIME fix.
Suppress OpenSSL 3.0 warnings.
Move optionparser to thirdparty.
Thread-safe access to endpoints collections.
MemberDescriptor fully qualified name.
Setting QoS fix.
Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.5.0 (EOL)¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
This minor release includes the following features:
Support for PKCS#11 format URIs for private keys
Added interfaces for content filter APIs
New API on DataWriter to wait for a specific instance to be acknowledged
Added interfaces for concatenation of transports
Allow disabling piggyback heartbeat on XML and DataWriter QoS
New basic configuration example
It also includes the following improvements:
Working implementation of instance_state and view_state
Allow zero-valued keys
Made some type aliases public to ease python bindings integration
Improved performance by avoiding unnecessary payload copies for samples that are going to be rejected
Removed unnecessary headers from Log module public headers
Add support for Key annotation in TypeObjectFactory
Only export public symbols on non-windows platforms
Some documentation improvements
Some important bugfixes are also included:
Fixed payload pool handling on EDPSimple destructor
Fixed null dereference on XML parser
Correctly export XTypes related methods on Windows
Ensure correct boost singleton destruction order
Avoid warning when environment file filename is empty
Correctly set GUID of DataWriter and DataReader upon creation
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.4 (EOL)¶
Version 2.4.2 (EOL)¶
This release includes the following improvements:
Enable memory protection on DataSharing readers
Add const overload of
DataReader::guid()Set recommended statistics DataReaderQos to
PREALLOCATED_WITH_REALLOCAllow fully qualified name on MemberDescriptor
This release includes the following bugfixes:
Fix and refactor EDPSimple destructor
Fix several build warnings on certain platforms
Fix OSS fuzz issues
Fix TCP synchronization issues
Correct reporting of MatchedStatus
last_*_handleEnsure correct boost singleton destruction order
Fix inserting minimum CacheChange_t in GAP message
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 2.4.1 (EOL)¶
This release includes the following improvements:
Fixed several flaky tests
Improved bandwidth usage of GAPs and HEARTBEATs
Correctly implement delete_contained_entities
Use native inter-process on Windows
Improved performance of unregister_instance
Improved OSS-fuzz integration
Support for partitions on DataWriterQoS and DataReaderQoS
Some documentation improvements
Removed unused macro to avoid naming clashes
This release includes the following bugfixes:
Avoid bad_node_size exception when cross building
Fixed build on old compilers
Fixed buffers exhaustion when compiled with statistics
Fixed runtime addition of Discovery Servers
Fixed dangling sample references with big data
Fixed history record issues with persistence
Correctly disable DataReader on destruction
Fixed alignment issues on XTypes QoS policies serialization
Fixed reconnection to Discovery Server
Correctly use builtin publisher for statistics DataWriters
Fixed various GCC-11 warnings
Use only public APIs from foonathan::memory
Fixed installation directories for DDS examples
Fixed read after free on security code
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.4.0 (EOL)¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
This minor release includes the following features:
Conditions and Wait-sets implementation.
It also includes the following improvements:
Allow setting custom folder for data-sharing files.
Allow setting persistence guid with static discovery.
Check for NDEBUG in logInfo.
Removed old unused CMake code.
Fixed TLS behavior on TCP example.
Prepare API for easy integration of python bindings.
Improved statistics performance.
Some important bugfixes are also included:
Fixed order of returned samples on topics with keys.
Allow updating partitions to an empty set.
Correctly propagate DomainParticipantQos updates.
Avoid a volatile data-sharing reader to block a writer.
Correctly give priority to intra-process over data-sharing.
Fixed reallocation issue on LivelinessManager.
Fixed deadline issue on volatile DataWriter
Fixed STRICT_REALTIME silently not active with Unix POSIX systems.
Fixed build errors with OpenSSL 3.0
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3 (EOL)¶
Version 2.3.6 (EOL)¶
This release includes the following improvements:
Improve rediscovery on lossy environments.
Upgrade CMake minimum requirement to 3.13.
