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).
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.
Throughput controllers. We support user-configurable throughput 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.
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).
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.
Throughput controllers. We support user-configurable throughput 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.
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.
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).fastrtps, the core library of eProsima Fast DDS library.fastrtpsgen, a Java application that generates source code using the data types defined in an IDL file.
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
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.
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.fastrtps, the core library of eProsima Fast DDS library.fastrtpsgen, a Java application that generates source code using the data types defined in an IDL file.
Environment variables¶
eProsima Fast DDS requires the following environment variable setup in order to function properly:
FASTRTPSHOME: 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.
Linux 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 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.fastrtps, 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:
Gtest [optional]
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
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. For a detailed description of the Gtest installation process, please refer to the Gtest Installation Guide.
Dependencies¶
eProsima Fast DDS has the following dependencies, when installed from binaries in a Linux environment:
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
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
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/fastrtps.repos mkdir src vcs import src < fastrtps.reposBuild the packages:
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:
source ~/Fast-DDS/install/setup.bashAdd 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-DDS
Clone 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: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¶
In order to compile Fast DDS-Gen, the following packages need to be installed in the system:
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. Download and install it at the following the steps given in the Oracle website.
Compiling Fast DDS-Gen¶
Once the requirements above are met, compile Fast DDS-Gen by following the steps below:
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
gradle assemble
Note
If errors occur during compilation or you do not wish to install gradle, an executable script is included which will download a gradle temporarily for the compilation step.
./gradlew 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.
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.fastrtps, 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]
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. For a detailed description of the Gtest installation process, please refer to the Gtest Installation Guide.
Dependencies¶
eProsima Fast RTPS has the following dependencies, when installed from sources in a Windows environment:
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.
Download and install the latest OpenSSL version for Windows at this
link.
After installing, add the environment variable OPENSSL_ROOT_DIR pointing to the installation root directory.
For example:
OPENSSL_ROOT_DIR=C:\Program Files\OpenSSL-Win64
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/fastrtps.repos -output fastrtps.repos mkdir src vcs import src --input fastrtps.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 ~\Fast-DDSClone the following dependencies and compile them using CMake.
-
cd ~\Fast-DDS git clone https://github.com/eProsima/foonathan_memory_vendor.git cd foonathan_memory_vendor mkdir build && cd build cmake .. -DBUILD_SHARED_LIBS=ON cmake --build . --target install
-
cd ~\Fast-DDS git clone https://github.com/eProsima/Fast-CDR.git cd Fast-CDR mkdir build && cd build cmake .. 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 cd Fast-DDS mkdir build && cd build cmake .. cmake --build . --target install
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.
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\fastrtps
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¶
In order to compile Fast DDS-Gen, the following packages need to be installed in the system:
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. Download and install it at the following the steps given in the Oracle website.
Compiling Fast DDS-Gen¶
Once the requirements above are met, install Fast DDS-Gen by following the steps below:
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
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.fastrtps, 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:
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. For a detailed description of the Gtest installation process, please refer to the Gtest Installation Guide.
Dependencies¶
eProsima Fast DDS has the following dependencies, when installed from binaries in a Linux environment:
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/fastrtps.repos mkdir src vcs import src < fastrtps.reposBuild 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.bashAdd 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-DDS
Clone 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¶
In order to compile Fast DDS-Gen, the following packages need to be installed in the system:
Java JDK¶
The JDK is a development environment for building applications and components using the Java language. Download and install it at the following the steps given in the Oracle website.
Gradle¶
Gradle is an open-source build automation tool. Download and install the last stable version of Gradle in the preferred way. with Homebrew it would be running the command:
brew install gradle
Note
If errors occur during compilation or you do not wish to install gradle, an executable script is included which will download gradle temporarily for the compilation step.
./gradlew assemble
Compiling Fast DDS-Gen¶
Once the requirements above are met, compile Fast DDS-Gen by following the steps below:
cd ~
git clone --recursive https://github.com/eProsima/Fast-DDS-Gen.git
cd Fast-DDS-Gen
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.
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 information |
|
|
|
Disables Transport Layer Security (TLS) Support. Please refer to TLS over TCP for |
|
|
|
Adds Shared Memory transport (SHM) to the default transports.
Please refer to SHM section |
|
|
|
Enables the Fast DDS Statistics module. Please refer to Statistics Module for more |
|
|
|
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 |
|
|
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 (See Disable Logging Module). |
|
|
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 |
|---|---|---|---|
|
Activate the individual building of GoogleTest tests, since Fast DDS tests are |
|
|
|
Activates special set of GTEST_ROOT, i.e. the root directory of the GoogleTest |
|
|
|
Activates special set of GMOCK_ROOT, i.e. the root directory of the GoogleTest C++ |
|
|
|
Enables the building of black-box tests for the verification of RTPS communications |
|
|
|
Enables the building of black-box tests for the verification of DDS communications |
|
|
|
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. |
|
|
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 publisher and subscriber application¶
This section details how to create an simple Fast DDS application with a publisher and a subscriber 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.cxx
├── HelloWorld.h
├── HelloWorld.idl
├── HelloWorldPublisher.cpp
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
└── HelloWorldSubscriber.cpp
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. The way we will make these accessible from the workspace depends on the installation procedure we have followed in the Installation Manual.
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/fastrtps/ 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¶
If you have followed the Colcon installation there are several ways to import the libraries. If you want these to be accessible only from the current shell session, run one of the following two commands.
source <path/to/Fast-DDS/workspace>/install/setup.bash
If you want these to be accessible from any session, you can add the Fast DDS installation directory to your $PATH
variable in the shell configuration files running the following command.
echo 'source <path/to/Fast-DDS/workspace>/install/setup.bash' >> ~/.bashrc
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 3.12.4)
if(NOT CMAKE_VERSION VERSION_LESS 3.0)
cmake_policy(SET CMP0048 NEW)
endif()
project(DDSHelloWorld)
# Find requirements
if(NOT fastcdr_FOUND)
find_package(fastcdr REQUIRED)
endif()
if(NOT fastrtps_FOUND)
find_package(fastrtps 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()
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 your favorite 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/fastrtpsgen HelloWorld.idl
This must have generated the following files:
HelloWorld.cxx: HelloWorld type definition.
HelloWorld.h: Header file for HelloWorld.cxx.
HelloWorldPubSubTypes.cxx: Serialization and Deserialization code for the HelloWorld type.
HelloWorldPubSubTypes.h: Header file for HelloWorldPubSubTypes.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.
message(STATUS "Configuring HelloWorld publisher/subscriber example...")
file(GLOB DDS_HELLOWORLD_SOURCES_CXX "src/*.cxx")
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
Now you have the publisher’s source code. The publisher is going to send 10 publications under the topic HelloWorld.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 | // Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @file HelloWorldPublisher.cpp
*
*/
#include "HelloWorldPubSubTypes.h"
#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/domain/DomainParticipant.hpp>
#include <fastdds/dds/topic/TypeSupport.hpp>
#include <fastdds/dds/publisher/Publisher.hpp>
#include <fastdds/dds/publisher/DataWriter.hpp>
#include <fastdds/dds/publisher/DataWriterListener.hpp>
using namespace eprosima::fastdds::dds;
class HelloWorldPublisher
{
private:
HelloWorld hello_;
DomainParticipant* participant_;
Publisher* publisher_;
Topic* topic_;
DataWriter* writer_;
TypeSupport type_;
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_;
public:
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_);
}
//!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;
}
//!Send a publication
bool publish()
{
if (listener_.matched_ > 0)
{
hello_.index(hello_.index() + 1);
writer_->write(&hello_);
return true;
}
return false;
}
//!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));
}
}
};
int main(
int argc,
char** argv)
{
std::cout << "Starting publisher." << std::endl;
int samples = 10;
HelloWorldPublisher* mypub = new HelloWorldPublisher();
if(mypub->init())
{
mypub->run(static_cast<uint32_t>(samples));
}
delete mypub;
return 0;
}
|
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. Is the object responsible for the creation of DataReaders.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 <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/domain/DomainParticipant.hpp>
#include <fastdds/dds/topic/TypeSupport.hpp>
#include <fastdds/dds/publisher/Publisher.hpp>
#include <fastdds/dds/publisher/DataWriter.hpp>
#include <fastdds/dds/publisher/DataWriterListener.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 allow us to execute routines in case of an event.
The overridden callback
on_publication_matched
allows you to define 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 you to track 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;
int samples = 10;
HelloWorldPublisher* mypub = new HelloWorldPublisher();
if(mypub->init())
{
mypub->run(static_cast<uint32_t>(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 fastrtps fastcdr)
At this point you can build, compile and run the publisher application. From the build directory in the workspace, run the following commands.
cmake ..
make
./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
Now you have the subscriber’s source code. The application runs a subscriber until it receives 10 samples under the topic HelloWorldTopic. At this point the subscriber stops.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 | // Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @file HelloWorldSubscriber.cpp
*
*/
#include "HelloWorldPubSubTypes.h"
#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/domain/DomainParticipant.hpp>
#include <fastdds/dds/topic/TypeSupport.hpp>
#include <fastdds/dds/subscriber/Subscriber.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>
using namespace eprosima::fastdds::dds;
class HelloWorldSubscriber
{
private:
DomainParticipant* participant_;
Subscriber* subscriber_;
DataReader* reader_;
Topic* topic_;
TypeSupport type_;
class SubListener : public DataReaderListener
{
public:
SubListener()
: samples_(0)
{
}
~SubListener() override
{
}
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;
}
}
void on_data_available(
DataReader* reader) override
{
SampleInfo info;
if (reader->take_next_sample(&hello_, &info) == ReturnCode_t::RETCODE_OK)
{
if (info.valid_data)
{
samples_++;
std::cout << "Message: " << hello_.message() << " with index: " << hello_.index()
<< " RECEIVED." << std::endl;
}
}
}
HelloWorld hello_;
std::atomic_int samples_;
} listener_;
public:
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_);
}
//!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;
}
//!Run the Subscriber
void run(
uint32_t samples)
{
while(listener_.samples_ < samples)
{
std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
}
};
int main(
int argc,
char** argv)
{
std::cout << "Starting subscriber." << std::endl;
int samples = 10;
HelloWorldSubscriber* mysub = new HelloWorldSubscriber();
if(mysub->init())
{
mysub->run(static_cast<uint32_t>(samples));
}
delete mysub;
return 0;
}
|
Examining the code¶
As you have noticed, the source code to implement the subscriber is practically identical to the source code implemented by the publisher. Therefore, we will focus on the main differences between them, without explaining all the code again.
Following the same structure as in the publisher explanation, we start with 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/DomainParticipantFactory.hpp>
#include <fastdds/dds/subscriber/SampleInfo.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) == ReturnCode_t::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_);
}
Then we have 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;
int samples = 10;
HelloWorldSubscriber* mysub = new HelloWorldSubscriber();
if(mysub->init())
{
mysub->run(static_cast<uint32_t>(samples));
}
delete mysub;
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(DDSHelloWorldSubscriber src/HelloWorldSubscriber.cpp ${DDS_HELLOWORLD_SOURCES_CXX})
target_link_libraries(DDSHelloWorldSubscriber fastrtps fastcdr)
At this point you can build, compile and run the subscriber application. From the build directory in the workspace, run the following commands.
cmake ..
make clean && make
./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.
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 the implements 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 reads the data from 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 following is a brief overview of how Fast DDS multithreading schedule work:
Main thread: Managed by the application.
Event thread: Each DomainParticipant owns one of these. It processes periodic and triggered time events.
Asynchronous writer thread: This thread manages asynchronous writes for all DomainParticipants. Even for synchronous writers, some forms of communication must be initiated in the background.
Reception threads: DomainParticipants spawn a thread for each reception channel, where the concept of a channel depends on the transport layer (e.g. a UDP port).
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 a hubs for discovery meta traffic.
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: logInfo, logWarning and logError.
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(). Within each callback entity hierarchy remains the same.
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.
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;
<publisher profile_name="publisher_xml_conf_deadline_profile">
<qos>
<deadline>
<period>
<sec>1</sec>
<nanosec>0</nanosec>
</period>
</deadline>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_deadline_profile">
<qos>
<deadline>
<period>
<sec>1</sec>
<nanosec>0</nanosec>
</period>
</deadline>
</qos>
</subscriber>
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.
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;
<publisher profile_name="publisher_xml_conf_durability_profile">
<qos>
<durability>
<kind>TRANSIENT_LOCAL</kind>
</durability>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_durability_profile">
<qos>
<durability>
<kind>VOLATILE</kind>
</durability>
</qos>
</subscriber>
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 |
|---|---|---|
int32_t |
1 |
|
int32_t |
-1 (Length Unlimited) |
|
int32_t |
-1 (Length Unlimited) |
|
int32_t |
-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 |
|---|---|---|
bool |
|
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.
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
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
group_data.data_vec(vec); //Setter function
This QoS Policy cannot be configured using XML for the moment.
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 |
|---|---|---|
int32_t |
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. If the limit is reached, the behavior of the system depends on the ReliabilityQosPolicy, if its kind is BEST_EFFORT the older values will be discarded, but if it is RELIABLE the service blocks the DataWriter until the old values are delivered to all existing Subscribers.
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};
<publisher profile_name="publisher_xml_conf_lifespan_profile">
<qos>
<lifespan>
<duration>
<sec>5</sec>
<nanosec>0</nanosec>
</duration>
</lifespan>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_lifespan_profile">
<qos>
<lifespan>
<duration>
<sec>5</sec>
<nanosec>0</nanosec>
</duration>
</lifespan>
</qos>
</subscriber>
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 also 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};
<publisher profile_name="publisher_xml_conf_liveliness_profile">
<qos>
<liveliness>
<announcement_period>
<sec>0</sec>
<nanosec>1000000</nanosec>
</announcement_period>
<lease_duration>
<sec>1</sec>
</lease_duration>
<kind>AUTOMATIC</kind>
</liveliness>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_liveliness_profile">
<qos>
<liveliness>
<lease_duration>
<sec>1</sec>
</lease_duration>
<kind>AUTOMATIC</kind>
</liveliness>
</qos>
</subscriber>
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.
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 |
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.
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 |
|---|---|---|
uint32_t |
0 (Length Unlimited) |
|
Empty List |
Note
This QoS Policy concerns to Publisher and Subscriber entities.
It can be changed on enabled entities.
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
<publisher profile_name="pub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</publisher>
<subscriber profile_name="sub_partition_example">
<qos>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
</subscriber>
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 |
|---|---|---|
bool |
|
|
bool |
|
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.
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};
<publisher profile_name="publisher_xml_conf_reliability_profile">
<qos>
<reliability>
<kind>RELIABLE</kind>
<max_blocking_time>
<sec>1</sec>
<nanosec>0</nanosec>
</max_blocking_time>
</reliability>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_reliability_profile">
<qos>
<reliability>
<kind>BEST_EFFORT</kind>
</reliability>
</qos>
</subscriber>
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.max_instances: Controls the maximum number of instances that a 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.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;
<publisher profile_name="publisher_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>
</publisher>
<subscriber profile_name="subscriber_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>
</subscriber>
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 new octet to topic data vector
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
topic_data.data_vec(vec); //Setter Function
This QoS Policy cannot be configured using XML for the moment.
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 new octet to topic data vector
eprosima::fastrtps::rtps::octet val = 3;
vec.push_back(val);
user_data.data_vec(vec); //Setter Function
This QoS Policy cannot be configured using XML for the moment.
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 |
|---|---|---|
bool |
|
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 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.
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();
<publisher profile_name="publisher_profile_qos_datasharing">
<qos>
<data_sharing>
<kind>AUTOMATIC</kind>
<domain_ids>
<domainId>0x1234</domainId>
<domainId>0xABCD</domainId>
</domain_ids>
</data_sharing>
</qos>
</publisher>
<subscriber profile_name="subscriber_profile_qos_datasharing">
<qos>
<data_sharing>
<kind>AUTOMATIC</kind>
<domain_ids>
<domainId>0x1234</domainId>
<domainId>0xABCD</domainId>
</domain_ids>
</data_sharing>
</qos>
</subscriber>
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 a sufficient
time before considering it as acknowledged.
See DisablePositiveACKsQosPolicy.
List of QoS Policy data members:
Data Member Name |
Type |
Default Value |
|---|---|---|
bool |
|
|
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.
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.
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};
<publisher profile_name="publisher_xml_conf_disable_positive_acks_profile">
<qos>
<disablePositiveAcks>
<enabled>true</enabled>
<duration>
<sec>1</sec>
</duration>
</disablePositiveAcks>
</qos>
</publisher>
<subscriber profile_name="subscriber_xml_conf_disable_positive_acks_profile">
<qos>
<disablePositiveAcks>
<enabled>true</enabled>
</disablePositiveAcks>
</qos>
</subscriber>
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.
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.
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;
<!--
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
-->
<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>
</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.
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"));
<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>
</properties>
</propertiesPolicy>
</rtps>
</participant>
PublishModeQosPolicy¶
This QoS Policy configures how the DataWriter sends the data.
See PublishModeQosPolicy.
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;
<publisher profile_name="publisher_profile_qos_publishmode">
<qos>
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
</qos>
</publisher>
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);
<subscriber 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>
</subscriber>
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 |
||
|
-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.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);
//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;
<publisher profile_name="publisher_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>
<!-- The history memory policy is changed to DYNAMIC_RESERVE -->
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
</publisher>
<subscriber profile_name="subscriber_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>
<historyMemoryPolicy>PREALLOCATED_WITH_REALLOC</historyMemoryPolicy>
</subscriber>
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.
It cannot be changed 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;
<subscriber profile_name="sub_profile_name">
<times> <!-- readerTimesType -->
<initialAcknackDelay> <!-- DURATION -->
<sec>0</sec>
<nanosec>70</nanosec>
</initialAcknackDelay>
<heartbeatResponseDelay> <!-- DURATION -->
<sec>0</sec>
<nanosec>5</nanosec>
</heartbeatResponseDelay>
</times>
<!--You can also change the values of DisablePositiveACKsQosPolicy.-->
<!--See DisablePositiveACKsQosPolicy section for further details-->
</subscriber>
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.
Note
This QoS Policy concerns to DataWriter entities.
It cannot be changed 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.
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;
<publisher profile_name="pub_profile_name">
<times> <!-- writerTimesType -->
<initialHeartbeatDelay> <!-- DURATION -->
<sec>0</sec>
<nanosec>20</nanosec>
</initialHeartbeatDelay>
<heartbeatPeriod> <!-- DURATION -->
<sec>5</sec>
<nanosec>0</nanosec>
</heartbeatPeriod>
<nackResponseDelay> <!-- DURATION -->
<sec>0</sec>
<nanosec>10</nanosec>
</nackResponseDelay>
<nackSupressionDuration> <!-- DURATION -->
<sec>0</sec>
<nanosec>20</nanosec>
</nackSupressionDuration>
</times>
<!--You can also change the values of DisablePositiveACKsQosPolicy.-->
<!--See DisablePositiveACKsQosPolicy section for further details-->
</publisher>
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.
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;
<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>
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 |
|---|---|---|
fastrtps::rtps::GuidPrefix_t |
0 |
|
int32_t |
-1 |
|
Empty List |
||
Empty List |
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.throughput_controller: It allows the configuration of the throughput settings.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.
Note
This QoS Policy concerns to DomainParticipant entities.
It cannot be changed on enabled entities.
This structure allows to limit the output bandwidth.
See ThroughputControllerDescriptor.
List of structure members:
Member Name |
Type |
|---|---|
|
|
|
bytesPerPeriod: This member states the number of bytes that this controller will allow in a given period.periodMillisecs: It specifies the window of time in which no more than bytesPerPeriod bytes are allowed.
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);
// Limit to 300kb per second.
eprosima::fastrtps::rtps::ThroughputControllerDescriptor slowPublisherThroughputController{300000, 1000};
wire_protocol.throughput_controller = slowPublisherThroughputController;
//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);
<participant profile_name="UDP SERVER" 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>
</builtin>
<throughputController>
<bytesPerPeriod>300000</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
<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>
</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);
<publisher 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>
</publisher>
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¶
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.
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.
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.
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 |
|---|---|
|
SampleLostStatus¶
This status changes every time a new data sample is lost and will never be received.
See SampleLostStatus.
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.
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.
SampleRejectedStatus¶
This status changes every time an incoming data sample is rejected by the DataReader.
The reason for the rejection is stored as a SampleRejectedStatusKind.
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.
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.
SampleRejectedStatusKind¶
There are four possible values (see SampleRejectedStatusKind):
NOT_REJECTED: It means there have been no rejections so far on this DataReader. The rejection reason will have this value only while the total count of rejections is zero.REJECTED_BY_INSTANCES_LIMIT: The sample was rejected because the max_instances limit was reached.REJECTED_BY_SAMPLES_LIMIT: The sample was rejected because the max_samples limit was reached.REJECTED_BY_SAMPLES_PER_INSTANCE_LIMIT: The sample was rejected because the max_samples_per_instance limit was reached.
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.
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.
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.
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 |
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) !=
ReturnCode_t::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) !=
ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (DomainParticipantFactory::get_instance()->set_default_participant_qos(DomainParticipantQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (participant->set_qos(DomainParticipantFactory::get_instance()->get_default_participant_qos())
!= ReturnCode_t::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 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.
on_subscriber_discovery(): A new Subscriber is discovered in the same domain, a previously known Subscriber has been removed, or some Subscriber has changed its QoS.
on_publisher_discovery(): A new Publisher is discovered in the same domain, a previously known Publisher has been removed, or some Publisher has changed its QoS.
on_type_discovery(): A new data Type is discovered in the same domain.
on_type_dependencies_reply(): The Type lookup client received a replay to agetTypeDependencies()request. This callback can be used to retrieve the new type using thegetTypes()request and create a new dynamic type using the retrieved type object.
on_type_information_received(): A newTypeInformationhas been received from a newly discovered DomainParticipant.
onParticipantAuthentication(): Informs about the result of the authentication process of a remote DomainParticipant (either on failure or success).
class CustomDomainParticipantListener : public DomainParticipantListener
{
public:
CustomDomainParticipantListener()
: DomainParticipantListener()
{
}
virtual ~CustomDomainParticipantListener()
{
}
virtual void on_participant_discovery(
DomainParticipant* /*participant*/,
eprosima::fastrtps::rtps::ParticipantDiscoveryInfo&& info)
{
if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DISCOVERED_PARTICIPANT)
{
std::cout << "New participant discovered" << std::endl;
}
else if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::REMOVED_PARTICIPANT ||
info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DROPPED_PARTICIPANT)
{
std::cout << "New participant lost" << std::endl;
}
}
#if HAVE_SECURITY
virtual void onParticipantAuthentication(
DomainParticipant* /*participant*/,
eprosima::fastrtps::rtps::ParticipantAuthenticationInfo&& info)
{
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
virtual void on_subscriber_discovery(
DomainParticipant* /*participant*/,
eprosima::fastrtps::rtps::ReaderDiscoveryInfo&& info)
{
if (info.status == eprosima::fastrtps::rtps::ReaderDiscoveryInfo::DISCOVERED_READER)
{
std::cout << "New subscriber discovered" << std::endl;
}
else if (info.status == eprosima::fastrtps::rtps::ReaderDiscoveryInfo::REMOVED_READER)
{
std::cout << "New subscriber lost" << std::endl;
}
}
virtual void on_publisher_discovery(
DomainParticipant* /*participant*/,
eprosima::fastrtps::rtps::WriterDiscoveryInfo&& info)
{
if (info.status == eprosima::fastrtps::rtps::WriterDiscoveryInfo::DISCOVERED_WRITER)
{
std::cout << "New publisher discovered" << std::endl;
}
else if (info.status == eprosima::fastrtps::rtps::WriterDiscoveryInfo::REMOVED_WRITER)
{
std::cout << "New publisher lost" << std::endl;
}
}
virtual void on_type_discovery(
DomainParticipant* participant,
const eprosima::fastrtps::rtps::SampleIdentity& request_sample_id,
const eprosima::fastrtps::string_255& topic,
const eprosima::fastrtps::types::TypeIdentifier* identifier,
const eprosima::fastrtps::types::TypeObject* object,
eprosima::fastrtps::types::DynamicType_ptr dyn_type)
{
(void)participant, (void)request_sample_id, (void)topic, (void)identifier, (void)object, (void)dyn_type;
std::cout << "New data type discovered" << std::endl;
}
virtual void on_type_dependencies_reply(
DomainParticipant* participant,
const eprosima::fastrtps::rtps::SampleIdentity& request_sample_id,
const eprosima::fastrtps::types::TypeIdentifierWithSizeSeq& dependencies)
{
(void)participant, (void)request_sample_id, (void)dependencies;
std::cout << "Answer to a request for type dependencies was received" << std::endl;
}
virtual void on_type_information_received(
DomainParticipant* participant,
const eprosima::fastrtps::string_255 topic_name,
const eprosima::fastrtps::string_255 type_name,
const eprosima::fastrtps::types::TypeInformation& type_information)
{
(void)participant, (void)topic_name, (void)type_name, (void)type_information;
std::cout << "New data type information received" << 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 |
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) != ReturnCode_t::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) != ReturnCode_t::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;
}
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 domain 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.
// 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 the DomainParticipant
if (DomainParticipantFactory::get_instance()->delete_participant(participant) != ReturnCode_t::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/XMLSchemas/fastRTPS_Profiles">
<publisher profile_name="pub_11">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>Partition_1</name>
<name>Partition_2</name>
</names>
</partition>
</qos>
</publisher>
<publisher profile_name="pub_12">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>*</name>
</names>
</partition>
</qos>
</publisher>
<publisher profile_name="pub_21">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
</publisher>
<publisher profile_name="pub_22">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>Partition*</name>
</names>
</partition>
</qos>
</publisher>
<subscriber profile_name="subs_31">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>Partition_1</name>
</names>
</partition>
</qos>
</subscriber>
<subscriber profile_name="subs_32">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>Partition_2</name>
</names>
</partition>
</qos>
</subscriber>
<subscriber profile_name="subs_33">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
<qos>
<partition>
<names>
<name>Partition_3</name>
</names>
</partition>
</qos>
</subscriber>
<subscriber profile_name="subs_34">
<topic>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
</topic>
</subscriber>
</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) != ReturnCode_t::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) != ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_publisher_qos(PublisherQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (publisher->set_qos(participant->get_default_publisher_qos())
!= ReturnCode_t::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()
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() 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.
// 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 Publisher
if (participant->delete_publisher(publisher) != ReturnCode_t::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 |
||
Yes |
||
Yes |
||
Yes |
||
No |
||
No (*) |
||
No |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
No |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
Yes |
||
No |
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.
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) != ReturnCode_t::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) != ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (publisher->set_default_datawriter_qos(DataWriterQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (data_writer->set_qos(publisher->get_default_datawriter_qos())
!= ReturnCode_t::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.
Warning
Currently on_offered_deadline_missed is not implemented (it will never be called), and will be implemented on a future release of Fast DDS.
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.
class CustomDataWriterListener : public DataWriterListener
{
public:
CustomDataWriterListener()
: DataWriterListener()
{
}
virtual ~CustomDataWriterListener()
{
}
virtual void on_publication_matched(
DataWriter* writer,
const PublicationMatchedStatus& info)
{
(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;
}
}
virtual void on_offered_deadline_missed(
DataWriter* writer,
const OfferedDeadlineMissedStatus& status)
{
(void)writer, (void)status;
std::cout << "Some data could not be delivered on time" << std::endl;
}
virtual void on_offered_incompatible_qos(
DataWriter* /*writer*/,
const OfferedIncompatibleQosStatus& status)
{
std::cout << "Found a remote Topic with incompatible QoS (QoS ID: " << status.last_policy_id <<
")" << std::endl;
}
virtual void on_liveliness_lost(
DataWriter* writer,
const LivelinessLostStatus& status)
{
(void)writer, (void)status;
std::cout << "Liveliness lost. Matched Subscribers will consider us offline" << 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;
}
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) != ReturnCode_t::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()) != ReturnCode_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 (ReturnCode_t::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()) != ReturnCode_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) != ReturnCode_t::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) != ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_subscriber_qos(SubscriberQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (subscriber->set_qos(participant->get_default_subscriber_qos())
!= ReturnCode_t::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.
class CustomSubscriberListener : public SubscriberListener
{
public:
CustomSubscriberListener()
: SubscriberListener()
{
}
virtual ~CustomSubscriberListener()
{
}
virtual void on_data_on_readers(
Subscriber* sub)
{
(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()
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() 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.
// 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 Subscriber
if (participant->delete_subscriber(subscriber) != ReturnCode_t::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 |
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.
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) != ReturnCode_t::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) != ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (subscriber->set_default_datareader_qos(DataReaderQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (data_reader->set_qos(subscriber->get_default_datareader_qos())
!= ReturnCode_t::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.
Warning
Currently
on_requested_deadline_missed()
is not implemented (it will never be called), and will be implemented on a future release of Fast DDS.
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.
Warning
Currently
on_sample_rejected()
is not implemented (it will never be called), and will be implemented on a future release of Fast DDS.
on_sample_lost(): A data sample was lost and will never be received.
Warning
Currently
on_sample_lost()
is not implemented (it will never be called), and will be implemented on a future release of Fast DDS.
class CustomDataReaderListener : public DataReaderListener
{
public:
CustomDataReaderListener()
: DataReaderListener()
{
}
virtual ~CustomDataReaderListener()
{
}
virtual void on_data_available(
DataReader* reader)
{
(void)reader;
std::cout << "Received new data message" << std::endl;
}
virtual void on_subscription_matched(
DataReader* reader,
const SubscriptionMatchedStatus& info)
{
(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;
}
}
virtual void on_requested_deadline_missed(
DataReader* reader,
const eprosima::fastrtps::RequestedDeadlineMissedStatus& info)
{
(void)reader, (void)info;
std::cout << "Some data was not received on time" << std::endl;
}
virtual void on_liveliness_changed(
DataReader* reader,
const eprosima::fastrtps::LivelinessChangedStatus& info)
{
(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;
}
}
virtual void on_sample_rejected(
DataReader* reader,
const eprosima::fastrtps::SampleRejectedStatus& info)
{
(void)reader, (void)info;
std::cout << "A received data sample was rejected" << std::endl;
}
virtual void on_requested_incompatible_qos(
DataReader* /*reader*/,
const RequestedIncompatibleQosStatus& info)
{
std::cout << "Found a remote Topic with incompatible QoS (QoS ID: " << info.last_policy_id <<
")" << std::endl;
}
virtual void on_sample_lost(
DataReader* reader,
const SampleLostStatus& info)
{
(void)reader, (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;
}
Deleting a DataReader¶
A DataReader can be deleted with the delete_datareader() member function on the
Subscriber instance where the DataReader was created.
// 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 DataReader
if (subscriber->delete_datareader(data_reader) != ReturnCode_t::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.
Note
Currently the sample_state is not implemented, and its value is always set to NOT_READ.
It will be implemented on a future release of Fast DDS.
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.
Note
Currently the view_state is not implemented, and its value is always set to NOT_NEW.
It will be implemented on a future release of Fast DDS.
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.
Note
Currently the instance_state is partially implemented, and the value NOT_ALIVE_NO_WRITERS will
never be set.
It will be fully implemented on a future release of Fast DDS.
disposed_generation_count¶
disposed_generation_count indicates the number of times the instance had become alive after it was
disposed.
Note
Currently the disposed_generation_count is not implemented, and its value is always set to 0.
It will be implemented on a future release of Fast DDS.
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.
Note
Currently the no_writers_generation_count is not implemented, and its value is always set to 1.
It will be implemented on a future release of Fast DDS.
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.
// 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 == ReturnCode_t::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 for which valid_data is true should be accessed
if (info_seq[n].valid_data)
{
// 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:
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()
{
}
virtual void on_data_available(
DataReader* reader)
{
// 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) == ReturnCode_t::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¶
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 with the 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 threat 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 (data_reader->take_next_sample(&data, &info) == ReturnCode_t::RETCODE_OK)
{
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¶
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.
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) != ReturnCode_t::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) != ReturnCode_t::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)
!= ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following
if (participant->set_default_topic_qos(TopicQos())
!= ReturnCode_t::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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
// The previous instruction is equivalent to the following:
if (topic->set_qos(participant->get_default_topic_qos())
!= ReturnCode_t::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().
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 specialization implemented is Topic.
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()
{
}
virtual void on_inconsistent_topic(
Topic* topic,
InconsistentTopicStatus status)
{
(void)topic, (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
eprosima::fastrtps::xmlparser::XMLProfileManager::loadXMLFile("example_type.xml");
// Retrieve the an instance of the desired type and register it
eprosima::fastrtps::types::DynamicType_ptr dyn_type =
eprosima::fastrtps::xmlparser::XMLProfileManager::getDynamicTypeByName("DynamicType")->build();
TypeSupport dyn_type_support(new eprosima::fastrtps::types::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 Dynamic Topic Types 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 Dynamic Topic Types.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) != ReturnCode_t::RETCODE_OK)
{
// Error
return;
}
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 fastrtpsgen on Linux or fastrtpsgen.bat on Windows.
The IDL file containing the data type definition is given with the <IDLfile> argument.
Linux |
fastrtpsgen [<options>] <IDLfile> [<IDLfile> ...]
|
Windows |
fastrtpsgen.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.-typeobject: It builds additional files forTypeObjectgeneration and management (see TypeObject).-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.cxx/.h: 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).
If the -typeobject argument was used, MyType.cxx is modified to register the TypeObject representation in
the TypeObjectFactory, and these files will also be generated:
MyTypeTypeObject.cxx/.h: TypeObject representation for MyType IDL.
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/C++/RTPSTest_as_socket and examples/C++/RTPSTest_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);
}
};
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) override
{
// Reserve new memory for the payload buffer
octet* payload = new octet[data.length];
// Copy the data
memcpy(payload, data.data, data.length);
// 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;
// Tell the CacheChange who needs to release its payload
cache_change.payload_owner(this);
return true;
}
bool release_payload(
CacheChange_t& cache_change) override
{
// Ensure precondition
assert(this == cache_change.payload_owner());
// 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.
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, act as a hub for discovery meta traffic.
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 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 the is no EDP phase. |
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.discoveryProtocol =
DiscoveryProtocol_t::SIMPLE;
|
XML |
<participant profile_name="participant_discovery_protocol">
<rtps>
<builtin>
<discovery_config>
<discoveryProtocol>SIMPLE</discoveryProtocol>
</discovery_config>
</builtin>
</rtps>
</participant>
|
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. |
C++ |
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 |
<participant profile_name="participant_discovery_ignore_flags">
<rtps>
<builtin>
<discovery_config>
<ignoreParticipantFlags>FILTER_DIFFERENT_PROCESS | FILTER_SAME_PROCESS</ignoreParticipantFlags>
</discovery_config>
</builtin>
</rtps>
</participant>
|
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.
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.leaseDuration = Duration_t(10, 20);
|
XML |
<participant profile_name="participant_discovery_lease_duration">
<rtps>
<builtin>
<discovery_config>
<leaseDuration>
<sec>10</sec>
<nanosec>20</nanosec>
</leaseDuration>
</discovery_config>
</builtin>
</rtps>
</participant>
|
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.
C++ |
DomainParticipantQos pqos;
pqos.wire_protocol().builtin.discovery_config.leaseDuration_announcementperiod = Duration_t(1, 2);
|
XML |
<participant profile_name="participant_discovery_lease_announcement">
<rtps>
<builtin>
<discovery_config>
<leaseAnnouncement>
<sec>1</sec>
<nanosec>2</nanosec>
</leaseAnnouncement>
</discovery_config>
</builtin>
</rtps>
</participant>
|
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>
<sec>0</sec>
<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
with 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.
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/XMLSchemas/fastRTPS_Profiles">
-->
<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>
|
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. |
|
|
|
Mandatory. |
|
|
|
The kind of topic. |
|
|
|
|||
|
The name of a partition of the remote peer. |
|
|
|
Unicast locator of the DomainParticipant. |
||
|
Multicast locator of the DomainParticipant. |
||
|
See the ReliabilityQosPolicy section. |
||
|
See the DurabilityQosPolicy section. |
||
|
See Ownership QoS. |
||
|
Defines the liveliness of the remote peer. |
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
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"/>
</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"/>
</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 |
<publisher profile_name="publisher_xml_conf_static_discovery">
<userDefinedID>3</userDefinedID>
</publisher>
<subscriber profile_name="subscriber_xml_conf_static_discovery">
<userDefinedID>5</userDefinedID>
</subscriber>
|
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.
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 on 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 a beforehand 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 all the discovery information known by the server, in opposition to clients, which only receive the information they need.Servers do not require any beforehand 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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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.
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/XMLSchemas/fastRTPS_Profiles">
<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">
<metatrafficUnicastLocatorList>
<locator/>
</metatrafficUnicastLocatorList>
</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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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.
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/XMLSchemas/fastRTPS_Profiles">
<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>
|
Full example¶
The following constitutes a full example on how to configure server and client both programmatically and using XML.
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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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>
|
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 four callbacks attached to events that may occur during discovery:
on_participant_discovery(),
on_subscriber_discovery(),
on_publisher_discovery(),
on_type_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 */
virtual void on_participant_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ParticipantDiscoveryInfo&& info)
{
(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;
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 << "New 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_subscriber_discovery */
virtual void on_subscriber_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::ReaderDiscoveryInfo&& info)
{
(void)participant;
switch (info.status){
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::DISCOVERED_READER:
/* Process the case when a new subscriber was found in the domain */
std::cout << "New DataReader subscribed to topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' discovered";
break;
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::CHANGED_QOS_READER:
/* Process the case when a subscriber changed its QOS */
break;
case eprosima::fastrtps::rtps::ReaderDiscoveryInfo::REMOVED_READER:
/* Process the case when a subscriber was removed from the domain */
std::cout << "New DataReader subscribed to topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' left the domain.";
break;
}
}
/* Custom Callback on_publisher_discovery */
virtual void on_publisher_discovery(
DomainParticipant* participant,
eprosima::fastrtps::rtps::WriterDiscoveryInfo&& info)
{
(void)participant;
switch (info.status){
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::DISCOVERED_WRITER:
/* Process the case when a new publisher was found in the domain */
std::cout << "New DataWriter publishing under topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' discovered";
break;
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::CHANGED_QOS_WRITER:
/* Process the case when a publisher changed its QOS */
break;
case eprosima::fastrtps::rtps::WriterDiscoveryInfo::REMOVED_WRITER:
/* Process the case when a publisher was removed from the domain */
std::cout << "New DataWriter publishing under topic '" << info.info.topicName() <<
"' of type '" << info.info.typeName() << "' left the domain.";
break;
}
}
/* Custom Callback on_type_discovery */
virtual void on_type_discovery(
DomainParticipant* participant,
const eprosima::fastrtps::rtps::SampleIdentity& request_sample_id,
const eprosima::fastrtps::string_255& topic,
const eprosima::fastrtps::types::TypeIdentifier* identifier,
const eprosima::fastrtps::types::TypeObject* object,
eprosima::fastrtps::types::DynamicType_ptr dyn_type)
{
(void)participant, (void)request_sample_id, (void)topic, (void)identifier, (void)object, (void)dyn_type;
std::cout << "New data type of topic '" << topic << "' discovered." << std::endl;
}
};
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);
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 transport_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;
// 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 |
|---|---|---|
|
|
None. Reserved value for internal use. |
|
|
UDP Transport over IPv4. |
|
|
UDP Transport over IPv6. |
|
|
TCP Transport over IPv4. |
|
|
TCP Transport over IPv6. |
|
|
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 stored in the two most significant bytes of the member
port.
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.
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");
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 TransportDescriptor.
However, all their TransportDescriptor data members are common.
The following table describes the common data members for both UDPv4 and UDPv6.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
|
Size of the sending buffer of the socket (octets). |
|
|
|
Size of the receiving buffer of the socket (octets). |
|
|
empty |
List of allowed interfaces. See Interface Whitelist |
|
|
|
Time to live, in number of hops. |
|
|
|
Port number for the outgoing messages. |
|
|
|
Do not block on send operations (*). |
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
eprosima::fastrtps::rtps::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
eprosima::fastrtps::rtps::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.
C++ |
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;
// 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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="UDPParticipant">
<rtps>
<userTransports>
<transport_id>udp_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
</rtps>
</participant>
</profiles>
|
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. 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 TransportDescriptor.
However, they share many of their features, and most of the TransportDescriptor data members are common.
The following table describes the common data members for both TCPv4 and TCPv6.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
|
Size of the sending buffer of the socket (octets). |
|
|
|
Size of the receiving buffer of the socket (octets). |
|
|
empty |
List of allowed interfaces. See Interface Whitelist |
|
|
|
Time to live, in number of hops. |
|
|
empty |
List of ports to listen as server. |
|
|
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. |
|
|
false |
Enables the TCP_NODELAY socket option. |
|
|
true |
True to calculate and send CRC on message headers. |
|
|
true |
True to check the CRC of incoming message headers. |
|
|
false |
True to use TLS. See TLS over TCP. |
|
|
Configuration for TLS. See TLS over TCP. |
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.
TCPv4TransportDescriptor¶
The following table describes the data members that are exclusive for TCPv4TransportDescriptor.