Improve
Guid_toperator < performance.
This release includes the following bugfixes:
Fixed validation on
ParameterPropertyList_t.Add python3 dependency to package.xml.
Fix null references and uncaught exceptions on XML parser.
Install Statistics IDL file.
Fix data races when creating DataWriters.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.5 (EOL)¶
This release includes the following improvements:
Fixed several flaky tests.
Use native inter-process on Windows.
Support for partitions on DataWriterQoS and DataReaderQoS.
Support for GCC 12.
Correctly implement delete_contained_entities.
This release also includes the following bugfixes:
Fixed deadline issue on volatile DataWriter.
Allow updating partitions to an empty set.
Fixed order of returned samples on topics with keys.
Fixed issues in LivelinessManager.
Correctly give priority to intra-process over data-sharing.
Avoid bad_node_size exception when cross-building.
Fixed build errors with OpenSSL 3.0.
Avoid a volatile data-sharing reader to block a writer.
Fixed history record issues with persistence.
Correctly disable DataReader on destruction.
Fixed various GCC 11 warnings.
Fixed payload pool handling on EDPSimple destructor.
Fixed read after free on security code.
Fixed null dereference on XML parser.
Ensure correct boost singleton destruction order.
Enable memory protection on DataSharing readers.
TCP reconnection issues.
MemberDescriptor fully qualified name.
Fix recommended statistics DataReaderQos to enable backwards compatibility.
Fixed dangling sample references with big data.
Fixed deadlocks and data races.
Fixed reconnection to Discovery Server.
Other minor fixes.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.4 (EOL)¶
This release includes the following improvements:
Support of googletest using colcon
Network latency reports source participant
Update Fast DDS Gen to v2.0.2
This release includes the following bugfixes:
Fix mutex lock count on
PDPListenerLimit
SequenceNumberSetnumber of bits on deserializationFix segmentation fault on discovery server
Fix deadlock with security and timers
Fix bug using not protected code in a test
Fix deadlock with
LivelinessManagerFix interval loop on events
Fix run event when was cancelled
Validate sequence range on
CDRMessage::readSequenceNumberSetFix subscription throughput data generation
Allow examples to build on QNX
Fix code on SHM clean
Accept Statistics DataWriters in Discovery Server
Fix read/take behavior when a future change is found
Correctly handle deserialization errors on
read_next_sample()/take_next_sample()Fixing
SequenceNumberSet_tdeserializationProper history clean up when a reader unmatches a writer
Unprotected code loaning samples
Fix publication throughput statistic on volatile writers
Fix Fast DDS CLI server name
Several fixes in examples and tests
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.3 (EOL)¶
This release includes the following improvements:
Added more durability kinds in Static Discovery xml parser
Explicitly enable/disable data-sharing on performance tests
Allow fully qualified name in TypeDescriptor
Added missing DynamicData::get_union_id() method
Change log severity in DiscoveryServer first announcement
Several corrections to README
This release includes the following bugfixes:
Fixed warnings and segfaults on 32-bit platforms
Fixed UDPv6 behavior
Fixed persistence guid issue on statistics writers
Fixed static linking with open SSL
Fixed statistics header file inclusion
Fixed build on RedHat systems
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.2 (EOL)¶
This release includes the following feature:
Statistics Module
It also includes the following improvements:
Update Asio submodule and avoid exporting Asio API
Improve Windows installers
Ease Google Fuzz integration
Improve Doxygen documentation on lifetime of pointers created with
RTPSDomainUpdate Fast CDR to v1.0.21
This release includes the following bugfixes:
Add a correct multicast address for UDPv6
Recover from out-of-sync TCP datagrams
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.1 (EOL)¶
This release includes several bugfixes and improvements:
Added Fast DDS Statistics Module implementation
Fixed alignment issues on generated code calculation of maximum serialized size
Fixed calculation of data-sharing domain id
Fixed issues on data-sharing with volatile writers
Fixed build issues on old compilers
Fixed some tests when the library is built without security
Fixed and exposed pull mode on writers
Fixed handling of –data_sharing on latency test
Fixed calculation of memory pools sizes on debug builds
Correctly update memory policy on writers and readers
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.3.0 (EOL)¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
This release adds the following features:
It also includes the following improvements:
Data-sharing delivery internal refactor
Additional metadata on persistence databases
Refactor on ReturnCode_t to make it switch friendly
Performance tests refactored to use DDS-PIM high-level API
Receive const pointers on delete_xxx methods
Discovery server improvements
Made SOVERSION follow major.minor
Some important bugfixes are also included:
Fixed shared memory usage on QNX
Fixed reference counting on internal pools
Fixed singleton destruction order
Fixed interoperability issues with x-types information
Fixed recovery of shared memory buffers
Lifespan support in persistent writers
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.2 (EOL)¶
Version 2.2.1 (EOL)¶
This release includes the following improvements:
Data-sharing delivery internal refactor.
Performance tests refactored to use DDS-PIM high-level API.
Discovery server improvements.
This release includes the following bugfixes:
Fixed reference counting on internal pools.
Fixed singleton destruction order.
Fixed default multicast locators.
Fixed interoperability issues with x-types information.
Fixed Reader history issues.
Fixed data races issues.
Fixed shared memory issues.
Fixed heartbeat and ACK issues.
Fixed LivelinessManager issues.
Fixed TCP reception synchronization.
Fixed build issues on old compilers.
Allow modifying Partition QoS in enabled entities.
Other minor fixes and improvements.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.2.0 (EOL)¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
This release adds the following features:
Data Sharing delivery (avoids transport encapsulation for localhost communications)
Complete DDS-PIM high-level API declarations
Extension APIs allowing zero-copy delivery (both intra-process and inter-process)
Upgrade to Quality Level 1
It also includes the following improvements:
Code coverage policy
Added several tests to increase coverage
Increased GUID uniqueness
Allow logInfo messages to be compiled on build types other than debug
Some important bugfixes are also included:
Fixed timed events manager race condition
Fixed payload protection issues with SHM transport
Writers correctly handle infinite resource limits on keyed topics
Fixed unsafe code on AESGCMGMAC plugin
Several fixes for IPv6 (whitelists, address parser)
Fixes on liveliness timing handling
Fixed warnings building on C++20
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from any older version, regenerating the code is highly recommended.
Version 2.1 (EOL)¶
Version 2.1.4 (EOL)¶
This release includes the following improvements:
Improve auto GAPs in Data Sharing
Improve behavior when
STRICT_REALTIMECMake option is not enabledHandle SIGTERM in fast discovery server CLI
This release includes the following bugfixes:
Select correct listener for on_requested_deadline_missed
Correctly assign multicast port to multicast initial peers
Fix chain of trust issues with a single CA certificate
Correctly handle builtin endpoints mask
Fix build on MSVC 19
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.1.3 (EOL)¶
This release includes the following improvements:
Improve rediscovery on lossy environments.
This release includes the following bugfixes:
Fixed validation on
ParameterPropertyList_t.Fixed
SequenceNumberSet_tdeserialization.Add python3 dependency to package.xml.
Fix data races when creating DataWriters.
Fix deadlock when removing remote DomainParticipants by expired liveliness when using Security.
Fix communication with asymmetric Ignore Participant flags.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.1.2 (EOL)¶
This release includes the following improvements:
Allow fully qualified name in TypeDescriptor.
Use native inter-process on Windows.
Support for GCC 12.
Support of googletest using colcon.
This release also includes the following bugfixes:
Fixed recovery of shared memory buffers.
Fixed issues in LivelinessManager.
Fixed default multicast locators.
Fixed TCP issues.
Fixed deadlocks and data races.
Fixed deadline issue on volatile DataWriter.
Avoid bad_node_size exception when cross-building.
Fixed order of returned samples on topics with keys.
Allow updating partitions to an empty set.
Suppress OpenSSL 3.0 warnings.