Member |
Data type |
Default |
Description |
|---|---|---|---|
|
|
empty |
Configuration for TLS. See WAN or Internet Communication over TCPv4. |
Note
The kind value for a TCPv4TransportDescriptor is given by the value
eprosima::fastrtps::rtps::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
eprosima::fastrtps::rtps::LOCATOR_KIND_TCPv6
Enabling TCP Transport¶
To enable TCP transport in a DomainParticipant, 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.
If you provide listening_ports on 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.
C++ |
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto tcp_transport = std::make_shared<TCPv4TransportDescriptor>();
tcp_transport->sendBufferSize = 9216;
tcp_transport->receiveBufferSize = 9216;
tcp_transport->add_listener_port(5100);
tcp_transport->set_WAN_address("80.80.99.45");
// 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;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp_transport</transport_id>
<type>TCPv4</type>
<sendBufferSize>9216</sendBufferSize>
<receiveBufferSize>9216</receiveBufferSize>
<listening_ports>
<port>5100</port>
</listening_ports>
<wan_addr>80.80.99.45</wan_addr>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCPParticipant">
<rtps>
<userTransports>
<transport_id>tcp_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
</rtps>
</participant>
</profiles>
|
If you provide initialPeersList to 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.
C++ |
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<TCPv4TransportDescriptor>();
qos.transport().user_transports.push_back(tcp_transport);
// Set initial peers.
Locator_t initial_peer_locator;
initial_peer_locator.kind = LOCATOR_KIND_TCPv4;
IPLocator::setIPv4(initial_peer_locator, "80.80.99.45");
initial_peer_locator.port = 5100;
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer_locator);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp2_transport</transport_id>
<type>TCPv4</type>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCP2Participant">
<rtps>
<userTransports>
<transport_id>tcp2_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<builtin>
<initialPeersList>
<locator>
<tcpv4>
<address>80.80.99.45</address>
<physical_port>5100</physical_port>
</tcpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
|
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_peerlist.
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.
C++ |
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto tcp_transport = std::make_shared<TCPv4TransportDescriptor>();
tcp_transport->sendBufferSize = 9216;
tcp_transport->receiveBufferSize = 9216;
tcp_transport->add_listener_port(5100);
tcp_transport->set_WAN_address("80.80.99.45");
// 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;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp_transport</transport_id>
<type>TCPv4</type>
<sendBufferSize>9216</sendBufferSize>
<receiveBufferSize>9216</receiveBufferSize>
<listening_ports>
<port>5100</port>
</listening_ports>
<wan_addr>80.80.99.45</wan_addr>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCPParticipant">
<rtps>
<userTransports>
<transport_id>tcp_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
</rtps>
</participant>
</profiles>
|
On the client side, the DomainParticipant must be configured
with the public IP address and listening_port of the TCP server as
initial_peer.
C++ |
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<TCPv4TransportDescriptor>();
qos.transport().user_transports.push_back(tcp_transport);
// Set initial peers.
Locator_t initial_peer_locator;
initial_peer_locator.kind = LOCATOR_KIND_TCPv4;
IPLocator::setIPv4(initial_peer_locator, "80.80.99.45");
initial_peer_locator.port = 5100;
qos.wire_protocol().builtin.initialPeersList.push_back(initial_peer_locator);
// Avoid using the default transport
qos.transport().use_builtin_transports = false;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>tcp2_transport</transport_id>
<type>TCPv4</type>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TCP2Participant">
<rtps>
<userTransports>
<transport_id>tcp2_transport</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<builtin>
<initialPeersList>
<locator>
<tcpv4>
<address>80.80.99.45</address>
<physical_port>5100</physical_port>
</tcpv4>
</locator>
</initialPeersList>
</builtin>
</rtps>
</participant>
</profiles>
|
HelloWorldExampleTCP¶
A TCP version of helloworld example can be found in the examples/C++/DDS/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.
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 that will help understanding how the Shared Memory Transport works in order to deliver the data messages to the appropriate DomainParticipant. The purpose is not to be a 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.
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.
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.
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. 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. 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.
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
C++ - Option 1: Manual setting of the |
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;
|
C++ - Option 2: Using the |
DomainParticipantQos participant_qos;
std::istringstream("77.73.71.85.69.76.95.66.65.82.82.79") >> participant_qos.wire_protocol().prefix;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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 TransportDescriptor.
The following is an example of configuration of TLS on the TCP server.
C++ |
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);
tls_transport->set_WAN_address("80.80.99.45");
// 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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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>
<wan_addr>80.80.99.45</wan_addr>
</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.
C++ |
DomainParticipantQos qos;
// Set initial peers.
Locator_t initial_peer_locator;
initial_peer_locator.kind = LOCATOR_KIND_TCPv4;
IPLocator::setIPv4(initial_peer_locator, "80.80.99.45");
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);
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(tls_transport);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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>
</tls>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="TLSClientParticipant">
<rtps>
<userTransports>
<transport_id>tls_transport_client</transport_id>
</userTransports>
<builtin>
<initialPeersList>
<locator>
<tcpv4>
<address>80.80.99.45</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 |
|---|---|---|---|
|
|
empty |
Password of the |
|
|
empty |
Path to the private key certificate file. |
|
|
empty |
Path to the private key RSA certificate file. |
|
|
empty |
Path to the public certificate chain file. |
|
|
empty |
Path to the Diffie-Hellman parameters file. |
|
|
empty |
Path to the CA (Certification- Authority) file. |
|
|
empty |
Establishes the verification mode mask. See TLS Verification Mode |
|
|
empty |
Establishes the SSL Context options mask. See TLS Options |
|
|
empty |
Paths where the system will look for verification files. |
|
|
empty |
Maximum allowed depth for verifying intermediate certificates. |
|
|
empty |
Look for verification files on the default paths. |
|
|
|
Role that the transport will take on handshaking. See TLS Handshake Role |
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 TransportDescriptor
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
using the field wire_protocol().builtin.metatrafficMulticastLocatorList.
C++ |
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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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
using the field wire_protocol().builtin.metatrafficUnicastLocatorList.
C++ |
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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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
using the field wire_protocol().default_multicast_locator_list.
C++ |
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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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
using the field wire_protocol().default_unicast_locator_list.
C++ |
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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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 user-traffic 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 |
PB + DG * domainId + offsetd0 |
Metatraffic unicast |
PB + DG * domainId + offsetd1 + PG * participantId |
User multicast |
PB + DG * domainId + offsetd2 |
User unicast |
PB + DG * domainId + offsetd3 + PG * participantId |
The values used in these rules are explained on the following table. The default values can be modified using the corresponding field on the DomainParticipantQos.
Symbol |
Meaning |
Default value |
QoS field |
|---|---|---|---|
|
DomainID gain |
|
|
|
ParticipantId gain |
|
|
|
Port Base number |
|
|
|
Additional offset |
|
|
|
Additional offset |
|
|
|
Additional offset |
|
|
|
Additional offset |
|
|
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’ IP addresses to the interfaceWhiteList
field in the TCPTransportDescriptor or UDPTransportDescriptor.
Thus, the communication interfaces used by the DomainParticipants whose TransportDescriptor defines an
interfaceWhiteList is limited to the interfaces’ IP addresses defined in that list,
therefore avoiding the use of the rest of the network interfaces available in the system.
The values on this list should match the IPs of your machine in that networks.
For example:
C++ |
DomainParticipantQos qos;
// Create a descriptor for the new transport.
auto tcp_transport = std::make_shared<TCPv4TransportDescriptor>();
// Add loopback to the whitelist
tcp_transport->interfaceWhiteList.emplace_back("127.0.0.1");
// Link the Transport Layer to the Participant.
qos.transport().user_transports.push_back(tcp_transport);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
<transport_descriptor>
<transport_id>CustomTcpTransport</transport_id>
<type>TCPv4</type>
<interfaceWhiteList>
<address>127.0.0.1</address>
</interfaceWhiteList>
</transport_descriptor>
</transport_descriptors>
<participant profile_name="CustomTcpTransportParticipant">
<rtps>
<userTransports>
<transport_id>CustomTcpTransport</transport_id>
</userTransports>
</rtps>
</participant>
</profiles>
|
Warning
The interface whitelist feature applies to network interfaces. Therefore, it is only available on TCP Transport and UDP Transport.
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.
C++ |
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 |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<participant profile_name="disable_multicast" is_default_profile="true">
<rtps>
<builtin>
<metatrafficUnicastLocatorList>
<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).
C++ |
/*
* 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";
eprosima::fastrtps::types::DynamicTypeBuilder_ptr struct_type_builder(
eprosima::fastrtps::types::DynamicTypeBuilderFactory::get_instance()->create_struct_builder());
struct_type_builder->set_name(topic_type_name);
// The type consists of two members, and index and a message. Add members to the struct.
struct_type_builder->add_member(0, "index",
eprosima::fastrtps::types::DynamicTypeBuilderFactory::get_instance()->create_uint32_type());
struct_type_builder->add_member(1, "message",
eprosima::fastrtps::types::DynamicTypeBuilderFactory::get_instance()->create_string_type());
// Build the type
eprosima::fastrtps::types::DynamicType_ptr dyn_type_ptr = struct_type_builder->build();
// Create type support and register the type
TypeSupport type_support(new eprosima::fastrtps::types::DynamicPubSubType(dyn_type_ptr));
type_support.register_type(participant);
// Create data sample a populate data. This is to be used when calling `writer->write()`
eprosima::fastrtps::types::DynamicData* dyn_helloworld;
dyn_helloworld = eprosima::fastrtps::types::DynamicDataFactory::get_instance()->create_data(dyn_type_ptr);
dyn_helloworld->set_uint32_value(0, 0);
dyn_helloworld->set_string_value("HelloWorld", 1);
/********************************************************************************************************
* 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 |
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_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 -->
<kind>TRANSIENT</kind>
</durability>
|
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>
|
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.auth.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");
|
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>
|
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 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | <dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="omg_shared_ca_domain_governance.xsd">
<domain_access_rules>
<domain_rule>
<domains>
<id_range>
<min>0</min>
<max>230</max>
</id_range>
</domains>
<allow_unauthenticated_participants>false</allow_unauthenticated_participants>
<enable_join_access_control>true</enable_join_access_control>
<discovery_protection_kind>ENCRYPT</discovery_protection_kind>
<liveliness_protection_kind>ENCRYPT</liveliness_protection_kind>
<rtps_protection_kind>ENCRYPT</rtps_protection_kind>
<topic_access_rules>
<topic_rule>
<topic_expression>HelloWorldTopic</topic_expression>
<enable_discovery_protection>true</enable_discovery_protection>
<enable_liveliness_protection>false</enable_liveliness_protection>
<enable_read_access_control>true</enable_read_access_control>
<enable_write_access_control>true</enable_write_access_control>
<metadata_protection_kind>ENCRYPT</metadata_protection_kind>
<data_protection_kind>ENCRYPT</data_protection_kind>
</topic_rule>
</topic_access_rules>
</domain_rule>
</domain_access_rules>
</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.
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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Topic name |
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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.
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.
false: the RTPS submessages shall not be encrypted.true: the RTPS submessages 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.
false: the data payload shall not be encrypted.true: the data payload shall be encrypted.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | <?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="dds" type="DomainAccessRulesNode" />
<xs:complexType name="DomainAccessRulesNode">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="domain_access_rules"
type="DomainAccessRules" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="DomainAccessRules">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="domain_rule" type="DomainRule" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="DomainRule">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="domains" type="DomainIdSet" />
<xs:element name="allow_unauthenticated_participants"
type="xs:boolean" />
<xs:element name="enable_join_access_control"
type="xs:boolean" />
<xs:element name="discovery_protection_kind"
type="ProtectionKind" />
<xs:element name="liveliness_protection_kind"
type="ProtectionKind" />
<xs:element name="rtps_protection_kind"
type="ProtectionKind" />
<xs:element name="topic_access_rules"
type="TopicAccessRules" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="DomainIdSet">
<xs:choice minOccurs="1" maxOccurs="unbounded">
<xs:element name="id" type="DomainId" />
<xs:element name="id_range" type="DomainIdRange" />
</xs:choice>
</xs:complexType>
<xs:simpleType name="DomainId">
<xs:restriction base="xs:nonNegativeInteger" />
</xs:simpleType>
<xs:complexType name="DomainIdRange">
<xs:choice>
<xs:sequence>
<xs:element name="min" type="DomainId" />
<xs:element name="max" type="DomainId" minOccurs="0" />
</xs:sequence>
<xs:element name="max" type="DomainId" />
</xs:choice>
</xs:complexType>
<xs:simpleType name="ProtectionKind">
<xs:restriction base="xs:string">
<xs:enumeration value="ENCRYPT_WITH_ORIGIN_AUTHENTICATION" />
<xs:enumeration value="SIGN_WITH_ORIGIN_AUTHENTICATION" />
<xs:enumeration value="ENCRYPT" />
<xs:enumeration value="SIGN" />
<xs:enumeration value="NONE" />
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="BasicProtectionKind">
<xs:restriction base="ProtectionKind">
<xs:enumeration value="ENCRYPT" />
<xs:enumeration value="SIGN" />
<xs:enumeration value="NONE" />
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TopicAccessRules">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="topic_rule" type="TopicRule" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="TopicRule">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="topic_expression" type="TopicExpression" />
<xs:element name="enable_discovery_protection"
type="xs:boolean" />
<xs:element name="enable_liveliness_protection"
type="xs:boolean" />
<xs:element name="enable_read_access_control"
type="xs:boolean" />
<xs:element name="enable_write_access_control"
type="xs:boolean" />
<xs:element name="metadata_protection_kind"
type="ProtectionKind" />
<xs:element name="data_protection_kind"
type="BasicProtectionKind" />
</xs:sequence>
</xs:complexType>
<xs:simpleType name="TopicExpression">
<xs:restriction base="xs:string" />
</xs:simpleType>
</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 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | <dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://www.omg.org/spec/DDS-Security/20170801/omg_shared_ca_permissions.xsd">
<permissions>
<grant name="PublisherPermissions">
<subject_name>emailAddress=mainpub@eprosima.com, CN=Main Publisher, OU=eProsima, O=eProsima, ST=MA, C=ES</subject_name>
<validity>
<not_before>2013-06-01T13:00:00</not_before>
<not_after>2038-06-01T13:00:00</not_after>
</validity>
<allow_rule>
<domains>
<id_range>
<min>0</min>
<max>230</max>
</id_range>
</domains>
<publish>
<topics>
<topic>HelloWorldTopic</topic>
</topics>
</publish>
</allow_rule>
<default>DENY</default>
</grant>
<grant name="SubscriberPermissions">
<subject_name> emailAddress=mainsub@eprosima.com, CN=Main Subscriber, OU=eProsima, O=eProsima, ST=MA, C=ES</subject_name>
<validity>
<not_before>2013-06-01T13:00:00</not_before>
<not_after>2038-06-01T13:00:00</not_after>
</validity>
<allow_rule>
<domains>
<id_range>
<min>0</min>
<max>230</max>
</id_range>
</domains>
<subscribe>
<topics>
<topic>HelloWorldTopic</topic>
</topics>
</subscribe>
</allow_rule>
<default>DENY</default>
</grant>
</permissions>
</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 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | <?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="dds" type="PermissionsNode" />
<xs:complexType name="PermissionsNode">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="permissions" type="Permissions" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="Permissions">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="grant" type="Grant" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="Grant">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="subject_name" type="xs:string" />
<xs:element name="validity" type="Validity" />
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:choice minOccurs="1" maxOccurs="1">
<xs:element name="allow_rule" minOccurs="0" type="Rule" />
<xs:element name="deny_rule" minOccurs="0" type="Rule" />
</xs:choice>
</xs:sequence>
<xs:element name="default" type="DefaultAction" />
</xs:sequence>
<xs:attribute name="name" type="xs:string" use="required" />
</xs:complexType>
<xs:complexType name="Validity">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="not_before" type="xs:dateTime" />
<xs:element name="not_after" type="xs:dateTime" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="Rule">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="domains" type="DomainIdSet" />
<xs:sequence minOccurs="0" maxOccurs="unbounded">
<xs:element name="publish" type="Criteria" />
</xs:sequence>
<xs:sequence minOccurs="0" maxOccurs="unbounded">
<xs:element name="subscribe" type="Criteria" />
</xs:sequence>
<xs:sequence minOccurs="0" maxOccurs="unbounded">
<xs:element name="relay" type="Criteria" />
</xs:sequence>
</xs:sequence>
</xs:complexType>
<xs:complexType name="DomainIdSet">
<xs:choice minOccurs="1" maxOccurs="unbounded">
<xs:element name="id" type="DomainId" />
<xs:element name="id_range" type="DomainIdRange" />
</xs:choice>
</xs:complexType>
<xs:simpleType name="DomainId">
<xs:restriction base="xs:nonNegativeInteger" />
</xs:simpleType>
<xs:complexType name="DomainIdRange">
<xs:choice>
<xs:sequence>
<xs:element name="min" type="DomainId" />
<xs:element name="max" type="DomainId" minOccurs="0" />
</xs:sequence>
<xs:element name="max" type="DomainId" />
</xs:choice>
</xs:complexType>
<xs:complexType name="Criteria">
<xs:all minOccurs="1">
<xs:element name="topics" minOccurs="1"
type="TopicExpressionList" />
<xs:element name="partitions" minOccurs="0"
type="PartitionExpressionList" />
<xs:element name="data_tags" minOccurs="0" type="DataTags" />
</xs:all>
</xs:complexType>
<xs:complexType name="TopicExpressionList">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="topic" type="TopicExpression" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="PartitionExpressionList">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="partition" type="PartitionExpression" />
</xs:sequence>
</xs:complexType>
<xs:simpleType name="TopicExpression">
<xs:restriction base="xs:string" />
</xs:simpleType>
<xs:simpleType name="PartitionExpression">
<xs:restriction base="xs:string" />
</xs:simpleType>
<xs:complexType name="DataTags">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="tag" type="TagNameValuePair" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="TagNameValuePair">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:element name="name" type="xs:string" />
<xs:element name="value" type="xs:string" />
</xs:sequence>
</xs:complexType>
<xs:simpleType name="DefaultAction">
<xs:restriction base="xs:string">
<xs:enumeration value="ALLOW" />
<xs:enumeration value="DENY" />
</xs:restriction>
</xs:simpleType>
</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.
If the Access control plugin: DDS:Access:Permissions plugin will not be used, you can configure the DDS:Crypto:AES-GCM-GMAC plugin
manually with the properties outlined in the following table.
Property name |
Description |
Property Value |
|---|---|---|
rtps.participant.rtps_protection_kind |
Encrypt whole RTPS messages |
|
rtps.endpoint.submessage_protection_kind |
Encrypt RTPS submessages of a particular entity |
|
rtps.endpoint.payload_protection_kind |
Encrypt payload of a particular Writer |
|
The following is an example of how to set the properties of DomainParticipantQoS for the DDS:Crypto:AES-GCM-GMAC configuration.
C++ |
DomainParticipantQos pqos;
// Activate DDS:Crypto:AES-GCM-GMAC plugin
pqos.properties().properties().emplace_back("dds.sec.crypto.plugin",
"builtin.AES-GCM-GMAC");
// Only if DDS:Access:Permissions plugin is not enabled
// Configure DDS:Crypto:AES-GCM-GMAC plugin
pqos.properties().properties().emplace_back(
"rtps.participant.rtps_protection_kind",
"ENCRYPT");
|
XML |
<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>
<!-- Only if DDS:Access:Permissions plugin is not enabled -->
<!-- Configure DDS:Crypto:AES-GCM-GMAC plugin -->
<property>
<name>rtps.participant.rtps_protection_kind</name>
<value>ENCRYPT</value>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
|
Next example shows how to configure DataWriters to encrypt their RTPS submessages and the RTPS message payload, i.e.
the user data.
This is done by setting the DDS:Crypto:AES-GCM-GMAC properties (properties()) corresponding to the
DataWriters in the DataWriterQos.
C++ |
DataWriterQos wqos;
// Only if DDS:Access:Permissions plugin is not enabled
// Configure DDS:Crypto:AES-GCM-GMAC plugin
wqos.properties().properties().emplace_back(
"rtps.endpoint.submessage_protection_kind",
"ENCRYPT");
wqos.properties().properties().emplace_back(
"rtps.endpoint.payload_protection_kind",
"ENCRYPT");
|
XML |
<publisher profile_name="secure_datawriter_conf_crypto_plugin_xml_profile">
<propertiesPolicy>
<properties>
<!-- Only if DDS:Access:Permissions plugin is not enabled -->
<!-- Configure DDS:Crypto:AES-GCM-GMAC plugin -->
<property>
<name>rtps.endpoint.submessage_protection_kind</name>
<value>ENCRYPT</value>
</property>
<property>
<name>rtps.endpoint.payload_protection_kind</name>
<value>ENCRYPT</value>
</property>
</properties>
</propertiesPolicy>
</publisher>
|
The last example shows how to configure DataReader to encrypt their RTPS submessages.
This is done by setting the DDS:Crypto:AES-GCM-GMAC properties (properties()) corresponding to the
DataReaders in the DataReaderQos.
C++ |
DataWriterQos rqos;
// Only if DDS:Access:Permissions plugin is not enabled
// Configure DDS:Crypto:AES-GCM-GMAC plugin
rqos.properties().properties().emplace_back(
"rtps.endpoint.submessage_protection_kind",
"ENCRYPT");
|
XML |
<subscriber profile_name="secure_datareader_conf_crypto_plugin_xml_profile">
<propertiesPolicy>
<properties>
<!-- Only if DDS:Access:Permissions plugin is not enabled -->
<!-- Configure DDS:Crypto:AES-GCM-GMAC plugin -->
<property>
<name>rtps.endpoint.submessage_protection_kind</name>
<value>ENCRYPT</value>
</property>
</properties>
</propertiesPolicy>
</subscriber>
|
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>
|
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().
// Block current thread until the log queue is empty.
Log::Flush();
// Stop the loggin thread and free its resources.
Log::KillThread();
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):
logInfo: Logs messages withLog::Kind::Infoverbosity.logWarning: Logs messages withLog::Kind::Warningverbosity.logError: 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).
logInfo(DOCUMENTATION_CATEGORY, "This is an info message");
logWarning(DOCUMENTATION_CATEGORY, "This is an warning message");
logError(DOCUMENTATION_CATEGORY, "This is an error message");
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
logError 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
logError(CATEGORY_1, "First log entry");
// Would be consumed
logError(CATEGORY_2, "Second log entry");
// Would NOT be consumed
logError(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
logError(CATEGORY, "First log entry");
// Set filter using regular expression so filename must match "other"
Log::SetFilenameFilter(std::regex("other"));
// Would NOT be consumed
logError(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
logError(CATEGORY, "First log entry");
// Would NOT be consumed
logError(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.
logInfois 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.
logWarningis fully disabled by either:Setting CMake option
LOG_NO_WARNINGtoON.Defining macro
HAVE_LOG_NO_WARNINGto1.
logErroris 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.
logInfohas a special behaviour to simplify working with Multi-Config capability IDEs. IfLOG_NO_INFOisOFForHAVE_LOG_NO_INFOis0the logging is enabled only forDebugconfiguration. By settingFASTDDS_ENFORCE_LOG_INFOtoONthe logging will always be enabled.
Warning
INTERNAL_DEBUG can be automatically set to ON if CMake option EPROSIMA_BUILD is set to ON.
Statistics Module¶
The Fast DDS Statistics module is an extension to Fast DDS that enables the recollection of data
concerning the DDS communication.
The collected data is published using DDS over some specific 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
performance.
The Statistics module 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 those topics that may be of interest for the user’s application. Therefore, the standard DDS Layer has been extended.
The following section explains this DDS extended API.
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. Finally, the recommended QoS for enabling the DataWriters and creating the user’s DataReaders that subscribe to the Statistics topics are described.
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 |
|---|---|
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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 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.
PUBLICATION_THROUGHPUT_TOPIC¶
The _fastdds_statistics_publication_throughput statistics topic collects the amount of data 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 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).
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¶
Warning
This method will be implemented in future releases. For the moment it always returns RETCODE_UNSUPPORTED.
Statistics DataWriters are enabled using the method enable_statistics_datawriter().
This 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).
Disable statistics DataWriters¶
Warning
This method will be implemented in future releases. For the moment it always returns RETCODE_UNSUPPORTED.
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¶
Warning
This method will be implemented in future releases. For the moment it always returns nullptr.
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.
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.
Qos Policy |
Value |
|---|---|
100 |
Statistics DataReader recommended QoS¶
The following table shows the recommended DataReaderQos profile for creating the monitoring DataReaders.
Qos Policy |
Value |
|---|---|
100 |
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_FASTRTPS_PROFILES.xml located in the current execution path.
Load an XML file which location is defined using the environment variable
FASTRTPS_DEFAULT_PROFILES_FILE(see FASTRTPS_DEFAULT_PROFILES_FILE).Load the configuration parameters directly from the classes’ definitions without looking for the DEFAULT_FASTRTPS_PROFILES.xml in the working directory (see SKIP_DEFAULT_XML).
An XML profile is defined by a unique name that is used to reference the XML profile during the creation of an Entity, the Trasport 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.
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>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
<participant profile_name="participant_profile">
<!-- ... -->
</participant>
<data_writer profile_name="datawriter_profile">
<!-- ... -->
</data_writer>
<data_reader profile_name="datareader_profile">
<!-- ... -->
</data_reader>
<transport_descriptors>
<!-- ... -->
</transport_descriptors>
<log>
<!-- ... -->
</log>
<types>
<!-- ... -->
</types>
</profiles>
</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.
Moreover, create_participant_with_profile(),
create_publisher(), and create_subscriber()
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 (ReturnCode_t::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");
Publisher* publisher = participant->create_publisher_with_profile("publisher_xml_profile");
Subscriber* subscriber = participant->create_subscriber_with_profile("subscriber_xml_profile");
}
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 dynamic types in a 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>,<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>, 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>
<type>
<!-- Type definition -->
</type>
<type>
<!-- Type definition -->
<!-- Type definition -->
</type>
</types>
|
Rooted |
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<types>
<type>
<!-- Type definition -->
</type>
<type>
<!-- Type definition -->
<!-- Type definition -->
</type>
</types>
</dds>
|
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 (ReturnCode_t::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);
}
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: <domain_id> and <rtps>.
All the DomainParticipant configuration options belong to the <rtps> element, except for the DDS DomainId
which is defined by the <domain_id> element.
Below a list with the configuration XML elements is presented:
Name |
Description |
Values |
Default |
|---|---|---|---|
|
DomainId to be used by the 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. |
|
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List of default reception unicast locators |
|
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List of default reception multicast |
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Size in bytes of the send socket buffer. |
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0 |
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Size in bytes of the reception socket |
|
0 |
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Allows defining the port and gains related |
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DomainParticipant’s identifier. Typically |
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0 |
|
Limits middleware’s bandwidth usage. |
||
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Transport descriptors to be used by the |
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Boolean field to indicate the system |
|
true |
|
Additional configuration properties. |
||
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Configuration regarding allocation behavior.
|
Example
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<participant profile_name="domainparticipant_profile_name">
<domainId>80</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>
<sendSocketBufferSize>8192</sendSocketBufferSize>
<listenSocketBufferSize>8192</listenSocketBufferSize>
<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>
<throughputController>
<bytesPerPeriod>8192</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
<userTransports>
<transport_id>TransportId1</transport_id>
<transport_id>TransportId2</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<propertiesPolicy>
<!-- PROPERTIES_POLICY -->
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
</properties>
</propertiesPolicy>
<allocation>
<!-- ALLOCATION -->
</allocation>
</participant>
Note
LOCATOR_LISTmeans a LocatorListType is expected.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
BUILTINdetails, please refer to Builtin parameters.For
ALLOCATIONdetails, please refer to ParticipantAllocationType.
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. |
|
|
|
Child element of |
|
4 |
|
Child element of |
|
1 |
|
DomainParticipant Allocation Configuration to specify the |
||
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DomainParticipant Allocation Configuration to specify the |
||
|
DomainParticipant Allocation Configuration related to the |
||
|
Maximum size of the partitions submessage. |
|
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Maximum size of the user data submessage. |
|
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Maximum size of the properties submessage. |
|
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>
</allocation>
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 |
|
|
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>NONE</discoveryProtocol>
<ignoreParticipantFlags>FILTER_DIFFERENT_HOST</ignoreParticipantFlags>
<EDP>SIMPLE</EDP>
<leaseDuration>
<!-- DURATION -->
<sec>20</sec>
<nanosec>0</nanosec>
</leaseDuration>
<leaseAnnouncement>
<!-- DURATION -->
<sec>3</sec>
<nanosec>0</nanosec>
</leaseAnnouncement>
<initialAnnouncements>
<!-- INITIAL_ANNOUNCEMENTS -->
</initialAnnouncements>
<simpleEDP>
<PUBWRITER_SUBREADER>true</PUBWRITER_SUBREADER>
<PUBREADER_SUBWRITER>true</PUBREADER_SUBWRITER>
</simpleEDP>
<static_edp_xml_config>file://filename.xml</static_edp_xml_config>
</discovery_config>
<avoid_builtin_multicast>true</avoid_builtin_multicast>
<use_WriterLivelinessProtocol>false</use_WriterLivelinessProtocol>
<metatrafficUnicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</metatrafficMulticastLocatorList>
<initialPeersList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</initialPeersList>
<readerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</readerHistoryMemoryPolicy>
<readerPayloadSize>512</readerPayloadSize>
<writerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</writerHistoryMemoryPolicy>
<writerPayloadSize>512</writerPayloadSize>
<mutation_tries>55</mutation_tries>
</builtin>
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 |
||
|
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 XML filename with the static EDP |
|
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 |
|
Discovery traffic from DomainParticipant’s own process is |
|
Discovery traffic from DomainParticipant’s own host is |
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 |
DataWriter profiles¶
The DataWriter profiles allow for configuring DataWriters from an XML file.
These profiles are defined within the <data_writer> or <publisher> XML tags.
Thus, the following XML code snippets are equivalent.
DataWriter profile - Definition method 1 |
DataWriter profile - Definition method 2 |
<data_writer profile_name="my_datawriter_profile">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<!-- Other elements -->
</data_writer>
|
<publisher profile_name="my_publisher_profile">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<!-- Other elements -->
</publisher>
|
Important
The <publisher> and <data_writer> XML tags are equivalent.
Therefore, XML profiles in which the DataWriters are defined with the <publisher>
tag are fully compatible with Fast DDS.
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. |
|
|
|
Limits the output bandwidth of the |
||
|
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>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
<data_writer profile_name="datawriter_profile_name">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<times> <!-- writerTimesType -->
<initialHeartbeatDelay>
<sec>0</sec>
<nanosec>12</nanosec>
</initialHeartbeatDelay>
<heartbeatPeriod>
<sec>3</sec>
<nanosec>0</nanosec>
</heartbeatPeriod>
<nackResponseDelay>
<sec>0</sec>
<nanosec>5</nanosec>
</nackResponseDelay>
<nackSupressionDuration>
<sec>0</sec>
<nanosec>0</nanosec>
</nackSupressionDuration>
</times>
<unicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</multicastLocatorList>
<throughputController>
<bytesPerPeriod>8192</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<propertiesPolicy>
<!-- PROPERTIES_POLICY -->
</propertiesPolicy>
<userDefinedID>55</userDefinedID>
<entityID>66</entityID>
<matchedSubscribersAllocation>
<initial>0</initial>
<maximum>0</maximum>
<increment>1</increment>
</matchedSubscribersAllocation>
</data_writer>
</profiles>
<dds>
Note
LOCATOR_LISTmeans a LocatorListType is expected.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
QOSdetails, please refer to QoS.TOPIC_TYPEis detailed in section TopicType.
Times¶
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> or <subscriber> XML tags.
Thus, the following XML codes are equivalent.
DataReader profile - Definition method 1 |
DataReader profile - Definition method 2 |
<data_reader profile_name="my_datareader_profile">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<!-- Other elements -->
</data_reader>
|
<subscriber profile_name="my_subscriber_profile">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<!-- Other elements -->
</subscriber>
|
Important
The <subscriber> and <data_reader> XML tags are equivalent.
Therefore, XML profiles in which the DataReaders are defined with the <subscriber> tag are fully compatible
with Fast DDS.
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 |
|
|
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>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
<data_reader profile_name="sub_profile_name">
<topic>
<!-- TOPIC_TYPE -->
</topic>
<qos>
<!-- QOS -->
</qos>
<times> <!-- readerTimesType -->
<initialAcknackDelay>
<sec>0</sec>
<nanosec>70</nanosec>
</initialAcknackDelay>
<heartbeatResponseDelay>
<sec>0</sec>
<nanosec>5</nanosec>
</heartbeatResponseDelay>
</times>
<unicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<!-- LOCATOR_LIST -->
<locator>
<udpv4/>
</locator>
</multicastLocatorList>
<expectsInlineQos>true</expectsInlineQos>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<propertiesPolicy>
<!-- PROPERTIES_POLICY -->
</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.PROPERTIES_POLICYmeans that the label is a PropertiesPolicyType block.For
QOSdetails, please refer to QoS.TOPIC_TYPEis detailed in section TopicType.
Times¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Initial ACKNACK delay. |
70 ms |
|
|
Response time delay when receiving a Heartbeat. |
5 ms |
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 |
|
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 |
|
|
|
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>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
<transport_descriptors>
<transport_descriptor>
<transport_id>TransportId1</transport_id>
<type>UDPv4</type>
<sendBufferSize>8192</sendBufferSize>
<receiveBufferSize>8192</receiveBufferSize>
<TTL>250</TTL>
<non_blocking_send>false</non_blocking_send>
<maxMessageSize>16384</maxMessageSize>
<maxInitialPeersRange>100</maxInitialPeersRange>
<interfaceWhiteList>
<address>192.168.1.41</address>
<address>127.0.0.1</address>
</interfaceWhiteList>
<wan_addr>80.80.55.44</wan_addr>
<output_port>5101</output_port>
<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>
<calculate_crc>false</calculate_crc>
<check_crc>false</check_crc>
<enable_tcp_nodelay>false</enable_tcp_nodelay>
<tls><!-- TLS Section --></tls>
<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. |
|
|
|
|||
|
An example of TLS protocol parameter configuration is shown below.
<?xml version="1.0" encoding="UTF-8" ?>
<dds>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_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>
</tls>
</transport_descriptor>
</transport_descriptors>
</profiles>
</dds>
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 |
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>
<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>
</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 DynamicType by defining them through XML files. Thus the Dynamic Types can be modified without the need to modify the source code of the DDS application.
XML Structure¶
The definition of 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>
<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 Fast DDS are presented . For further information about the supported DynamicType, please, refer to Supported Types. For each of the types detailed below, an example of how to build the type’s XML profile is provided.
Enum¶
The <enum> type is defined by its attribute name and a set of <enumerator> child elements.
Each <enumerator> is defined by two attributes: a name and an optional value.
Please, refer to Enumeration for more information on the <enum> type.
<enum name="MyEnum">
<enumerator name="A" value="0"/>
<enumerator name="B" value="1"/>
<enumerator name="C" value="2"/>
</enum>
Typedef¶
The <typedef> XML element is defined by a name and a type mandatory attributes, and various optional
attributes for complex types definition.
These optional attributes are: key_type, arrayDimensions, nonBasicTypeName, sequenceMaxLength, and
mapMaxLength.
See Complex types attributes for more information on these attributes.
The <typedef> element corresponds to Alias in Supported Types
section.
<typedef name="MyAliasEnum" type="nonBasic" nonBasicTypeName="MyEnum"/>
<typedef name="MyAliasArray" type="int32" arrayDimension="2,2"/>
Struct¶
The <struct> element is defined by its name attribute and its <member> child elements.
Please, refer to Structure for more information on the <struct> type.
<struct name="MyStruct">
<member name="first" type="int32"/>
<member name="second" type="int64"/>
</struct>
Structs can inherit from another structs.
This is implemented by defining the value of the baseType attribute, on the child <struct> element to be the
value of the name attribute of the parent <struct> element.
This is exemplified by the code snippet below.
<struct name="ParentStruct">
<member name="first" type="int32"/>
<member name="second" type="int64"/>
</struct>
<struct name="ChildStruct" baseType="ParentStruct">
<member name="third" type="int32"/>
<member name="fourth" type="int64"/>
</struct>
Union¶
The <union> type is defined by a name attribute, a <discriminator> child element and a set of <case>
child elements.
Each <case> element has one or more <caseDiscriminator> and a <member> child elements.
Please, refer to Union for more information on the <union> type.
<union name="MyUnion">
<discriminator type="byte"/>
<case>
<caseDiscriminator value="0"/>
<caseDiscriminator value="1"/>
<member name="first" type="int32"/>
</case>
<case>
<caseDiscriminator value="2"/>
<member name="second" type="nonBasic" nonBasicTypeName="MyStruct"/>
</case>
<case>
<caseDiscriminator value="default"/>
<member name="third" type="nonBasic" nonBasicTypeName="int64"/>
</case>
</union>
Bitset¶
The <bitset> element defines the Bitset type.
It is comprised by a name attribute and a set of <bitfield> child elements.
In turn, the <bitfield> element has the mandatory bit_bound attribute, which can not be higher than 64, and
two optional attributes:
name and type.
A <bitfield> with a blank name attribute is an inaccessible set of bits.
Its management type can ease the <bitfield> modification and access.
Please, refer to Bitset for more information about the <bitset> type.
<bitset name="MyBitSet">
<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>
Moreover, bitsets can inherit from another bitsets:
<bitset name="ParentBitSet">
<bitfield name="a" bit_bound="10"/>
<bitfield name="b" bit_bound="15"/>
</bitset>
<bitset name="ChildBitSet" baseType="ParentBitSet">
<bitfield bit_bound="1"/>
<bitfield bit_bound="5" type="uint16"/>
</bitset>
Bitmask¶
The <bitmask> element, which corresponds to the Bitmask type, is defined by
a mandatory name attribute, an optional bit_bound attribute, and several <bit_value> child elements.
The bit_bound attribute specifies the number of bits that the type will manage.
The maximum value allowed for the bit_bound is 64.
The <bit_value> element can define its position in the bitmask setting the positition attribute.
Please, refer to Bitmask for more information on the <bitmask> type.
<bitmask name="MyBitMask" bit_bound="8">
<bit_value name="flag0" position="0"/>
<bit_value name="flag1"/>
<bit_value name="flag2" position="2"/>
<bit_value name="flag5" position="5"/>
</bitmask>
Member types¶
Member types are defined as any type that can belong to a <struct> or a <union>, or be aliased by a
<typedef>.
These can be defined by the <member> XML tag.
Primitive types¶
The identifiers of the available basic types are listed in the table below. Please, refer to Primitive Types for more information on the primitive types.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
All of them are defined as follows:
<struct name="primitive_types_example">
<!-- Primitive type definitions inside a struct -->
<member name="my_long" type="int64"/>
<member name="my_bool" type="boolean"/>
<member name="my_string" type="string"/>
</struct>
Arrays¶
Arrays are defined in the same way as any other member type but they add the attribute arrayDimensions.
The format of the arrayDimensions attribute value is the size of each dimension separated by commas.
Please, refer to Array explanation for more information on array type.
<struct name="arrays_example">
<member name="long_array" type="int32" arrayDimensions="2,3,4"/>
</struct>
Sequences¶
The sequence type is implemented by setting three attributes: name, the type, and the
sequenceMaxLength.
The type of its content should be defined by the type attribute.
The following example shows the implementation of a sequence of maximum length equal to 3.
In turn, this is a sequence of sequences of maximum length of 2 and contents of type int32.
Please, refer to Sequence section for more information on sequence type.
<typedef name="my_sequence_inner" type="int32" sequenceMaxLength="2"/>
<struct name="SeqSeqStruct">
<member name="my_sequence_sequence" type="nonBasic" nonBasicTypeName="my_sequence_inner" sequenceMaxLength="3"/>
</struct>
Maps¶
Maps are similar to sequences, but they need to define two content types.
The key_type defines the type of the map key, while the type defines the map value type.
Again, both types can be defined as attributes of a <typedef> element, or as a <member> child element of a
<struct> or <union> elements.
See section Map for more information on map type.
<typedef name="my_map_inner" type="int32" key_type="int32" mapMaxLength="2"/>
<struct name="MapMapStruct">
<member name="my_map_map" type="nonBasic" nonBasicTypeName="my_map_inner" key_type="int32" mapMaxLength="2"/>
</struct>
Complex types¶
The complex types are a combination of the aforementioned types.
Complex types can be defined using the <member> element in the same way a basic or an array type would be.
Please, refer to Complex Types section for more information on complex types.
<struct name="OtherStruct">
<member name="my_enum" type="nonBasic" nonBasicTypeName="MyEnum"/>
<member name="my_struct" type="nonBasic" nonBasicTypeName="MyStruct" arrayDimensions="5"/>
</struct>
Complex types attributes¶
The attributes of a complex type element can be highly varied depending on the type being defined. Since the attributes that can be defined for each of the types have already been listed, these attributes are then defined in the following table.
Name |
Description |
|---|---|
|
Data type.
This can be a Primitive types or a |
|
Name of the complex type. Only applies if the |
|
Dimensions of an array. |
|
Maximum length of a Sequences. |
|
Maximum length of a Maps. |
|
Data type of a map key. |
Loading dynamic types in a Fast DDS application¶
In the Fast DDS application that will make use of the XML Types, the XML files that define the types must be loaded before trying to instantiate DynamicPubSubType objects of these types.