MemberDescriptor fully qualified name.
Fixed history record issues with persistence.
Fixed reconnection to Discovery Server.
Other minor fixes.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.1.1 (EOL)¶
This release includes the following bugfixes:
Fixed race condition on security handshake
Fixed SHM data corruption when using both payload and sub-message protection
Fixed some interoperability issues
Fixed race condition on timed-events thread
Fixed usage of SHM on QNX systems
It also includes the following improvements:
Increased uniqueness of GUID prefix
Discovery server improvements
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.1.0 (EOL)¶
This minor release is API compatible with the previous minor release, but introduces ABI breaks on two of the three public APIs:
Methods and attributes have been added on several classes of the DDS-PIM high-level API, so indexes of symbols on dynamic libraries may have changed.
Methods and attributes have been added on several classes of the RTPS low-level API, so indexes of symbols on dynamic libraries may have changed.
Old Fast-RTPS high-level API remains ABI compatible.
Users of the RTPS low-level API should also be aware of the following API deprecations:
History::reserve_Cache has been deprecated
Methods RTPSWriter::new_change or RTPSReader::reserveCache should be used instead
History::release_Cache has been deprecated
Methods RTPSWriter::release_change or RTPSReader::releaseCache should be used instead
This release adds the following features:
Support persistence for large data
Added support for on_requested_incompatible_qos and on_offered_incompatible_qos
SKIP_DEFAULT_XML environment variable
Added FORCE value to THIRDPARTY cmake options
New log consumer (StdOutErrConsumer)
Added methods to get qos defined in XML Profile
Support for persistence on TRANSIENT_LOCAL
It also includes the following improvements:
Internal refactor for intra-process performance boost
Allow usage of foonathan/memory library built without debug tool
Large data support on performance tests
Reduced flakiness of several tests
Some important bugfixes are also included:
Fixed behavior of several DDS API methods
Fixed interoperability issues with RTI connext
Fixed DLL export of some methods
Avoid redefinition of compiler defined macros
Fixed some intra-process related segmentation faults and deadlocks
Fixed large data payload protection issues on intra-process
Fixed C++17 and VS 2019 warnings
Fixed linker problems on some platforms
Fixed transient local retransmission after participant drop
Fixed assertion failure on persistent writers
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0 (EOL)¶
Version 2.0.3 (EOL)¶
It also includes the following improvements:
Increased uniqueness of GUID prefix (#1648)
Upgrade Fast CDR to v1.0.20 (#1793)
This release includes the following bugfixes:
Fixed some race conditions (#1540, #2023)
Fixed SHM issues (#1644, #1895, #2266)
Fixed some interoperability issues (#1624, #1752, #1849)
Fixed Discovery Server 2.0 issues (#1639, #1651, #1761, #1796)
Fixed several issues on QNX systems (#1744, #1773, #1776)
Fix singleton destruction order (#1758)
Fix heartbeat and ACK issues (#1865)
Fix issues in LivelinessManager (#1872, #2147)
Fix multicast issues (#1966, #1905)
Fix TCP reception synchronization (#1981)
XTypes standard compliance and fixes (#2006, #2278)
Other minor fixes (#1558, #1734, #1814, #1935, #1978, #2121)
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.2 (EOL)¶
This release includes the following improvements:
Improve QNX support
Security improvements
Fast DDS Quality Declaration (QL 2)
Large traffic reduction when using Discovery Server (up to 85-90% for large deployments)
Configuration of Clients of Discovery Server using an environment variable
A CLI for Fast DDS:
This can be used to launch a discovery server
Clean SHM directories with one command
Shared memory transport enabled by default
Solved edge-case interoperability issue with CycloneDDS
Add package.xml
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.1 (EOL)¶
This release includes the following bug fixes:
Fixed sending GAPs to late joiners
Fixed asserting liveliness on data reception
Avoid calling
OpenSSL_add_all_algorithms()when not required
Other improvements:
Fixing warnings
PRs in merge order: #1295, #1300, #1304, #1290, #1307.
Note
If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.0 (EOL)¶
This release has the following API breaks:
eClock API, which was deprecated on v1.9.1, has been removed
eprosima::fastrtps::rtps::RTPSDomain::createParticipant methods now have an additional first argument domain_id
Data member domainId has been removed from eprosima::fastrtps::rtps::RTPSParticipantAttributes and added to eprosima::fastrtps::ParticipantAttributes
Users should also be aware of the following deprecation announcement:
All classes inside the namespace eprosima::fastrtps should be considered deprecated. Equivalent functionality is offered through namespace eprosima::fastdds.
Namespaces beneath eprosima::fastrtps are not included in this deprecation, i.e. eprosima::fastrtps::rtps can still be used)
This release adds the following features:
Added support for register/unregister/dispose instance
Added DDS compliant API. This new API exposes all the functionality of the Publisher-Subscriber Fast RTPS API adhering to the Data Distribution Service (DDS) version 1.4 specification
Added Security Logging Plugin (contributed by Cannonical Ltd.)
Bump to FastCDR v1.0.14
It also includes the following bug fixes and improvements:
Support for OpenSSL 1.1.1d and higher
Support for latest versions of gtest
Support for FreeBSD
Fault tolerance improvements to Shared Memory transport
Fixed segfault when no network interfaces are detected
Correctly ignoring length of PID_SENTINEL on parameter list
Improved traffic on PDP simple mode
Reduced CPU and memory usage
Version 1.10 (EOL)¶
Version 1.10.1 (EOL)¶
This release includes the following improvements:
Add new CMake option: SHM_TRANSPORT_DEFAULT. Shared Memory (SHM) Transport disabled by default.
Comply with the RTPS standard concerning PID_SENTINEL.
Support for OpenSSL 1.1.1d.
This release includes the following bugfixes:
Fix crash when there are no network interfaces.
Several Shared Memory Transport fixes.
Other minor fixes.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 1.10.0 (EOL)¶
This release adds the following features:
New built-in Shared Memory Transport
Transport API refactored to support locator iterators
Added subscriber API to retrieve info of first non-taken sample
Added parameters to fully avoid dynamic allocations
History of built-in endpoints can be configured
Bump to FastCDR v1.0.13.
Bump to Fast-RTPS-Gen v1.0.4.
Require CMake 3.5 but use policies from 3.13
It also includes the following bug fixes and improvements:
Fixed alignment on parameter lists
Fixed error sending more than 256 fragments.
Fix handling of STRICT_REALTIME.
Fixed submessage_size calculation on last data_frag.
Solved an issue when recreating a publishing participant with the same GUID.
Solved an issue where a publisher could block on write for a long time when a new subscriber (late joiner) is matched, if the publisher had already sent a large number of messages.
Correctly handling the case where lifespan expires at the same time on several samples.
Solved some issues regarding liveliness on writers with no readers.
Correctly removing changes from histories on keyed topics.
Not reusing cache change when sample does not fit.
Fixed custom wait_until methods when time is in the past.
Several data races and ABBA locks fixed.
Reduced CPU and memory usage.
Reduced flakiness of liveliness tests.
Allow for more use cases on performance tests.
Several bug fixes on discovery server:
Fixed local host communications.
Correctly trimming server history.
Fixed backup server operation.
Fixed timing issues.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 1.9 (EOL)¶
Version 1.9.5 (EOL)¶
This release includes the following improvements:
Propagate serialization error when reading samples from Subscriber History.
Improvements in test suite.
Improvements to reduce memory consumption.
Update CMake (3.5) using newer policies.
Improve PDP StatefulWriter announcement.
Performance improvements.
Message receiver improvements.
QoS Policies improvements.
This release includes the following bugfixes:
Fix compiler warnings in Windows when building the test suite.
Fix several data races.
Fix History issues.
Fix errors when sending data fragments.
Fix strict real-time behavior.
Fix in Discovery Server.