// Create a DomainParticipant
DomainParticipant* participant =
DomainParticipantFactory::get_instance()->create_participant(0, PARTICIPANT_QOS_DEFAULT);
if (nullptr == participant)
{
// Error
return;
}
// Load the XML File
if (ReturnCode_t::RETCODE_OK ==
DomainParticipantFactory::get_instance()->load_XML_profiles_file("my_profiles.xml"))
{
// Retrieve the an instance of MyStruct type
eprosima::fastrtps::types::DynamicType_ptr my_struct_type =
eprosima::fastrtps::xmlparser::XMLProfileManager::getDynamicTypeByName("MyStruct")->build();
// Register MyStruct type
TypeSupport my_struct_type_support(new eprosima::fastrtps::types::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. |
|
0 |
|
TCP’s physical port. |
|
0 |
|
IP address of the locator. |
|
“” |
|
The LAN ID uniquely identifies the LAN the |
|
|
|
WAN IPv4 address (TCPv4 only). |
|
|
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>
</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>
</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>
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. |
|
|
|
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 two mandatory elements <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>
<leaseDuration>
<sec>500</sec>
<nanosec>0</nanosec>
</leaseDuration>
<leaseAnnouncement>
<sec>1</sec>
<nanosec>856000</nanosec>
</leaseAnnouncement>
</discovery_config>
TopicType¶
The Topic name and data type are used to determine whether Datawriters and DataReaders can exchange messages. Please refer to Topic section for a a deeper explanation on the Topic class.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
It defines the Topic’s key kind. See |
||
|
It defines the Topic’s name. It must |
|
|
|
It references the Topic’s data type. |
|
|
|
It controls the behavior of Fast DDS |
||
|
It controls the resources that Fast DDS
|
Warning
The <kind> child element is only used if the Topic is defined using the Fast DDS RTPS-layer API, and will
be ignored if the Topic is defined via the Fast DDS DDS-layer API.
Example
<topic>
<kind>NO_KEY</kind>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
<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>
</resourceLimitsQos>
</topic>
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. |
|
100 |
|
The number of extra samples to allocate on the pool. |
|
1 |
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 DurabilityQosPolicy. |
|
|
See LivelinessQosPolicy. |
|
|
See ReliabilityQosPolicy. |
|
|
See PartitionQosPolicy. |
|
|
See DeadlineQosPolicy. |
|
|
See LifespanQosPolicy. |
|
|
||
|
Example
<qos> <!-- readerQosPoliciesType -->
<durability>
<kind>VOLATILE</kind>
</durability>
<liveliness>
<kind>AUTOMATIC</kind>
<lease_duration>
<sec>1</sec>
</lease_duration>
<announcement_period>
<sec>1</sec>
</announcement_period>
</liveliness>
<reliability>
<kind>BEST_EFFORT</kind>
</reliability>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
<deadline>
<period>
<sec>1</sec>
</period>
</deadline>
<lifespan>
<duration>
<sec>1</sec>
</duration>
</lifespan>
<disablePositiveAcks>
<enabled>true</enabled>
</disablePositiveAcks>
</qos>
Durability¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|||
Liveliness¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|||
|
See LivelinessQosPolicy. |
||
|
See LivelinessQosPolicy. |
ReliabilityQosPolicy¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
DataReaders: |
||
|
See ReliabilityQosPolicy. |
100 ms |
Partition¶
Name |
Description |
Values |
|---|---|---|
|
It comprises a set of |
|
Deadline¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See DeadlineQosPolicy. |
Lifespan¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
See LifespanQosPolicy. |
DisablePositiveAcks¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
|
|
|
|
LatencyBudget¶
Name |
Description |
Values |
Default |
|---|---|---|---|
|
0 |
Throughput Configuration¶
The <throughputController> element allows to limit the output bandwidth.
It contains two child elements which are explained in the following table.
Name |
Description |
Values |
Default |
|---|---|---|---|
|
Packet size in bytes that the throughput controller
will allow to send |
|
4294967295 bytes |
|
Window of time in which no more than |
|
0 |
Example
<participant profile_name="participant_thoughput">
<rtps>
<throughputController>
<bytesPerPeriod>8192</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
</rtps>
</participant>
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.
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<dds>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
<transport_descriptors>
<transport_descriptor>
<transport_id>ExampleTransportId1</transport_id>
<type>TCPv4</type>
<sendBufferSize>8192</sendBufferSize>
<receiveBufferSize>8192</receiveBufferSize>
<TTL>250</TTL>
<maxMessageSize>16384</maxMessageSize>
<maxInitialPeersRange>100</maxInitialPeersRange>
<interfaceWhiteList>
<address>192.168.1.41</address>
<address>127.0.0.1</address>
</interfaceWhiteList>
<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>200</max_logical_port>
<logical_port_range>20</logical_port_range>
<logical_port_increment>2</logical_port_increment>
<listening_ports>
<port>5100</port>
<port>5200</port>
</listening_ports>
</transport_descriptor>
<transport_descriptor>
<transport_id>ExampleTransportId2</transport_id>
<type>UDPv6</type>
</transport_descriptor>
<!-- SHM sample transport descriptor -->
<transport_descriptor>
<transport_id>SHM_SAMPLE_DESCRIPTOR</transport_id>
<type>SHM</type> <!-- REQUIRED -->
<maxMessageSize>524288</maxMessageSize> <!-- OPTIONAL uint32 valid of all transports-->
<segment_size>1048576</segment_size> <!-- OPTIONAL uint32 SHM only-->
<port_queue_capacity>1024</port_queue_capacity> <!-- OPTIONAL uint32 SHM only-->
<healthy_check_timeout_ms>250</healthy_check_timeout_ms> <!-- OPTIONAL uint32 SHM only-->
<rtps_dump_file>test_file.dump</rtps_dump_file> <!-- OPTIONAL string SHM only-->
</transport_descriptor>
</transport_descriptors>
<participant profile_name="participant_profile_example">
<domainId>4</domainId>
<rtps>
<name>Participant Name</name> <!-- String -->
<defaultUnicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</defaultUnicastLocatorList>
<defaultMulticastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</defaultMulticastLocatorList>
<sendSocketBufferSize>8192</sendSocketBufferSize>
<listenSocketBufferSize>8192</listenSocketBufferSize>
<builtin>
<discovery_config>
<discoveryProtocol>NONE</discoveryProtocol>
<EDP>SIMPLE</EDP>
<leaseDuration>
<sec>DURATION_INFINITY</sec>
</leaseDuration>
<leaseAnnouncement>
<sec>1</sec>
<nanosec>856000</nanosec>
</leaseAnnouncement>
<simpleEDP>
<PUBWRITER_SUBREADER>true</PUBWRITER_SUBREADER>
<PUBREADER_SUBWRITER>true</PUBREADER_SUBWRITER>
</simpleEDP>
<staticEndpointXMLFilename>filename.xml</staticEndpointXMLFilename>
</discovery_config>
<use_WriterLivelinessProtocol>false</use_WriterLivelinessProtocol>
<metatrafficUnicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</metatrafficUnicastLocatorList>
<metatrafficMulticastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</metatrafficMulticastLocatorList>
<initialPeersList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</initialPeersList>
<readerHistoryMemoryPolicy>PREALLOCATED_WITH_REALLOC</readerHistoryMemoryPolicy>
<writerHistoryMemoryPolicy>PREALLOCATED</writerHistoryMemoryPolicy>
</builtin>
<allocation>
<remote_locators>
<max_unicast_locators>4</max_unicast_locators> <!-- uint32 -->
<max_multicast_locators>1</max_multicast_locators> <!-- uint32 -->
</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>
</allocation>
<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>
<throughputController>
<bytesPerPeriod>8192</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
<userTransports>
<transport_id>ExampleTransportId1</transport_id>
<transport_id>ExampleTransportId1</transport_id>
</userTransports>
<useBuiltinTransports>false</useBuiltinTransports>
<propertiesPolicy>
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
<property>
<name>Property2Name</name>
<value>Property2Value</value>
<propagate>false</propagate>
</property>
</properties>
</propertiesPolicy>
</rtps>
</participant>
<data_writer profile_name="datawriter_profile_example">
<topic>
<kind>WITH_KEY</kind>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
<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>
</resourceLimitsQos>
</topic>
<qos> <!-- dataWriterQosPoliciesType -->
<durability>
<kind>VOLATILE</kind>
</durability>
<liveliness>
<kind>AUTOMATIC</kind>
<lease_duration>
<sec>1</sec>
<nanosec>856000</nanosec>
</lease_duration>
<announcement_period>
<sec>1</sec>
<nanosec>856000</nanosec>
</announcement_period>
</liveliness>
<reliability>
<kind>BEST_EFFORT</kind>
<max_blocking_time>
<sec>1</sec>
<nanosec>856000</nanosec>
</max_blocking_time>
</reliability>
<lifespan>
<duration>
<sec>5</sec>
<nanosec>0</nanosec>
</duration>
</lifespan>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
<publishMode>
<kind>ASYNCHRONOUS</kind>
</publishMode>
<disablePositiveAcks>
<enabled>true</enabled>
<duration>
<sec>1</sec>
</duration>
</disablePositiveAcks>
</qos>
<times>
<initialHeartbeatDelay>
<sec>1</sec>
<nanosec>856000</nanosec>
</initialHeartbeatDelay>
<heartbeatPeriod>
<sec>1</sec>
<nanosec>856000</nanosec>
</heartbeatPeriod>
<nackResponseDelay>
<sec>1</sec>
<nanosec>856000</nanosec>
</nackResponseDelay>
<nackSupressionDuration>
<sec>1</sec>
<nanosec>856000</nanosec>
</nackSupressionDuration>
</times>
<unicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</multicastLocatorList>
<throughputController>
<bytesPerPeriod>8192</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<matchedSubscribersAllocation>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
<propertiesPolicy>
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
<property>
<name>Property2Name</name>
<value>Property2Value</value>
<propagate>false</propagate>
</property>
</properties>
</propertiesPolicy>
<userDefinedID>45</userDefinedID>
<entityID>76</entityID>
</data_writer>
<data_reader profile_name="datareader_profile_example">
<topic>
<kind>WITH_KEY</kind>
<name>TopicName</name>
<dataType>TopicDataTypeName</dataType>
<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>
</resourceLimitsQos>
</topic>
<qos> <!-- dataReaderQosPoliciesType -->
<durability>
<kind>PERSISTENT</kind>
</durability>
<liveliness>
<kind>MANUAL_BY_PARTICIPANT</kind>
<lease_duration>
<sec>1</sec>
<nanosec>856000</nanosec>
</lease_duration>
<announcement_period>
<sec>1</sec>
<nanosec>856000</nanosec>
</announcement_period>
</liveliness>
<reliability>
<kind>BEST_EFFORT</kind>
<max_blocking_time>
<sec>1</sec>
<nanosec>856000</nanosec>
</max_blocking_time>
</reliability>
<lifespan>
<duration>
<sec>5</sec>
<nanosec>0</nanosec>
</duration>
</lifespan>
<partition>
<names>
<name>part1</name>
<name>part2</name>
</names>
</partition>
</qos>
<times>
<initialAcknackDelay>
<sec>1</sec>
<nanosec>856000</nanosec>
</initialAcknackDelay>
<heartbeatResponseDelay>
<sec>1</sec>
<nanosec>856000</nanosec>
</heartbeatResponseDelay>
</times>
<unicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</unicastLocatorList>
<multicastLocatorList>
<locator>
<udpv4>
<!-- Access as physical, like UDP -->
<port>7400</port>
<address>192.168.1.41</address>
</udpv4>
</locator>
<locator>
<tcpv4>
<!-- Both physical and logical (port), like TCP -->
<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>
</locator>
</multicastLocatorList>
<expectsInlineQos>true</expectsInlineQos>
<historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>
<matchedPublishersAllocation>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</matchedPublishersAllocation>
<propertiesPolicy>
<properties>
<property>
<name>Property1Name</name>
<value>Property1Value</value>
<propagate>false</propagate>
</property>
<property>
<name>Property2Name</name>
<value>Property2Value</value>
<propagate>false</propagate>
</property>
</properties>
</propertiesPolicy>
<userDefinedID>55</userDefinedID>
<entityID>66</entityID>
</data_reader>
</profiles>
<log>
<use_default>FALSE</use_default>
<consumer>
<class>StdoutConsumer</class>
</consumer>
<consumer>
<class>FileConsumer</class>
<property>
<name>filename</name>
<value>execution.log</value>
</property>
<property>
<name>append</name>
<value>TRUE</value>
</property>
</consumer>
</log>
<types>
<type> <!-- Types can be defined in its own type of tag or sharing the same tag -->
<enum name="MyAloneEnumType">
<enumerator name="A" value="0"/>
<enumerator name="B" value="1"/>
<enumerator name="C" value="2"/>
</enum>
</type>
<type>
<enum name="MyEnum">
<enumerator name="A" value="0"/>
<enumerator name="B" value="1"/>
<enumerator name="C" value="2"/>
</enum>
<typedef name="MyAlias1" type="nonBasic" nonBasicTypeName="MyEnum"/>
<typedef name="MyAlias2" type="int32" arrayDimensions="2,2"/>
<typedef name="my_map_inner" type="int32" key_type="int32" mapMaxLength="2"/>
<bitset name="MyBitSet">
<bitfield name="a" bit_bound="3"/>
<bitfield name="b" bit_bound="10"/>
<bitfield name="c" bit_bound="12" type="int16"/>
</bitset>
<bitmask name="MyBitMask" bit_bound="8">
<bit_value name="flag0" position="0"/>
<bit_value name="flag1"/>
</bitmask>
<struct name="MyStruct">
<member name="first" type="int32"/>
<member name="second" type="int64"/>
</struct>
<struct name="OtherStruct">
<member name="my_enum" type="nonBasic" nonBasicTypeName="MyEnum"/>
<member name="my_struct" type="nonBasic" nonBasicTypeName="MyStruct" arrayDimensions="5"/>
</struct>
<union name="MyUnion1">
<discriminator type="byte"/>
<case>
<caseDiscriminator value="0"/>
<caseDiscriminator value="1"/>
<member name="first" type="int32"/>
</case>
<case>
<caseDiscriminator value="2"/>
<member name="second" type="nonBasic" nonBasicTypeName="MyStruct"/>
</case>
<case>
<caseDiscriminator value="default"/>
<member name="third" type="int64"/>
</case>
</union>
<!-- All possible members struct type -->
<struct name="MyFullStruct">
<!-- Primitives & basic -->
<member name="my_bool" type="boolean"/>
<member name="my_byte" type="byte"/>
<member name="my_char" type="char8"/>
<member name="my_wchar" type="char16"/>
<member name="my_short" type="int16"/>
<member name="my_long" type="int32"/>
<member name="my_longlong" type="int64"/>
<member name="my_unsignedshort" type="uint16"/>
<member name="my_unsignedlong" type="uint32"/>
<member name="my_unsignedlonglong" type="uint64"/>
<member name="my_float" type="float32"/>
<member name="my_double" type="float64"/>
<member name="my_longdouble" type="float128"/>
<member name="my_string" type="string"/>
<member name="my_wstring" type="wstring"/>
<member name="my_boundedString" type="string" stringMaxLength="41925"/>
<member name="my_boundedWString" type="wstring" stringMaxLength="41925"/>
<!-- long long_array[2][3][4]; -->
<member name="long_array" arrayDimensions="2,3,4" type="int32"/>
<!-- map<long,map<long,long,2>,2> my_map_map; -->
<member name="my_map_map" type="nonBasic" nonBasicTypeName="my_map_inner" key_type="int32" mapMaxLength="2"/>
<!-- Complex types -->
<member name="my_other_struct" type="nonBasic" nonBasicTypeName="OtherStruct"/>
</struct>
</type>
</types>
</dds>
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Environment variables¶
This is the list of environment variables that affect the behavior of Fast DDS:
FASTRTPS_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 FASTRTPS_DEFAULT_PROFILES_FILE=/home/user/profiles.xml
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Windows |
set FASTRTPS_DEFAULT_PROFILES_FILE=C:\profiles.xml
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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_FASTRTPS_PROFILES.xml in the working directory. For more information about XML profiles, please refer to XML profiles.
Linux |
export SKIP_DEFAULT_XML=1
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Windows |
set SKIP_DEFAULT_XML=1
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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 isSERVERorBACKUP, 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 the IP address (e.g., ‘192.168.2.23’) or IP-port pair (e.g., ‘192.168.2.23:24353’).
If no port is specified, the default port 11811 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.
The following example shows how to set the address of two remote discovery servers with addresses ‘84.22.259.329:8888’ and ‘81.41.17.102:1234’ and IDs 0 and 2 respectively.
Linux
Windows
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.
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.
PushMode QoS Policy¶
Warning
This section is still under work.
Unique network flows QoS Policy¶
Warning
This section is still under work.
Statistics Module Settings¶
Warning
This section is still under work.
Persistence Service Settings¶
Warning
This section is still under work.
Security Plugins Settings¶
Warning
This section is still under work.
Logging Module Settings¶
Warning
This section is still under work.
Dynamic Topic Types¶
eProsima Fast DDS provides a dynamic way to define and use topic types and topic data. Our implementation follows the OMG Extensible and Dynamic Topic Types for DDS interface. For more information, you can read the specification for DDS-XTypes V1.2.
The dynamic topic types offer the possibility to work over RTPS without the restrictions related to the IDLs. Using them, the users can declare the different types that they need and manage the information directly, avoiding the additional step of updating the IDL file and the generation of C++ classes.
Overview of Dynamic Types¶
This section describes the classes related to dynamic types that are used through the rest of the documentation. At the bottom of the section you can also find a short example using the functionality.
Involved classes¶
The following class diagram describes the relationship among the classes related to dynamic types. Please, refer to the description of each class to find its purpose and the nature of the relationship with the rest of the classes.
Dynamic types class diagram¶
DynamicType¶
Base class of all types declared dynamically. It represents a dynamic data type that can be used to create DynamicData values. By design, the structure of a dynamic type (its member fields) cannot be modified once the type is created.
DynamicTypeBuilderFactory¶
Singleton class that is in charge of the creation and the management of every DynamicType and DynamicTypeBuilder. It declares functions to create builders for each kind of supported types. Given a builder for a specific type, it can also create the corresponding DynamicType. Some simpler types can be created directly, avoiding the step of creating a DynamicTypeBuilder. Please, refer to the Supported Types documentation for details about which ones support this option.
Every object created by the factory must be deleted to avoid memory leaking. Refer to the Memory management section for details.
DynamicTypeBuilder¶
Intermediate class used to configure a DynamicType before it is created. By design, the structure of a DynamicType (its member fields) cannot be modified once the object is created. Therefore, all its structure must be defined prior to its creation. The builder is the object used to set up this structure.
Once defined, the DynamicTypeBuilderFactory is used to create
the DynamicType from the information contained in the builder.
As a shortcut, the builder exposes a function build() that internally uses the
DynamicTypeBuilderFactory to return a fully constructed
DynamicType.
The types created with build() are still subject to the Memory management
restrictions, and must be deleted by the DynamicTypeBuilderFactory.
Builders can be reused after the creation of a DynamicType, as the changes applied to the builder do not affect to types created previously.
TypeDescriptor¶
Stores the information about one type with its relationships and restrictions. This is the class that describes the inner structure of a DynamicType. The DynamicTypeBuilder has an internal instance of TypeDescriptor that modifies during the type building process. When the DynamicType is created, the DynamicTypeBuilderFactory uses the information of the TypeDescriptor in the builder to create the DynamicType. During the creation, the TypeDescriptor is copied to the DynamicType, so that it becomes independent from the DynamicTypeBuilder, and the builder can be reused for another type.
DynamicTypeMember¶
Represents a data member of a DynamicType that is also a DynamicType. Compound types (dynamic types that are composed of other dynamic types) have a DynamicTypeMember for every child DynamicType added to it.
MemberDescriptor¶
Just as a TypeDescriptor describes the inner structure of a DynamicType, a MemberDescriptor stores all the information needed to manage a DynamicTypeMember, like their name, their unique ID, or the default value after the creation. This information is copied to the DynamicData on its creation.
DynamicData¶
While a DynamicType describes a type, DynamicData represents a data instance of a DynamicType. It provides functions to access and modify the data values in the instance.
There are two ways to work with DynamicData:
Activating the macro
DYNAMIC_TYPES_CHECKING, which creates a variable for each primitive kind to help the debug process.Without this macro, the size of the DynamicData is reduced, using only the minimum needed internal values, but it makes the code harder to debug.
DynamicDataFactory¶
Singleton class that is in charge of the creation and the management of every DynamicData. It can take a DynamicType and create an instance of a corresponding DynamicData. Every data object created by the factory must be deleted to avoid memory leaking. Refer to the Memory management section for details.
It also allows to create a TypeIdentifier and a (Minimal and Complete) TypeObject from a
TypeDescriptor.
DynamicPubSubType¶
This class is an adapter that allows using DynamicData on Fast DDS.
It inherits from TopicDataType and implements the functions needed to communicate the
DynamicData between Publishers and Subscribers.
Minimum example¶
This is a short example to illustrate the use of the dynamic types and how the classes describe above interact with each other. While the code snippet can be used as a quick reference for code building, the sequence diagram below provides a visual interpretation of the actions.
// Create a builder for a specific type
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_enum_builder();
// Use the builder to configure the type
builder->add_empty_member(0, "DEFAULT");
builder->add_empty_member(1, "FIRST");
builder->add_empty_member(2, "SECOND");
// Create the data type using the builder
// The builder will internally use the DynamicTypeBuilderFactory to create the type
DynamicType_ptr type = builder->build();
// Create a new data instance of the create data type
DynamicData_ptr data (DynamicDataFactory::get_instance()->create_data(type));
// Now we can set or read data values
data->set_int32_value(1);
// No need of deleting the objects, since we used the
// automanaged smart pointers
Sequence diagram of the code above¶
Supported Types¶
In order to provide maximum flexibility and capability to the defined dynamic types, eProsima Fast DDS supports several member types, ranging from simple primitives to nested structures.
This section describes the basic (not nested) supported types. For more complex structures and examples, please, refer to Complex Types.
Primitive Types¶
This section includes every simple kind:
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By definition, primitive types are self-described and can be created without configuration parameters.
Therefore, DynamicTypeBuilderFactory exposes several functions to allow users create
the dynamic type avoiding the DynamicTypeBuilder step.
The DynamicTypeBuilder can still be used to create dynamic data of primitive types,
as shown on the example below.
The DynamicData class has a specific get() and set() functions for each primitive
type of the list.
// Using Builders
DynamicTypeBuilder_ptr created_builder = DynamicTypeBuilderFactory::get_instance()->create_int32_builder();
DynamicType_ptr created_type = DynamicTypeBuilderFactory::get_instance()->create_type(created_builder.get());
DynamicData* data = DynamicDataFactory::get_instance()->create_data(created_type);
data->set_int32_value(1);
// Creating directly the Dynamic Type
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicData* data2 = DynamicDataFactory::get_instance()->create_data(pType);
data2->set_int32_value(1);
String and WString¶
Strings are pretty similar to primitive types, the main difference being
that they need to set the size of the buffer that they can manage.
By default this size is set to 255 characters.
DynamicTypeBuilderFactory exposes the functions create_string_type() and create_wstring_type()
to allow users create the DynamicTypes avoiding the DynamicTypeBuilder step.
The DynamicTypeBuilder can still be used to create String type dynamic data,
as shown on the example below.
// Using Builders
DynamicTypeBuilder_ptr created_builder = DynamicTypeBuilderFactory::get_instance()->create_string_builder(100);
DynamicType_ptr created_type = DynamicTypeBuilderFactory::get_instance()->create_type(created_builder.get());
DynamicData* data = DynamicDataFactory::get_instance()->create_data(created_type);
data->set_string_value("Dynamic String");
// Creating directly the Dynamic Type
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_string_type(100);
DynamicData* data2 = DynamicDataFactory::get_instance()->create_data(pType);
data2->set_string_value("Dynamic String");
Alias¶
Alias types provide an alternative name to an already existing type. Once the DynamicData is created, users can access its information as if they were working with the base type.
DynamicTypeBuilderFactory exposes the function create_alias_type() to allow users
create the Alias types avoiding the DynamicTypeBuilder step.
The DynamicTypeBuilder can still be used to create Alias,
as shown on the example below.
// Create the base type
DynamicTypeBuilder_ptr base_builder = DynamicTypeBuilderFactory::get_instance()->create_string_builder(100);
DynamicType_ptr base_type = DynamicTypeBuilderFactory::get_instance()->create_type(base_builder.get());
// Create alias using Builders
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_alias_builder(base_type,
"alias");
DynamicData* data = DynamicDataFactory::get_instance()->create_data(builder.get());
data->set_string_value("Dynamic Alias String");
// Create alias type directly
DynamicType_ptr pAliasType = DynamicTypeBuilderFactory::get_instance()->create_alias_type(base_type, "alias");
DynamicData* data2 = DynamicDataFactory::get_instance()->create_data(pAliasType);
data2->set_string_value("Dynamic Alias String");
Enumeration¶
An enumeration contains a set of supported values and a selected value among those supported.
The supported values must be configured using the DynamicTypeBuilder, using the add_member() function
for each supported value.
The input to this function is the index and the name of the value we want to add.
The DynamicData class has functions get_enum_value() and set_enum_value() to work
with value index or value name name strings.
// Add enumeration values using the DynamicTypeBuilder
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_enum_builder();
builder->add_empty_member(0, "DEFAULT");
builder->add_empty_member(1, "FIRST");
builder->add_empty_member(2, "SECOND");
// Create the data instance
DynamicData* data = DynamicDataFactory::get_instance()->create_data(builder.get());
// Access value using the name
std::string sValue = "SECOND";
data->set_enum_value(sValue);
std::string sStoredValue;
data->get_enum_value(sStoredValue, MEMBER_ID_INVALID);
// Access value using the index
uint32_t uValue = 2;
data->set_enum_value(uValue);
uint32_t uStoredValue;
data->get_enum_value(uStoredValue, MEMBER_ID_INVALID);
Bitmask¶
Bitmasks are similar to enumeration types, but their members work as bit flags that can be individually turned on and
off. Bit operations can be applied when testing or setting a bitmask value.
DynamicData has the special functions get_bitmask_value() and set_bitmask_value() which allow to retrieve or
modify the full value instead of accessing each bit.
Bitmasks can be bound to any number of bits up to 64.
uint32_t limit = 5; // Stores as "octet"
// Add bitmask flags using the DynamicTypeBuilder
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_bitmask_builder(limit);
builder->add_empty_member(0, "FIRST");
builder->add_empty_member(1, "SECOND");
// Create the data instance
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(builder.get()));
// Access the mask values using the name
data->set_bool_value(true, "FIRST"); // Set the "FIRST" bit
bool bSecondValue = data->get_bool_value("SECOND"); // Get the "SECOND" bit
// Access the mask values using the index
data->set_bool_value(true, 1); // Set the "SECOND" bit
bool bFirstValue = data->get_bool_value(0); // Get the "FIRST" bit
// Get the complete bitmask as integer
uint64_t fullValue;
data->get_bitmask_value(fullValue);
Structure¶
Structures are the common complex types, they allow to add any kind of members inside them. They do not have any value, they are only used to contain other types.
To manage the types inside the structure, users can call the get() and set() functions
according to the kind of the type inside the structure using their ids.
If the structure contains a complex value, it should be used with loan_value to
access to it and return_loaned_value to release that pointer.
DynamicData manages the counter of loaned values and users can not loan a value that
has been loaned previously without calling return_loaned_value before.
The ids must be consecutive starting by zero, and the DynamicType will change that
Id if it doesn’t match with the next value.
If two members have the same Id, after adding the second one, the previous
will change its Id to the next value.
To get the Id of a member by name, DynamicData exposes the function get_member_id_by_name().
// Build a structure with two fields ("first" as int32, "other" as uint64) using DynamicTypeBuilder
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type());
builder->add_member(1, "other", DynamicTypeBuilderFactory::get_instance()->create_uint64_type());
DynamicType_ptr struct_type(builder->build());
// Create the data instance
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(struct_type));
// Access struct members
data->set_int32_value(5, 0);
data->set_uint64_value(13, 1);
Structures allow inheritance, exactly with the same OOP meaning. To inherit from another structure, we must create the
structure calling the create_child_struct_builder() of the factory. This function is shared with bitsets and will
deduce our type depending on the parent’s type.
DynamicTypeBuilder_ptr child_builder =
DynamicTypeBuilderFactory::get_instance()->create_child_struct_builder(builder.get());
Bitset¶
Bitset types are similar to structure types, but their members are merely bitfields, which are stored optimally. In the static version of bitsets, each bit uses just one bit in memory (with platform limitations) without alignment considerations. A bitfield can be anonymous (cannot be addressed) to skip unused bits within a bitset.
Each bitfield in a bitset can be modified through their minimal needed primitive representation.
Number of bits |
Primitive |
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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.
Bit_bound and position of the bitfield can be set using annotations (useful when converting between static and dynamic bitsets).
// Create bitfields with the appropriate type for their size
DynamicTypeBuilder_ptr base_type_byte_builder =
DynamicTypeBuilderFactory::get_instance()->create_byte_builder();
auto base_type_byte = base_type_byte_builder->build();
DynamicTypeBuilder_ptr base_type_uint32_builder =
DynamicTypeBuilderFactory::get_instance()->create_uint32_builder();
auto base_type_uint32 = base_type_uint32_builder->build();
// Create the bitset with two bitfields
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_bitset_builder();
builder->add_member(0, "byte", base_type_byte);
builder->add_member(1, "uint32", base_type_uint32);
// Apply members' annotations
builder->apply_annotation_to_member(0, ANNOTATION_POSITION_ID, "value", "0"); // "byte" starts at position 0
builder->apply_annotation_to_member(0, ANNOTATION_BIT_BOUND_ID, "value", "2"); // "byte" is 2 bit length
builder->apply_annotation_to_member(1, ANNOTATION_POSITION_ID, "value", "10"); // "uint32" starts at position 10 (8 bits empty)
builder->apply_annotation_to_member(1, ANNOTATION_BIT_BOUND_ID, "value", "20"); // "uint32" is 20 bits length
// Create the data instance
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(builder.get()));
// Access values
data->set_byte_value(234, 0);
data->set_uint32_value(2340, 1);
octet bValue;
uint32_t uValue;
data->get_byte_value(bValue, 0);
data->get_uint32_value(uValue, 1);
Bitsets allows inheritance, exactly with the same OOP meaning. To inherit from another bitset, we must create the
bitset calling the create_child_struct_builder of the factory. This function is shared with structures and will
deduce our type depending on the parent’s type.
DynamicTypeBuilder_ptr child_builder =
DynamicTypeBuilderFactory::get_instance()->create_child_struct_builder(builder.get());
Union¶
Unions are a special kind of structures where only one of the members is active
at the same time.
To control these members, users must set the discriminator type that is going to be used
to select the current member calling the create_union_builder function.
The discriminator itself is a DynamicType of any primitive type, string type or union type.
Every member that is going to be added needs at least one union_case_index to set
how it is going to be selected and, optionally, if it is the default value of the union.
// Create the union DynamicTypeBuilder with an int32 discriminator
DynamicType_ptr discriminator = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_union_builder(discriminator);
// Add the union members. "firts" will be the default value
builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type(), "", { 0 },
true);
builder->add_member(0, "second", DynamicTypeBuilderFactory::get_instance()->create_int64_type(), "", { 1 },
false);
// Create the data instance
DynamicType_ptr union_type = builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(union_type));
// Access the values using the member index
data->set_int32_value(9, 0);
data->set_int64_value(13, 1);
// Get the label of the currently selected member
uint64_t unionLabel;
data->get_union_label(unionLabel);
Sequence¶
A complex type that manages its members as a list of items allowing users to insert, remove or access to a member of the list. To create this type users need to specify the type that it is going to store and optionally the size limit of the list.
To ease the memory management of this type, DynamicData has these functions:
insert_sequence_data(): Creates a new element at the end of the list and returns theidof the new element.
remove_sequence_data(): Removes the element of the given index and refreshes theidsto keep the consistency of the list.
clear_data(): Removes all the elements of the list.
// Create a DynamicTypeBuilder for a sequence of two elements of type inte32
uint32_t length = 2;
DynamicType_ptr base_type = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicTypeBuilder_ptr builder =
DynamicTypeBuilderFactory::get_instance()->create_sequence_builder(base_type, length);
// Create the data instance
DynamicType_ptr sequence_type = builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(sequence_type));
// Insert and remove elements
MemberId newId, newId2;
data->insert_int32_value(10, newId);
data->insert_int32_value(12, newId2);
data->remove_sequence_data(newId);
Array¶
Arrays are pretty similar to sequences with two main differences: they can have multiple dimensions and they do not need their elements to be stored consecutively.
An array needs to know the number of dimensions it is managing.
For that, users must provide a vector with as many elements as dimensions in the array.
Each element in the vector represents the size of the given dimension.
If the value of an element is set to zero, the default value applies (100).
Id values on the set() and get() functions of DynamicData correspond to the array index.
To ease the management of array elements, every set() function in DynamicData class creates
the item if the given index is empty.
To ease the memory management of this type, DynamicData has these functions:
insert_array_data(): Creates a new element at the end of the array and returns theidof the new element.
remove_array_data(): Clears the element of the given index.
clear_data(): Removes all the elements of the array.
get_array_index(): Returns the position id giving a vector of indexes on every dimension that the arrays support, which is useful in multidimensional arrays.
// Create an array DynamicTypeBuilder for a 2x2 elements of type int32
std::vector<uint32_t> lengths = { 2, 2 };
DynamicType_ptr base_type = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicTypeBuilder_ptr builder =
DynamicTypeBuilderFactory::get_instance()->create_array_builder(base_type, lengths);
// Create the data instance
DynamicType_ptr array_type = builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(array_type));
// Access elements in the multidimensional array
MemberId pos = data->get_array_index({1, 0});
data->set_int32_value(11, pos);
data->set_int32_value(27, pos + 1);
data->clear_array_data(pos);
Map¶
Maps contain a list of ‘key-value’ pair types, allowing users to insert, remove or modify the element types of the map. The main difference with sequences is that the map works with pairs of elements and creates copies of the key element to block the access to these elements.
To create a map, users must set the types of the key and the value elements, and, optionally, the size limit of the map.
To ease the memory management of this type, DynamicData has these functions:
insert_map_data(): Inserts a new key value pair and returns the ids of the newly created key and value elements.
remove_map_data(): Uses the given id to find the key element and removes the key and the value elements from the map.
clear_data(): Removes all the elements from the map.
// Create DynamicTypeBuilder for a map of two pairs of {key:int32, value:int32}
uint32_t length = 2;
DynamicType_ptr base = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicTypeBuilder_ptr builder =
DynamicTypeBuilderFactory::get_instance()->create_map_builder(base, base, length);
// Create the data instance
DynamicType_ptr map_type = builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(map_type));
// Add a new element to the map with key 1
DynamicData_ptr key(DynamicDataFactory::get_instance()->create_data(base));
MemberId keyId;
MemberId valueId;
key->set_int32_value(1);
data->insert_map_data(key.get(), keyId, valueId);
// Add a new element to the map with key 2
// insert_map_data creates a copy of the key, so the same instance can be reused
MemberId keyId2;
MemberId valueId2;
key->set_int32_value(2);
data->insert_map_data(key.get(), keyId2, valueId2);
// Set the value to the element with key 2, using the returned value Id
data->set_int32_value(53, valueId2);
// Remove elements from the map
data->remove_map_data(keyId);
data->remove_map_data(keyId2);
Complex Types¶
If the application’s data model is complex, it is possible to combine the basic types to create complex types, including nested composed types (structures within structures within unions). Types can also be extended using inheritance, improving the flexibility of the definition of the data types to fit the model.
The following subsections describe these complex types and their use.
Nested structures¶
Structures can contain other structures as members.
The access to these compound members is restricted and managed by the DynamicData instance.
Users must request access calling loan_value before using them, and release
them with return_loaned_value once they finished.
The loan operation will fail if the member is already loaned and has not been released yet.
// Create a struct type
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type());
builder->add_member(1, "other", DynamicTypeBuilderFactory::get_instance()->create_uint64_type());
DynamicType_ptr struct_type = builder->build();
// Create a struct type with the previous struct as member
DynamicTypeBuilder_ptr parent_builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
parent_builder->add_member(0, "child_struct", struct_type);
parent_builder->add_member(1, "second", DynamicTypeBuilderFactory::get_instance()->create_int32_type());
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(parent_builder.get()));
// Access the child struct with the loan operations
DynamicData* child_data = data->loan_value(0);
child_data->set_int32_value(5, 0);
child_data->set_uint64_value(13, 1);
data->return_loaned_value(child_data);
Structure inheritance¶
To inherit a structure from another one, use the create_child_struct_type function from
DynamicTypeBuilderFactory.
The resultant type contains all members from the base class and the new ones added to the child.
Structures support several levels of inheritance, so the base class can be another derived type itself.
// Create a base struct type
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type());
builder->add_member(1, "other", DynamicTypeBuilderFactory::get_instance()->create_uint64_type());
// Create a struct type derived from the previous struct
DynamicTypeBuilder_ptr child_builder =
DynamicTypeBuilderFactory::get_instance()->create_child_struct_builder(builder.get());
// Add new members to the derived type
builder->add_member(2, "third", DynamicTypeBuilderFactory::get_instance()->create_uint64_type());
// Create the data instance
DynamicType_ptr struct_type = child_builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(struct_type));
// The derived type includes the members defined on the base type
data->set_int32_value(5, 0);
data->set_uint64_value(13, 1);
data->set_uint64_value(47, 2);
Alias of an alias¶
Alias types support recursion, simply use an alias name as base type for create_alias_type().
// Using Builders
DynamicTypeBuilder_ptr created_builder = DynamicTypeBuilderFactory::get_instance()->create_string_builder(100);
DynamicType_ptr created_type = DynamicTypeBuilderFactory::get_instance()->create_type(created_builder.get());
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_alias_builder(
created_builder.get(), "alias");
DynamicTypeBuilder_ptr builder2 = DynamicTypeBuilderFactory::get_instance()->create_alias_builder(
builder.get(), "alias2");
DynamicData* data(DynamicDataFactory::get_instance()->create_data(builder2->build()));
data->set_string_value("Dynamic Alias 2 String");
// Creating directly the Dynamic Type
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_string_type(100);
DynamicType_ptr pAliasType = DynamicTypeBuilderFactory::get_instance()->create_alias_type(pType, "alias");
DynamicType_ptr pAliasType2 =
DynamicTypeBuilderFactory::get_instance()->create_alias_type(pAliasType, "alias2");
DynamicData* data2(DynamicDataFactory::get_instance()->create_data(pAliasType));
data2->set_string_value("Dynamic Alias 2 String");
Unions with complex types¶
Unions support complex type fields.
The access to these complex type fields is restricted and managed by the DynamicData instance.
Users must request access calling loan_value before using them, and release
them with return_loaned_value once they finished.
The loan operation will fail if the fields is already loaned and has not been released yet.
// Create a union DynamicTypeBuilder
DynamicType_ptr discriminator = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_union_builder(discriminator);
// Add a int32 to the union
builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type(), "", { 0 },
true);
// Create a struct type and add it to the union
DynamicTypeBuilder_ptr struct_builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
struct_builder->add_member(0, "first", DynamicTypeBuilderFactory::get_instance()->create_int32_type());
struct_builder->add_member(1, "other", DynamicTypeBuilderFactory::get_instance()->create_uint64_type());
builder->add_member(1, "first", struct_builder.get(), "", { 1 }, false);
// Create the union data instance
DynamicType_ptr union_type = builder->build();
DynamicData_ptr data(DynamicDataFactory::get_instance()->create_data(union_type));
// Access the struct member using the loan operations
DynamicData* child_data = data->loan_value(1);
child_data->set_int32_value(9, 0);
child_data->set_int64_value(13, 1);
data->return_loaned_value(child_data);
Annotations¶
DynamicTypeBuilder allows applying an annotation to both current type and inner members with the functions:
apply_annotation()apply_annotation_to_member()
Both functions take the name, the key and the value of the annotation.
apply_annotation_to_member() additionally receives the MemberId of the inner member.
For example, if we define an annotation like:
@annotation MyAnnotation
{
long value;
string name;
};
And then we apply it through IDL to a struct:
@MyAnnotation(5, "length")
struct MyStruct
{
...
The equivalent code using DynamicType will be:
// Apply the annotation
DynamicTypeBuilder_ptr builder = DynamicTypeBuilderFactory::get_instance()->create_struct_builder();
//...
builder->apply_annotation("MyAnnotation", "value", "5");
builder->apply_annotation("MyAnnotation", "name", "length");
Dynamic Types Discovery and Endpoint Matching¶
When using DynamicType support, Fast DDS checks the optional TypeObject and TypeIdentifier values during endpoint matching. Currently, the matching only verifies that both endpoints are using the same topic data type, but will not negotiate about it.
The process of checking the types is as follows:
It checks
CompleteTypeObjecton TypeObject first.If one or both endpoints do not define the
CompleteTypeObject, it tries withMinimalTypeObject.If one or both endpoints do not define
MinimalTypeObjecteither, it compares the TypeIdentifier.If none is defined, then just the type name is checked.
If one of the endpoints transmits a CompleteTypeObject, Discovery-Time Data Typing can be performed.
TypeObject¶
TypeObject fully describes a data type, the same way as the IDL representation does.
There are two kinds of TypeObjects: CompleteTypeObject and MinimalTypeObject .
CompleteTypeObjectfully describes the type, the same way as the IDL representation does.
MinimalTypeObjectis a compact representation of the data type, that contains only the information relevant for the remote Endpoint to be able to interpret the data.
TypeObject is an IDL union with both Minimal and Complete representation. Both are described in the annexes of DDS-XTypes V1.2 document, please refer to this document for details.
TypeInformation¶
TypeInformation is an extension of XTypes 1.2 that allow Endpoints to
share information about data types without sending the TypeObject.
Endpoints instead share a TypeInformation containing the
TypeIdentifier of the data type.
Then each Endpoint can request the complete TypeObject for the data
types it is interested in.
This avoids sending the complete data type to Endpoints that may not be interested.
TypeInformation is described in the annexes of DDS-XTypes V1.2 document,
please refer to this document for details.
TypeIdentifier¶
TypeIdentifier provides a unique way to identify each type.
For basic types, the information contained in the TypeIdentifier
completely describes the type, while for complex ones, it serves as a search key to
retrieve the complete TypeObject.
TypeIdentifier is described in the annexes of DDS-XTypes V1.2 document,
please refer to this document for details.
TypeObjectFactory¶
Singleton class that manages the creation and access for every registered TypeObject
and TypeIdentifier.
It can generate a full DynamicType from a basic
TypeIdentifier (i.e., one whose discriminator is not EK_MINIMAL
or EK_COMPLETE).
Fast DDS-Gen¶
Fast DDS-Gen supports the generation of XXXTypeObject.h and XXXTypeObject.cxx files,
taking XXX as our IDL type.
These files provide a small Type Factory for the type XXX.
Generally, these files are not used directly, as now the type XXX will register itself through its factory to
TypeObjectFactory in its constructor, making it very easy to use static types
with dynamic types.
Discovery-Time Data Typing¶
Using the Fast DDS API, when a participant discovers a remote endpoint that sends a complete
TypeObject or a simple TypeIdentifier describing a type
that the participant does not know, the participant listener’s function
on_type_discovery
is called with the received TypeObject or TypeIdentifier,
and, when possible, a pointer to a DynamicType ready to be used.
Discovery-Time Data Typing allows the discovering of simple DynamicTypes. A TypeObject that depends on other TypeObjects, cannot be built locally using Discovery-Time Data Typing and should use TypeLookup Service instead.
To ease the sharing of the TypeObject and TypeIdentifier
used by Discovery-Time Data Typing,
TopicDataType contains a function member named
auto_fill_type_object.
If set to true, the local participant will send the TypeObject and
TypeIdentifier to the remote endpoint during discovery.
TypeLookup Service¶
Using the Fast DDS API, when a participant discovers an endpoint that sends a type information
describing a type that the participant doesn’t know, the participant listener’s function
on_type_information_received()
is called with the received TypeInformation.
The user can then try to retrieve the full TypeObject hierarchy to build the remote type locally, using the
TypeLookup Service.
To enable this builtin TypeLookup Service, the user must enable it in the QoS of the DomainParticipant:
DomainParticipantQos qos;
qos.wire_protocol().builtin.typelookup_config.use_client = true;
qos.wire_protocol().builtin.typelookup_config.use_server = true;
A participant can be enabled to act as a TypeLookup server, client, or both.
The process of retrieving the remote type from its TypeInformation, and then registering it, can be simplified
using the register_remote_type
function on the DomainParticipant.
This function takes the name of the type, the type information, and a callback function.
Internally it uses the TypeLookup Service to retrieve the full TypeObject,
and, if successful, it will call the callback.
This callback has the following signature:
void(std::string& type_name, const DynamicType_ptr type)
type_name: Is the name given to the type when calling
register_remote_type, to allow the same callback to be used across different calls.type: If the
register_remote_typewas able to build and register a DynamicType, this parameter contains a pointer to the type. Otherwise it containsnullptr. In the latter case, the user can still try to build the type manually using the factories, but it is very likely that the build process will fail.
TopicDataType contains a data member named
auto_fill_type_information.
If set to true, the local participant will send the type information to the remote endpoint during discovery.
Serialization¶
Dynamic Types have their own pubsub type like any class generated with an IDL, and
their management is pretty similar to them.
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicPubSubType pubsubType(pType);
// SERIALIZATION EXAMPLE
DynamicData* pData = DynamicDataFactory::get_instance()->create_data(pType);
uint32_t payloadSize = static_cast<uint32_t>(pubsubType.getSerializedSizeProvider(pData)());
SerializedPayload_t payload(payloadSize);
pubsubType.serialize(pData, &payload);
// DESERIALIZATION EXAMPLE
types::DynamicData* data2 = DynamicDataFactory::get_instance()->create_data(pType);
pubsubType.deserialize(&payload, data2);
A member can be marked to be ignored by serialization with the annotation @non_serialized.
XML profiles¶
Dynamic Types profiles allows eProsima Fast DDS to create DynamicTypes directly defining them through XML. This allows any application to change TopicDataTypes without the need to change its source code.
Please, refer to Dynamic Types profiles for further information about how to use this feature.
Memory management¶
Memory management is critical for dynamic types since every dynamic type and dynamic data is managed with pointers. Every object stored inside of a dynamic object is managed by its owner, and users must delete every object they create using the factories.
DynamicTypeBuilder* pBuilder = DynamicTypeBuilderFactory::get_instance()->create_uint32_builder();
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicData* pData = DynamicDataFactory::get_instance()->create_data(pType);
DynamicTypeBuilderFactory::get_instance()->delete_builder(pBuilder);
DynamicDataFactory::get_instance()->delete_data(pData);
To ease this management, the library defines smart pointers (DynamicTypeBuilder_ptr,
DynamicType and DynamicData_ptr) that will delete the objects automatically when they are not
needed anymore.
DynamicType will always be returned as DynamicType_ptr because there is no internal management of its memory.
DynamicTypeBuilder_ptr pBuilder = DynamicTypeBuilderFactory::get_instance()->create_uint32_builder();
DynamicType_ptr pType = DynamicTypeBuilderFactory::get_instance()->create_int32_type();
DynamicData_ptr pData(DynamicDataFactory::get_instance()->create_data(pType));
The only case where these smart pointers cannot be used is with functions loan_value and return_loaned_value.
Raw pointers should be used with these functions, because the returned value should not be deleted, and using
a smart pointer with them will cause a crash.
Dynamic HelloWorld Examples¶
These are complete working examples that make use of dynamic types. You can explore them to find how this feature connects to the rest of Fast DDS, and learn how to integrate it in your own application.
DynamicHelloWorldExample¶
This example is in folder examples/C++/DynamicHelloWorldExample of the Fast DDS GitHub repository. It shows the use of DynamicType generation to provide the TopicDataType. This example is compatible with the classic HelloWorldExample.
As a quick reference, the following piece of code shows how the HelloWorld type is created using DynamicTypes:
// In HelloWorldPublisher.h
// Dynamic Types
eprosima::fastrtps::types::DynamicData* m_DynHello;
eprosima::fastrtps::types::DynamicPubSubType m_DynType;
// In HelloWorldPublisher.cpp
// Create basic builders
DynamicTypeBuilder_ptr struct_type_builder(DynamicTypeBuilderFactory::get_instance()->create_struct_builder());
// Add members to the struct.
struct_type_builder->add_member(0, "index", DynamicTypeBuilderFactory::get_instance()->create_uint32_type());
struct_type_builder->add_member(1, "message", DynamicTypeBuilderFactory::get_instance()->create_string_type());
struct_type_builder->set_name("HelloWorld");
DynamicType_ptr dynType = struct_type_builder->build();
m_DynType.SetDynamicType(dynType);
m_DynHello = DynamicDataFactory::get_instance()->create_data(dynType);
m_DynHello->set_uint32_value(0, 0);
m_DynHello->set_string_value("HelloWorld", 1);
DDSDynamicHelloWorldExample¶
This example uses the DDS API, and can be retrieve from folder
examples/C++/DDS/DynamicHelloWorldExample
of the Fast DDS GitHub repository.
It shows a publisher that loads a type from an XML file, and shares it during discovery.
The subscriber discovers the type using Discovery-Time Data Typing, and registers the
discovered type on the on_type_discovery() listener function.
TypeLookupService¶
This example uses the DDS API, and it is located in folder
examples/C++/DDS/TypeLookupService
of the Fast DDS GitHub repository.
It is very similar to DDSDynamicHelloWorldExample, but the shared type is complex enough to require the
TypeLookup Service due to the dependency of inner struct types.
Specifically, it uses the register_remote_type approach with a callback.
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:
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:
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.
ROS 2 using Fast DDS middleware. Since Fast DDS is the default middleware implementation in the OSRF Robot Operation System 2 (ROS 2), 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.
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.
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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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>
</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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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 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 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/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles">
<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 case.
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/C++/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/XMLSchemas/fastRTPS_Profiles">
<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>
<publisher profile_name="uc_publisher_xml_conf_static_discovery">
<topic>
<name>HelloWorldTopic</name>
<dataType>HelloWorld</dataType>
</topic>
<userDefinedID>1</userDefinedID>
<entityID>2</entityID>
</publisher>
</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/XMLSchemas/fastRTPS_Profiles">
<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>
<subscriber profile_name="uc_subscriber_xml_conf_static_discovery">
<topic>
<name>HelloWorldTopic</name>
<dataType>HelloWorld</dataType>
</topic>
<userDefinedID>3</userDefinedID>
<entityID>4</entityID>
</subscriber>
</profiles>
|
Large Data Rates¶
When the amount of data exchanged between a Publisher and a Subscriber is large, some tuning 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 limitations have to be taken into account:
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 be fragmented into several transport packets.
Warning
The loss of a fragment means the loss of the entire message.
This has 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/XMLSchemas/fastRTPS_Profiles">
<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
Flow Controllers¶
eProsima Fast DDS provides a mechanism to limit the rate at which the data is sent by a
DataWriter.
These controllers can be configured at DataWriter or DomainParticipant
level.
On the DomainParticipant the throughput controller is configured on the wire_protocol()
member function, while the DataWriterQos uses the
throughput_controller() member function.
C++ |
// Limit to 300kb per second.
ThroughputControllerDescriptor slowPublisherThroughputController{300000, 1000};
DataWriterQos qos;
qos.throughput_controller(slowPublisherThroughputController);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<publisher profile_name="publisher_profile_qos_flowcontroller">
<throughputController>
<bytesPerPeriod>300000</bytesPerPeriod>
<periodMillisecs>1000</periodMillisecs>
</throughputController>
</publisher>
</profiles>
|
Warning
Specifying a throughput 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_ALL_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/XMLSchemas/fastRTPS_Profiles">
<subscriber profile_name="subscriber_xml_conf_multicast_locators_profile">
<multicastLocatorList>
<locator>
<udpv4>
<address>239.255.0.4</address>
<port>7900</port>
</udpv4>
</locator>
</multicastLocatorList>
</subscriber>
</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/XMLSchemas/fastRTPS_Profiles">
<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.
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;
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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>
</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 an internal collection with information about every
DataReader to which it matches.
By default, this collection is 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 a data member matched_subscriber_allocation
of type ResourceLimitedContainerConfig that allows configuring
the maximum expected size of the collection of matched DataReader,
so that it 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 this data member.
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);
|
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<publisher profile_name="writer_profile_qos_resource_limit">
<!-- Limit to 3 matching readers -->
<matchedSubscribersAllocation>
<initial>3</initial>
<maximum>3</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
</publisher>
</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/XMLSchemas/fastRTPS_Profiles">
<subscriber profile_name="reader_profile_qos_resource_limit">
<!-- Limit to 1 matching writer -->
<matchedPublishersAllocation>
<initial>1</initial>
<maximum>1</maximum>
<increment>0</increment>
</matchedPublishersAllocation>
</subscriber>
</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 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;
// DataWriter configuration for Topic 1
///////////////////////////////////////
DataWriterQos writer1_qos;
// We know we will only have three matching subscribers
writer1_qos.writer_resource_limits().matched_subscriber_allocation =
eprosima::fastrtps::ResourceLimitedContainerConfig::fixed_size_configuration(3u);
// 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);
// 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/XMLSchemas/fastRTPS_Profiles">
<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>
</allocation>
</rtps>
</participant>
<publisher 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>
</publisher>
<publisher profile_name="alloc_qos_example_pub_for_topic_2">
<!-- we know we will have two matching subscribers -->
<matchedSubscribersAllocation>
<initial>2</initial>
<maximum>2</maximum>
<increment>0</increment>
</matchedSubscribersAllocation>
</publisher>
<subscriber 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>
</subscriber>
</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/XMLSchemas/fastRTPS_Profiles">
<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_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_reader>
</profiles>
|
Set Dynamic Allocation¶
By default MemoryManagementPolicy is set to PREALLOCATED_MEMORY_MODE, meaning that the amount of memory
required by the configured ResourceLimitsQosPolicy will be allocated at initialization.
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/XMLSchemas/fastRTPS_Profiles">
<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 (ReturnCode_t::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.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)
{
// 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 (ReturnCode_t::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 << 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.
Suitable for
PREALLOCATED_MEMORY_MODEandPREALLOCATED_WITH_REALLOC_MEMORY_MODEmemory configurations only.
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;
}
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.
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 is rmw_fastrtps_cpp.
However, it is still possible to select rmw_fastrtps_dynamic_cpp by using the environment variable
RMW_IMPLEMENTATION:
Exporting
RMW_IMPLEMENTATIONenvironment variable:export RMW_IMPLEMENTATION=rmw_fastrtps_dynamic_cpp
When launching your ROS 2 application:
RMW_IMPLEMENTATION=rmw_fastrtps_dynamic_cpp ros2 run <package> <application>
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
FASTRTPS_DEFAULT_PROFILES_FILEto contain the path to the XML configuration file (see Environment variables).export FASTRTPS_DEFAULT_PROFILES_FILE=<path_to_xml_file>
Alternative: Placing the XML file in the running application directory under the name DEFAULT_FASTRTPS_PROFILES.xml.
For example:
export FASTRTPS_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
<publisher>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the topic before mangling, i.e., the topic name used to create the publisher. If such profile is not defined, rmw_fastrtps attempts to load the<publisher>profile with attributeis_default_profile="true".To configure a subscriber, define a
<subscriber>profile with attributeprofile_name=topic_name, wheretopic_nameis the name of the topic before mangling. If such profile is not defined, rmw_fastrtps attempts to load the<subscriber>profile with attributeis_default_profile="true".
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
<subscriber>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<subscriber>profile with attributeprofile_name="service". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<subscriber>profile with attributeis_default_profile="true".To configure the reply publisher, define a
<publisher>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<publisher>profile withattribute profile_name="service". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<publisher>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
<publisher>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<publisher>profile with attributeprofile_name="client". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<publisher>profile with attributeis_default_profile="true".To configure the reply subscription, define a
<subscriber>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<subscriber>profile with attributeprofile_name="client". If neither of the previous profiles exist, rmw_fastrtps attempts to load the<subscriber>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 in Foxy |
Fast DDS entity in Eloquent & below |
|---|---|---|
Context |
Participant |
Not DDS direct mapping |
Node |
Not DDS direct mapping |
Participant |
This means that on Foxy, 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 would be specified as:
XML |
<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<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/XMLSchemas/fastRTPS_Profiles"> <participant profile_name="participant_profile_ros2" is_default_profile="true"> <rtps> <name>profile_for_ros2_context</name> </rtps> </participant> <!-- Default publisher profile --> <publisher profile_name="default publisher profile" is_default_profile="true"> <qos> <publishMode> <kind>SYNCHRONOUS</kind> </publishMode> </qos> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </publisher> <!-- Publisher profile for topic helloworld --> <publisher profile_name="helloworld"> <qos> <publishMode> <kind>SYNCHRONOUS</kind> </publishMode> </qos> </publisher> <!-- Request subscriber profile for services --> <subscriber profile_name="service"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </subscriber> <!-- Request publisher profile for clients --> <publisher profile_name="client"> <qos> <publishMode> <kind>ASYNCHRONOUS</kind> </publishMode> </qos> </publisher> <!-- Request subscriber profile for server of service "add_two_ints" --> <subscriber profile_name="rq/add_two_intsRequest"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </subscriber> <!-- Reply subscriber profile for client of service "add_two_ints" --> <subscriber profile_name="rr/add_two_intsReply"> <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy> </subscriber> </profiles>
Open one terminal and run:
export RMW_IMPLEMENTATION=rmw_fastrtps_cpp export FASTRTPS_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 FASTRTPS_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 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.
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 FASTRTPS_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 FASTRTPS_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.
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.
DDS DCPS PIM¶
Data Distribution Service (DDS) Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API
Core¶
Entity¶
-
class
eprosima::fastdds::dds::Entity¶ The Entity class is the abstract base class for all the objects that support QoS policies, a listener and a status condition.
Subclassed by eprosima::fastdds::dds::DomainEntity, eprosima::fastdds::dds::DomainParticipant
Public Functions
-
Entity(const StatusMask &mask = StatusMask::all())¶ Constructor.
- Parameters
mask: StatusMask (default: all)
-
const StatusMask &
get_status_mask() const¶ Retrieves the set of relevant statuses for the Entity.
- Return
Reference to the StatusMask with the relevant statuses set to 1
-
const StatusMask &
get_status_changes() const¶ 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
const reference to the StatusMask with the triggered statuses set to 1
-
DomainEntity¶
-
class
eprosima::fastdds::dds::DomainEntity: public eprosima::fastdds::dds::Entity¶ The DomainEntity class is a subclass of Entity created in order to differentiate between DomainParticipants and the rest of Entities.
Subclassed by eprosima::fastdds::dds::DataReader, eprosima::fastdds::dds::DataWriter, eprosima::fastdds::dds::Publisher, eprosima::fastdds::dds::Subscriber, eprosima::fastdds::dds::Topic
Public Functions
-
DomainEntity(const StatusMask &mask = StatusMask::all())¶ Constructor.
- Parameters
mask: StatusMask (default: all)
-
Policy¶
DataRepresentationId¶
-
enum
eprosima::fastdds::dds::DataRepresentationId¶ Enum DataRepresentationId, different kinds of topic data representation
Values:
-
enumerator
XCDR_DATA_REPRESENTATION= 0¶ Extended CDR Encoding version 1.
-
enumerator
XML_DATA_REPRESENTATION= 1¶ XML Data Representation (Unsupported)
-
enumerator
XCDR2_DATA_REPRESENTATION= 2¶ Extended CDR Encoding version 2.
-
enumerator
DataRepresentationQosPolicy¶
-
class
eprosima::fastdds::dds::DataRepresentationQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Functions
-
DataRepresentationQosPolicy()¶ Constructor.
-
~DataRepresentationQosPolicy() override = default¶ Destructor.
-
bool
operator==(const DataRepresentationQosPolicy &b) const¶ Compares the given policy to check if it’s equal.
- Return
True if the policy is equal.
- Parameters
b: QoS Policy.
Public Members
-
std::vector<DataRepresentationId_t>
m_value¶ List of DataRepresentationId.
By default, empty list.
DataSharingQosPolicy¶
-
class
eprosima::fastdds::dds::DataSharingQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Qos Policy to configure the data sharing
- Note
Immutable Qos Policy
Public Functions
-
DataSharingQosPolicy()¶ Constructor.
-
~DataSharingQosPolicy() = default¶ Destructor.
-
DataSharingQosPolicy(const DataSharingQosPolicy &b)¶ Copy constructor.
- Parameters
b: Another DataSharingQosPolicy instance
-
const DataSharingKind &
kind() const¶ - Return
the current DataSharing configuration mode
-
const std::string &
shm_directory() const¶ - Return
the current DataSharing shared memory directory
-
const std::vector<uint64_t> &
domain_ids() const¶ 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
the current DataSharing domain IDs
-
void
set_max_domains(uint32_t size)¶ - Parameters
size: the new maximum number of domain IDs
-
const uint32_t &
max_domains() const¶ - Return
the current configured maximum number of domain IDs
-
void
automatic()¶ Configures the DataSharing in automatic mode.
The default shared memory directory of the OS is used. A default domain ID is automatically computed.
-
void
automatic(const std::vector<uint16_t> &domain_ids)¶ Configures the DataSharing in automatic mode.
The default shared memory directory of the OS is used.
- Parameters
domain_ids: the user configured DataSharing domain IDs (16 bits).
-
void
automatic(const std::string &directory)¶ Configures the DataSharing in automatic mode.
A default domain ID is automatically computed.
- Parameters
directory: The shared memory directory to use.
-
void
automatic(const std::string &directory, const std::vector<uint16_t> &domain_ids)¶ Configures the DataSharing in automatic mode.
- Parameters
directory: The shared memory directory to use.domain_ids: the user configured DataSharing domain IDs (16 bits).
-
void
on(const std::string &directory)¶ Configures the DataSharing in active mode.
A default domain ID is automatically computed.
- Parameters
directory: The shared memory directory to use. It is mandatory to provide a non-empty name or the creation of endpoints will fail.
-
void
on(const std::string &directory, const std::vector<uint16_t> &domain_ids)¶ Configures the DataSharing in active mode.
- Parameters
directory: The shared memory directory to use. It is mandatory to provide a non-empty name or the creation of endpoints will fail.domain_ids: the user configured DataSharing domain IDs (16 bits).
-
void
off()¶ Configures the DataSharing in disabled mode.
-
void
add_domain_id(uint16_t id)¶ Adds a user-specific DataSharing domain ID.
- Parameters
id: 16 bit identifier
DataSharingKind¶
-
enum
eprosima::fastdds::dds::DataSharingKind¶ Data sharing configuration kinds
Values:
-
enumerator
AUTO= 0x01¶ Automatic configuration. DataSharing will be used if requirements are met.
-
enumerator
ON= 0x02¶ Activate the use of DataSharing. Entity creation will fail if requirements for DataSharing are not met
-
enumerator
OFF= 0x03¶ Disable the use of DataSharing
-
enumerator
DeadlineQosPolicy¶
-
class
eprosima::fastdds::dds::DeadlineQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Members
-
fastrtps::Duration_t
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.
DestinationOrderQosPolicy¶
-
class
eprosima::fastdds::dds::DestinationOrderQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Functions
-
DestinationOrderQosPolicy()¶ Constructor.
-
~DestinationOrderQosPolicy() = default¶ Destructor.
Public Members
-
DestinationOrderQosPolicyKind
kind¶ DestinationOrderQosPolicyKind.
By default, BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS.
DestinationOrderQosPolicyKind¶
-
enum
eprosima::fastdds::dds::DestinationOrderQosPolicyKind¶ Enum DestinationOrderQosPolicyKind, different kinds of destination order for DestinationOrderQosPolicy.
Values:
-
enumerator
BY_RECEPTION_TIMESTAMP_DESTINATIONORDER_QOS¶ Indicates that data is ordered based on the reception time at each Subscriber. Since each subscriber may receive the data at different times there is no guaranteed that the changes will be seen in the same order. Consequently, it is possible for each subscriber to end up with a different final value for the data.
-
enumerator
BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS¶ Indicates that data is ordered based on a timestamp placed at the source (by the Service or by the application). In any case this guarantees a consistent final value for the data in all subscribers.
-
enumerator
DisablePositiveACKsQosPolicy¶
-
class
eprosima::fastdds::dds::DisablePositiveACKsQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Class DisablePositiveACKsQosPolicy to disable sending of positive ACKs
- Note
Immutable Qos Policy
Public Functions
-
DisablePositiveACKsQosPolicy()¶ Constructor.
-
~DisablePositiveACKsQosPolicy() = default¶ Destructor.
Public Members
-
bool
enabled¶ True if this QoS is enabled.
By default, false.
-
fastrtps::Duration_t
duration¶ The duration to keep samples for (not serialized as not needed by reader).
By default, c_TimeInfinite.
DurabilityQosPolicy¶
-
class
eprosima::fastdds::dds::DurabilityQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ This policy expresses if the data should ‘outlive’ their writing time.
- Note
Immutable Qos Policy
Public Functions
-
DurabilityQosPolicy()¶ Constructor.
-
~DurabilityQosPolicy() = default¶ Destructor.
-
fastrtps::rtps::DurabilityKind_t
durabilityKind() const¶ Translates kind to rtps layer equivalent
- Return
fastrtps::rtps::DurabilityKind_t
-
void
durabilityKind(const fastrtps::rtps::DurabilityKind_t new_kind)¶ Set kind passing the rtps layer equivalent kind
- Parameters
new_kind: fastrtps::rtps::DurabilityKind_t
Public Members
-
DurabilityQosPolicyKind_t
kind¶ DurabilityQosPolicyKind.
By default the value for DataReaders: VOLATILE_DURABILITY_QOS, for DataWriters TRANSIENT_LOCAL_DURABILITY_QOS.
DurabilityQosPolicyKind¶
-
enum
eprosima::fastdds::dds::DurabilityQosPolicyKind¶ Enum DurabilityQosPolicyKind_t, different kinds of durability for DurabilityQosPolicy.
Values:
-
enumerator
VOLATILE_DURABILITY_QOS¶ The Service does not need to keep any samples of data-instances on behalf of any DataReader that is not known by the DataWriter at the time the instance is written. In other words the Service will only attempt to provide the data to existing subscribers
-
enumerator
TRANSIENT_LOCAL_DURABILITY_QOS¶ For TRANSIENT_LOCAL, the service is only required to keep the data in the memory of the DataWriter that wrote the data and the data is not required to survive the DataWriter.
-
enumerator
TRANSIENT_DURABILITY_QOS¶ For TRANSIENT, the service is only required to keep the data in memory and not in permanent storage; but the data is not tied to the lifecycle of the DataWriter and will, in general, survive it.
-
enumerator
PERSISTENT_DURABILITY_QOS¶ Data is kept on permanent storage, so that they can outlive a system session.
- Warning
Not Supported
-
enumerator
DurabilityServiceQosPolicy¶
-
class
eprosima::fastdds::dds::DurabilityServiceQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Functions
-
DurabilityServiceQosPolicy()¶ Constructor.
-
~DurabilityServiceQosPolicy() = default¶ Destructor.
Public Members
-
fastrtps::Duration_t
service_cleanup_delay¶ Control when the service is able to remove all information regarding a data-instance.
By default, c_TimeZero.
-
HistoryQosPolicyKind
history_kind¶ Controls the HistoryQosPolicy of the fictitious DataReader that stores the data within the durability service.
By default, KEEP_LAST_HISTORY_QOS.
-
int32_t
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.
-
int32_t
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.
-
int32_t
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.
-
int32_t
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.
EntityFactoryQosPolicy¶
-
class
eprosima::fastdds::dds::EntityFactoryQosPolicy¶ 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.
- Note
Mutable Qos Policy
GenericDataQosPolicy¶
-
class
eprosima::fastdds::dds::GenericDataQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy, public fastrtps::ResourceLimitedVector<fastrtps::rtps::octet>¶ Class GenericDataQosPolicy, base class to transmit user data during the discovery phase.
Subclassed by eprosima::fastdds::dds::GroupDataQosPolicy, eprosima::fastdds::dds::TopicDataQosPolicy, eprosima::fastdds::dds::UserDataQosPolicy
Public Functions
-
GenericDataQosPolicy(const GenericDataQosPolicy &data)¶ Construct from another GenericDataQosPolicy.
The resulting GenericDataQosPolicy will have the same size limits as the input attribute
- Parameters
data: data to copy in the newly created object
-
GenericDataQosPolicy(ParameterId_t pid, const collection_type &data)¶ Construct from underlying collection type.
Useful to easy integration on old APIs where a traditional container was used. The resulting GenericDataQosPolicy will always be unlimited in size
- Parameters
pid: Id of the parameterdata: data to copy in the newly created object
-
GenericDataQosPolicy &
operator=(const collection_type &b)¶ Copies data from underlying collection type.
Useful to easy integration on old APIs where a traditional container was used. The resulting GenericDataQosPolicy will keep the current size limit. If the input data is larger than the current limit size, the elements exceeding that maximum will be silently discarded.
- Return
reference to the current object.
- Parameters
b: object to be copied
-
GenericDataQosPolicy &
operator=(const GenericDataQosPolicy &b)¶ Copies another GenericDataQosPolicy.
The resulting GenericDataQosPolicy will have the same size limit as the input parameter, so all data in the input will be copied.
- Return
reference to the current object.
- Parameters
b: object to be copied
-
void
set_max_size(size_t size)¶ Set the maximum size of the user data and reserves memory for that much.
- Parameters
size: new maximum size of the user data. Zero for unlimited size
-
const collection_type &
dataVec() const¶ - Return
const reference to the internal raw data.
-
const collection_type &
data_vec() const¶ Returns raw data vector.
- Return
raw data as vector of octets.
-
collection_type &
data_vec()¶ Returns raw data vector.
- Return
raw data as vector of octets.
-
void
data_vec(const collection_type &vec)¶ Sets raw data vector.
- Parameters
vec: raw data to set.
-
const collection_type &
getValue() const¶ Returns raw data vector.
- Return
raw data as vector of octets.
-
void
setValue(const collection_type &vec)¶ Sets raw data vector.
- Parameters
vec: raw data to set.
-
GroupDataQosPolicy¶
-
class
GroupDataQosPolicy: public eprosima::fastdds::dds::GenericDataQosPolicy¶ Class derived from GenericDataQosPolicy.
The purpose of this QoS is to allow the application to attach additional information to the created Publisher or Subscriber. The value of the GROUP_DATA is available to the application on the DataReader and DataWriter entities and is propagated by means of the built-in topics.
This QoS can be used by an application combination with the DataReaderListener and DataWriterListener to implement matching policies similar to those of the PARTITION QoS except the decision can be made based on an application-defined policy.
HistoryQosPolicy¶
-
class
eprosima::fastdds::dds::HistoryQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Members
-
HistoryQosPolicyKind
kind¶ HistoryQosPolicyKind.
By default, KEEP_LAST_HISTORY_QOS.
-
int32_t
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.
HistoryQosPolicyKind¶
-
enum
eprosima::fastdds::dds::HistoryQosPolicyKind¶ Enum HistoryQosPolicyKind, different kinds of History Qos for HistoryQosPolicy.
Values:
-
enumerator
KEEP_LAST_HISTORY_QOS¶ On the publishing side, the Service will only attempt to keep the most recent “depth” samples of each instance of data (identified by its key) managed by the DataWriter. On the subscribing side, the DataReader will only attempt to keep the most recent “depth” samples received for each instance (identified by its key) until the application “takes” them via the DataReader’s take operation.
-
enumerator
KEEP_ALL_HISTORY_QOS¶ On the publishing side, the Service will attempt to keep all samples (representing each value written) of each instance of data (identified by its key) managed by the DataWriter until they can be delivered to all subscribers. On the subscribing side, the Service will attempt to keep all samples of each instance of data (identified by its key) managed by the DataReader. These samples are kept until the application “takes” them from the Service via the take operation.
-
enumerator
LatencyBudgetQosPolicy¶
-
class
eprosima::fastdds::dds::LatencyBudgetQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Functions
-
LatencyBudgetQosPolicy()¶ Constructor.
-
~LatencyBudgetQosPolicy() = default¶ Destructor.
Public Members
-
fastrtps::Duration_t
duration¶ Maximum acceptable delay from the time data is written until it is received.
By default, c_TimeZero.
LifespanQosPolicy¶
-
class
eprosima::fastdds::dds::LifespanQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Specifies the maximum duration of validity of the data written by the DataWriter.
- Note
Mutable Qos Policy
Public Members
-
fastrtps::Duration_t
duration¶ Period of validity.
By default, c_TimeInfinite.
LivelinessQosPolicy¶
-
class
eprosima::fastdds::dds::LivelinessQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
Public Members
-
LivelinessQosPolicyKind
kind¶ Liveliness kind
By default, AUTOMATIC_LIVELINESS.
-
fastrtps::Duration_t
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.
-
fastrtps::Duration_t
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.
-
LivelinessQosPolicyKind
LivelinessQosPolicyKind¶
-
enum
eprosima::fastdds::dds::LivelinessQosPolicyKind¶ Enum LivelinessQosPolicyKind, different kinds of liveliness for LivelinessQosPolicy
Values:
-
enumerator
AUTOMATIC_LIVELINESS_QOS¶ The infrastructure will automatically signal liveliness for the DataWriters at least as often as required by the lease_duration.
-
enumerator
MANUAL_BY_PARTICIPANT_LIVELINESS_QOS¶ The Service will assume that as long as at least one Entity within the DomainParticipant has asserted its liveliness the other Entities in that same DomainParticipant are also alive.
-
enumerator
MANUAL_BY_TOPIC_LIVELINESS_QOS¶ The Service will only assume liveliness of the DataWriter if the application has asserted liveliness of that DataWriter itself.
-
enumerator
OwnershipQosPolicy¶
-
class
eprosima::fastdds::dds::OwnershipQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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
- Note
Immutable Qos Policy
Public Members
-
OwnershipQosPolicyKind
kind¶ OwnershipQosPolicyKind.
OwnershipQosPolicyKind¶
-
enum
eprosima::fastdds::dds::OwnershipQosPolicyKind¶ Enum OwnershipQosPolicyKind, different kinds of ownership for OwnershipQosPolicy.
Values:
-
enumerator
SHARED_OWNERSHIP_QOS¶ Indicates shared ownership for each instance. Multiple writers are allowed to update the same instance and all the updates are made available to the readers. In other words there is no concept of an “owner” for the instances.
-
enumerator
EXCLUSIVE_OWNERSHIP_QOS¶ Indicates each instance can only be owned by one DataWriter, but the owner of an instance can change dynamically. The selection of the owner is controlled by the setting of the OwnershipStrengthQosPolicy. The owner is always set to be the highest-strength DataWriter object among the ones currently “active” (as determined by the LivelinessQosPolicy).
-
enumerator
OwnershipStrengthQosPolicy¶
-
class
eprosima::fastdds::dds::OwnershipStrengthQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Functions
-
OwnershipStrengthQosPolicy()¶ Constructor.
-
~OwnershipStrengthQosPolicy() = default¶ Destructor.
Public Members
-
uint32_t
value¶ Strength
By default, 0.
ParticipantResourceLimitsQos¶
-
using
eprosima::fastdds::dds::ParticipantResourceLimitsQos= fastrtps::rtps::RTPSParticipantAllocationAttributes¶ Holds allocation limits affecting collections managed by a participant.
PartitionQosPolicy¶
-
class
eprosima::fastdds::dds::PartitionQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Functions
-
PartitionQosPolicy()¶ Constructor without parameters.
-
PartitionQosPolicy(uint16_t in_length)¶ Constructor using Parameter length.
- Parameters
in_length: Length of the parameter
-
PartitionQosPolicy(const PartitionQosPolicy &b)¶ Copy constructor.
- Parameters
b: Another PartitionQosPolicy instance
-
~PartitionQosPolicy() = default¶ Destructor.
-
const_iterator
begin() const¶ Getter for the first position of the partition list.
- Return
-
const_iterator
end() const¶ Getter for the end of the partition list.
- Return
-
uint32_t
size() const¶ Getter for the number of partitions.
- Return
uint32_t with the size
-
uint32_t
empty() const¶ Check if the set is empty.
- Return
true if it is empty, false otherwise
-
void
set_max_size(uint32_t size)¶ Setter for the maximum size.
- Parameters
size: Size to be set
-
uint32_t
max_size() const¶ Getter for the maximum size.
- Return
uint32_t with the maximum size
-
void
push_back(const char *name)¶ Appends a name to the list of partition names.
- Parameters
name: Name to append.
-
void
clear() override¶ Clears list of partition names
-
const std::vector<std::string>
getNames() const¶ Returns partition names.
- Return
Vector of partition name strings.
-
void
setNames(std::vector<std::string> &nam)¶ Overrides partition names
- Parameters
nam: Vector of partition name strings.
-
const std::vector<std::string>
names() const¶ Returns partition names.
- Return
Vector of partition name strings.
-
void
names(std::vector<std::string> &nam)¶ Overrides partition names
- Parameters
nam: Vector of partition name strings.
-
class
const_iterator¶
PresentationQosPolicy¶
-
class
eprosima::fastdds::dds::PresentationQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Functions
-
PresentationQosPolicy()¶ Constructor without parameters.
-
~PresentationQosPolicy() = default¶ Destructor.
Public Members
-
PresentationQosPolicyAccessScopeKind
access_scope¶ Access Scope Kind
By default, INSTANCE_PRESENTATION_QOS.
-
bool
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.
-
bool
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.
PresentationQosPolicyAccessScopeKind¶
-
enum
eprosima::fastdds::dds::PresentationQosPolicyAccessScopeKind¶ Enum PresentationQosPolicyAccessScopeKind, different kinds of Presentation Policy order for PresentationQosPolicy.
Values:
-
enumerator
INSTANCE_PRESENTATION_QOS¶ Scope spans only a single instance. Indicates that changes to one instance need not be coherent nor ordered with respect to changes to any other instance. In other words, order and coherent changes apply to each instance separately.
-
enumerator
TOPIC_PRESENTATION_QOS¶ Scope spans to all instances within the same DataWriter (or DataReader), but not across instances in different DataWriter (or DataReader).
-
enumerator
GROUP_PRESENTATION_QOS¶ Scope spans to all instances belonging to DataWriter (or DataReader) entities within the same Publisher (or Subscriber).
-
enumerator
PropertyPolicyQos¶
-
using
eprosima::fastdds::dds::PropertyPolicyQos= fastrtps::rtps::PropertyPolicy¶ Property policies.
PublishModeQosPolicy¶
-
class
eprosima::fastdds::dds::PublishModeQosPolicy: public eprosima::fastdds::dds::QosPolicy¶ Class PublishModeQosPolicy, defines the publication mode for a specific writer.
Public Members
-
PublishModeQosPolicyKind
kind= SYNCHRONOUS_PUBLISH_MODE¶ PublishModeQosPolicyKind
By default, SYNCHRONOUS_PUBLISH_MODE.
-
const char *
flow_controller_name= fastdds::rtps::FASTDDS_FLOW_CONTROLLER_DEFAULT¶ Name of the flow controller used when publish mode kind is ASYNCHRONOUS_PUBLISH_MODE.
- Since
Functionality not implemented yet. Coming soon.
-
PublishModeQosPolicyKind
PublishModeQosPolicyKind¶
QosPolicy¶
-
class
eprosima::fastdds::dds::QosPolicy¶ Class QosPolicy, base for all QoS policies defined for Writers and Readers.
Subclassed by eprosima::fastdds::dds::DataRepresentationQosPolicy, eprosima::fastdds::dds::DataSharingQosPolicy, eprosima::fastdds::dds::DeadlineQosPolicy, eprosima::fastdds::dds::DestinationOrderQosPolicy, eprosima::fastdds::dds::DisablePositiveACKsQosPolicy, eprosima::fastdds::dds::DurabilityQosPolicy, eprosima::fastdds::dds::DurabilityServiceQosPolicy, eprosima::fastdds::dds::GenericDataQosPolicy, eprosima::fastdds::dds::HistoryQosPolicy, eprosima::fastdds::dds::LatencyBudgetQosPolicy, eprosima::fastdds::dds::LifespanQosPolicy, eprosima::fastdds::dds::LivelinessQosPolicy, eprosima::fastdds::dds::OwnershipQosPolicy, eprosima::fastdds::dds::OwnershipStrengthQosPolicy, eprosima::fastdds::dds::PartitionQosPolicy, eprosima::fastdds::dds::PresentationQosPolicy, eprosima::fastdds::dds::PublishModeQosPolicy, eprosima::fastdds::dds::ReliabilityQosPolicy, eprosima::fastdds::dds::ResourceLimitsQosPolicy, eprosima::fastdds::dds::TimeBasedFilterQosPolicy, eprosima::fastdds::dds::TransportConfigQos, eprosima::fastdds::dds::TransportPriorityQosPolicy, eprosima::fastdds::dds::TypeConsistencyEnforcementQosPolicy, eprosima::fastdds::dds::TypeConsistencyQos, eprosima::fastdds::dds::TypeIdV1, eprosima::fastdds::dds::TypeObjectV1, eprosima::fastdds::dds::WireProtocolConfigQos, eprosima::fastdds::dds::xtypes::TypeInformation
Public Functions
-
QosPolicy()¶ Constructor without parameters.
-
QosPolicy(bool send_always)¶ Constructor.
- Parameters
send_always: Boolean that set if the Qos need to be sent even if it is not changed
-
QosPolicy(const QosPolicy &b) = default¶ Copy Constructor.
- Parameters
b: Another instance of QosPolicy
-
~QosPolicy() = default¶ Destructor.
-
bool
send_always() const¶ Whether it should always be sent.
- Return
True if it should always be sent.
Public Members
-
bool
hasChanged¶ Boolean that indicates if the Qos has been changed.
-
QosPolicyId_t¶
-
enum
eprosima::fastdds::dds::QosPolicyId_t¶ The identifier for each QosPolicy.
Each QosPolicy class has a different ID that is then used to refer to the incompatible policies on OfferedIncompatibleQosStatus and RequestedIncompatibleQosStatus.