Fix CMake option.
Fix interoperability issues.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.9.4 (EOL)¶
This release adds the following features:
Intra-process delivery mechanism is now active by default.
Synchronous writers are now allowed to send fragments.
New memory mode DYNAMIC_RESERVE on history pool.
Performance tests can now be run on Windows and Mac.
XML profiles for requester and replier.
It also includes the following bug fixes and improvements:
Bump to FastCDR v1.0.12.
Bump to Fast-RTPS-Gen v1.0.3.
Fixed deadlock between PDP and StatefulReader.
Improved CPU usage and allocations on timed events management.
Performance improvements on reliable writers.
Fixing bugs when Intra-process delivery is activated.
Reducing dynamic allocations and memory footprint.
Improvements and fixes on performance tests.
Other minor bug fixes and improvements.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.9.3 (EOL)¶
This release adds the following features:
Participant discovery filtering flags.
Intra-process delivery mechanism opt-in.
It also includes the following bug fixes and improvements:
Bump to Fast-RTPS-Gen v1.0.2.
Bring back compatibility with XTypes 1.1 on PID_TYPE_CONSISTENCY.
Ensure correct alignment when reading a parameter list.
Add CHECK_DOCUMENTATION cmake option.
EntityId_t and GuidPrefix_t have now their own header files.
Fix potential race conditions and deadlocks.
Improve the case where check_acked_status is called between reader matching process and its acknack reception.
RTPSMessageGroup_t instances now use the thread-local storage.
FragmentedChangePitStop manager removed.
Remove the data fragments vector on CacheChange_t.
Only call find_package for TinyXML2 if third-party options are off
Allow XMLProfileManager methods to not show error log messages if a profile is not found.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.9.2 (EOL)¶
This release includes the following feature:
Multiple initial PDP announcements.
Flag to avoid builtin multicast.
It also adds the following bug fixes and improvements:
Bump to Fast-RTPS-Gen v1.0.1.
Bump to IDL-Parser v1.0.1.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.9.1 (EOL)¶
This release includes the following features:
Fast-RTPS-Gen is now an independent project.
Header eClock.h is now marked as deprecated.
It also adds the following bug fixes and improvements:
Bump to FastCDR v1.0.11.
Installation from sources documentation fixed.
Fixed assertion on WriterProxy.
Fixed potential fall through while parsing Parameters.
Removed deprecated guards causing compilation errors in some 32 bits platforms.
addTOCDRMessage method is now exported in the DLL, fixing issues related with Parameters’ constructors.
Improve windows performance by avoiding usage of _Cnd_timedwait method.
Fixed reported communication issues by sending multicast through localhost too.
Fixed potential race conditions and deadlocks.
Eliminating use of acceptMsgDirectTo.
Discovery Server framework reconnect/recreate strategy.
Removed unused folders.
Restored subscriber API.
SequenceNumber_t improvements.
Added STRICT_REALTIME cmake option.
SubscriberHistory improvements.
Assertion of participant liveliness by receiving RTPS messages from the remote participant.
Fixed error while setting next deadline event in create_new_change_with_params.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.9.0 (EOL)¶
This release includes the following features:
Partial implementation of allocation QoS.
Implementation of Discovery Server.
Implementation of non-blocking calls.
It also adds the following bug fixes and improvements:
Added sliding window to BitmapRange.
Modified default behavior for unknown writers.
A Flush() method was added to the logger to ensure all info is logged.
A test for loading Duration_t from XML was added.
Optimized WLP when removing local writers.
Some liveliness tests were updated so that they are more stable on Windows.
A fix was added to CMakeLists.txt for installing static libraries.
A fix was added to performance tests so that they can run on the RT kernel.
Fix for race condition on built-in protocols creation.
Fix for setting nullptr in a fixed_string.
Fix for v1.8.1 not building with -DBUILD_JAVA=ON.
Fix for GAP messages not being sent in some cases.
Fix for coverity report.
Several memory issues fixes.
fastrtps.repos file was updated.