Values:
-
enumerator
INVALID_QOS_POLICY_ID= 0¶
-
enumerator
USERDATA_QOS_POLICY_ID= 1¶
-
enumerator
DURABILITY_QOS_POLICY_ID= 2¶
-
enumerator
PRESENTATION_QOS_POLICY_ID= 3¶
-
enumerator
DEADLINE_QOS_POLICY_ID= 4¶
-
enumerator
LATENCYBUDGET_QOS_POLICY_ID= 5¶
-
enumerator
OWNERSHIP_QOS_POLICY_ID= 6¶
-
enumerator
OWNERSHIPSTRENGTH_QOS_POLICY_ID= 7¶
-
enumerator
LIVELINESS_QOS_POLICY_ID= 8¶
-
enumerator
TIMEBASEDFILTER_QOS_POLICY_ID= 9¶
-
enumerator
PARTITION_QOS_POLICY_ID= 10¶
-
enumerator
RELIABILITY_QOS_POLICY_ID= 11¶
-
enumerator
DESTINATIONORDER_QOS_POLICY_ID= 12¶
-
enumerator
HISTORY_QOS_POLICY_ID= 13¶
-
enumerator
RESOURCELIMITS_QOS_POLICY_ID= 14¶
-
enumerator
ENTITYFACTORY_QOS_POLICY_ID= 15¶
-
enumerator
WRITERDATALIFECYCLE_QOS_POLICY_ID= 16¶
-
enumerator
READERDATALIFECYCLE_QOS_POLICY_ID= 17¶
-
enumerator
TOPICDATA_QOS_POLICY_ID= 18¶
-
enumerator
GROUPDATA_QOS_POLICY_ID= 19¶
-
enumerator
TRANSPORTPRIORITY_QOS_POLICY_ID= 20¶
-
enumerator
LIFESPAN_QOS_POLICY_ID= 21¶
-
enumerator
DURABILITYSERVICE_QOS_POLICY_ID= 22¶
-
enumerator
DATAREPRESENTATION_QOS_POLICY_ID= 23¶
-
enumerator
TYPECONSISTENCYENFORCEMENT_QOS_POLICY_ID= 24¶
-
enumerator
DISABLEPOSITIVEACKS_QOS_POLICY_ID= 25¶
-
enumerator
PARTICIPANTRESOURCELIMITS_QOS_POLICY_ID= 26¶
-
enumerator
PROPERTYPOLICY_QOS_POLICY_ID= 27¶
-
enumerator
PUBLISHMODE_QOS_POLICY_ID= 28¶
-
enumerator
READERRESOURCELIMITS_QOS_POLICY_ID= 29¶
-
enumerator
RTPSENDPOINT_QOS_POLICY_ID= 30¶
-
enumerator
RTPSRELIABLEREADER_QOS_POLICY_ID= 31¶
-
enumerator
RTPSRELIABLEWRITER_QOS_POLICY_ID= 32¶
-
enumerator
TRANSPORTCONFIG_QOS_POLICY_ID= 33¶
-
enumerator
TYPECONSISTENCY_QOS_POLICY_ID= 34¶
-
enumerator
WIREPROTOCOLCONFIG_QOS_POLICY_ID= 35¶
-
enumerator
WRITERRESOURCELIMITS_QOS_POLICY_ID= 36¶
-
enumerator
NEXT_QOS_POLICY_ID¶
-
enumerator
ReaderDataLifecycleQosPolicy¶
-
class
eprosima::fastdds::dds::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.
- Note
Mutable Qos Policy
Public Functions
-
ReaderDataLifecycleQosPolicy()¶ Constructor.
-
~ReaderDataLifecycleQosPolicy()¶ Destructor.
Public Members
-
Duration_t
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.
-
Duration_t
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.
ReliabilityQosPolicy¶
-
class
eprosima::fastdds::dds::ReliabilityQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Indicates the reliability of the endpoint.
- Note
Immutable Qos Policy
Public Functions
-
ReliabilityQosPolicy()¶ Constructor.
-
~ReliabilityQosPolicy() = default¶ Destructor.
Public Members
-
ReliabilityQosPolicyKind
kind¶ Defines the reliability kind of the endpoint.
By default, BEST_EFFORT_RELIABILITY_QOS for DataReaders and RELIABLE_RELIABILITY_QOS for DataWriters.
-
fastrtps::Duration_t
max_blocking_time¶ Defines the maximum period of time certain methods will be blocked.
Methods affected by this property are:
DataReader::takeNextData
DataReader::readNextData
By default, 100 ms.
ReliabilityQosPolicyKind¶
-
enum
eprosima::fastdds::dds::ReliabilityQosPolicyKind¶ Enum ReliabilityQosPolicyKind, different kinds of reliability for ReliabilityQosPolicy.
Values:
-
enumerator
BEST_EFFORT_RELIABILITY_QOS= 0x01¶ Indicates that it is acceptable to not retry propagation of any samples. Presumably new values for the samples are generated often enough that it is not necessary to re-send or acknowledge any samples
-
enumerator
RELIABLE_RELIABILITY_QOS= 0x02¶ Specifies the Service will attempt to deliver all samples in its history. Missed samples may be retried. In steady-state (no modifications communicated via the DataWriter) the middleware guarantees that all samples in the DataWriter history will eventually be delivered to all the DataReader objects. Outside steady state the HistoryQosPolicy and ResourceLimitsQosPolicy will determine how samples become part of the history and whether samples can be discarded from it.
-
enumerator
ResourceLimitsQosPolicy¶
-
class
eprosima::fastdds::dds::ResourceLimitsQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Specifies the resources that the Service can consume in order to meet the requested QoS
- Note
Immutable Qos Policy
Public Functions
-
ResourceLimitsQosPolicy()¶ Constructor.
-
~ResourceLimitsQosPolicy() = default¶ Destructor.
Public Members
-
int32_t
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).
By default, 5000.
- Warning
It is inconsistent for this value to be less than max_samples_per_instance.
-
int32_t
max_instances¶ Represents the maximum number of instances DataWriter (or DataReader) can manage.
By default, 10.
-
int32_t
max_samples_per_instance¶ Represents the maximum number of samples of any one instance a DataWriter(or DataReader) can manage.
By default, 400.
- Warning
It is inconsistent for this value to be greater than max_samples.
-
int32_t
allocated_samples¶ Number of samples currently allocated.
By default, 100.
-
int32_t
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.
RTPSEndpointQos¶
-
class
eprosima::fastdds::dds::RTPSEndpointQos¶ Qos Policy to configure the endpoint.
Public Members
-
rtps::LocatorList
unicast_locator_list¶ Unicast locator list.
-
rtps::LocatorList
multicast_locator_list¶ Multicast locator list.
-
rtps::LocatorList
remote_locator_list¶ Remote locator list.
-
int16_t
user_defined_id¶ User Defined ID, used for StaticEndpointDiscovery.
By default, -1.
-
int16_t
entity_id¶ Entity ID, if the user wants to specify the EntityID of the endpoint.
By default, -1.
-
fastrtps::rtps::MemoryManagementPolicy_t
history_memory_policy¶ Underlying History memory policy.
By default, PREALLOCATED_MEMORY_MODE.
-
rtps::LocatorList
TimeBasedFilterQosPolicy¶
-
class
eprosima::fastdds::dds::TimeBasedFilterQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Functions
-
TimeBasedFilterQosPolicy()¶ Constructor.
-
~TimeBasedFilterQosPolicy() = default¶ Destructor.
Public Members
-
fastrtps::Duration_t
minimum_separation¶ Minimum interval between samples. By default, c_TimeZero (the DataReader is interested in all values)
TopicDataQosPolicy¶
-
class
TopicDataQosPolicy: public eprosima::fastdds::dds::GenericDataQosPolicy¶ Class derived from GenericDataQosPolicy.
The purpose of this QoS is to allow the application to attach additional information to the created Topic such that when a remote application discovers their existence it can examine the information and use it in an application-defined way.
In combination with the listeners on the DataReader and DataWriter as well as by means of operations such as ignore_topic,these QoS can assist an application to extend the provided QoS.
TransportConfigQos¶
-
class
eprosima::fastdds::dds::TransportConfigQos: public eprosima::fastdds::dds::QosPolicy¶ Qos Policy to configure the transport layer.
Public Members
-
std::vector<std::shared_ptr<fastdds::rtps::TransportDescriptorInterface>>
user_transports¶ User defined transports to use alongside or in place of builtins.
-
bool
use_builtin_transports¶ Set as false to disable the default UDPv4 implementation.
By default, true.
-
uint32_t
send_socket_buffer_size¶ Send socket buffer size for the send resource.
Zero value indicates to use default system buffer size.
By default, 0.
-
uint32_t
listen_socket_buffer_size¶ Listen socket buffer for all listen resources.
Zero value indicates to use default system buffer size.
By default, 0.
-
std::vector<std::shared_ptr<fastdds::rtps::TransportDescriptorInterface>>
TransportPriorityQosPolicy¶
-
class
eprosima::fastdds::dds::TransportPriorityQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Mutable Qos Policy
Public Functions
-
TransportPriorityQosPolicy()¶ Constructor.
-
~TransportPriorityQosPolicy() = default¶ Destructor.
Public Members
-
uint32_t
value¶ Priority
By default, 0.
TypeConsistencyEnforcementQosPolicy¶
-
class
eprosima::fastdds::dds::TypeConsistencyEnforcementQosPolicy: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ 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.
- Note
Immutable Qos Policy
Public Functions
-
TypeConsistencyEnforcementQosPolicy()¶ Constructor.
-
~TypeConsistencyEnforcementQosPolicy() override = default¶ Destructor.
Public Members
-
TypeConsistencyKind
m_kind¶ TypeConsistencyKind.
By default, ALLOW_TYPE_COERCION.
-
bool
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.
-
bool
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.
-
bool
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.
-
bool
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.
-
bool
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.
TypeConsistencyKind¶
-
enum
eprosima::fastdds::dds::TypeConsistencyKind¶ Values:
-
enumerator
DISALLOW_TYPE_COERCION¶ The DataWriter and the DataReader must support the same data type in order for them to communicate.
-
enumerator
ALLOW_TYPE_COERCION¶ The DataWriter and the DataReader need not support the same data type in order for them to communicate as long as the reader’s type is assignable from the writer’s type.
-
enumerator
UserDataQosPolicy¶
-
class
UserDataQosPolicy: public eprosima::fastdds::dds::GenericDataQosPolicy¶ Class derived from GenericDataQosPolicy.
The purpose of this QoS is to allow the application to attach additional information to the created Entity objects such that when a remote application discovers their existence it can access that information and use it for its own purposes.
One possible use of this QoS is to attach security credentials or some other information that can be used by the remote application to authenticate the source.
WireProtocolConfigQos¶
-
class
eprosima::fastdds::dds::WireProtocolConfigQos: public eprosima::fastdds::dds::QosPolicy¶ Qos Policy that configures the wire protocol.
Public Functions
-
WireProtocolConfigQos()¶ Constructor.
-
~WireProtocolConfigQos() = default¶ Destructor.
Public Members
-
fastrtps::rtps::GuidPrefix_t
prefix¶ Optionally allows user to define the GuidPrefix_t.
-
int32_t
participant_id¶ Participant ID
By default, -1.
-
fastrtps::rtps::BuiltinAttributes
builtin¶ Builtin parameters.
-
fastrtps::rtps::PortParameters
port¶ Port Parameters.
-
fastrtps::rtps::ThroughputControllerDescriptor
throughput_controller¶ Throughput controller parameters. Leave default for uncontrolled flow.
-
rtps::LocatorList
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.
-
rtps::LocatorList
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 UnicastLocators. This is usually left empty.
-
WriterDataLifecycleQosPolicy¶
-
class
eprosima::fastdds::dds::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.
- Note
Mutable Qos Policy
Public Functions
-
WriterDataLifecycleQosPolicy()¶ Constructor.
-
~WriterDataLifecycleQosPolicy()¶ Destructor.
Public Members
-
bool
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.
WriterResourceLimitsQos¶
-
class
eprosima::fastdds::dds::WriterResourceLimitsQos¶ Qos Policy to configure the limit of the writer resources.
Public Functions
-
WriterResourceLimitsQos()¶ Constructor.
-
~WriterResourceLimitsQos() = default¶ Destructor.
Public Members
-
fastrtps::ResourceLimitedContainerConfig
matched_subscriber_allocation¶ Matched subscribers allocation limits.
-
Status¶
DeadlineMissedStatus¶
-
struct
eprosima::fastdds::dds::DeadlineMissedStatus¶ A struct storing the deadline status.
Public Members
-
uint32_t
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
-
uint32_t
total_count_change¶ The change in total_count since the last time the listener was called or the status was read.
-
InstanceHandle_t
last_instance_handle¶ Handle to the last instance missing the deadline.
-
uint32_t
IncompatibleQosStatus¶
-
struct
eprosima::fastdds::dds::IncompatibleQosStatus¶ A struct storing the requested incompatible QoS status.
Public Members
-
uint32_t
total_count= 0¶ 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
-
uint32_t
total_count_change= 0¶ The change in total_count since the last time the listener was called or the status was read.
-
QosPolicyId_t
last_policy_id= INVALID_QOS_POLICY_ID¶ The id of the policy that was found to be incompatible the last time an incompatibility is detected.
-
QosPolicyCountSeq
policies¶ A list of QosPolicyCount.
-
uint32_t
InconsistentTopicStatus¶
-
using
eprosima::fastdds::dds::InconsistentTopicStatus= BaseStatus¶ Alias of BaseStatus.
LivelinessChangedStatus¶
-
struct
eprosima::fastdds::dds::LivelinessChangedStatus¶ A struct storing the liveliness changed status.
Public Members
-
int32_t
alive_count= 0¶ 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
-
int32_t
not_alive_count= 0¶ 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
-
int32_t
alive_count_change= 0¶ The change in the alive_count since the last time the listener was called or the status was read.
-
int32_t
not_alive_count_change= 0¶ The change in the not_alive_count since the last time the listener was called or the status was read.
-
InstanceHandle_t
last_publication_handle¶ Handle to the last publisher whose change in liveliness caused this status to change.
-
int32_t
MatchedStatus¶
-
struct
eprosima::fastdds::dds::MatchedStatus¶ A structure storing a matching status.
Subclassed by eprosima::fastdds::dds::PublicationMatchedStatus, eprosima::fastdds::dds::SubscriptionMatchedStatus
Public Members
-
int32_t
total_count= 0¶ 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
-
int32_t
total_count_change= 0¶ The change in total_count since the last time the listener was called or the status was read.
-
int32_t
current_count= 0¶ The number of writers currently matched to the concerned reader.
-
int32_t
current_count_change= 0¶ The change in current_count since the last time the listener was called or the status was read.
-
int32_t
OfferedDeadlineMissedStatus¶
-
typedef DeadlineMissedStatus
eprosima::fastdds::dds::OfferedDeadlineMissedStatus¶ Typedef of DeadlineMissedStatus.
OfferedIncompatibleQosStatus¶
-
using
eprosima::fastdds::dds::OfferedIncompatibleQosStatus= IncompatibleQosStatus¶ Alias of IncompatibleQosStatus.
PublicationMatchedStatus¶
-
struct
eprosima::fastdds::dds::PublicationMatchedStatus: public eprosima::fastdds::dds::MatchedStatus¶ A structure storing the publication status.
Public Members
-
InstanceHandle_t
last_subscription_handle¶ Handle to the last reader that matched the writer causing the status to change.
-
InstanceHandle_t
QosPolicyCount¶
-
struct
eprosima::fastdds::dds::QosPolicyCount¶ A struct storing the id of the incompatible QoS Policy and the number of times it fails.
Public Functions
-
QosPolicyCount(QosPolicyId_t id, int32_t c)¶ Constructor.
Public Members
-
QosPolicyId_t
policy_id= INVALID_QOS_POLICY_ID¶ The id of the policy.
-
uint32_t
count= 0¶ 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
-
QosPolicyCountSeq¶
-
using
eprosima::fastdds::dds::QosPolicyCountSeq= std::vector<QosPolicyCount>¶ Alias of std::vector<QosPolicyCount>
RequestedDeadlineMissedStatus¶
-
typedef DeadlineMissedStatus
eprosima::fastdds::dds::RequestedDeadlineMissedStatus¶ Typedef of DeadlineMissedStatus.
RequestedIncompatibleQosStatus¶
-
using
eprosima::fastdds::dds::RequestedIncompatibleQosStatus= IncompatibleQosStatus¶ Alias of IncompatibleQosStatus.
LivelinessLostStatus¶
-
using
eprosima::fastdds::dds::LivelinessLostStatus= BaseStatus¶ Alias of BaseStatus.
SampleLostStatus¶
-
using
eprosima::fastdds::dds::SampleLostStatus= BaseStatus¶ Alias of BaseStatus.
SampleRejectedStatus¶
-
struct
eprosima::fastdds::dds::SampleRejectedStatus¶ A struct storing the sample lost status.
Public Members
-
uint32_t
total_count= 0¶ Total cumulative count of samples rejected by the DataReader.
-
uint32_t
total_count_change= 0¶ The incremental number of samples rejected since the last time the listener was called or the status was read.
-
SampleRejectedStatusKind
last_reason= NOT_REJECTED¶ Reason for rejecting the last sample rejected. If no samples have been rejected, the reason is the special value NOT_REJECTED.
-
InstanceHandle_t
last_instance_handle¶ Handle to the instance being updated by the last sample that was rejected.
-
uint32_t
SampleRejectedStatusKind¶
-
enum
eprosima::fastdds::dds::SampleRejectedStatusKind¶ An enum with the possible values for the sample rejected reason.
Values:
-
enumerator
NOT_REJECTED¶ Default value.
-
enumerator
REJECTED_BY_INSTANCES_LIMIT¶ Exceeds the max_instance limit.
-
enumerator
REJECTED_BY_SAMPLES_LIMIT¶ Exceeds the max_samples limit.
-
enumerator
REJECTED_BY_SAMPLES_PER_INSTANCE_LIMIT¶ Exceeds the max_samples_per_instance limit.
-
enumerator
StatusMask¶
-
class
eprosima::fastdds::dds::StatusMask: public std::bitset<FASTDDS_STATUS_COUNT>¶ 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
Public Types
-
typedef std::bitset<FASTDDS_STATUS_COUNT>
MaskType¶ Convenience typedef for std::bitset<FASTDDS_STATUS_COUNT>.
Public Functions
-
StatusMask()¶ Construct an StatusMask with no flags set.
-
StatusMask(uint32_t mask)¶ Construct an StatusMask with an uint32_t bit mask.
- Parameters
mask: the bit array to initialize the bitset with
-
StatusMask &
operator<<(const StatusMask &mask)¶ Add given StatusMask bits into this StatusMask bitset.
- Return
StatusMask this
-
StatusMask &
operator>>(const StatusMask &mask)¶ Remove given StatusMask bits into this StatusMask bitset.
- Return
StatusMask this
-
bool
is_active(StatusMask status) const¶ Checks if the status passed as parameter is 1 in the actual StatusMask.
- Return
true if the status is active and false if not
- Parameters
status: Status that need to be checked
Public Static Functions
-
StatusMask
all()¶ Get all StatusMasks
- Return
StatusMask all
-
StatusMask
none()¶ Get no StatusMasks
- Return
StatusMask none
-
StatusMask
inconsistent_topic()¶ Get the StatusMask associated with dds::core::status::InconsistentTopicStatus
- Return
StatusMask inconsistent_topic
-
StatusMask
offered_deadline_missed()¶ Get the StatusMask associated with dds::core::status::OfferedDeadlineMissedStatus
- Return
StatusMask offered_deadline_missed
-
StatusMask
requested_deadline_missed()¶ Get the StatusMask associated with dds::core::status::RequestedDeadlineMissedStatus
- Return
StatusMask requested_deadline_missed
-
StatusMask
offered_incompatible_qos()¶ Get the StatusMask associated with dds::core::status::OfferedIncompatibleQosStatus
- Return
StatusMask offered_incompatible_qos
-
StatusMask
requested_incompatible_qos()¶ Get the StatusMask associated with dds::core::status::RequestedIncompatibleQosStatus
- Return
StatusMask requested_incompatible_qos
-
StatusMask
sample_lost()¶ Get the StatusMask associated with dds::core::status::SampleLostStatus
- Return
StatusMask sample_lost
-
StatusMask
sample_rejected()¶ Get the StatusMask associated with dds::core::status::SampleRejectedStatus
- Return
StatusMask sample_rejected
-
StatusMask
data_on_readers()¶ Get the StatusMask associated with dds::core::status::data_on_readers
- Return
StatusMask data_on_readers
-
StatusMask
data_available()¶ get the statusmask associated with dds::core::status::data_available
- Return
statusmask data_available
-
StatusMask
liveliness_lost()¶ Get the StatusMask associated with dds::core::status::LivelinessLostStatus
- Return
StatusMask liveliness_lost
-
StatusMask
liveliness_changed()¶ Get the StatusMask associated with dds::core::status::LivelinessChangedStatus
- Return
StatusMask liveliness_changed
-
StatusMask
publication_matched()¶ Get the statusmask associated with dds::core::status::PublicationMatchedStatus
- Return
StatusMask publication_matched
-
StatusMask
subscription_matched()¶ Get the statusmask associated with dds::core::status::SubscriptionMatchedStatus
- Return
StatusMask subscription_matched
-
FASTDDS_STATUS_COUNT¶ Alias of size_t(16)
SubscriptionMatchedStatus¶
-
struct
eprosima::fastdds::dds::SubscriptionMatchedStatus: public eprosima::fastdds::dds::MatchedStatus¶ A structure storing the subscription status.
Public Members
-
InstanceHandle_t
last_publication_handle¶ Handle to the last writer that matched the reader causing the status change.
-
InstanceHandle_t
LoanableArray¶
-
template<typename
T, std::size_tnum_items>
structeprosima::fastdds::dds::LoanableArray: public std::array<T, num_items>¶ A type-safe, ordered collection of elements allocated on the stack, which can be loaned to a LoanableCollection.
Public Functions
-
void **
buffer_for_loans() const¶ Get a buffer pointer that could be used on LoanableCollection::loan.
- Return
buffer pointer for loans.
-
void **
LoanableCollection¶
-
class
eprosima::fastdds::dds::LoanableCollection¶ A collection of generic opaque pointers that can receive the buffer from outside (loan).
This is an abstract class. See LoanableSequence for details.
Subclassed by eprosima::fastdds::dds::LoanableTypedCollection< T >, eprosima::fastdds::dds::UserAllocatedSequence
Public Functions
-
const element_type *
buffer() const¶ 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
the pointer to the elements buffer.
-
bool
has_ownership() const¶ Get the ownership flag.
- Return
whether the collection has ownership of the buffer.
-
size_type
maximum() const¶ Get the maximum number of elements currently allocated.
- Return
the maximum number of elements currently allocated.
-
size_type
length() const¶ Get the number of elements currently accessible.
- Return
the number of elements currently accessible.
-
bool
length(size_type new_length)¶ 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.
-
bool
loan(element_type *buffer, size_type new_maximum, size_type new_length)¶ Loan a buffer to the collection.
- Pre
(has_ownership() == false) || (maximum() == 0)
- Pre
new_maximum > 0
- Pre
new_maximum >= new_length
- Pre
buffer != nullptr
- Return
false if preconditions are not met.
- Return
true if operation succeeds.
- Post
buffer() == buffer
- Post
has_ownership() == false
- Post
maximum() == new_maximum
- Post
length() == new_length
- 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.
-
element_type *
unloan(size_type &maximum, size_type &length)¶ Remove the loan from the collection.
- Pre
has_ownership() == false
- Return
nullptr if preconditions are not met.
- Return
pointer to the previously loaned buffer of elements.
- Post
buffer() == nullptr
- Post
has_ownership() == true
- Post
length() == 0
- Post
maximum() == 0
- Parameters
[out] maximum: number of allocated elements on the returned buffer.[out] length: number of accessible elements on the returned buffer.
-
element_type *
unloan()¶ Remove the loan from the collection.
- Pre
has_ownership() == false
- Return
nullptr if preconditions are not met.
- Return
pointer to the previously loaned buffer of elements.
- Post
buffer() == nullptr
- Post
has_ownership() == true
- Post
length() == 0
- Post
maximum() == 0
-
const element_type *
LoanableSequence¶
-
template<typename
T>
classeprosima::fastdds::dds::LoanableSequence: public eprosima::fastdds::dds::LoanableTypedCollection<T>¶ A type-safe, ordered collection of elements that can receive the buffer from outside (loan).
For users who define data types in OMG IDL, this type corresponds to the IDL express sequence<T>.
For any user-data type Foo that an application defines for the purpose of data-distribution with Fast DDS, a ‘
using FooSeq = LoanableSequence<Foo>’ is generated. The sequence offers a subset of the methods defined by the standard OMG IDL to C++ mapping for sequences. We refer to an IDL ‘sequence<Foo>’ asFooSeq.The state of a sequence is described by the properties ‘maximum’, ‘length’ and ‘has_ownership’.
The ‘maximum’ represents the size of the underlying buffer; this is the maximum number of elements it can possibly hold. It is returned by the maximum() operation.
The ‘length’ represents the actual number of elements it currently holds. It is returned by the length() operation.
The ‘has_ownership’ flag represents whether the sequence owns the underlying buffer. It is returned by the has_ownership() operation. If the sequence does not own the underlying buffer, the underlying buffer is loaned from somewhere else. This flag influences the lifecycle of the sequence and what operations are allowed on it. The general guidelines are provided below and more details are described in detail as pre-conditions and post-conditions of each of the sequence’s operations:
If has_ownership == true, the sequence has ownership on the buffer. It is then responsible for destroying the buffer when the sequence is destroyed.
If has_ownership == false, the sequence does not have ownership on the buffer. This implies that the sequence is loaning the buffer. The sequence should not be destroyed until the loan is returned.
A sequence with a zero maximum always has has_ownership == true
Public Functions
-
LoanableSequence() = default¶ Default constructor.
Creates the sequence with no data.
- Post
buffer() == nullptr
- Post
has_ownership() == true
- Post
length() == 0
- Post
maximum() == 0
-
LoanableSequence(size_type max)¶ Pre-allocation constructor.
Creates the sequence with an initial number of allocated elements. When the input parameter is less than or equal to 0, the behavior is equivalent to the default constructor. Otherwise, the post-conditions below will apply.
- Post
buffer() != nullptr
- Post
has_ownership() == true
- Post
length() == 0
- Post
maximum() == max
- Parameters
[in] max: Number of elements to pre-allocate.
-
~LoanableSequence()¶ Deallocate this sequence’s buffer.
- Pre
has_ownership() == true. If this precondition is not met, no memory will be released and a warning will be logged.
- Post
maximum() == 0 and the underlying buffer is released.
-
LoanableSequence(const LoanableSequence &other)¶ Construct a sequence with the contents of another sequence.
This method performs a deep copy of the sequence received into this one. Allocations will happen when other.length() > 0
- Post
has_ownership() == true
- Post
maximum() == other.length()
- Post
length() == other.length()
- Post
buffer() != nullptr when other.length() > 0
- Parameters
[in] other: The sequence from where contents are to be copied.
-
LoanableSequence &
operator=(const LoanableSequence &other)¶ Copy the contents of another sequence into this one.
This method performs a deep copy of the sequence received into this one. If this sequence had a buffer loaned, it will behave as if unloan has been called. Allocations will happen when (a) has_ownership() == false and other.length() > 0 (b) has_ownership() == true and other.length() > maximum()
- Post
has_ownership() == true
- Post
maximum() >= other.length()
- Post
length() == other.length()
- Post
buffer() != nullptr when other.length() > 0
- Parameters
[in] other: The sequence from where contents are to be copied.
-
FASTDDS_SEQUENCE(FooSeq, Foo)¶
StackAllocatedSequence¶
-
template<typename
T, LoanableCollection::size_typenum_items>
structStackAllocatedSequence: public eprosima::fastdds::dds::LoanableTypedCollection<T>¶ A type-safe, ordered collection of elements allocated on the stack.
Domain¶
DomainParticipant¶
-
class
eprosima::fastdds::dds::DomainParticipant: public eprosima::fastdds::dds::Entity¶ Class DomainParticipant used to group Publishers and Subscribers into a single working unit.
Subclassed by eprosima::fastdds::statistics::dds::DomainParticipant
Public Functions
-
~DomainParticipant()¶ Destructor.
-
ReturnCode_t
get_qos(DomainParticipantQos &qos) const¶ This operation returns the value of the DomainParticipant QoS policies
- Return
RETCODE_OK
- Parameters
qos: DomainParticipantQos reference where the qos is going to be returned
-
const DomainParticipantQos &
get_qos() const¶ This operation returns the value of the DomainParticipant QoS policies.
- Return
A reference to the DomainParticipantQos
-
ReturnCode_t
set_qos(const DomainParticipantQos &qos) const¶ This operation sets the value of the DomainParticipant QoS policies.
- Return
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.
- Parameters
qos: DomainParticipantQos to be set
-
const DomainParticipantListener *
get_listener() const¶ Allows accessing the DomainParticipantListener.
- Return
DomainParticipantListener pointer
-
ReturnCode_t
set_listener(DomainParticipantListener *listener)¶ Modifies the DomainParticipantListener, sets the mask to StatusMask::all()
- Return
RETCODE_OK
- Parameters
listener: new value for the DomainParticipantListener
-
ReturnCode_t
set_listener(DomainParticipantListener *listener, const StatusMask &mask)¶ Modifies the DomainParticipantListener.
- Return
RETCODE_OK
- Parameters
listener: new value for the DomainParticipantListenermask: StatusMask that holds statuses the listener responds to
-
ReturnCode_t
enable() override¶ This operation enables the DomainParticipant.
- Return
RETCODE_OK
-
Publisher *
create_publisher(const PublisherQos &qos, PublisherListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Publisher in this Participant.
- Return
Pointer to the created Publisher.
- Parameters
qos: QoS of the Publisher.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
Publisher *
create_publisher_with_profile(const std::string &profile_name, PublisherListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Publisher in this Participant.
- Return
Pointer to the created Publisher.
- Parameters
profile_name: Publisher profile name.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
ReturnCode_t
delete_publisher(const Publisher *publisher)¶ Deletes an existing Publisher.
- Return
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.
- Parameters
publisher: to be deleted.
-
Subscriber *
create_subscriber(const SubscriberQos &qos, SubscriberListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Subscriber in this Participant.
- Return
Pointer to the created Subscriber.
- Parameters
qos: QoS of the Subscriber.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
Subscriber *
create_subscriber_with_profile(const std::string &profile_name, SubscriberListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Subscriber in this Participant.
- Return
Pointer to the created Subscriber.
- Parameters
profile_name: Subscriber profile name.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
ReturnCode_t
delete_subscriber(const Subscriber *subscriber)¶ Deletes an existing Subscriber.
- Return
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.
- Parameters
subscriber: to be deleted.
-
Topic *
create_topic(const std::string &topic_name, const std::string &type_name, const TopicQos &qos, TopicListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Topic in this Participant.
- Return
Pointer to the created Topic.
- Parameters
topic_name: Name of the Topic.type_name: Data type of the Topic.qos: QoS of the Topic.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
Topic *
create_topic_with_profile(const std::string &topic_name, const std::string &type_name, const std::string &profile_name, TopicListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Topic in this Participant.
- Return
Pointer to the created Topic.
- Parameters
topic_name: Name of the Topic.type_name: Data type of the Topic.profile_name: Topic profile name.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all)
-
ReturnCode_t
delete_topic(const Topic *topic)¶ Deletes an existing Topic.
- Return
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.
- Parameters
topic: to be deleted.
-
ContentFilteredTopic *
create_contentfilteredtopic(const std::string &name, const Topic *related_topic, const std::string &filter_expression, const std::vector<std::string> &expression_parameters)¶ Create a ContentFilteredTopic in this Participant.
- Return
Pointer to the created ContentFilteredTopic, nullptr in error case
- Parameters
name: Name of the ContentFilteredTopicrelated_topic: Related Topic to being subscribedfilter_expression: Logic expression to create filterexpression_parameters: Parameters to filter content
-
ReturnCode_t
delete_contentfilteredtopic(const ContentFilteredTopic *a_contentfilteredtopic)¶ Deletes an existing ContentFilteredTopic.
- Return
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.
- Parameters
a_contentfilteredtopic: ContentFilteredTopic to be deleted
-
MultiTopic *
create_multitopic(const std::string &name, const std::string &type_name, const std::string &subscription_expression, const std::vector<std::string> &expression_parameters)¶ Create a MultiTopic in this Participant.
- Return
Pointer to the created ContentFilteredTopic, nullptr in error case
- Parameters
name: Name of the MultiTopictype_name: Result type of the MultiTopicsubscription_expression: Logic expression to combine filterexpression_parameters: Parameters to subscription content
-
ReturnCode_t
delete_multitopic(const MultiTopic *a_multitopic)¶ Deletes an existing MultiTopic.
- Return
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.
- Parameters
a_multitopic: MultiTopic to be deleted
-
Topic *
find_topic(const std::string &topic_name, const fastrtps::Duration_t &timeout)¶ Gives access to an existing (or ready to exist) enabled Topic. Topics obtained by this method must be destroyed by delete_topic.
-
TopicDescription *
lookup_topicdescription(const std::string &topic_name) const¶ Looks up an existing, locally created TopicDescription, based on its name. May be called on a disabled participant.
- Return
Pointer to the topic description, if it has been created locally. Otherwise, nullptr is returned.
- Remark
UNSAFE. It is unsafe to lookup a topic description while another thread is creating a topic.
- Parameters
topic_name: Name of the TopicDescription to search for.
-
const Subscriber *
get_builtin_subscriber() const¶ Allows access to the builtin Subscriber.
- Return
Pointer to the builtin Subscriber, nullptr in error case
-
ReturnCode_t
ignore_participant(const InstanceHandle_t &handle)¶ Locally ignore a remote domain participant.
- Note
This action is not required to be reversible.
- Return
RETURN_OK code if everything correct, error code otherwise
- Parameters
handle: Identifier of the remote participant to ignore
-
ReturnCode_t
ignore_topic(const InstanceHandle_t &handle)¶ Locally ignore a topic.
- Note
This action is not required to be reversible.
- Return
RETURN_OK code if everything correct, error code otherwise
- Parameters
handle: Identifier of the topic to ignore
-
ReturnCode_t
ignore_publication(const InstanceHandle_t &handle)¶ Locally ignore a datawriter.
- Note
This action is not required to be reversible.
- Return
RETURN_OK code if everything correct, error code otherwise
- Parameters
handle: Identifier of the datawriter to ignore
-
ReturnCode_t
ignore_subscription(const InstanceHandle_t &handle)¶ Locally ignore a datareader.
- Note
This action is not required to be reversible.
- Return
RETURN_OK code if everything correct, error code otherwise
- Parameters
handle: Identifier of the datareader to ignore
-
DomainId_t
get_domain_id() const¶ This operation retrieves the domain_id used to create the DomainParticipant. The domain_id identifies the DDS domain to which the DomainParticipant belongs.
- Return
The Participant’s domain_id
-
ReturnCode_t
delete_contained_entities()¶ Deletes all the entities that were created by means of the “create” methods
- Return
RETURN_OK code if everything correct, error code otherwise
-
ReturnCode_t
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.
- Note
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
RETCODE_OK if the liveliness was asserted, RETCODE_ERROR otherwise.
-
ReturnCode_t
set_default_publisher_qos(const PublisherQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: PublisherQos to be set
-
const PublisherQos &
get_default_publisher_qos() const¶ 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
Current default publisher qos.
-
ReturnCode_t
get_default_publisher_qos(PublisherQos &qos) const¶ 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
RETCODE_OK
- Parameters
qos: PublisherQos reference where the default_publisher_qos is returned
-
ReturnCode_t
get_publisher_qos_from_profile(const std::string &profile_name, PublisherQos &qos) const¶ Fills the PublisherQos with the values of the XML profile.
- Return
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- Parameters
profile_name: Publisher profile name.qos: PublisherQos object where the qos is returned.
-
ReturnCode_t
set_default_subscriber_qos(const SubscriberQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: SubscriberQos to be set
-
const SubscriberQos &
get_default_subscriber_qos() const¶ 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
Current default subscriber qos.
-
ReturnCode_t
get_default_subscriber_qos(SubscriberQos &qos) const¶ 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
RETCODE_OK
- Parameters
qos: SubscriberQos reference where the default_subscriber_qos is returned
-
ReturnCode_t
get_subscriber_qos_from_profile(const std::string &profile_name, SubscriberQos &qos) const¶ Fills the SubscriberQos with the values of the XML profile.
- Return
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- Parameters
profile_name: Subscriber profile name.qos: SubscriberQos object where the qos is returned.
-
ReturnCode_t
set_default_topic_qos(const TopicQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: TopicQos to be set
-
const TopicQos &
get_default_topic_qos() const¶ 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
Current default topic qos.
-
ReturnCode_t
get_default_topic_qos(TopicQos &qos) const¶ 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
RETCODE_OK
- Parameters
qos: TopicQos reference where the default_topic_qos is returned
-
ReturnCode_t
get_topic_qos_from_profile(const std::string &profile_name, TopicQos &qos) const¶ Fills the TopicQos with the values of the XML profile.
-
ReturnCode_t
get_discovered_participants(std::vector<InstanceHandle_t> &participant_handles) const¶ Retrieves the list of DomainParticipants that have been discovered in the domain and are not “ignored”.
- Return
RETCODE_OK if everything correct, error code otherwise
- Parameters
[out] participant_handles: Reference to the vector where discovered participants will be returned
-
ReturnCode_t
get_discovered_participant_data(builtin::ParticipantBuiltinTopicData &participant_data, const InstanceHandle_t &participant_handle) const¶ Retrieves the DomainParticipant data of a discovered not ignored participant.
- Return
RETCODE_OK if everything correct, PRECONDITION_NOT_MET if participant does not exist
- Parameters
[out] participant_data: Reference to the ParticipantBuiltinTopicData object to return the dataparticipant_handle: InstanceHandle of DomainParticipant to retrieve the data from
-
ReturnCode_t
get_discovered_topics(std::vector<InstanceHandle_t> &topic_handles) const¶ Retrieves the list of topics that have been discovered in the domain and are not “ignored”.
- Return
RETCODE_OK if everything correct, error code otherwise
- Parameters
[out] topic_handles: Reference to the vector where discovered topics will be returned
-
ReturnCode_t
get_discovered_topic_data(builtin::TopicBuiltinTopicData &topic_data, const InstanceHandle_t &topic_handle) const¶ Retrieves the Topic data of a discovered not ignored topic.
- Return
RETCODE_OK if everything correct, PRECONDITION_NOT_MET if topic does not exist
- Parameters
[out] topic_data: Reference to the TopicBuiltinTopicData object to return the datatopic_handle: InstanceHandle of Topic to retrieve the data from
-
bool
contains_entity(const InstanceHandle_t &a_handle, bool recursive = true) const¶ This operation checks whether or not the given handle represents an Entity that was created from the DomainParticipant.
- Return
True if entity is contained. False otherwise.
- Parameters
a_handle: InstanceHandle of the entity to look for.recursive: 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)
-
ReturnCode_t
get_current_time(fastrtps::Time_t ¤t_time) const¶ 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.
- Return
RETCODE_OK
- Parameters
current_time: Time_t reference where the current time is returned
-
ReturnCode_t
register_type(TypeSupport type, const std::string &type_name)¶ Register a type in this participant.
- Return
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.
- Parameters
type: TypeSupport.type_name: The name that will be used to identify the Type.
-
ReturnCode_t
register_type(TypeSupport type)¶ Register a type in this participant.
- Return
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.
- Parameters
type: TypeSupport.
-
ReturnCode_t
unregister_type(const std::string &typeName)¶ Unregister a type in this participant.
- Return
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.
- Parameters
typeName: Name of the type
-
TypeSupport
find_type(const std::string &type_name) const¶ This method gives access to a registered type based on its name.
- Return
TypeSupport corresponding to the type_name
- Parameters
type_name: Name of the type
-
const InstanceHandle_t &
get_instance_handle() const¶ Returns the DomainParticipant’s handle.
- Return
InstanceHandle of this DomainParticipant.
-
const fastrtps::rtps::GUID_t &
guid() const¶ Getter for the Participant GUID.
- Return
A reference to the GUID
-
std::vector<std::string>
get_participant_names() const¶ Getter for the participant names.
- Return
Vector with the names
-
bool
new_remote_endpoint_discovered(const fastrtps::rtps::GUID_t &partguid, uint16_t userId, fastrtps::rtps::EndpointKind_t 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.
- Return
True if correctly found and activated.
- Parameters
partguid: Participant GUID_t.userId: User defined ID as shown in the XML file.kind: EndpointKind (WRITER or READER)
-
fastrtps::rtps::ResourceEvent &
get_resource_event() const¶ Getter for the resource event.
- Return
A reference to the resource event
-
fastrtps::rtps::SampleIdentity
get_type_dependencies(const fastrtps::types::TypeIdentifierSeq &in) const¶ 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.
- Return
SampleIdentity
- Parameters
in: TypeIdentifier sequence
-
fastrtps::rtps::SampleIdentity
get_types(const fastrtps::types::TypeIdentifierSeq &in) const¶ A DomainParticipant may invoke the operation getTypes to retrieve the TypeObjects associated with a list of TypeIdentifiers.
- Return
SampleIdentity
- Parameters
in: TypeIdentifier sequence
-
ReturnCode_t
register_remote_type(const fastrtps::types::TypeInformation &type_information, const std::string &type_name, std::function<void(const std::string &name, const fastrtps::types::DynamicType_ptr type)> &callback)¶ Helps the user to solve all dependencies calling internally to the typelookup service and registers the resulting dynamic type. The registration will be perform asynchronously and the user will be notified through the given callback, which receives the type_name as unique argument. If the type is already registered, the function will return true, but the callback will not be called. If the given type_information is enough to build the type without using the typelookup service, it will return true and the callback will be never called.
- Return
true if type is already available (callback will not be called). false if type isn’t available yet (the callback will be called if negotiation is success, and ignored in other case).
- Parameters
type_information:type_name:callback:
-
bool
has_active_entities()¶ Check if the Participant has any Publisher, Subscriber or Topic.
- Return
true if any, false otherwise.
-
DomainParticipantFactory¶
-
class
eprosima::fastdds::dds::DomainParticipantFactory¶ Class DomainParticipantFactory
Public Functions
-
DomainParticipant *
create_participant(DomainId_t domain_id, const DomainParticipantQos &qos, DomainParticipantListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Participant.
- Return
DomainParticipant pointer. (nullptr if not created.)
- Parameters
domain_id: Domain Id.qos: DomainParticipantQos Reference.listener: DomainParticipantListener Pointer (default: nullptr)mask: StatusMask Reference (default: all)
-
DomainParticipant *
create_participant_with_profile(DomainId_t domain_id, const std::string &profile_name, DomainParticipantListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Participant.
- Return
DomainParticipant pointer. (nullptr if not created.)
- Parameters
domain_id: Domain Id.profile_name: Participant profile name.listener: DomainParticipantListener Pointer (default: nullptr)mask: StatusMask Reference (default: all)
-
DomainParticipant *
create_participant_with_profile(const std::string &profile_name, DomainParticipantListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ Create a Participant.
- Return
DomainParticipant pointer. (nullptr if not created.)
- Parameters
profile_name: Participant profile name.listener: DomainParticipantListener Pointer (default: nullptr)mask: StatusMask Reference (default: all)
-
DomainParticipant *
lookup_participant(DomainId_t domain_id) const¶ 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.
- Return
previously created DomainParticipant within the specified domain
- Parameters
domain_id:
-
std::vector<DomainParticipant*>
lookup_participants(DomainId_t domain_id) const¶ Returns all participants that belongs to the specified domain_id.
- Return
previously created DomainParticipants within the specified domain
- Parameters
domain_id:
-
ReturnCode_t
get_default_participant_qos(DomainParticipantQos &qos) const¶ 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
RETCODE_OK
- Parameters
qos: DomainParticipantQos where the qos is returned
-
const DomainParticipantQos &
get_default_participant_qos() const¶ 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
A reference to the default DomainParticipantQos
-
ReturnCode_t
set_default_participant_qos(const DomainParticipantQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: DomainParticipantQos to be set
-
ReturnCode_t
get_participant_qos_from_profile(const std::string &profile_name, DomainParticipantQos &qos) const¶ Fills the DomainParticipantQos with the values of the XML profile.
- Return
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- Parameters
profile_name: DomainParticipant profile name.qos: DomainParticipantQos object where the qos is returned.
-
ReturnCode_t
delete_participant(DomainParticipant *part)¶ Remove a Participant and all associated publishers and subscribers.
- Return
RETCODE_PRECONDITION_NOT_MET if the participant has active entities, RETCODE_OK if the participant is correctly deleted and RETCODE_ERROR otherwise.
- Parameters
part: Pointer to the participant.
-
ReturnCode_t
load_profiles()¶ Load profiles from default XML file.
- Return
RETCODE_OK
-
ReturnCode_t
load_XML_profiles_file(const std::string &xml_profile_file)¶ Load profiles from XML file.
- Return
RETCODE_OK if it is correctly loaded, RETCODE_ERROR otherwise.
- Parameters
xml_profile_file: XML profile file.
-
ReturnCode_t
get_qos(DomainParticipantFactoryQos &qos) const¶ This operation returns the value of the DomainParticipantFactory QoS policies.
- Return
RETCODE_OK
- Parameters
qos: DomaParticipantFactoryQos reference where the qos is returned
-
ReturnCode_t
set_qos(const DomainParticipantFactoryQos &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.
- Return
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.
- Parameters
qos: DomainParticipantFactoryQos to be set.
Public Static Functions
-
DomainParticipantFactory *
get_instance()¶ Returns the DomainParticipantFactory singleton.
- Return
The DomainParticipantFactory singleton.
-
DomainParticipant *
DomainParticipantFactoryQos¶
-
class
eprosima::fastdds::dds::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.
Public Functions
-
DomainParticipantFactoryQos()¶ Constructor.
-
~DomainParticipantFactoryQos()¶ Destructor.
-
const EntityFactoryQosPolicy &
entity_factory() const¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
EntityFactoryQosPolicy &
entity_factory()¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
void
entity_factory(const EntityFactoryQosPolicy &entity_factory)¶ Setter for EntityFactoryQosPolicy
- Parameters
entity_factory: EntityFactoryQosPolicy
-
DomainParticipantListener¶
-
class
eprosima::fastdds::dds::DomainParticipantListener: public eprosima::fastdds::dds::PublisherListener, public eprosima::fastdds::dds::SubscriberListener, public eprosima::fastdds::dds::TopicListener¶ Class DomainParticipantListener, overrides behaviour towards certain events.
Public Functions
-
DomainParticipantListener()¶ Constructor.
-
~DomainParticipantListener()¶ Destructor.
-
void
on_participant_discovery(DomainParticipant *participant, fastrtps::rtps::ParticipantDiscoveryInfo &&info)¶ This method is called when a new Participant is discovered, or a previously discovered participant changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote participant.info: Remote participant information. User can take ownership of the object.
-
void
onParticipantAuthentication(DomainParticipant *participant, fastrtps::rtps::ParticipantAuthenticationInfo &&info)¶ This method is called when a new Participant is authenticated.
- Parameters
participant: Pointer to the authenticated Participant.info: Remote participant authentication information. User can take ownership of the object.
-
void
on_subscriber_discovery(DomainParticipant *participant, fastrtps::rtps::ReaderDiscoveryInfo &&info)¶ This method is called when a new Subscriber is discovered, or a previously discovered subscriber changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote subscriber.info: Remote subscriber information. User can take ownership of the object.
-
void
on_publisher_discovery(DomainParticipant *participant, fastrtps::rtps::WriterDiscoveryInfo &&info)¶ This method is called when a new Publisher is discovered, or a previously discovered publisher changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote publisher.info: Remote publisher information. User can take ownership of the object.
-
void
on_type_discovery(DomainParticipant *participant, const fastrtps::rtps::SampleIdentity &request_sample_id, const fastrtps::string_255 &topic, const fastrtps::types::TypeIdentifier *identifier, const fastrtps::types::TypeObject *object, fastrtps::types::DynamicType_ptr 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;
-
void
on_type_dependencies_reply(DomainParticipant *participant, const fastrtps::rtps::SampleIdentity &request_sample_id, const fastrtps::types::TypeIdentifierWithSizeSeq &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.
-
void
on_type_information_received(DomainParticipant *participant, const fastrtps::string_255 topic_name, const fastrtps::string_255 type_name, const fastrtps::types::TypeInformation &type_information)¶ This method is called when a participant receives a TypeInformation while discovering another participant.
-
DomainParticipantQos¶
-
class
eprosima::fastdds::dds::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.
Public Functions
-
DomainParticipantQos()¶ Constructor.
-
~DomainParticipantQos()¶ Destructor.
-
const UserDataQosPolicy &
user_data() const¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy reference
-
UserDataQosPolicy &
user_data()¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy reference
-
void
user_data(const UserDataQosPolicy &value)¶ Setter for UserDataQosPolicy
- Parameters
value: UserDataQosPolicy
-
const EntityFactoryQosPolicy &
entity_factory() const¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
EntityFactoryQosPolicy &
entity_factory()¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
void
entity_factory(const EntityFactoryQosPolicy &value)¶ Setter for EntityFactoryQosPolicy
- Parameters
value: EntityFactoryQosPolicy
-
const ParticipantResourceLimitsQos &
allocation() const¶ Getter for ParticipantResourceLimitsQos
- Return
ParticipantResourceLimitsQos reference
-
ParticipantResourceLimitsQos &
allocation()¶ Getter for ParticipantResourceLimitsQos
- Return
ParticipantResourceLimitsQos reference
-
void
allocation(const ParticipantResourceLimitsQos &allocation)¶ Setter for ParticipantResourceLimitsQos
- Parameters
allocation: ParticipantResourceLimitsQos
-
const PropertyPolicyQos &
properties() const¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos reference
-
PropertyPolicyQos &
properties()¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos reference
-
void
properties(const PropertyPolicyQos &properties)¶ Setter for PropertyPolicyQos
- Parameters
properties: PropertyPolicyQos
-
const WireProtocolConfigQos &
wire_protocol() const¶ Getter for WireProtocolConfigQos
- Return
WireProtocolConfigQos reference
-
WireProtocolConfigQos &
wire_protocol()¶ Getter for WireProtocolConfigQos
- Return
WireProtocolConfigQos reference
-
void
wire_protocol(const WireProtocolConfigQos &wire_protocol)¶ Setter for WireProtocolConfigQos
- Parameters
wire_protocol: WireProtocolConfigQos
-
const TransportConfigQos &
transport() const¶ Getter for TransportConfigQos
- Return
TransportConfigQos reference
-
TransportConfigQos &
transport()¶ Getter for TransportConfigQos
- Return
TransportConfigQos reference
-
void
transport(const TransportConfigQos &transport)¶ Setter for TransportConfigQos
- Parameters
transport: TransportConfigQos
-
const fastrtps::string_255 &
name() const¶ Getter for the Participant name
- Return
name
-
fastrtps::string_255 &
name()¶ Getter for the Participant name
- Return
name
-
void
name(const fastrtps::string_255 &value)¶ Setter for the Participant name
- Return
value New name to be set
-
-
const DomainParticipantQos
eprosima::fastdds::dds::PARTICIPANT_QOS_DEFAULT¶
Publisher¶
DataWriter¶
-
class
eprosima::fastdds::dds::DataWriter: public eprosima::fastdds::dds::DomainEntity¶ Class DataWriter, contains the actual implementation of the behaviour of the DataWriter.
Public Types
-
enum
LoanInitializationKind¶ How to initialize samples loaned with loan_sample
Values:
-
enumerator
NO_LOAN_INITIALIZATION¶ Do not perform initialization of sample.
This is the default initialization scheme of loaned samples. It is the fastest scheme, but implies the user should take care of writing every field on the data type before calling write on the loaned sample.
-
enumerator
ZERO_LOAN_INITIALIZATION¶ Initialize all memory with zero-valued bytes.
The contents of the loaned sample will be zero-initialized upon return of loan_sample.
-
enumerator
CONSTRUCTED_LOAN_INITIALIZATION¶ Use in-place constructor initialization.
This will call the constructor of the data type over the memory space being returned by loan_sample.
-
enumerator
Public Functions
-
ReturnCode_t
enable() override¶ This operation enables the DataWriter.
- Return
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the Publisher creating this DataWriter is not enabled.
-
bool
write(void *data)¶ Write data to the topic.
- Return
True if correct, false otherwise
- Parameters
data: Pointer to the data
-
bool
write(void *data, fastrtps::rtps::WriteParams ¶ms)¶ Write data with params to the topic.
- Return
True if correct, false otherwise
- Parameters
data: Pointer to the dataparams: Extra write parameters.
-
ReturnCode_t
write(void *data, const InstanceHandle_t &handle)¶ 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).
- 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.
- Parameters
data: Pointer to the datahandle: InstanceHandle_t.
-
ReturnCode_t
write_w_timestamp(void *data, const InstanceHandle_t &handle, const fastrtps::rtps::Time_t ×tamp)¶ 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.NOT YET IMPLEMENTED
- Return
Any of the standard return codes.
- Parameters
data: Pointer to the datahandle: InstanceHandle_ttimestamp: Time_t used to set the source_timestamp.
-
InstanceHandle_t
register_instance(void *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.
- Return
Handle containing the instance’s key. This handle could be used in successive
writeordisposeoperations. In case of error, HANDLE_NIL will be returned.- Parameters
[in] instance: Sample used to get the instance’s key.
-
InstanceHandle_t
register_instance_w_timestamp(void *instance, const fastrtps::rtps::Time_t ×tamp)¶ 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.
NOT YET IMPLEMENTED 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.
- Return
Handle containing the instance’s key.
- Parameters
instance: Sample used to get the instance’s key.timestamp: Time_t used to set the source_timestamp.
-
ReturnCode_t
unregister_instance(void *instance, const InstanceHandle_t &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.
- Return
Returns the operation’s result. If the operation finishes successfully, ReturnCode_t::RETCODE_OK is returned.
- Parameters
[in] instance: Sample used to deduce instance’s key in case ofhandleparameter is HANDLE_NIL.[in] handle: Instance’s key to be unregistered.
-
ReturnCode_t
unregister_instance_w_timestamp(void *instance, const InstanceHandle_t &handle, const fastrtps::rtps::Time_t ×tamp)¶ 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.
NOT YET IMPLEMENTED 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
- Return
Handle containing the instance’s key.
- Parameters
instance: Sample used to deduce instance’s key in case ofhandleparameter is HANDLE_NIL.handle: Instance’s key to be unregistered.timestamp: Time_t used to set the source_timestamp.
-
ReturnCode_t
get_key_value(void *key_holder, const InstanceHandle_t &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 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.
- Return
Any of the standard return codes.
- Parameters
[inout] key_holder:[in] handle:
-
InstanceHandle_t
lookup_instance(const void *instance) const¶ 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.
- Return
handle of the given instance
- Parameters
[in] instance: Data pointer to the sample
-
const fastrtps::rtps::GUID_t &
guid() const¶ Returns the DataWriter’s GUID
- Return
Reference to the DataWriter GUID
-
InstanceHandle_t
get_instance_handle() const¶ Returns the DataWriter’s InstanceHandle
- Return
Copy of the DataWriter InstanceHandle
-
TypeSupport
get_type() const¶ Get data type associated to the DataWriter
- Return
Copy of the TypeSupport
-
ReturnCode_t
wait_for_acknowledgments(const fastrtps::Duration_t &max_wait)¶ Waits the current thread until all writers have received their acknowledgments.
- Return
RETCODE_OK if the DataWriter receive the acknowledgments before the time expires and RETCODE_ERROR otherwise
- Parameters
max_wait: Maximum blocking time for this operation
-
ReturnCode_t
get_offered_deadline_missed_status(OfferedDeadlineMissedStatus &status)¶ Returns the offered deadline missed status.
- Return
RETCODE_OK
- Parameters
[out] status: Deadline missed status struct
-
ReturnCode_t
get_offered_incompatible_qos_status(OfferedIncompatibleQosStatus &status)¶ Returns the offered incompatible qos status.
- Return
RETCODE_OK
- Parameters
[out] status: Offered incompatible qos status struct
-
ReturnCode_t
get_publication_matched_status(PublicationMatchedStatus &status) const¶ Returns the publication matched status.
- Return
RETCODE_OK
- Parameters
[out] status: publication matched status struct
-
ReturnCode_t
set_qos(const DataWriterQos &qos)¶ Establishes the DataWriterQos for this DataWriter.
- Return
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.
- Parameters
qos: DataWriterQos to be set
-
const DataWriterQos &
get_qos() const¶ Retrieves the DataWriterQos for this DataWriter.
- Return
Reference to the current DataWriterQos
-
ReturnCode_t
get_qos(DataWriterQos &qos) const¶ Fills the DataWriterQos with the values of this DataWriter.
- Return
RETCODE_OK
- Parameters
qos: DataWriterQos object where the qos is returned.
-
Topic *
get_topic() const¶ Retrieves the topic for this DataWriter.
- Return
Pointer to the associated Topic
-
const DataWriterListener *
get_listener() const¶ Retrieves the listener for this DataWriter.
- Return
Pointer to the DataWriterListener
-
ReturnCode_t
set_listener(DataWriterListener *listener)¶ Modifies the DataWriterListener, sets the mask to StatusMask::all()
- Return
RETCODE_OK
- Parameters
listener: new value for the DataWriterListener
-
ReturnCode_t
set_listener(DataWriterListener *listener, const StatusMask &mask)¶ Modifies the DataWriterListener.
- Return
RETCODE_OK
- Parameters
listener: new value for the DataWriterListenermask: StatusMask that holds statuses the listener responds to (default: all).
-
ReturnCode_t
dispose(void *data, const InstanceHandle_t &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.
- 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.
- Parameters
[in] data: Sample used to deduce instance’s key in case ofhandleparameter is HANDLE_NIL.[in] handle: InstanceHandle of the data
-
ReturnCode_t
dispose_w_timestamp(void *data, const InstanceHandle_t &handle)¶ 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.
- Return
RTPS_DllAPI
- Parameters
data: Pointer to the data.handle: InstanceHandle_t
-
ReturnCode_t
get_liveliness_lost_status(LivelinessLostStatus &status)¶ Returns the liveliness lost status.
- Return
RETCODE_OK
- Parameters
status: Liveliness lost status struct
-
const Publisher *
get_publisher() const¶ Getter for the Publisher that creates this DataWriter.
- Return
Pointer to the Publisher
-
ReturnCode_t
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.
- Note
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
RETCODE_OK if asserted, RETCODE_ERROR otherwise
-
ReturnCode_t
get_matched_subscription_data(builtin::SubscriptionBuiltinTopicData &subscription_data, const fastrtps::rtps::InstanceHandle_t &subscription_handle) const¶ Retrieves in a subscription associated with the DataWriter.
- Return
RETCODE_OK
- Parameters
[out] subscription_data: subscription data structsubscription_handle: InstanceHandle_t of the subscription
-
ReturnCode_t
get_matched_subscriptions(std::vector<fastrtps::rtps::InstanceHandle_t*> &subscription_handles) const¶ Fills the given vector with the InstanceHandle_t of matched DataReaders.
- Return
RETCODE_OK
- Parameters
[out] subscription_handles: Vector where the InstanceHandle_t are returned
-
ReturnCode_t
clear_history(size_t *removed)¶ Clears the DataWriter history.
- Return
RETCODE_OK if the samples are removed and RETCODE_ERROR otherwise
- Parameters
removed: size_t pointer to return the size of the data removed
-
ReturnCode_t
loan_sample(void *&sample, LoanInitializationKind initialization = LoanInitializationKind::NO_LOAN_INITIALIZATION)¶ 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.
- Return
ReturnCode_t::RETCODE_ILLEGAL_OPERATION when the data type does not support loans.
- Return
ReturnCode_t::RETCODE_NOT_ENABLED if the writer has not been enabled.
- Return
ReturnCode_t::RETCODE_OUT_OF_RESOURCES if the pool has been exhausted.
- Return
ReturnCode_t::RETCODE_OK if a pointer to a sample is successfully obtained.
- Parameters
[out] sample: Pointer to the sample on the internal pool.[in] initialization: How to initialize the loaned sample.
-
ReturnCode_t
discard_loan(void *&sample)¶ Discards a loaned sample pointer.
See the description on loan_sample for how and when to call this method.
- Return
ReturnCode_t::RETCODE_ILLEGAL_OPERATION when the data type does not support loans.
- Return
ReturnCode_t::RETCODE_NOT_ENABLED if the writer has not been enabled.
- Return
ReturnCode_t::RETCODE_BAD_PARAMETER if the pointer does not correspond to a loaned sample.
- Return
ReturnCode_t::RETCODE_OK if the loan is successfully discarded.
- Parameters
[inout] sample: Pointer to the previously loaned sample.
-
ReturnCode_t
get_sending_locators(rtps::LocatorList &locators) const¶ Get the list of locators from which this DataWriter may send data.
- Return
NOT_ENABLED if the reader has not been enabled.
- Return
OK if a list of locators is returned.
- Parameters
[out] locators: LocatorList where the list of locators will be stored.
-
enum
DataWriterListener¶
-
class
eprosima::fastdds::dds::DataWriterListener¶ Class DataWriterListener, allows the end user to implement callbacks triggered by certain events.
Subclassed by eprosima::fastdds::dds::PublisherListener
Public Functions
-
DataWriterListener()¶ Constructor.
-
~DataWriterListener()¶ Destructor.
-
void
on_publication_matched(DataWriter *writer, const PublicationMatchedStatus &info)¶ This method is called when the Publisher is matched (or unmatched) against an endpoint.
- Parameters
writer: Pointer to the associated Publisherinfo: Information regarding the matched subscriber
-
void
on_offered_deadline_missed(DataWriter *writer, const OfferedDeadlineMissedStatus &status)¶ A method called when a deadline is missed
- Parameters
writer: Pointer to the associated Publisherstatus: The deadline missed status
-
void
on_offered_incompatible_qos(DataWriter *writer, const OfferedIncompatibleQosStatus &status)¶ A method called when an incompatible QoS is offered
- Parameters
writer: Pointer to the associated Publisherstatus: The deadline missed status
-
void
on_liveliness_lost(DataWriter *writer, const LivelinessLostStatus &status)¶ Method called when the liveliness of a publisher is lost.
- Parameters
writer: The publisherstatus: The liveliness lost status
-
DataWriterQos¶
-
class
eprosima::fastdds::dds::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.
Subclassed by eprosima::fastdds::statistics::dds::DataWriterQos
Public Functions
-
DataWriterQos()¶ Constructor.
-
~DataWriterQos() = default¶ Destructor.
-
DurabilityQosPolicy &
durability()¶ Getter for DurabilityQosPolicy
- Return
DurabilityQosPolicy reference
-
const DurabilityQosPolicy &
durability() const¶ Getter for DurabilityQosPolicy
- Return
DurabilityQosPolicy reference
-
void
durability(const DurabilityQosPolicy &durability)¶ Setter for DurabilityQosPolicy
- Parameters
durability: new value for the DurabilityQosPolicy
-
DurabilityServiceQosPolicy &
durability_service()¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQosPolicy reference
-
const DurabilityServiceQosPolicy &
durability_service() const¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQosPolicy reference
-
void
durability_service(const DurabilityServiceQosPolicy &durability_service)¶ Setter for DurabilityServiceQosPolicy
- Parameters
durability_service: new value for the DurabilityServiceQosPolicy
-
DeadlineQosPolicy &
deadline()¶ Getter for DeadlineQosPolicy
- Return
DeadlineQosPolicy reference
-
const DeadlineQosPolicy &
deadline() const¶ Getter for DeadlineQosPolicy
- Return
DeadlineQosPolicy reference
-
void
deadline(const DeadlineQosPolicy &deadline)¶ Setter for DeadlineQosPolicy
- Parameters
deadline: new value for the DeadlineQosPolicy
-
LatencyBudgetQosPolicy &
latency_budget()¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQosPolicy reference
-
const LatencyBudgetQosPolicy &
latency_budget() const¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQosPolicy reference
-
void
latency_budget(const LatencyBudgetQosPolicy &latency_budget)¶ Setter for LatencyBudgetQosPolicy
- Parameters
latency_budget: new value for the LatencyBudgetQosPolicy
-
LivelinessQosPolicy &
liveliness()¶ Getter for LivelinessQosPolicy
- Return
LivelinessQosPolicy reference
-
const LivelinessQosPolicy &
liveliness() const¶ Getter for LivelinessQosPolicy
- Return
LivelinessQosPolicy reference
-
void
liveliness(const LivelinessQosPolicy &liveliness)¶ Setter for LivelinessQosPolicy
- Parameters
liveliness: new value for the LivelinessQosPolicy
-
ReliabilityQosPolicy &
reliability()¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQosPolicy reference
-
const ReliabilityQosPolicy &
reliability() const¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQosPolicy reference
-
void
reliability(const ReliabilityQosPolicy &reliability)¶ Setter for ReliabilityQosPolicy
- Parameters
reliability: new value for the ReliabilityQosPolicy
-
DestinationOrderQosPolicy &
destination_order()¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQosPolicy reference
-
const DestinationOrderQosPolicy &
destination_order() const¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQosPolicy reference
-
void
destination_order(const DestinationOrderQosPolicy &destination_order)¶ Setter for DestinationOrderQosPolicy
- Parameters
destination_order: new value for the DestinationOrderQosPolicy
-
HistoryQosPolicy &
history()¶ Getter for HistoryQosPolicy
- Return
HistoryQosPolicy reference
-
const HistoryQosPolicy &
history() const¶ Getter for HistoryQosPolicy
- Return
HistoryQosPolicy reference
-
void
history(const HistoryQosPolicy &history)¶ Setter for HistoryQosPolicy
- Parameters
history: new value for the HistoryQosPolicy
-
ResourceLimitsQosPolicy &
resource_limits()¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQosPolicy reference
-
const ResourceLimitsQosPolicy &
resource_limits() const¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQosPolicy reference
-
void
resource_limits(const ResourceLimitsQosPolicy &resource_limits)¶ Setter for ResourceLimitsQosPolicy
- Parameters
resource_limits: new value for the ResourceLimitsQosPolicy
-
TransportPriorityQosPolicy &
transport_priority()¶ Getter for TransportPriorityQosPolicy
- Return
TransportPriorityQosPolicy reference
-
const TransportPriorityQosPolicy &
transport_priority() const¶ Getter for TransportPriorityQosPolicy
- Return
TransportPriorityQosPolicy reference
-
void
transport_priority(const TransportPriorityQosPolicy &transport_priority)¶ Setter for TransportPriorityQosPolicy
- Parameters
transport_priority: new value for the TransportPriorityQosPolicy
-
LifespanQosPolicy &
lifespan()¶ Getter for LifespanQosPolicy
- Return
LifespanQosPolicy reference
-
const LifespanQosPolicy &
lifespan() const¶ Getter for LifespanQosPolicy
- Return
LifespanQosPolicy reference
-
void
lifespan(const LifespanQosPolicy &lifespan)¶ Setter for LifespanQosPolicy
- Parameters
lifespan: new value for the LifespanQosPolicy
-
UserDataQosPolicy &
user_data()¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy reference
-
const UserDataQosPolicy &
user_data() const¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy reference
-
void
user_data(const UserDataQosPolicy &user_data)¶ Setter for UserDataQosPolicy
- Parameters
user_data: new value for the UserDataQosPolicy
-
OwnershipQosPolicy &
ownership()¶ Getter for OwnershipQosPolicy
- Return
OwnershipQosPolicy reference
-
const OwnershipQosPolicy &
ownership() const¶ Getter for OwnershipQosPolicy
- Return
OwnershipQosPolicy reference
-
void
ownership(const OwnershipQosPolicy &ownership)¶ Setter for OwnershipQosPolicy
- Parameters
ownership: new value for the OwnershipQosPolicy
-
OwnershipStrengthQosPolicy &
ownership_strength()¶ Getter for OwnershipStrengthQosPolicy
- Return
OwnershipStrengthQosPolicy reference
-
const OwnershipStrengthQosPolicy &
ownership_strength() const¶ Getter for OwnershipStrengthQosPolicy
- Return
OwnershipStrengthQosPolicy reference
-
void
ownership_strength(const OwnershipStrengthQosPolicy &ownership_strength)¶ Setter for OwnershipStrengthQosPolicy
- Parameters
ownership_strength: new value for the OwnershipStrengthQosPolicy
-
WriterDataLifecycleQosPolicy &
writer_data_lifecycle()¶ Getter for WriterDataLifecycleQosPolicy
- Return
WriterDataLifecycleQosPolicy reference
-
const WriterDataLifecycleQosPolicy &
writer_data_lifecycle() const¶ Getter for WriterDataLifecycleQosPolicy
- Return
WriterDataLifecycleQosPolicy reference
-
void
writer_data_lifecycle(const WriterDataLifecycleQosPolicy &writer_data_lifecycle)¶ Setter for WriterDataLifecycleQosPolicy
- Parameters
writer_data_lifecycle: new value for the WriterDataLifecycleQosPolicy
-
PublishModeQosPolicy &
publish_mode()¶ Getter for PublishModeQosPolicy
- Return
PublishModeQosPolicy reference
-
const PublishModeQosPolicy &
publish_mode() const¶ Getter for PublishModeQosPolicy
- Return
PublishModeQosPolicy reference
-
void
publish_mode(const PublishModeQosPolicy &publish_mode)¶ Setter for PublishModeQosPolicy
- Parameters
publish_mode: new value for the PublishModeQosPolicy
-
DataRepresentationQosPolicy &
representation()¶ Getter for DataRepresentationQosPolicy
- Return
DataRepresentationQosPolicy reference
-
const DataRepresentationQosPolicy &
representation() const¶ Getter for DataRepresentationQosPolicy
- Return
DataRepresentationQosPolicy reference
-
void
representation(const DataRepresentationQosPolicy &representation)¶ Setter for DataRepresentationQosPolicy
- Parameters
representation: new value for the DataRepresentationQosPolicy
-
PropertyPolicyQos &
properties()¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos reference
-
const PropertyPolicyQos &
properties() const¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos reference
-
void
properties(const PropertyPolicyQos &properties)¶ Setter for PropertyPolicyQos
- Parameters
properties: new value for the PropertyPolicyQos
-
RTPSReliableWriterQos &
reliable_writer_qos()¶ Getter for RTPSReliableWriterQos
- Return
RTPSReliableWriterQos reference
-
const RTPSReliableWriterQos &
reliable_writer_qos() const¶ Getter for RTPSReliableWriterQos
- Return
RTPSReliableWriterQos reference
-
void
reliable_writer_qos(const RTPSReliableWriterQos &reliable_writer_qos)¶ Setter for RTPSReliableWriterQos
- Parameters
reliable_writer_qos: new value for the RTPSReliableWriterQos
-
RTPSEndpointQos &
endpoint()¶ Getter for RTPSEndpointQos
- Return
RTPSEndpointQos reference
-
const RTPSEndpointQos &
endpoint() const¶ Getter for RTPSEndpointQos
- Return
RTPSEndpointQos reference
-
void
endpoint(const RTPSEndpointQos &endpoint)¶ Setter for RTPSEndpointQos
- Parameters
endpoint: new value for the RTPSEndpointQos
-
WriterResourceLimitsQos &
writer_resource_limits()¶ Getter for WriterResourceLimitsQos
- Return
WriterResourceLimitsQos reference
-
const WriterResourceLimitsQos &
writer_resource_limits() const¶ Getter for WriterResourceLimitsQos
- Return
WriterResourceLimitsQos reference
-
void
writer_resource_limits(const WriterResourceLimitsQos &writer_resource_limits)¶ Setter for WriterResourceLimitsQos
- Parameters
writer_resource_limits: new value for the WriterResourceLimitsQos
-
fastrtps::rtps::ThroughputControllerDescriptor &
throughput_controller()¶ Getter for ThroughputControllerDescriptor
- Return
ThroughputControllerDescriptor reference
-
const fastrtps::rtps::ThroughputControllerDescriptor &
throughput_controller() const¶ Getter for ThroughputControllerDescriptor
- Return
ThroughputControllerDescriptor reference
-
void
throughput_controller(const fastrtps::rtps::ThroughputControllerDescriptor &throughput_controller)¶ Setter for ThroughputControllerDescriptor
- Parameters
throughput_controller: new value for the ThroughputControllerDescriptor
-
DataSharingQosPolicy &
data_sharing()¶ Getter for DataSharingQosPolicy
- Return
DataSharingQosPolicy reference
-
const DataSharingQosPolicy &
data_sharing() const¶ Getter for DataSharingQosPolicy
- Return
DataSharingQosPolicy reference
-
void
data_sharing(const DataSharingQosPolicy &data_sharing)¶ Setter for DataSharingQosPolicy
- Parameters
data_sharing: new value for the DataSharingQosPolicy
-
-
const DataWriterQos
eprosima::fastdds::dds::DATAWRITER_QOS_DEFAULT¶
Publisher¶
-
class
eprosima::fastdds::dds::Publisher: public eprosima::fastdds::dds::DomainEntity¶ Class Publisher, used to send data to associated subscribers.
Public Functions
-
~Publisher()¶ Destructor.
-
ReturnCode_t
enable() override¶ This operation enables the Publisher.
- Return
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the participant creating this Publisher is not enabled.
-
const PublisherQos &
get_qos() const¶ Allows accessing the Publisher Qos.
- Return
PublisherQos reference
-
ReturnCode_t
get_qos(PublisherQos &qos) const¶ Retrieves the Publisher Qos.
- Return
RETCODE_OK
-
ReturnCode_t
set_qos(const PublisherQos &qos)¶ Allows modifying the Publisher Qos. The given Qos must be supported by the PublisherQos.
- Return
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.
- Parameters
qos: PublisherQos to be set
-
const PublisherListener *
get_listener() const¶ Retrieves the attached PublisherListener.
- Return
PublisherListener pointer
-
ReturnCode_t
set_listener(PublisherListener *listener)¶ Modifies the PublisherListener, sets the mask to StatusMask::all()
- Return
RETCODE_OK
- Parameters
listener: new value for the PublisherListener
-
ReturnCode_t
set_listener(PublisherListener *listener, const StatusMask &mask)¶ Modifies the PublisherListener.
- Return
RETCODE_OK
- Parameters
listener: new value for the PublisherListenermask: StatusMask that holds statuses the listener responds to
-
DataWriter *
create_datawriter(Topic *topic, const DataWriterQos &qos, DataWriterListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ This operation creates a DataWriter. The returned DataWriter will be attached and belongs to the Publisher.
- Return
Pointer to the created DataWriter. nullptr if failed.
- Parameters
topic: Topic the DataWriter will be listeningqos: QoS of the DataWriter.listener: Pointer to the listener (default: nullptr).mask: StatusMask that holds statuses the listener responds to (default: all).
-
DataWriter *
create_datawriter_with_profile(Topic *topic, const std::string &profile_name, DataWriterListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ This operation creates a DataWriter. The returned DataWriter will be attached and belongs to the Publisher.
- Return
Pointer to the created DataWriter. nullptr if failed.
- Parameters
topic: Topic the DataWriter will be listeningprofile_name: DataWriter profile name.listener: Pointer to the listener (default: nullptr).mask: StatusMask that holds statuses the listener responds to (default: all).
-
ReturnCode_t
delete_datawriter(const 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.
- Return
RETCODE_PRECONDITION_NOT_MET if it does not belong to this Publisher, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- Parameters
writer: DataWriter to delete
-
DataWriter *
lookup_datawriter(const std::string &topic_name) const¶ 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.
- Return
Pointer to a previously created DataWriter associated to a Topic with the requested topic_name
- Parameters
topic_name: Name of the Topic
-
ReturnCode_t
suspend_publications()¶ Indicates to FastDDS that the contained DataWriters are about to be modified.
- Return
RETCODE_OK if successful, an error code otherwise
-
ReturnCode_t
resume_publications()¶ Indicates to FastDDS that the modifications to the DataWriters are complete.
- Return
RETCODE_OK if successful, an error code otherwise
-
ReturnCode_t
begin_coherent_changes()¶ Signals the beginning of a set of coherent cache changes using the Datawriters attached to the publisher.
- Return
RETCODE_OK if successful, an error code otherwise
-
ReturnCode_t
end_coherent_changes()¶ Signals the end of a set of coherent cache changes.
- Return
RETCODE_OK if successful, an error code otherwise
-
ReturnCode_t
wait_for_acknowledgments(const fastrtps::Duration_t &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.
- Return
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.
- Parameters
max_wait: Maximum blocking time for this operation
-
const DomainParticipant *
get_participant() const¶ This operation returns the DomainParticipant to which the Publisher belongs.
- Return
Pointer to the DomainParticipant
-
ReturnCode_t
delete_contained_entities()¶ Deletes all contained DataWriters.
- Return
RETCODE_OK if successful, an error code otherwise
-
ReturnCode_t
set_default_datawriter_qos(const DataWriterQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: DataWriterQos to be set
-
const DataWriterQos &
get_default_datawriter_qos() const¶ 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
Current default WriterQos
-
ReturnCode_t
get_default_datawriter_qos(DataWriterQos &qos) const¶ 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.
- Return
RETCODE_OK
- Parameters
qos: Reference to the current default WriterQos.
-
ReturnCode_t
copy_from_topic_qos(fastdds::dds::DataWriterQos &writer_qos, const fastdds::dds::TopicQos &topic_qos) const¶ Copies TopicQos into the corresponding DataWriterQos.
- Return
RETCODE_OK if successful, an error code otherwise
- Parameters
[out] writer_qos:[in] topic_qos:
-
ReturnCode_t
get_datawriter_qos_from_profile(const std::string &profile_name, DataWriterQos &qos) const¶ Fills the DataWriterQos with the values of the XML profile.
- Return
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- Parameters
profile_name: DataWriter profile name.qos: DataWriterQos object where the qos is returned.
-
const InstanceHandle_t &
get_instance_handle() const¶ Returns the Publisher’s handle.
- Return
InstanceHandle of this Publisher.
-
bool
get_datawriters(std::vector<DataWriter*> &writers) const¶ Fills the given vector with all the datawriters of this publisher.
- Return
true
- Parameters
writers: Vector where the DataWriters are returned
-
bool
has_datawriters() const¶ This operation checks if the publisher has DataWriters
- Return
true if the publisher has one or several DataWriters, false otherwise
-
PublisherListener¶
-
class
eprosima::fastdds::dds::PublisherListener: public eprosima::fastdds::dds::DataWriterListener¶ Class PublisherListener, allows the end user to implement callbacks triggered by certain events. It inherits all the DataWriterListener callbacks.
Subclassed by eprosima::fastdds::dds::DomainParticipantListener
PublisherQos¶
-
class
eprosima::fastdds::dds::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.
Public Functions
-
PublisherQos()¶ Constructor.
-
~PublisherQos() = default¶ Destructor.
-
const PresentationQosPolicy &
presentation() const¶ Getter for PresentationQosPolicy
- Return
PresentationQosPolicy reference
-
PresentationQosPolicy &
presentation()¶ Getter for PresentationQosPolicy
- Return
PresentationQosPolicy reference
-
void
presentation(const PresentationQosPolicy &presentation)¶ Setter for PresentationQosPolicy
- Parameters
presentation: PresentationQosPolicy
-
const PartitionQosPolicy &
partition() const¶ Getter for PartitionQosPolicy
- Return
PartitionQosPolicy reference
-
PartitionQosPolicy &
partition()¶ Getter for PartitionQosPolicy
- Return
PartitionQosPolicy reference
-
void
partition(const PartitionQosPolicy &partition)¶ Setter for PartitionQosPolicy
- Parameters
partition: PartitionQosPolicy
-
const GroupDataQosPolicy &
group_data() const¶ Getter for GroupDataQosPolicy
- Return
GroupDataQosPolicy reference
-
GroupDataQosPolicy &
group_data()¶ Getter for GroupDataQosPolicy
- Return
GroupDataQosPolicy reference
-
void
group_data(const GroupDataQosPolicy &group_data)¶ Setter for GroupDataQosPolicy
- Parameters
group_data: GroupDataQosPolicy
-
const EntityFactoryQosPolicy &
entity_factory() const¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
EntityFactoryQosPolicy &
entity_factory()¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
void
entity_factory(const EntityFactoryQosPolicy &entity_factory)¶ Setter for EntityFactoryQosPolicy
- Parameters
entity_factory: EntityFactoryQosPolicy
-
-
const PublisherQos
eprosima::fastdds::dds::PUBLISHER_QOS_DEFAULT¶
RTPSReliableWriterQos¶
-
class
eprosima::fastdds::dds::RTPSReliableWriterQos¶ Qos Policy to configure the DisablePositiveACKsQos and the writer timing attributes.
Public Functions
-
RTPSReliableWriterQos()¶ Constructor.
-
~RTPSReliableWriterQos() = default¶ Destructor.
Public Members
-
fastrtps::rtps::WriterTimes
times¶ Writer Timing Attributes.
-
DisablePositiveACKsQosPolicy
disable_positive_acks¶ Disable positive acks QoS, implemented in the library.
-
Subscriber¶
DataReader¶
-
class
eprosima::fastdds::dds::DataReader: public eprosima::fastdds::dds::DomainEntity¶ Class DataReader, contains the actual implementation of the behaviour of the Subscriber.
Read or take data methods.
Methods to read or take data from the History.
-
ReturnCode_t
read(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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 thedata_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 verifyingmax_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 > 0and the inputowns == 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 > 0and the inputowns == 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 mostmax_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 mostmax_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 tomax_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 havemax_len == 0andowns == 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 hassample_rank == 0does 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
-
ReturnCode_t
read_w_condition(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, ReadCondition *a_condition = nullptr)¶ NOT YET IMPLEMENTED 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] sample_infos: A SampleInfoSeq object where the received sample info will be returned.[in] max_samples: The maximum number of samples to be returned.[in] a_condition: A ReadCondition that returnedsample_statesmust pass
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ReturnCode_t
read_instance(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &a_handle = HANDLE_NIL, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
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ReturnCode_t
read_next_instance(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &previous_handle = HANDLE_NIL, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
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ReturnCode_t
read_next_instance_w_condition(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &previous_handle = HANDLE_NIL, ReadCondition *a_condition = nullptr)¶ NOT YET IMPLEMENTED 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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] a_condition: A ReadCondition that returnedsample_statesmust pass
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ReturnCode_t
read_next_sample(void *data, SampleInfo *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, thesample_states = NOT_READ_SAMPLE_STATE, theview_states = ANY_VIEW_STATE, and theinstance_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
- Return
Any of the standard return codes.