Documentation for building with Colcon was added.
Change CMake configuration directory if INSTALLER_PLATFORM is set.
IDL sub-module updated to current version.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.8 (EOL)¶
Version 1.8.5 (EOL)¶
This release includes the following bugfixes:
Fix Subscriber History to correctly notify late-joiners in case of KEEP_LAST, RELIABLE, and TRANSIENT_LOCAL.
Fix Writer History behavior when there are no matched readers.
Fix heartbeat and ACK issues.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.8.4 (EOL)¶
This release adds the following feature:
XML profiles for requester and replier
It also has the following important bug fixes:
Solved an issue when recreating a publishing participant with the same GUID (either on purpose or by chance)
Solved an issue where a publisher could block on write for a long time when, after a large number of samples have been sent, a new subscriber is matched.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen
Version 1.8.3 (EOL)¶
This release adds the following bug fixes and improvements:
Fix serialization of TypeConsistencyEnforcementQosPolicy.
Bump to Fast-RTPS-Gen v1.0.2.
Bump to IDL-Parser v1.0.1.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen
Version 1.8.2 (EOL)¶
This release includes the following features:
Modified unknown writers default behavior.
Multiple initial PDP announcements.
Flag to avoid builtin multicast.
STRICT_REALTIME compilation flag.
It also adds the following bug fixes and improvements:
Fix for setting nullptr in a fixed string.
Fix for not sending GAP in several cases.
Solve Coverity report issues.
Fix issue of fastddsgen failing to open IDL.g4 file.
Fix unnamed lock in AESGCMGMAC_KeyFactory.cpp.
Improve XMLProfiles example.
Multicast is now sent through localhost too.
BitmapRange now implements sliding window.
Improve SequenceNumber_t struct.
Participant’s liveliness is now asserted when receiving any RTPS message.
Fix leak on RemoteParticipantLeaseDuration.
Modified default values to improve behavior in Wi-Fi scenarios.
SubscriberHistory improvements.
Removed use of acceptMsgDirectTo.
WLP improvements.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen
Version 1.8.1 (EOL)¶
This release includes the following features:
Implementation of LivelinessQosPolicy QoS.
It also adds the following bug fixes and improvements:
Fix for get_change on history, which was causing issues during discovery.
Fix for announcement of participant state, which was sending ParticipantBuiltinData twice.
Fix for closing multicast UDP channel.
Fix for race conditions in SubscriberHistory, UDPTransportInterface and StatefulReader.
Fix for lroundl error on Windows in Time_t.
CDR & IDL submodules update.
Use of java 1.8 or greater for fastddsgen.jar generation.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.8.0 (EOL)¶
This release included the following features:
Implementation of IDL 4.2.
Implementation of DeadlineQosPolicy QoS.
Implementation of LifespanQosPolicy QoS.
Implementation of DisablePositiveACKsQosPolicy QoS.
Secure sockets on TCP transport (TLS over TCP).
It also adds the following improvements and bug fixes:
Real-time improvements: non-blocking write calls for best-effort writers, addition of fixed size strings, fixed size bitmaps, resource limited vectors, etc.
Duration parameters now use nanoseconds.
Configuration of participant mutation tries.
Automatic calculation of the port when a value of 0 is received on the endpoint custom locators.
Non-local addresses are now filtered from whitelists.
Optimization of check for acked status for stateful writers.
Linked libs are now not exposed when the target is a shared lib.
Limitation on the domain ID has been added.
UDP non-blocking send is now optional and configurable via XML.
Fix for non-deterministic tests.
Fix for ReaderProxy history being reloaded incorrectly in some cases.
Fix for RTPS domain hostid being potentially not unique.
Fix for participants with different lease expiration times failing to reconnect.
Known issues
When using TPC transport, sometimes callbacks are not invoked when removing a participant due to a bug in ASIO.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.7 (EOL)¶
Version 1.7.3 (EOL)¶
This release includes the following bugfixes:
Remove inline specifier from public method not defined in header file.