- Parameters
[out] data: Data pointer to store the sample[out] info: SampleInfo pointer to store the sample information
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ReturnCode_t
take(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
-
ReturnCode_t
take_w_condition(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, ReadCondition *a_condition = nullptr)¶ NOT YET IMPLEMENTED 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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.[in] a_condition: A ReadCondition that returnedsample_statesmust pass
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ReturnCode_t
take_instance(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &a_handle = HANDLE_NIL, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
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ReturnCode_t
take_next_instance(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &previous_handle = HANDLE_NIL, SampleStateMask sample_states = ANY_SAMPLE_STATE, ViewStateMask view_states = ANY_VIEW_STATE, InstanceStateMask instance_states = ANY_INSTANCE_STATE)¶ 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.
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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 withsample_statematching one of these will be returned.[in] view_states: Only data samples withview_statematching one of these will be returned.[in] instance_states: Only data samples withinstance_statematching one of these will be returned.
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ReturnCode_t
take_next_instance_w_condition(LoanableCollection &data_values, SampleInfoSeq &sample_infos, int32_t max_samples = LENGTH_UNLIMITED, const InstanceHandle_t &previous_handle = HANDLE_NIL, ReadCondition *a_condition = nullptr)¶ NOT YET IMPLEMENTED 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
- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples will be returned.[inout] 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] a_condition: A ReadCondition that returnedsample_statesmust pass
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ReturnCode_t
take_next_sample(void *data, SampleInfo *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, thesample_states = NOT_READ_SAMPLE_STATE, theview_states = ANY_VIEW_STATE, and theinstance_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.
- Return
Any of the standard return codes.
- Parameters
[out] data: Data pointer to store the sample[out] info: SampleInfo pointer to store the sample information
Public Functions
-
~DataReader()¶ Destructor.
-
ReturnCode_t
enable() override¶ This operation enables the DataReader.
- Return
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the Subscriber creating this DataReader is not enabled.
-
bool
wait_for_unread_message(const fastrtps::Duration_t &timeout)¶ Method to block the current thread until an unread message is available.
- Return
true if there is new unread message, false if timeout
- Parameters
[in] timeout: Max blocking time for this operation.
-
ReturnCode_t
wait_for_historical_data(const fastrtps::Duration_t &max_wait) const¶ Method to block the current thread until an unread message is available.
- Return
RETCODE_OK if there is new unread message, ReturnCode_t::RETCODE_TIMEOUT if timeout
- Parameters
[in] max_wait: Max blocking time for this operation.
-
ReturnCode_t
return_loan(LoanableCollection &data_values, SampleInfoSeq &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 hadmax_len == 0at 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.- Return
Any of the standard return codes.
- Parameters
[inout] data_values: A LoanableCollection object where the received data samples were obtained from an earlier invocation of read or take on this DataReader.[inout] sample_infos: A SampleInfoSeq object where the received sample infos were obtained from an earlier invocation of read or take on this DataReader.
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ReturnCode_t
get_key_value(void *key_holder, const InstanceHandle_t &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.
- Return
Any of the standard return codes.
- Parameters
[inout] key_holder:[in] handle:
-
InstanceHandle_t
lookup_instance(const void *instance) const¶ 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.
- Return
handle of the given instance
- Parameters
[in] instance: Data pointer to the sample
-
ReturnCode_t
get_first_untaken_info(SampleInfo *info)¶ Returns information about the first untaken sample.
- Return
RETCODE_OK if sample info was returned. RETCODE_NO_DATA if there is no sample to take.
- Parameters
[out] info: Pointer to a SampleInfo_t structure to store first untaken sample information.
-
uint64_t
get_unread_count() const¶ 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
the number of samples on the reader history that have never been read.
-
InstanceHandle_t
get_instance_handle() const¶ Getter for the associated InstanceHandle.
- Return
Copy of the InstanceHandle
-
TypeSupport
type()¶ Getter for the data type.
- Return
TypeSupport associated to the DataReader.
-
const TopicDescription *
get_topicdescription() const¶ Get TopicDescription.
- Return
TopicDescription pointer.
-
ReturnCode_t
get_requested_deadline_missed_status(RequestedDeadlineMissedStatus &status)¶ Get the requested deadline missed status.
- Return
The deadline missed status.
-
ReturnCode_t
get_requested_incompatible_qos_status(RequestedIncompatibleQosStatus &status)¶ Get the requested incompatible qos status.
- Return
RETCODE_OK
- Parameters
[out] status: Requested incompatible qos status.
-
ReturnCode_t
set_qos(const DataReaderQos &qos)¶ Setter for the DataReaderQos.
- Return
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.
- Parameters
[in] qos: new value for the DataReaderQos.
-
const DataReaderQos &
get_qos() const¶ Getter for the DataReaderQos.
- Return
Pointer to the DataReaderQos.
-
ReturnCode_t
get_qos(DataReaderQos &qos) const¶ Getter for the DataReaderQos.
- Return
RETCODE_OK
- Parameters
[in] qos: DataReaderQos where the qos is returned.
-
ReturnCode_t
set_listener(DataReaderListener *listener)¶ Modifies the DataReaderListener, sets the mask to StatusMask::all().
- Return
RETCODE_OK
- Parameters
[in] listener: new value for the DataReaderListener.
-
ReturnCode_t
set_listener(DataReaderListener *listener, const StatusMask &mask)¶ Modifies the DataReaderListener.
- Return
RETCODE_OK
- Parameters
[in] listener: new value for the DataReaderListener.[in] mask: StatusMask that holds statuses the listener responds to (default: all).
-
const DataReaderListener *
get_listener() const¶ Getter for the DataReaderListener.
- Return
Pointer to the DataReaderListener
-
ReturnCode_t
get_liveliness_changed_status(LivelinessChangedStatus &status) const¶ Get the liveliness changed status.
- Return
RETCODE_OK
- Parameters
[out] status: LivelinessChangedStatus object where the status is returned.
-
ReturnCode_t
get_sample_lost_status(SampleLostStatus &status) const¶ Get the SAMPLE_LOST communication status.
- Return
RETCODE_OK
- Parameters
[out] status: SampleLostStatus object where the status is returned.
-
ReturnCode_t
get_sample_rejected_status(SampleRejectedStatus &status) const¶ Get the SAMPLE_REJECTED communication status.
- Return
RETCODE_OK
- Parameters
[out] status: SampleRejectedStatus object where the status is returned.
-
ReturnCode_t
get_subscription_matched_status(SubscriptionMatchedStatus &status) const¶ Returns the subscription matched status.
- Return
RETCODE_OK
- Parameters
[out] status: subscription matched status struct
-
ReturnCode_t
get_matched_publication_data(builtin::PublicationBuiltinTopicData &publication_data, const fastrtps::rtps::InstanceHandle_t &publication_handle) const¶ Retrieves in a publication associated with the DataWriter.
- Return
RETCODE_OK
- Parameters
[out] publication_data: publication data structpublication_handle: InstanceHandle_t of the publication
-
ReturnCode_t
get_matched_publications(std::vector<fastrtps::rtps::InstanceHandle_t> &publication_handles) const¶ Fills the given vector with the InstanceHandle_t of matched DataReaders.
- Return
RETCODE_OK
- Parameters
[out] publication_handles: Vector where the InstanceHandle_t are returned
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ReadCondition *
create_readcondition(const std::vector<SampleStateKind> &sample_states, const std::vector<ViewStateKind> &view_states, const std::vector<InstanceStateKind> &instance_states)¶ This operation creates a ReadCondition. The returned ReadCondition will be attached and belong to the DataReader.
- Return
ReadCondition pointer
- Parameters
sample_states: Vector of SampleStateKindview_states: Vector of ViewStateKindinstance_states: Vector of InstanceStateKind
-
QueryCondition *
create_querycondition(const std::vector<SampleStateKind> &sample_states, const std::vector<ViewStateKind> &view_states, const std::vector<InstanceStateKind> &instance_states, const std::string &query_expression, const std::vector<std::string> &query_parameters)¶ This operation creates a QueryCondition. The returned QueryCondition will be attached and belong to the DataReader.
- Return
QueryCondition pointer
- Parameters
sample_states: Vector of SampleStateKindview_states: Vector of ViewStateKindinstance_states: Vector of InstanceStateKindquery_expression: string containing queryquery_parameters: Vector of strings containing parameters of query expression
-
ReturnCode_t
delete_readcondition(const ReadCondition *a_condition)¶ This operation deletes a ReadCondition attached to the DataReader.
- Return
RETCODE_OK
- Parameters
a_condition: pointer to a ReadCondition belonging to the DataReader
-
const Subscriber *
get_subscriber() const¶ Getter for the Subscriber.
- Return
Subscriber pointer
-
ReturnCode_t
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
Any of the standard return codes.
-
bool
is_sample_valid(const void *data, const SampleInfo *info) const¶ Checks whether the sample is still valid or is corrupted
- Return
true if the sample is valid
- Parameters
data: Pointer to the sample data to checkinfo: Pointer to the SampleInfo related todata
-
ReturnCode_t
get_listening_locators(rtps::LocatorList &locators) const¶ Get the list of locators on which this DataReader is listening.
- Return
NOT_ENABLED if the reader has not been enabled.
- Return
OK if a list of locators is returned.
- Parameters
[out] locators: LocatorList where the list of locators will be stored.
-
ReturnCode_t
DataReaderListener¶
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class
eprosima::fastdds::dds::DataReaderListener¶ Class DataReaderListener, it should be used by the end user to implement specific callbacks to certain actions.
Subclassed by eprosima::fastdds::dds::SubscriberListener
Public Functions
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DataReaderListener()¶ Constructor.
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~DataReaderListener()¶ Destructor.
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void
on_data_available(DataReader *reader)¶ Virtual function to be implemented by the user containing the actions to be performed when a new Data Message is received.
- Parameters
reader: DataReader
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void
on_subscription_matched(DataReader *reader, const fastdds::dds::SubscriptionMatchedStatus &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: DataReaderinfo: The subscription matched status
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void
on_requested_deadline_missed(DataReader *reader, const fastrtps::RequestedDeadlineMissedStatus &status)¶ Virtual method to be called when a topic misses the deadline period
- Parameters
reader: DataReaderstatus: The requested deadline missed status
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void
on_liveliness_changed(DataReader *reader, const fastrtps::LivelinessChangedStatus &status)¶ Method called when the liveliness status associated to a subscriber changes.
- Parameters
reader: The DataReaderstatus: The liveliness changed status
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void
on_sample_rejected(DataReader *reader, const fastrtps::SampleRejectedStatus &status)¶ Method called when a sample was rejected.
- Parameters
reader: The DataReaderstatus: The rejected status
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void
on_requested_incompatible_qos(DataReader *reader, const RequestedIncompatibleQosStatus &status)¶ Method called an incompatible QoS was requested.
- Parameters
reader: The DataReaderstatus: The requested incompatible QoS status
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void
on_sample_lost(DataReader *reader, const SampleLostStatus &status)¶ Method called when a sample was lost.
- Parameters
reader: The DataReaderstatus: The sample lost status
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DataReaderQos¶
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class
eprosima::fastdds::dds::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.
Subclassed by eprosima::fastdds::statistics::dds::DataReaderQos
Public Functions
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DataReaderQos()¶ Constructor.
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DurabilityQosPolicy &
durability()¶ Getter for DurabilityQosPolicy
- Return
DurabilityQosPolicy reference
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const DurabilityQosPolicy &
durability() const¶ Getter for DurabilityQosPolicy
- Return
DurabilityQosPolicy const reference
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void
durability(const DurabilityQosPolicy &new_value)¶ Setter for DurabilityQosPolicy
- Parameters
new_value: new value for the DurabilityQosPolicy
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DeadlineQosPolicy &
deadline()¶ Getter for DeadlineQosPolicy
- Return
DeadlineQosPolicy reference
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const DeadlineQosPolicy &
deadline() const¶ Getter for DeadlineQosPolicy
- Return
DeadlineQosPolicy const reference
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void
deadline(const DeadlineQosPolicy &new_value)¶ Setter for DeadlineQosPolicy
- Parameters
new_value: new value for the DeadlineQosPolicy
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LatencyBudgetQosPolicy &
latency_budget()¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQosPolicy reference
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const LatencyBudgetQosPolicy &
latency_budget() const¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQosPolicy const reference
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void
latency_budget(const LatencyBudgetQosPolicy &new_value)¶ Setter for LatencyBudgetQosPolicy
- Parameters
new_value: new value for the LatencyBudgetQosPolicy
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LivelinessQosPolicy &
liveliness()¶ Getter for LivelinessQosPolicy
- Return
LivelinessQosPolicy reference
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const LivelinessQosPolicy &
liveliness() const¶ Getter for LivelinessQosPolicy
- Return
LivelinessQosPolicy const reference
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void
liveliness(const LivelinessQosPolicy &new_value)¶ Setter for LivelinessQosPolicy
- Parameters
new_value: new value for the LivelinessQosPolicy
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ReliabilityQosPolicy &
reliability()¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQosPolicy reference
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const ReliabilityQosPolicy &
reliability() const¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQosPolicy const reference
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void
reliability(const ReliabilityQosPolicy &new_value)¶ Setter for ReliabilityQosPolicy
- Parameters
new_value: new value for the ReliabilityQosPolicy
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DestinationOrderQosPolicy &
destination_order()¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQosPolicy reference
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const DestinationOrderQosPolicy &
destination_order() const¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQosPolicy const reference
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void
destination_order(const DestinationOrderQosPolicy &new_value)¶ Setter for DestinationOrderQosPolicy
- Parameters
new_value: new value for the DestinationOrderQosPolicy
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HistoryQosPolicy &
history()¶ Getter for HistoryQosPolicy
- Return
HistoryQosPolicy reference
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const HistoryQosPolicy &
history() const¶ Getter for HistoryQosPolicy
- Return
HistoryQosPolicy const reference
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void
history(const HistoryQosPolicy &new_value)¶ Setter for HistoryQosPolicy
- Parameters
new_value: new value for the HistoryQosPolicy
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ResourceLimitsQosPolicy &
resource_limits()¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQosPolicy reference
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const ResourceLimitsQosPolicy &
resource_limits() const¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQosPolicy const reference
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void
resource_limits(const ResourceLimitsQosPolicy &new_value)¶ Setter for ResourceLimitsQosPolicy
- Parameters
new_value: new value for the ResourceLimitsQosPolicy
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UserDataQosPolicy &
user_data()¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy reference
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const UserDataQosPolicy &
user_data() const¶ Getter for UserDataQosPolicy
- Return
UserDataQosPolicy const reference
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void
user_data(const UserDataQosPolicy &new_value)¶ Setter for UserDataQosPolicy
- Parameters
new_value: new value for the UserDataQosPolicy
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OwnershipQosPolicy &
ownership()¶ Getter for OwnershipQosPolicy
- Return
OwnershipQosPolicy reference
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const OwnershipQosPolicy &
ownership() const¶ Getter for OwnershipQosPolicy
- Return
OwnershipQosPolicy const reference
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void
ownership(const OwnershipQosPolicy &new_value)¶ Setter for OwnershipQosPolicy
- Parameters
new_value: new value for the OwnershipQosPolicy
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TimeBasedFilterQosPolicy &
time_based_filter()¶ Getter for TimeBasedFilterQosPolicy
- Return
TimeBasedFilterQosPolicy reference
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const TimeBasedFilterQosPolicy &
time_based_filter() const¶ Getter for TimeBasedFilterQosPolicy
- Return
TimeBasedFilterQosPolicy const reference
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void
time_based_filter(const TimeBasedFilterQosPolicy &new_value)¶ Setter for TimeBasedFilterQosPolicy
- Parameters
new_value: new value for the TimeBasedFilterQosPolicy
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ReaderDataLifecycleQosPolicy &
reader_data_lifecycle()¶ Getter for ReaderDataLifecycleQosPolicy
- Return
ReaderDataLifecycleQosPolicy reference
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const ReaderDataLifecycleQosPolicy &
reader_data_lifecycle() const¶ Getter for ReaderDataLifecycleQosPolicy
- Return
ReaderDataLifecycleQosPolicy const reference
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void
reader_data_lifecycle(const ReaderDataLifecycleQosPolicy &new_value)¶ Setter for ReaderDataLifecycleQosPolicy
- Parameters
new_value: new value for the ReaderDataLifecycleQosPolicy
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LifespanQosPolicy &
lifespan()¶ Getter for LifespanQosPolicy
- Return
LifespanQosPolicy reference
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const LifespanQosPolicy &
lifespan() const¶ Getter for LifespanQosPolicy
- Return
LifespanQosPolicy const reference
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void
lifespan(const LifespanQosPolicy &new_value)¶ Setter for LifespanQosPolicy
- Parameters
new_value: new value for the LifespanQosPolicy
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DurabilityServiceQosPolicy &
durability_service()¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQosPolicy reference
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const DurabilityServiceQosPolicy &
durability_service() const¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQosPolicy const reference
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void
durability_service(const DurabilityServiceQosPolicy &new_value)¶ Setter for DurabilityServiceQosPolicy
- Parameters
new_value: new value for the DurabilityServiceQosPolicy
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RTPSReliableReaderQos &
reliable_reader_qos()¶ Getter for RTPSReliableReaderQos
- Return
RTPSReliableReaderQos reference
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const RTPSReliableReaderQos &
reliable_reader_qos() const¶ Getter for RTPSReliableReaderQos
- Return
RTPSReliableReaderQos const reference
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void
reliable_reader_qos(const RTPSReliableReaderQos &new_value)¶ Setter for RTPSReliableReaderQos
- Parameters
new_value: new value for the RTPSReliableReaderQos
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TypeConsistencyQos &
type_consistency()¶ Getter for TypeConsistencyQos
- Return
TypeConsistencyQos reference
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const TypeConsistencyQos &
type_consistency() const¶ Getter for TypeConsistencyQos
- Return
TypeConsistencyQos const reference
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void
type_consistency(const TypeConsistencyQos &new_value)¶ Setter for TypeConsistencyQos
- Parameters
new_value: new value for the TypeConsistencyQos
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bool
expects_inline_qos() const¶ Getter for expectsInlineQos_
- Return
expectsInlineQos_
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void
expects_inline_qos(bool new_value)¶ Setter for expectsInlineQos_
- Parameters
new_value: new value for the expectsInlineQos_
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PropertyPolicyQos &
properties()¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos reference
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const PropertyPolicyQos &
properties() const¶ Getter for PropertyPolicyQos
- Return
PropertyPolicyQos const reference
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void
properties(const PropertyPolicyQos &new_value)¶ Setter for PropertyPolicyQos
- Parameters
new_value: new value for the PropertyPolicyQos
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RTPSEndpointQos &
endpoint()¶ Getter for RTPSEndpointQos
- Return
RTPSEndpointQos reference
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const RTPSEndpointQos &
endpoint() const¶ Getter for RTPSEndpointQos
- Return
RTPSEndpointQos const reference
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void
endpoint(const RTPSEndpointQos &new_value)¶ Setter for RTPSEndpointQos
- Parameters
new_value: new value for the RTPSEndpointQos
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ReaderResourceLimitsQos &
reader_resource_limits()¶ Getter for ReaderResourceLimitsQos
- Return
ReaderResourceLimitsQos reference
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const ReaderResourceLimitsQos &
reader_resource_limits() const¶ Getter for ReaderResourceLimitsQos
- Return
ReaderResourceLimitsQos const reference
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void
reader_resource_limits(const ReaderResourceLimitsQos &new_value)¶ Setter for ReaderResourceLimitsQos
- Parameters
new_value: new value for the ReaderResourceLimitsQos
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DataSharingQosPolicy &
data_sharing()¶ Getter for DataSharingQosPolicy
- Return
DataSharingQosPolicy reference
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const DataSharingQosPolicy &
data_sharing() const¶ Getter for DataSharingQosPolicy
- Return
DataSharingQosPolicy reference
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void
data_sharing(const DataSharingQosPolicy &data_sharing)¶ Setter for DataSharingQosPolicy
- Parameters
data_sharing: new value for the DataSharingQosPolicy
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const DataReaderQos
eprosima::fastdds::dds::DATAREADER_QOS_DEFAULT¶
InstanceStateKind¶
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enum
eprosima::fastdds::dds::InstanceStateKind¶ Indicates if the samples are from an alive DataWriter or not.
For each instance, the middleware internally maintains an instance state. The instance state can be:
ALIVE_INSTANCE_STATE indicates that (a) samples have been received for the instance, (b) there are alive DataWriter entities writing the instance, and (c) the instance has not been explicitly disposed (or else more samples have been received after it was disposed).
NOT_ALIVE_DISPOSED_INSTANCE_STATE indicates the instance was explicitly disposed by a DataWriter by means of the dispose operation.
NOT_ALIVE_NO_WRITERS_INSTANCE_STATE indicates the instance has been declared as not-alive by the DataReader because it detected that there are no alive DataWriter entities writing that instance.
The precise behavior events that cause the instance state to change depends on the setting of the OWNERSHIP QoS:
If OWNERSHIP is set to EXCLUSIVE_OWNERSHIP_QOS, then the instance state becomes NOT_ALIVE_DISPOSED_INSTANCE_STATE only if the DataWriter that “owns” the instance explicitly disposes it. The instance state becomes ALIVE_INSTANCE_STATE again only if the DataWriter that owns the instance writes it.
If OWNERSHIP is set to SHARED_OWNERSHIP_QOS, then the instance state becomes NOT_ALIVE_DISPOSED_INSTANCE_STATE if any DataWriter explicitly disposes the instance. The instance state becomes ALIVE_INSTANCE_STATE as soon as any DataWriter writes the instance again.
The instance state available in the
SampleInfo is a snapshot of the instance state of the instance at the time the collection was obtained (i.e. at the time read or take was called). The instance state is therefore the same for all samples in the returned collection that refer to the same instance.Values:
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enumerator
ALIVE_INSTANCE_STATE= 0x0001 << 0¶ Instance is currently in existence.
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enumerator
NOT_ALIVE_DISPOSED_INSTANCE_STATE= 0x0001 << 1¶ Not alive disposed instance. The instance has been disposed by a DataWriter.
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enumerator
NOT_ALIVE_NO_WRITERS_INSTANCE_STATE= 0x0001 << 2¶ Not alive no writers for instance. None of the DataWriter objects that are currently alive (according to the LIVELINESS QoS) are writing the instance.
ReaderResourceLimitsQos¶
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class
eprosima::fastdds::dds::ReaderResourceLimitsQos¶ Qos Policy to configure the limit of the reader resources.
Public Functions
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ReaderResourceLimitsQos() = default¶ Constructor.
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~ReaderResourceLimitsQos() = default¶ Destructor.
Public Members
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fastrtps::ResourceLimitedContainerConfig
matched_publisher_allocation¶ Matched publishers allocation limits.
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fastrtps::ResourceLimitedContainerConfig
sample_infos_allocation= {32u}¶ SampleInfo allocation limits.
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fastrtps::ResourceLimitedContainerConfig
outstanding_reads_allocation= {2u}¶ Loaned collections allocation limits.
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int32_t
max_samples_per_read= 32¶ 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.
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RTPSReliableReaderQos¶
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class
eprosima::fastdds::dds::RTPSReliableReaderQos¶ Qos Policy to configure the DisablePositiveACKsQos and the reader attributes.
Public Functions
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RTPSReliableReaderQos()¶ Constructor.
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~RTPSReliableReaderQos() = default¶ Destructor.
Public Members
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fastrtps::rtps::ReaderTimes
times¶ Times associated with the Reliable Readers events.
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DisablePositiveACKsQosPolicy
disable_positive_ACKs¶ Control the sending of positive ACKs.
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SampleInfo¶
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struct
eprosima::fastdds::dds::SampleInfo¶ SampleInfo is the information that accompanies each sample that is ‘read’ or ‘taken.
’
Public Members
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SampleStateKind
sample_state¶ indicates whether or not the corresponding data sample has already been read
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ViewStateKind
view_state¶ indicates whether the DataReader has already seen samples for the most-current generation of the related instance.
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InstanceStateKind
instance_state¶ indicates whether the instance is currently in existence or, if it has been disposed, the reason why it was disposed.
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int32_t
disposed_generation_count¶ number of times the instance had become alive after it was disposed
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int32_t
no_writers_generation_count¶ number of times the instance had become alive after it was disposed because no writers
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int32_t
sample_rank¶ number of samples related to the same instance that follow in the collection
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int32_t
generation_rank¶ the generation difference between the time the sample was received, and the time the most recent sample in the collection was received.
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int32_t
absoulte_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
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fastrtps::rtps::Time_t
source_timestamp¶ time provided by the DataWriter when the sample was written
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fastrtps::rtps::Time_t
reception_timestamp¶ time provided by the DataReader when the sample was added to its history
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InstanceHandle_t
instance_handle¶ identifies locally the corresponding instance
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InstanceHandle_t
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
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bool
valid_data¶ whether the DataSample contains data or is only used to communicate of a change in the instance
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fastrtps::rtps::SampleIdentity
sample_identity¶ Sample Identity (Extension for RPC)
Related Sample Identity (Extension for RPC)
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SampleStateKind
SampleStateKind¶
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enum
eprosima::fastdds::dds::SampleStateKind¶ Indicates whether or not a sample has ever been read.
For each sample received, the middleware internally maintains a sample state relative to each DataReader. This sample state can have the following values:
READ_SAMPLE_STATE indicates that the DataReader has already accessed that sample by means of a read or take operation
NOT_READ_SAMPLE_STATE indicates that the DataReader has not accessed that sample before.
The sample state will, in general, be different for each sample in the collection returned by read or take.
Values:
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enumerator
READ_SAMPLE_STATE= 0x0001 << 0¶ Sample has been read.
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enumerator
NOT_READ_SAMPLE_STATE= 0x0001 << 1¶ Sample has not been read.
Subscriber¶
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class
eprosima::fastdds::dds::Subscriber: public eprosima::fastdds::dds::DomainEntity¶ 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.
Public Functions
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~Subscriber()¶ Destructor.
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ReturnCode_t
enable() override¶ This operation enables the Subscriber.
- Return
RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the participant creating this Subscriber is not enabled.
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const SubscriberQos &
get_qos() const¶ Allows accessing the Subscriber Qos.
- Return
SubscriberQos reference
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ReturnCode_t
get_qos(SubscriberQos &qos) const¶ Retrieves the Subscriber Qos.
- Return
RETCODE_OK
- Parameters
qos: SubscriberQos where the qos is returned
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ReturnCode_t
set_qos(const SubscriberQos &qos)¶ Allows modifying the Subscriber Qos. The given Qos must be supported by the SubscriberQos.
- Return
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.
- Parameters
qos: new value for SubscriberQos
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const SubscriberListener *
get_listener() const¶ Retrieves the attached SubscriberListener.
- Return
Pointer to the SubscriberListener
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ReturnCode_t
set_listener(SubscriberListener *listener)¶ Modifies the SubscriberListener, sets the mask to StatusMask::all()
- Return
RETCODE_OK
- Parameters
listener: new value for SubscriberListener
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ReturnCode_t
set_listener(SubscriberListener *listener, const StatusMask &mask)¶ Modifies the SubscriberListener.
- Return
RETCODE_OK
- Parameters
listener: new value for the SubscriberListenermask: StatusMask that holds statuses the listener responds to.
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DataReader *
create_datareader(TopicDescription *topic, const DataReaderQos &reader_qos, DataReaderListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ This operation creates a DataReader. The returned DataReader will be attached and belong to the Subscriber.
- Return
Pointer to the created DataReader. nullptr if failed.
- Parameters
topic: Topic the DataReader will be listening.reader_qos: QoS of the DataReader.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all).
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DataReader *
create_datareader_with_profile(TopicDescription *topic, const std::string &profile_name, DataReaderListener *listener = nullptr, const StatusMask &mask = StatusMask::all())¶ This operation creates a DataReader. The returned DataReader will be attached and belongs to the Subscriber.
- Return
Pointer to the created DataReader. nullptr if failed.
- Parameters
topic: Topic the DataReader will be listening.profile_name: DataReader profile name.listener: Pointer to the listener (default: nullptr)mask: StatusMask that holds statuses the listener responds to (default: all).
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ReturnCode_t
delete_datareader(const 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.
- Return
RETCODE_PRECONDITION_NOT_MET if the datareader does not belong to this subscriber, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.
- Parameters
reader: DataReader to delete
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DataReader *
lookup_datareader(const std::string &topic_name) const¶ 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.
- Return
Pointer to a previously created DataReader created on a Topic with that topic_name
- Parameters
topic_name: Name of the topic associated to the DataReader
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ReturnCode_t
get_datareaders(std::vector<DataReader*> &readers) const¶ This operation allows the application to access the DataReader objects.
- Return
RETCODE_OK
- Parameters
readers: Vector of DataReader where the list of existing readers is returned
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ReturnCode_t
get_datareaders(std::vector<DataReader*> &readers, const std::vector<SampleStateKind> &sample_states, const std::vector<ViewStateKind> &view_states, const std::vector<InstanceStateKind> &instance_states) const¶ This operation allows the application to access the DataReader objects that contain samples with the specified sample_states, view_states, and instance_states.
- Return
RETCODE_OK
- Parameters
[out] readers: Vector of DataReader where the list of existing readers is returnedsample_states: Vector of SampleStateKindview_states: Vector of ViewStateKindinstance_states: Vector of InstanceStateKind
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bool
has_datareaders() const¶ This operation checks if the subscriber has DataReaders
- Return
true if the subscriber has one or several DataReaders, false in other case
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ReturnCode_t
begin_access()¶ Indicates that the application is about to access the data samples in any of the DataReader objects attached to the Subscriber.
- Return
RETCODE_OK
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ReturnCode_t
end_access()¶ Indicates that the application has finished accessing the data samples in DataReader objects managed by the Subscriber.
- Return
RETCODE_OK
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ReturnCode_t
notify_datareaders() const¶ 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
RETCODE_OK
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ReturnCode_t
delete_contained_entities()¶ Deletes all contained DataReaders. If the DataReaders have any QueryCondition or ReadCondition, they are deleted before the DataReader itself.
- Return
RETCODE_OK if successful, an error code otherwise
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ReturnCode_t
set_default_datareader_qos(const DataReaderQos &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.
- Return
RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.
- Parameters
qos: new value for DataReaderQos to set as default
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const DataReaderQos &
get_default_datareader_qos() const¶ 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
Current default DataReaderQos.
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DataReaderQos &
get_default_datareader_qos()¶ 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
Current default DataReaderQos.
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ReturnCode_t
get_default_datareader_qos(DataReaderQos &qos) const¶ 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.
- Return
RETCODE_OK
- Parameters
qos: DataReaderQos where the default_qos is returned
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ReturnCode_t
get_datareader_qos_from_profile(const std::string &profile_name, DataReaderQos &qos) const¶ Fills the DataReaderQos with the values of the XML profile.
- Return
RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.
- Parameters
profile_name: DataReader profile name.qos: DataReaderQos object where the qos is returned.
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const DomainParticipant *
get_participant() const¶ This operation returns the DomainParticipant to which the Subscriber belongs.
- Return
DomainParticipant Pointer
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const InstanceHandle_t &
get_instance_handle() const¶ Returns the Subscriber’s handle.
- Return
InstanceHandle of this Subscriber.
Public Static Functions
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ReturnCode_t
copy_from_topic_qos(DataReaderQos &reader_qos, const TopicQos &topic_qos)¶ Copies TopicQos into the corresponding DataReaderQos.
- Return
RETCODE_OK if successful, an error code otherwise
- Parameters
[inout] reader_qos:[in] topic_qos:
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SubscriberListener¶
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class
eprosima::fastdds::dds::SubscriberListener: public eprosima::fastdds::dds::DataReaderListener¶ Class SubscriberListener, it should be used by the end user to implement specific callbacks to certain actions. It also inherits all DataReaderListener callbacks.
Subclassed by eprosima::fastdds::dds::DomainParticipantListener
Public Functions
-
SubscriberListener()¶ Constructor.
-
~SubscriberListener()¶ Destructor.
-
void
on_data_on_readers(Subscriber *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
-
SubscriberQos¶
-
class
eprosima::fastdds::dds::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.
Public Functions
-
SubscriberQos()¶ Constructor.
-
~SubscriberQos()¶ Destructor.
-
const PresentationQosPolicy &
presentation() const¶ Getter for PresentationQosPolicy
- Return
PresentationQosPolicy reference
-
PresentationQosPolicy &
presentation()¶ Getter for PresentationQosPolicy
- Return
PresentationQosPolicy reference
-
void
presentation(const PresentationQosPolicy &presentation)¶ Setter for PresentationQosPolicy
- Parameters
presentation: new value for the PresentationQosPolicy
-
const PartitionQosPolicy &
partition() const¶ Getter for PartitionQosPolicy
- Return
PartitionQosPolicy reference
-
PartitionQosPolicy &
partition()¶ Getter for PartitionQosPolicy
- Return
PartitionQosPolicy reference
-
void
partition(const PartitionQosPolicy &partition)¶ Setter for PartitionQosPolicy
- Parameters
partition: new value for the PartitionQosPolicy
-
const GroupDataQosPolicy &
group_data() const¶ Getter for GroupDataQosPolicy
- Return
GroupDataQosPolicy reference
-
GroupDataQosPolicy &
group_data()¶ Getter for GroupDataQosPolicy
- Return
GroupDataQosPolicy reference
-
void
group_data(const GroupDataQosPolicy &group_data)¶ Setter for GroupDataQosPolicy
- Parameters
group_data: new value for the GroupDataQosPolicy
-
const EntityFactoryQosPolicy &
entity_factory() const¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
EntityFactoryQosPolicy &
entity_factory()¶ Getter for EntityFactoryQosPolicy
- Return
EntityFactoryQosPolicy reference
-
void
entity_factory(const EntityFactoryQosPolicy &entity_factory)¶ Setter for EntityFactoryQosPolicy
- Parameters
entity_factory: new value for the EntityFactoryQosPolicy
-
-
const SubscriberQos
eprosima::fastdds::dds::SUBSCRIBER_QOS_DEFAULT¶
TypeConsistencyQos¶
-
class
eprosima::fastdds::dds::TypeConsistencyQos: public eprosima::fastdds::dds::QosPolicy¶ Qos Policy to configure the XTypes Qos associated to the DataReader.
Public Members
-
TypeConsistencyEnforcementQosPolicy
type_consistency¶ Type consistency enforcement Qos.
-
DataRepresentationQosPolicy
representation¶ Data Representation Qos.
-
TypeConsistencyEnforcementQosPolicy
ViewStateKind¶
-
enum
eprosima::fastdds::dds::ViewStateKind¶ Indicates whether or not an instance is new.
For each instance (identified by the key), the middleware internally maintains a view state relative to each DataReader. This view state can have the following values:
NEW_VIEW_STATE indicates that either this is the first time that the DataReader has ever accessed samples of that instance, or else that the DataReader has accessed previous samples of the instance, but the instance has since been reborn (i.e. become not-alive and then alive again). These two cases are distinguished by examining the SampleInfo::disposed_generation_count and the SampleInfo::no_writers_generation_count.
NOT_NEW_VIEW_STATE indicates that the DataReader has already accessed samples of the same instance and that the instance has not been reborn since.
The view_state available in the
SampleInfo is a snapshot of the view state of the instance relative to the DataReader used to access the samples at the time the collection was obtained (i.e. at the time read or take was called). The view_state is therefore the same for all samples in the returned collection that refer to the same instance.Once an instance has been detected as not having any “live” writers and all the samples associated with the instance are “taken” from the DDSDataReader, the middleware can reclaim all local resources regarding the instance. Future samples will be treated as “never seen.”
Values:
-
enumerator
NEW_VIEW_STATE= 0x0001 << 0¶ New instance.This latest generation of the instance has not previously been accessed.
-
enumerator
NOT_NEW_VIEW_STATE= 0x0001 << 1¶ Not a new instance. This latest generation of the instance has previously been accessed.
Topic¶
Topic¶
-
class
eprosima::fastdds::dds::Topic: public eprosima::fastdds::dds::DomainEntity, public eprosima::fastdds::dds::TopicDescription¶ Class TopicDescription, represents the fact that both publications and subscriptions are tied to a single data-type
Public Functions
-
~Topic()¶ Destructor.
-
DomainParticipant *
get_participant() const override¶ Getter for the DomainParticipant.
- Return
DomainParticipant pointer
-
ReturnCode_t
get_inconsistent_topic_status(InconsistentTopicStatus &status)¶ Allows the application to retrieve the INCONSISTENT_TOPIC_STATUS status of a Topic.
- Return
RETCODE_OK
- Parameters
status: [out] Status to be retrieved.
-
ReturnCode_t
get_qos(TopicQos &qos) const¶ Retrieves the Topic Qos.
- Return
RETCODE_OK
- Parameters
qos: TopicQos where the qos is returned
-
ReturnCode_t
set_qos(const TopicQos &qos)¶ Allows modifying the Topic Qos. The given Qos must be supported by the Topic.
-
const TopicListener *
get_listener() const¶ Retrieves the attached TopicListener.
- Return
pointer to TopicListener
-
ReturnCode_t
set_listener(TopicListener *listener, const StatusMask &mask = StatusMask::all())¶ Modifies the TopicListener.
- Return
RETCODE_OK
- Parameters
listener: new value for the TopicListenermask: StatusMask that holds statuses the listener responds to (default: all).
-
TopicDescriptionImpl *
get_impl() const override¶ Getter for the TopicDescriptionImpl.
- Return
pointer to TopicDescriptionImpl
-
TopicDataType¶
-
class
eprosima::fastdds::dds::TopicDataType¶ 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. ,
Subclassed by eprosima::fastdds::dds::builtin::TypeLookup_ReplyPubSubType, eprosima::fastdds::dds::builtin::TypeLookup_RequestPubSubType
Public Functions
-
TopicDataType()¶ Constructor.
-
~TopicDataType()¶ Destructor.
-
bool
serialize(void *data, fastrtps::rtps::SerializedPayload_t *payload) = 0¶ 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.
- Return
True if correct.
- Parameters
[in] data: Pointer to the data[out] payload: Pointer to the payload
-
bool
deserialize(fastrtps::rtps::SerializedPayload_t *payload, void *data) = 0¶ Deserialize method, it should be implemented by the user, since it is abstract.
- Return
True if correct.
- Parameters
[in] payload: Pointer to the payload[out] data: Pointer to the data
-
std::function<uint32_t()>
getSerializedSizeProvider(void *data) = 0¶ Gets the SerializedSizeProvider function.
- Return
function
- Parameters
data: Pointer
-
void *
createData() = 0¶ Create a Data Type.
- Return
Void pointer to the created object.
-
void
deleteData(void *data) = 0¶ Remove a previously created object.
- Parameters
data: Pointer to the created Data.
-
bool
getKey(void *data, fastrtps::rtps::InstanceHandle_t *ihandle, bool force_md5 = false) = 0¶ Get the key associated with the data.
- Return
True if correct.
- Parameters
[in] data: Pointer to the data.[out] ihandle: Pointer to the Handle.[in] force_md5: Force MD5 checking.
-
bool
auto_fill_type_object() const¶ Get the type object auto-fill configuration
- Return
true if the type object should be auto-filled
-
void
auto_fill_type_object(bool auto_fill_type_object)¶ Set the type object auto-fill configuration
- Parameters
auto_fill_type_object: new value to set
-
bool
auto_fill_type_information() const¶ Get the type information auto-fill configuration
- Return
true if the type information should be auto-filled
-
void
auto_fill_type_information(bool auto_fill_type_information)¶ Set type information auto-fill configuration
- Parameters
auto_fill_type_information: new value to set
Set type identifier
- Parameters
id: shared pointer to TypeIdV1
-
const std::shared_ptr<TypeObjectV1>
type_object() const¶ Get the type object
- Return
-
void
type_object(const TypeObjectV1 &object)¶ Set type object
- Parameters
object: new value for TypeObjectV1
Set type object
- Parameters
object: shared pointer to TypeObjectV1
-
const std::shared_ptr<xtypes::TypeInformation>
type_information() const¶ Get the type information
- Return
TypeInformation
-
void
type_information(const xtypes::TypeInformation &info)¶ Set type information
- Parameters
info: new value for TypeInformation
Set type information
- Parameters
info: shared pointer to TypeInformation
-
bool
is_bounded() const¶ Checks if the type is bounded.
-
bool
is_plain() const¶ Checks if the type is plain.
-
bool
construct_sample(void *memory) const¶ Construct a sample on a memory location.
- Return
whether this type supports in-place construction or not.
- Parameters
memory: Pointer to the memory location where the sample should be constructed.
-
TopicDescription¶
-
class
eprosima::fastdds::dds::TopicDescription¶ Class TopicDescription, represents the fact that both publications and subscriptions are tied to a single data-type
Subclassed by eprosima::fastdds::dds::Topic
Public Functions
-
DomainParticipant *
get_participant() const = 0¶ Get the DomainParticipant to which the TopicDescription belongs.
- Return
The DomainParticipant to which the TopicDescription belongs.
-
const std::string &
get_name() const¶ Get the name used to create this TopicDescription.
- Return
the name used to create this TopicDescription.
-
const std::string &
get_type_name() const¶ Get the associated type name.
- Return
the type name.