Fix FastRTPS-Gen version generation
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.7.2 (EOL)¶
This release fixes an important bug:
Allocation limits on subscribers with a KEEP_LAST QoS was taken from resource limits configuration and didn’t take history depth into account.
It also has the following improvements:
Vendor FindThreads.cmake from CMake 3.14 release candidate to help with sanitizers.
Fixed format of gradle file.
Some other minor bugs and performance improvements.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.7.1 (EOL)¶
This release included the following features:
LogFileConsumer added to the logging system.
Handle FASTRTPS_DEFAULT_PROFILES_FILE environment variable indicating the default profiles XML file.
XML parser made more restrictive and with better error messages.
It also fixes some important bugs: * Fixed discovery issues related to the selected network interfaces on Windows. * Improved discovery times. * Workaround ASIO issue with multicast on QNX systems. * Improved TCP transport performance. * Improved handling of key-only data submessages.
Some other minor bugs and performance improvements.
KNOWN ISSUES
Allocation limits on subscribers with a KEEP_LAST QoS is taken from resource limits configuration and doesn’t take history depth into account.
Note: If you are upgrading from a version older than 1.7.0, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.7.0 (EOL)¶
This release included the following features:
Security 1.1 compliance.
Also bug fixing, allocation and performance improvements.
Note: If you are upgrading from an older version, it is required to regenerate generated source from IDL files using fastddsgen.
Version 1.6 (EOL)¶
Version 1.6.0 (EOL)¶
This release included the following features:
Persistence.
Security access control plugin API and builtin Access control plugin: DDS:Access:Permissions plugin.
Also bug fixing.
Note: If you are upgrading from an older version than 1.4.0, it is advisable to regenerate generated source from IDL files using fastddsgen.
Version 1.5 (EOL)¶
Version 1.5.0 (EOL)¶
This release included the following features:
Configuration of Fast RTPS entities through XML profiles.
Added heartbeat piggyback support.
Also bug fixing.
Note: If you are upgrading from an older version than 1.4.0, it is advisable to regenerate generated source from IDL files using fastddsgen.
Version 1.4 (EOL)¶
Version 1.4.0 (EOL)¶
This release included the following:
Added secure communications.
Removed all Boost dependencies. Fast RTPS is not using Boost libraries anymore.
Added compatibility with Android.
Bug fixing.
Note: After upgrading to this release, it is advisable to regenerate generated source from IDL files using fastddsgen.
Version 1.3 (EOL)¶
Version 1.3.1 (EOL)¶
This release included the following:
New examples that illustrate how to tweak Fast RTPS towards different applications.
Improved support for embedded Linux.
Bug fixing.
Version 1.3.0 (EOL)¶
This release introduced several new features:
Unbound Arrays support: Now you can send variable size data arrays.
Extended Fragmentation Configuration: It allows you to setup a Message/Fragment max size different to the standard 64Kb limit.
Improved logging system: Get even more introspection about the status of your communications system.
Static Discovery: Use XML to map your network and keep discovery traffic to a minimum.
Stability and performance improvements: A new iteration of our built-in performance tests will make benchmarking easier for you.
ReadTheDocs Support: We improved our documentation format and now our installation and user manuals are available online on ReadTheDocs.
Version 1.2 (EOL)¶
Version 1.2.0 (EOL)¶
This release introduced two important new features:
Flow Controllers: A mechanism to control how you use the available bandwidth avoiding data bursts. The controllers allow you to specify the maximum amount of data to be sent in a specific period of time. This is very useful when you are sending large messages requiring fragmentation.
Discovery Listeners: Now the user can subscribe to the discovery information to know the entities present in the network (Topics, Publishers & Subscribers) dynamically without prior knowledge of the system. This enables the creation of generic tools to inspect your system.
But there is more:
Full ROS 2 Support: Fast RTPS is used by ROS 2, the upcoming release of the Robot Operating System (ROS).
Better documentation: More content and examples.
Improved performance.
Bug fixing.