-
TopicDescriptionImpl *
get_impl() const = 0¶ Get the TopicDescriptionImpl
- Return
pointer to TopicDescriptionImpl
-
DomainParticipant *
TopicListener¶
-
class
eprosima::fastdds::dds::TopicListener¶ Class TopicListener, it should be used by the end user to implement specific callbacks to certain actions.
Subclassed by eprosima::fastdds::dds::DomainParticipantListener
Public Functions
-
TopicListener()¶ Constructor.
-
~TopicListener()¶ Destructor.
-
void
on_inconsistent_topic(Topic *topic, InconsistentTopicStatus 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: Topicstatus: The inconsistent topic status
-
TopicQos¶
-
class
eprosima::fastdds::dds::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.
Public Functions
-
TopicQos()¶ Constructor.
-
const TopicDataQosPolicy &
topic_data() const¶ Getter for TopicDataQosPolicy
- Return
TopicDataQos reference
-
TopicDataQosPolicy &
topic_data()¶ Getter for TopicDataQosPolicy
- Return
TopicDataQos reference
-
void
topic_data(const TopicDataQosPolicy &value)¶ Setter for TopicDataQosPolicy
- Parameters
value: new value for the TopicDataQosPolicy
-
const DurabilityQosPolicy &
durability() const¶ Getter for DurabilityQosPolicy
- Return
DurabilityQos reference
-
DurabilityQosPolicy &
durability()¶ Getter for DurabilityQosPolicy
- Return
DurabilityQos reference
-
void
durability(const DurabilityQosPolicy &durability)¶ Setter for DurabilityQosPolicy
- Parameters
durability: new value for the DurabilityQosPolicy
-
const DurabilityServiceQosPolicy &
durability_service() const¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQos reference
-
DurabilityServiceQosPolicy &
durability_service()¶ Getter for DurabilityServiceQosPolicy
- Return
DurabilityServiceQos reference
-
void
durability_service(const DurabilityServiceQosPolicy &durability_service)¶ Setter for DurabilityServiceQosPolicy
- Parameters
durability_service: new value for the DurabilityServiceQosPolicy
-
const DeadlineQosPolicy &
deadline() const¶ Getter for DeadlineQosPolicy
- Return
DeadlineQos reference
-
DeadlineQosPolicy &
deadline()¶ Getter for DeadlineQosPolicy
- Return
DeadlineQos reference
-
void
deadline(const DeadlineQosPolicy &deadline)¶ Setter for DeadlineQosPolicy
- Parameters
deadline: new value for the DeadlineQosPolicy
-
const LatencyBudgetQosPolicy &
latency_budget() const¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQos reference
-
LatencyBudgetQosPolicy &
latency_budget()¶ Getter for LatencyBudgetQosPolicy
- Return
LatencyBudgetQos reference
-
void
latency_budget(const LatencyBudgetQosPolicy &latency_budget)¶ Setter for LatencyBudgetQosPolicy
- Parameters
latency_budget: new value for the LatencyBudgetQosPolicy
-
const LivelinessQosPolicy &
liveliness() const¶ Getter for LivelinessQosPolicy
- Return
LivelinessQos reference
-
LivelinessQosPolicy &
liveliness()¶ Getter for LivelinessQosPolicy
- Return
LivelinessQos reference
-
void
liveliness(const LivelinessQosPolicy &liveliness)¶ Setter for LivelinessQosPolicy
- Parameters
liveliness: new value for the LivelinessQosPolicy
-
const ReliabilityQosPolicy &
reliability() const¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQos reference
-
ReliabilityQosPolicy &
reliability()¶ Getter for ReliabilityQosPolicy
- Return
ReliabilityQos reference
-
void
reliability(const ReliabilityQosPolicy &reliability)¶ Setter for ReliabilityQosPolicy
- Parameters
reliability: new value for the ReliabilityQosPolicy
-
const DestinationOrderQosPolicy &
destination_order() const¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQos reference
-
DestinationOrderQosPolicy &
destination_order()¶ Getter for DestinationOrderQosPolicy
- Return
DestinationOrderQos reference
-
void
destination_order(const DestinationOrderQosPolicy &destination_order)¶ Setter for DestinationOrderQosPolicy
- Parameters
destination_order: new value for the DestinationOrderQosPolicy
-
const HistoryQosPolicy &
history() const¶ Getter for HistoryQosPolicy
- Return
HistoryQos reference
-
HistoryQosPolicy &
history()¶ Getter for HistoryQosPolicy
- Return
HistoryQos reference
-
void
history(const HistoryQosPolicy &history)¶ Setter for HistoryQosPolicy
- Parameters
history: new value for the HistoryQosPolicy
-
const ResourceLimitsQosPolicy &
resource_limits() const¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQos reference
-
ResourceLimitsQosPolicy &
resource_limits()¶ Getter for ResourceLimitsQosPolicy
- Return
ResourceLimitsQos reference
-
void
resource_limits(const ResourceLimitsQosPolicy &resource_limits)¶ Setter for ResourceLimitsQosPolicy
- Parameters
resource_limits: new value for the ResourceLimitsQosPolicy
-
const TransportPriorityQosPolicy &
transport_priority() const¶ Getter for TransportPriorityQosPolicy
- Return
TransportPriorityQos reference
-
TransportPriorityQosPolicy &
transport_priority()¶ Getter for TransportPriorityQosPolicy
- Return
TransportPriorityQos reference
-
void
transport_priority(const TransportPriorityQosPolicy &transport_priority)¶ Setter for TransportPriorityQosPolicy
- Parameters
transport_priority: new value for the TransportPriorityQosPolicy
-
const LifespanQosPolicy &
lifespan() const¶ Getter for LifespanQosPolicy
- Return
LifespanQos reference
-
LifespanQosPolicy &
lifespan()¶ Getter for LifespanQosPolicy
- Return
LifespanQos reference
-
void
lifespan(const LifespanQosPolicy &lifespan)¶ Setter for LifespanQosPolicy
- Parameters
lifespan: new value for the LifespanQosPolicy
-
const OwnershipQosPolicy &
ownership() const¶ Getter for OwnershipQosPolicy
- Return
OwnershipQos reference
-
OwnershipQosPolicy &
ownership()¶ Getter for OwnershipQosPolicy
- Return
OwnershipQos reference
-
void
ownership(const OwnershipQosPolicy &ownership)¶ Setter for OwnershipQosPolicy
- Parameters
ownership: new value for the OwnershipQosPolicy
-
const DataRepresentationQosPolicy &
representation() const¶ Getter for DataRepresentationQosPolicy
- Return
DataRepresentationQosPolicy reference
-
DataRepresentationQosPolicy &
representation()¶ Getter for DataRepresentationQosPolicy
- Return
DataRepresentationQosPolicy reference
-
void
representation(const DataRepresentationQosPolicy &representation)¶ Setter for DataRepresentationQosPolicy
- Parameters
representation: new value for the DataRepresentationQosPolicy
-
TypeIdV1¶
-
class
eprosima::fastdds::dds::TypeIdV1: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Class TypeIdV1
Public Functions
-
TypeIdV1()¶ Constructor without parameters.
-
TypeIdV1(const fastrtps::types::TypeIdentifier &identifier)¶ Constructor using a TypeIndentifier.
- Parameters
identifier: TypeIdentifier to be set
-
~TypeIdV1() override = default¶ Destructor.
-
const fastrtps::types::TypeIdentifier &
get() const¶ Getter for the TypeIndentifier.
- Return
TypeIdentifier reference
Public Members
-
fastrtps::types::TypeIdentifier
m_type_identifier¶ Type Identifier.
-
TypeInformation¶
-
class
eprosima::fastdds::dds::xtypes::TypeInformation: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Class xtypes::TypeInformation
Public Functions
-
TypeInformation()¶ Constructor.
-
TypeInformation(const TypeInformation &type)¶ Copy constructor.
- Parameters
type: Another instance of TypeInformation
-
TypeInformation(const fastrtps::types::TypeInformation &info)¶ Constructor using a fastrtps::types::TypeInformation.
- Parameters
info: fastrtps::types::TypeInformation to be set
-
TypeInformation(TypeInformation &&type)¶ Move Constructor.
- Parameters
type: Another instance of TypeInformation
-
~TypeInformation() override = default¶ Destructor.
-
bool
assigned() const¶ Check if it is assigned.
- Return
true if assigned, false if not
-
void
assigned(bool value)¶ Setter for assigned boolean.
- Parameters
value: Boolean to be set
Public Members
-
fastrtps::types::TypeInformation
type_information¶ Type Information.
-
TypeObjectV1¶
-
class
eprosima::fastdds::dds::TypeObjectV1: public eprosima::fastdds::dds::Parameter_t, public eprosima::fastdds::dds::QosPolicy¶ Class TypeObjectV1
Public Functions
-
TypeObjectV1()¶ Constructor.
-
TypeObjectV1(const TypeObjectV1 &type)¶ Copy constructor.
- Parameters
type: Another instance of TypeObjectV1
-
TypeObjectV1(const fastrtps::types::TypeObject &type)¶ Constructor using a TypeObject.
- Parameters
type: TypeObject to be set
-
TypeObjectV1(TypeObjectV1 &&type)¶ Move constructor.
- Parameters
type: Another instance of TypeObjectV1
-
~TypeObjectV1() override = default¶ Destructor.
-
const fastrtps::types::TypeObject &
get() const¶ Getter for the TypeObject.
- Return
TypeObject reference
Public Members
-
fastrtps::types::TypeObject
m_type_object¶ Type Object.
-
TypeSupport¶
-
class
eprosima::fastdds::dds::TypeSupport: public std::shared_ptr<fastdds::dds::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.
- Note
This class inherits from std::shared_ptr<TopicDataType>.
Subclassed by eprosima::fastdds::dds::builtin::TypeLookup_ReplyTypeSupport, eprosima::fastdds::dds::builtin::TypeLookup_RequestTypeSupport
Public Functions
-
TypeSupport()¶ Constructor.
-
TypeSupport(const TypeSupport &type)¶ Copy Constructor.
- Parameters
type: Another instance of TypeSupport
-
TypeSupport(fastdds::dds::TopicDataType *ptr)¶ TypeSupport constructor that receives a TopicDataType pointer.
The passed pointer will be managed by the TypeSupport object, so creating two TypeSupport from the same pointer or deleting the passed pointer will produce a runtime error.
- Parameters
ptr:
-
TypeSupport(fastrtps::types::DynamicPubSubType ptr)¶ TypeSupport constructor that receives a DynamicPubSubType.
It will copy the instance so the user will keep the ownership of his object.
- Parameters
ptr:
-
ReturnCode_t
register_type(DomainParticipant *participant) const¶ Registers the type on a participant.
- Return
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
- Parameters
participant: DomainParticipant where the type is going to be registered
-
ReturnCode_t
register_type(DomainParticipant *participant, std::string type_name) const¶ Registers the type on a participant.
- Return
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
- Parameters
participant: DomainParticipant where the type is going to be registeredtype_name: Name of the type to register
-
const std::string &
get_type_name() const¶ Getter for the type name.
- Return
name of the data type
-
bool
serialize(void *data, fastrtps::rtps::SerializedPayload_t *payload)¶ Serializes the data.
- Return
true if it is serialized correctly, false if not
- Parameters
data: Pointer to datapayload: Pointer to payload
-
bool
deserialize(fastrtps::rtps::SerializedPayload_t *payload, void *data)¶ Deserializes the data.
- Return
true if it is deserialized correctly, false if not
- Parameters
payload: Pointer to payloaddata: Pointer to data
-
std::function<uint32_t()>
get_serialized_size_provider(void *data)¶ Getter for the SerializedSizeProvider.
- Return
function
- Parameters
data: Pointer to data
-
void *
create_data()¶ Creates new data.
- Return
Pointer to the data
-
void
delete_data(void *data)¶ Deletes data.
- Parameters
data: Pointer to the data to delete
-
bool
get_key(void *data, InstanceHandle_t *i_handle, bool force_md5 = false)¶ Getter for the data key.
- Return
true if the key is returned, false if not
- Parameters
data: Pointer to datai_handle: InstanceHandle pointer to store the keyforce_md5: boolean to force md5 (default: false)
-
bool
empty() const¶ Check if the TypeSupport is empty.
- Return
true if empty, false if not
-
bool
is_bounded() const¶ Checks if the type is bounded.
-
bool
is_plain() const¶ Checks if the type is plain.
RTPS¶
eProsima Fast DDS Real-Time Publish-Subscribe (RTPS) layer API.
Attributes¶
BuiltinAttributes¶
-
class
eprosima::fastrtps::rtps::BuiltinAttributes¶ Class BuiltinAttributes, to define the behavior of the RTPSParticipant builtin protocols.
Public Members
-
DiscoverySettings
discovery_config¶ Discovery protocol related attributes.
-
bool
use_WriterLivelinessProtocol= true¶ Indicates to use the WriterLiveliness protocol.
-
TypeLookupSettings
typelookup_config¶ TypeLookup Service settings.
-
LocatorList_t
metatrafficUnicastLocatorList¶ Metatraffic Unicast Locator List.
-
LocatorList_t
metatrafficMulticastLocatorList¶ Metatraffic Multicast Locator List.
-
LocatorList_t
initialPeersList¶ Initial peers.
-
MemoryManagementPolicy_t
readerHistoryMemoryPolicy= MemoryManagementPolicy_t::PREALLOCATED_WITH_REALLOC_MEMORY_MODE¶ Memory policy for builtin readers.
-
uint32_t
readerPayloadSize= BUILTIN_DATA_MAX_SIZE¶ Maximum payload size for builtin readers.
-
MemoryManagementPolicy_t
writerHistoryMemoryPolicy= MemoryManagementPolicy_t::PREALLOCATED_WITH_REALLOC_MEMORY_MODE¶ Memory policy for builtin writers.
-
uint32_t
writerPayloadSize= BUILTIN_DATA_MAX_SIZE¶ Maximum payload size for builtin writers.
-
uint32_t
mutation_tries= 100u¶ Mutation tries if the port is being used.
-
bool
avoid_builtin_multicast= true¶ Set to true to avoid multicast traffic on builtin endpoints.
-
DiscoverySettings
c_default_RTPSParticipantAllocationAttributes¶
-
const RTPSParticipantAllocationAttributes
eprosima::fastrtps::rtps::c_default_RTPSParticipantAllocationAttributes= RTPSParticipantAllocationAttributes()¶
DiscoveryProtocol¶
-
enum
eprosima::fastrtps::rtps::DiscoveryProtocol¶ PDP subclass choice.
Values:
-
enumerator
NONE¶ NO discovery whatsoever would be used.
Publisher and Subscriber defined with the same topic name would NOT be linked. All matching must be done manually through the addReaderLocator, addReaderProxy, addWriterProxy methods.
-
enumerator
SIMPLE¶ Discovery works according to ‘The Real-time Publish-Subscribe Protocol(RTPS) DDS Interoperability Wire Protocol Specification’.
-
enumerator
EXTERNAL¶ A user defined PDP subclass object must be provided in the attributes that deals with the discovery.
Framework is not responsible of this object lifetime.
-
enumerator
CLIENT¶ The participant will behave as a client concerning discovery operation.
Server locators should be specified as attributes.
-
enumerator
SERVER¶ The participant will behave as a server concerning discovery operation.
Discovery operation is volatile (discovery handshake must take place if shutdown).
-
enumerator
BACKUP¶ The participant will behave as a server concerning discovery operation.
Discovery operation persist on a file (discovery handshake wouldn’t repeat if shutdown).
-
enumerator
SUPER_CLIENT¶ The participant will behave as a client concerning all internal behaviour.
Remote servers will treat it as a server and will share every discovery information.
-
enumerator
DiscoverySettings¶
-
class
eprosima::fastrtps::rtps::DiscoverySettings¶ Class DiscoverySettings, to define the attributes of the several discovery protocols available
Public Functions
-
const char *
getStaticEndpointXMLFilename() const¶ Get the static endpoint XML filename
- Return
Static endpoint XML filename
-
void
setStaticEndpointXMLFilename(const char *str)¶ Set the static endpoint XML filename
- Parameters
str: Static endpoint XML filename
Public Members
-
DiscoveryProtocol_t
discoveryProtocol= DiscoveryProtocol_t::SIMPLE¶ Chosen discovery protocol.
-
bool
use_SIMPLE_EndpointDiscoveryProtocol= true¶ If set to true, SimpleEDP would be used.
-
bool
use_STATIC_EndpointDiscoveryProtocol= false¶ If set to true, StaticEDP based on an XML file would be implemented. The XML filename must be provided.
-
Duration_t
leaseDuration= {20, 0}¶ Lease Duration of the RTPSParticipant, indicating how much time remote RTPSParticipants should consider this RTPSParticipant alive.
-
Duration_t
leaseDuration_announcementperiod= {3, 0}¶ The period for the RTPSParticipant to send its Discovery Message to all other discovered RTPSParticipants as well as to all Multicast ports.
-
InitialAnnouncementConfig
initial_announcements¶ Initial announcements configuration.
-
SimpleEDPAttributes
m_simpleEDP¶ Attributes of the SimpleEDP protocol.
-
PDPFactory
m_PDPfactory= {}¶ function that returns a PDP object (only if EXTERNAL selected)
-
Duration_t
discoveryServer_client_syncperiod= {0, 450 * 1000000}¶ The period for the RTPSParticipant to: send its Discovery Message to its servers check for EDP endpoints matching
-
eprosima::fastdds::rtps::RemoteServerList_t
m_DiscoveryServers¶ Discovery Server settings, only needed if use_CLIENT_DiscoveryProtocol=true.
-
ParticipantFilteringFlags_t
ignoreParticipantFlags= ParticipantFilteringFlags::NO_FILTER¶ Filtering participants out depending on location.
-
const char *
EndpointAttributes¶
-
class
eprosima::fastrtps::rtps::EndpointAttributes¶ Structure EndpointAttributes, describing the attributes associated with an RTPS Endpoint.
Public Functions
-
int16_t
getUserDefinedID() const¶ Get the user defined ID
- Return
User defined ID
-
int16_t
getEntityID() const¶ Get the entity defined ID
- Return
Entity ID
-
void
setUserDefinedID(uint8_t id)¶ Set the user defined ID
- Parameters
id: User defined ID to be set
-
void
setEntityID(uint8_t id)¶ Set the entity ID
- Parameters
id: Entity ID to be set
-
void
set_data_sharing_configuration(DataSharingQosPolicy cfg)¶ Set the DataSharing configuration
- Parameters
cfg: Configuration to be set
-
const DataSharingQosPolicy &
data_sharing_configuration() const¶ Get the DataSharing configuration
- Return
Configuration of data sharing
Public Members
-
EndpointKind_t
endpointKind¶ Endpoint kind, default value WRITER.
-
TopicKind_t
topicKind¶ Topic kind, default value NO_KEY.
-
ReliabilityKind_t
reliabilityKind¶ Reliability kind, default value BEST_EFFORT.
-
DurabilityKind_t
durabilityKind¶ Durability kind, default value VOLATILE.
-
LocatorList_t
unicastLocatorList¶ Unicast locator list.
-
LocatorList_t
multicastLocatorList¶ Multicast locator list.
-
LocatorList_t
remoteLocatorList¶ Remote locator list.
-
PropertyPolicy
properties¶ Properties.
-
int16_t
HistoryAttributes¶
-
class
eprosima::fastrtps::rtps::HistoryAttributes¶ Class HistoryAttributes, to specify the attributes of a WriterHistory or a ReaderHistory. This class is only intended to be used with the RTPS API. The Publisher-Subscriber API has other fields to define this values (HistoryQosPolicy and ResourceLimitsQosPolicy).
Public Functions
-
HistoryAttributes()¶ Default constructor.
-
HistoryAttributes(MemoryManagementPolicy_t memoryPolicy, uint32_t payload, int32_t initial, int32_t maxRes)¶ Constructor
- Parameters
memoryPolicy: Set whether memory can be dynamically reallocated or notpayload: Maximum payload size. It is used when memory management policy is PREALLOCATED_MEMORY_MODE or PREALLOCATED_WITH_REALLOC_MEMORY_MODE.initial: Initial reserved caches. It is used when memory management policy is PREALLOCATED_MEMORY_MODE or PREALLOCATED_WITH_REALLOC_MEMORY_MODE.maxRes: Maximum reserved caches.
-
HistoryAttributes(MemoryManagementPolicy_t memoryPolicy, uint32_t payload, int32_t initial, int32_t maxRes, int32_t extra)¶ Constructor
- Parameters
memoryPolicy: Set whether memory can be dynamically reallocated or notpayload: Maximum payload size. It is used when memory management policy is PREALLOCATED_MEMORY_MODE or PREALLOCATED_WITH_REALLOC_MEMORY_MODE.initial: Initial reserved caches. It is used when memory management policy is PREALLOCATED_MEMORY_MODE or PREALLOCATED_WITH_REALLOC_MEMORY_MODE.maxRes: Maximum reserved caches.extra: Extra reserved caches.
Public Members
-
MemoryManagementPolicy_t
memoryPolicy¶ Memory management policy.
-
uint32_t
payloadMaxSize¶ Maximum payload size of the history, default value 500.
-
int32_t
initialReservedCaches¶ Number of the initial Reserved Caches, default value 500.
-
int32_t
maximumReservedCaches¶ Maximum number of reserved caches. Default value is 0 that indicates to keep reserving until something breaks.
-
int32_t
extraReservedCaches¶ Number of extra caches that can be reserved for other purposes than the history. For example, on a full history, the writer could give as many as these to be used by the application but they will not be able to be inserted in the history unless some cache from the history is released.
Default value is 1.
-
InitialAnnouncementConfig¶
-
struct
eprosima::fastrtps::rtps::InitialAnnouncementConfig¶ Struct InitialAnnouncementConfig defines the behavior of the RTPSParticipant initial announcements.
Public Members
-
uint32_t
count= 5u¶ Number of initial announcements with specific period (default 5)
-
Duration_t
period= {0, 100000000u}¶ Specific period for initial announcements (default 100ms)
-
uint32_t
ParticipantFilteringFlags¶
PropertyPolicy¶
-
class
eprosima::fastrtps::rtps::PropertyPolicy¶ Public Functions
-
const PropertySeq &
properties() const¶ Get properties.
-
PropertySeq &
properties()¶ Set properties.
-
const BinaryPropertySeq &
binary_properties() const¶ Get binary_properties.
-
BinaryPropertySeq &
binary_properties()¶ Set binary_properties.
-
const PropertySeq &
PropertyPolicyHelper¶
-
class
eprosima::fastrtps::rtps::PropertyPolicyHelper¶ Public Static Functions
-
PropertyPolicy
get_properties_with_prefix(const PropertyPolicy &property_policy, const std::string &prefix)¶ Returns only the properties whose name starts with the prefix.
Prefix is removed in returned properties.
- Return
A copy of properties whose name starts with the prefix.
- Parameters
property_policy: PropertyPolicy where properties will be searched.prefix: Prefix used to search properties.
-
size_t
length(const PropertyPolicy &property_policy)¶ Get the length of the property_policy.
-
std::string *
find_property(PropertyPolicy &property_policy, const std::string &name)¶ Look for a property_policy by name.
-
const std::string *
find_property(const PropertyPolicy &property_policy, const std::string &name)¶ Retrieves a property_policy by name.
-
PropertyPolicy
ReaderAttributes¶
-
class
eprosima::fastrtps::rtps::ReaderAttributes¶ Class ReaderAttributes, to define the attributes of a RTPSReader.
Public Members
-
EndpointAttributes
endpoint¶ Attributes of the associated endpoint.
-
ReaderTimes
times¶ Times associated with this reader (only for stateful readers)
-
LivelinessQosPolicyKind
liveliness_kind_¶ Liveliness kind.
-
Duration_t
liveliness_lease_duration¶ Liveliness lease duration.
-
bool
expectsInlineQos¶ Indicates if the reader expects Inline qos, default value 0.
-
bool
disable_positive_acks¶ Disable positive ACKs.
-
ResourceLimitedContainerConfig
matched_writers_allocation¶ Define the allocation behaviour for matched-writer-dependent collections.
-
EndpointAttributes
ReaderTimes¶
-
class
eprosima::fastrtps::rtps::ReaderTimes¶ Class ReaderTimes, defining the times associated with the Reliable Readers events.
Public Members
-
Duration_t
initialAcknackDelay¶ Initial AckNack delay. Default value 70ms.
-
Duration_t
heartbeatResponseDelay¶ Delay to be applied when a HEARTBEAT message is received, default value 5ms.
-
Duration_t
RemoteLocatorsAllocationAttributes¶
-
struct
eprosima::fastrtps::rtps::RemoteLocatorsAllocationAttributes¶ Holds limits for collections of remote locators.
Public Members
-
size_t
max_unicast_locators= 4u¶ Maximum number of unicast locators per remote entity.
This attribute controls the maximum number of unicast locators to keep for each discovered remote entity (be it a participant, reader of writer). It is recommended to use the highest number of local addresses found on all the systems belonging to the same domain as this participant.
-
size_t
max_multicast_locators= 1u¶ Maximum number of multicast locators per remote entity.
This attribute controls the maximum number of multicast locators to keep for each discovered remote entity (be it a participant, reader of writer). The default value of 1 is usually enough, as it doesn’t make sense to add more than one multicast locator per entity.
-
size_t
RemoteServerAttributes¶
-
class
eprosima::fastdds::rtps::RemoteServerAttributes¶ Class RemoteServerAttributes, to define the attributes of the Discovery Server Protocol.
Public Members
-
LocatorList
metatrafficUnicastLocatorList¶ Metatraffic Unicast Locator List.
-
LocatorList
metatrafficMulticastLocatorList¶ Metatraffic Multicast Locator List.
-
fastrtps::rtps::GuidPrefix_t
guidPrefix¶ Guid prefix.
-
LocatorList
RemoteServerList_t¶
-
typedef std::list<RemoteServerAttributes>
eprosima::fastdds::rtps::RemoteServerList_t¶
RTPSParticipantAllocationAttributes¶
-
struct
eprosima::fastrtps::rtps::RTPSParticipantAllocationAttributes¶ Holds allocation limits affecting collections managed by a participant.
Public Functions
-
ResourceLimitedContainerConfig
total_readers() const¶ - Return
the allocation config for the total of readers in the system (participants * readers)
-
ResourceLimitedContainerConfig
total_writers() const¶ - Return
the allocation config for the total of writers in the system (participants * writers)
Public Members
-
RemoteLocatorsAllocationAttributes
locators¶ Holds limits for collections of remote locators.
-
ResourceLimitedContainerConfig
participants¶ Defines the allocation behaviour for collections dependent on the total number of participants.
-
ResourceLimitedContainerConfig
readers¶ Defines the allocation behaviour for collections dependent on the total number of readers per participant.
-
ResourceLimitedContainerConfig
writers¶ Defines the allocation behaviour for collections dependent on the total number of writers per participant.
-
SendBuffersAllocationAttributes
send_buffers¶ Defines the allocation behaviour for the send buffer manager.
-
VariableLengthDataLimits
data_limits¶ Holds limits for variable-length data.
-
ResourceLimitedContainerConfig
RTPSParticipantAttributes¶
-
class
eprosima::fastrtps::rtps::RTPSParticipantAttributes¶ Class RTPSParticipantAttributes used to define different aspects of a RTPSParticipant.
Public Functions
-
void
setName(const char *nam)¶ Set the name of the participant.
-
const char *
getName() const¶ Get the name of the participant.
Public Members
-
LocatorList_t
defaultUnicastLocatorList¶ 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.
-
LocatorList_t
defaultMulticastLocatorList¶ Default list of Multicast Locators to be used for any Endpoint defined inside this RTPSParticipant in the case that it was defined with NO UnicastLocators. This is usually left empty.
-
uint32_t
sendSocketBufferSize¶ Send socket buffer size for the send resource.
Zero value indicates to use default system buffer size. Default value: 0.
-
uint32_t
listenSocketBufferSize¶ Listen socket buffer for all listen resources.
Zero value indicates to use default system buffer size. Default value: 0.
-
GuidPrefix_t
prefix¶ Optionally allows user to define the GuidPrefix_t.
-
BuiltinAttributes
builtin¶ Builtin parameters.
-
PortParameters
port¶ Port Parameters.
-
int32_t
participantID¶ Participant ID.
-
ThroughputControllerDescriptor
throughputController¶ Throughput controller parameters. Leave default for uncontrolled flow.
-
std::vector<std::shared_ptr<fastdds::rtps::TransportDescriptorInterface>>
userTransports¶ User defined transports to use alongside or in place of builtins.
-
bool
useBuiltinTransports¶ Set as false to disable the default UDPv4 implementation.
-
RTPSParticipantAllocationAttributes
allocation¶ Holds allocation limits affecting collections managed by a participant.
-
PropertyPolicy
properties¶ Property policies.
-
void
RTPSWriterPublishMode¶
SendBuffersAllocationAttributes¶
-
struct
eprosima::fastrtps::rtps::SendBuffersAllocationAttributes¶ Holds limits for send buffers allocations.
Public Members
-
size_t
preallocated_number= 0u¶ Initial number of send buffers to allocate.
This attribute controls the initial number of send buffers to be allocated. The default value of 0 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.
-
bool
dynamic= false¶ Whether the number of send buffers is allowed to grow.
This attribute controls how the buffer manager behaves when a send buffer is not available. When true, a new buffer will be created. When false, it will wait for a buffer to be returned. This is a trade-off between latency and dynamic allocations.
-
size_t
SimpleEDPAttributes¶
-
class
eprosima::fastrtps::rtps::SimpleEDPAttributes¶ Class SimpleEDPAttributes, to define the attributes of the Simple Endpoint Discovery Protocol.
VariableLengthDataLimits¶
-
struct
eprosima::fastrtps::rtps::VariableLengthDataLimits¶ Holds limits for variable-length data.
Public Members
-
size_t
max_properties= 0¶ Defines the maximum size (in octets) of properties data in the local or remote participant.
-
size_t
max_user_data= 0¶ Defines the maximum size (in octets) of user data in the local or remote participant.
-
size_t
max_partitions= 0¶ Defines the maximum size (in octets) of partitions data.
-
size_t
max_datasharing_domains= 0¶ Defines the maximum size (in elements) of the list of data sharing domain IDs.
-
size_t
WriterAttributes¶
-
class
eprosima::fastrtps::rtps::WriterAttributes¶ Class WriterAttributes, defining the attributes of a RTPSWriter.
Public Members
-
EndpointAttributes
endpoint¶ Attributes of the associated endpoint.
-
WriterTimes
times¶ Writer Times (only used for RELIABLE).
-
fastrtps::LivelinessQosPolicyKind
liveliness_kind¶ Liveliness kind.
-
Duration_t
liveliness_lease_duration¶ Liveliness lease duration.
-
Duration_t
liveliness_announcement_period¶ Liveliness announcement period.
-
RTPSWriterPublishMode
mode¶ Indicates if the Writer is synchronous or asynchronous.
-
bool
disable_heartbeat_piggyback¶ Disable the sending of heartbeat piggybacks.
-
ResourceLimitedContainerConfig
matched_readers_allocation¶ Define the allocation behaviour for matched-reader-dependent collections.
-
bool
disable_positive_acks¶ Disable the sending of positive ACKs.
-
Duration_t
keep_duration¶ Keep duration to keep a sample before considering it has been acked.
-
EndpointAttributes
WriterTimes¶
-
struct
eprosima::fastrtps::rtps::WriterTimes¶ Struct WriterTimes, defining the times associated with the Reliable Writers events.
Public Members
-
Duration_t
initialHeartbeatDelay¶ Initial heartbeat delay. Default value ~11ms.
-
Duration_t
heartbeatPeriod¶ Periodic HB period, default value 3s.
-
Duration_t
nackResponseDelay¶ Delay to apply to the response of a ACKNACK message, default value ~5ms.
-
Duration_t
nackSupressionDuration¶ This time allows the RTPSWriter to ignore nack messages too soon after the data as sent, default value 0s.
-
Duration_t
Common¶
BinaryProperty¶
CacheChange¶
CacheChange_t¶
-
struct
eprosima::fastrtps::rtps::CacheChange_t¶ Structure CacheChange_t, contains information on a specific CacheChange.
Public Functions
-
CacheChange_t() = default¶ Default constructor.
Creates an empty CacheChange_t.
-
CacheChange_t(uint32_t payload_size, bool is_untyped = false)¶ Constructor with payload size
- Parameters
payload_size: Serialized payload sizeis_untyped: Flag to mark the change as untyped.
-
bool
copy(const CacheChange_t *ch_ptr)¶ Copy a different change into this one.
All the elements are copied, included the data, allocating new memory.
- Return
True if correct.
- Parameters
[in] ch_ptr: Pointer to the change.
-
void
copy_not_memcpy(const CacheChange_t *ch_ptr)¶ Copy information form a different change into this one.
All the elements are copied except data.
- Parameters
[in] ch_ptr: Pointer to the change.
-
uint32_t
getFragmentCount() const¶ Get the number of fragments this change is split into.
- Return
number of fragments.
-
uint16_t
getFragmentSize() const¶ Get the size of each fragment this change is split into.
- Return
size of fragment (0 means change is not fragmented).
-
bool
is_fully_assembled()¶ Checks if all fragments have been received.
- Return
true when change is fully assembled (i.e. no missing fragments).
-
void
get_missing_fragments(FragmentNumberSet_t &frag_sns)¶ Fills a FragmentNumberSet_t with the list of missing fragments.
- Parameters
[out] frag_sns: FragmentNumberSet_t where result is stored.
-
void
setFragmentSize(uint16_t fragment_size, bool create_fragment_list = false)¶ Set fragment size for this change.
- Remark
Parameter create_fragment_list should only be true when receiving the first fragment of a change.
- Parameters
fragment_size: Size of fragments.create_fragment_list: Whether to create missing fragments list or not.
Public Members
-
ChangeKind_t
kind= ALIVE¶ Kind of change, default value ALIVE.
-
InstanceHandle_t
instanceHandle¶ Handle of the data associated with this change.
-
SequenceNumber_t
sequenceNumber¶ SequenceNumber of the change.
-
SerializedPayload_t
serializedPayload¶ Serialized Payload associated with the change.
-
bool
isRead= false¶ Indicates if the cache has been read (only used in READERS)
-
ChangeForReader_t¶
-
class
eprosima::fastrtps::rtps::ChangeForReader_t¶ Struct ChangeForReader_t used to represent the state of a specific change with respect to a specific reader, as well as its relevance.
Public Functions
-
CacheChange_t *
getChange() const¶ Get the cache change
- Return
Cache change
-
void
notValid()¶ Set change as not valid.
-
bool
isValid() const¶ Set change as valid.
-
CacheChange_t *
ChangeForReaderStatus_t¶
-
enum
eprosima::fastrtps::rtps::ChangeForReaderStatus_t¶ Enum ChangeForReaderStatus_t, possible states for a CacheChange_t in a ReaderProxy.
Values:
-
enumerator
UNSENT= 0¶ UNSENT.
-
enumerator
REQUESTED= 1¶ REQUESTED.
-
enumerator
UNACKNOWLEDGED= 2¶ UNACKNOWLEDGED.
-
enumerator
ACKNOWLEDGED= 3¶ ACKNOWLEDGED.
-
enumerator
UNDERWAY= 4¶ UNDERWAY.
-
enumerator
ChangeKind_t¶
-
enum
eprosima::fastrtps::rtps::ChangeKind_t¶ , different types of CacheChange_t.
Values:
-
enumerator
ALIVE¶ ALIVE.
-
enumerator
NOT_ALIVE_DISPOSED¶ NOT_ALIVE_DISPOSED.
-
enumerator
NOT_ALIVE_UNREGISTERED¶ NOT_ALIVE_UNREGISTERED.
-
enumerator
NOT_ALIVE_DISPOSED_UNREGISTERED¶ NOT_ALIVE_DISPOSED_UNREGISTERED.
-
enumerator
CDRMessage¶
CDRMessage_t¶
-
struct
eprosima::fastrtps::rtps::CDRMessage_t¶ Structure CDRMessage_t, contains a serialized message.
Public Functions
-
CDRMessage_t(uint32_t size)¶ Constructor with maximum size
- Parameters
size: Maximum size
-
CDRMessage_t(const SerializedPayload_t &payload)¶ Constructor to wrap a serialized payload
- Parameters
payload: Payload to wrap
-
Macro definitions (#define)¶
-
RTPSMESSAGE_DEFAULT_SIZE¶ Max size of RTPS message in bytes.
-
RTPSMESSAGE_COMMON_RTPS_PAYLOAD_SIZE¶
-
RTPSMESSAGE_COMMON_DATA_PAYLOAD_SIZE¶
-
RTPSMESSAGE_HEADER_SIZE¶
-
RTPSMESSAGE_SUBMESSAGEHEADER_SIZE¶
-
RTPSMESSAGE_DATA_EXTRA_INLINEQOS_SIZE¶
-
RTPSMESSAGE_INFOTS_SIZE¶
-
RTPSMESSAGE_OCTETSTOINLINEQOS_DATASUBMSG¶
-
RTPSMESSAGE_OCTETSTOINLINEQOS_DATAFRAGSUBMSG¶
-
RTPSMESSAGE_DATA_MIN_LENGTH¶
EntityId¶
Const values¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_Unknown= ENTITYID_UNKNOWN¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SPDPReader= ENTITYID_SPDP_BUILTIN_RTPSParticipant_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SPDPWriter= ENTITYID_SPDP_BUILTIN_RTPSParticipant_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SEDPPubWriter= ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SEDPPubReader= ENTITYID_SEDP_BUILTIN_PUBLICATIONS_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SEDPSubWriter= ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_SEDPSubReader= ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_RTPSParticipant= ENTITYID_RTPSParticipant¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_WriterLiveliness= ENTITYID_P2P_BUILTIN_RTPSParticipant_MESSAGE_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_ReaderLiveliness= ENTITYID_P2P_BUILTIN_RTPSParticipant_MESSAGE_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::participant_stateless_message_writer_entity_id= ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::participant_stateless_message_reader_entity_id= ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_TypeLookup_request_writer= ENTITYID_TL_SVC_REQ_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_TypeLookup_request_reader= ENTITYID_TL_SVC_REQ_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_TypeLookup_reply_writer= ENTITYID_TL_SVC_REPLY_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_TypeLookup_reply_reader= ENTITYID_TL_SVC_REPLY_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::sedp_builtin_publications_secure_writer= ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::sedp_builtin_publications_secure_reader= ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::sedp_builtin_subscriptions_secure_writer= ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::sedp_builtin_subscriptions_secure_reader= ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::participant_volatile_message_secure_writer_entity_id= ENTITYID_P2P_BUILTIN_PARTICIPANT_VOLATILE_MESSAGE_SECURE_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::participant_volatile_message_secure_reader_entity_id= ENTITYID_P2P_BUILTIN_PARTICIPANT_VOLATILE_MESSAGE_SECURE_READER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_WriterLivelinessSecure= ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER¶
-
const EntityId_t
eprosima::fastrtps::rtps::c_EntityId_ReaderLivelinessSecure= ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER¶
Macro definitions (#define)¶
-
ENTITYID_UNKNOWN¶
-
ENTITYID_RTPSParticipant¶
-
ENTITYID_SEDP_BUILTIN_TOPIC_WRITER¶
-
ENTITYID_SEDP_BUILTIN_TOPIC_READER¶
-
ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER¶
-
ENTITYID_SEDP_BUILTIN_PUBLICATIONS_READER¶
-
ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER¶
-
ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_READER¶
-
ENTITYID_SPDP_BUILTIN_RTPSParticipant_WRITER¶
-
ENTITYID_SPDP_BUILTIN_RTPSParticipant_READER¶
-
ENTITYID_P2P_BUILTIN_RTPSParticipant_MESSAGE_WRITER¶
-
ENTITYID_P2P_BUILTIN_RTPSParticipant_MESSAGE_READER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_WRITER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_READER¶
-
ENTITYID_TL_SVC_REQ_WRITER¶
-
ENTITYID_TL_SVC_REQ_READER¶
-
ENTITYID_TL_SVC_REPLY_WRITER¶
-
ENTITYID_TL_SVC_REPLY_READER¶
-
ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER¶
-
ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER¶
-
ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER¶
-
ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_VOLATILE_MESSAGE_SECURE_WRITER¶
-
ENTITYID_P2P_BUILTIN_PARTICIPANT_VOLATILE_MESSAGE_SECURE_READER¶
-
ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER¶
-
ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER¶
EntityId_t¶
-
struct
eprosima::fastrtps::rtps::EntityId_t¶ Structure EntityId_t, entity id part of GUID_t.
Public Functions
-
EntityId_t()¶ Default constructor. Unknown entity.
-
EntityId_t(uint32_t id)¶ Main constructor.
- Parameters
id: Entity id
-
EntityId_t(const EntityId_t &id)¶ Copy constructor.
-
EntityId_t(EntityId_t &&id)¶ Move constructor.
-
EntityId_t &
operator=(uint32_t id)¶ Assignment operator.
- Parameters
id: Entity id to copy
-
EntityId_t Operators¶
-
bool
eprosima::fastrtps::rtps::operator==(EntityId_t &id1, const uint32_t id2)¶ Guid prefix comparison operator
- Return
True if equal
- Parameters
id1: EntityId to compareid2: ID prefix to compare
-
bool
eprosima::fastrtps::rtps::operator==(const EntityId_t &id1, const EntityId_t &id2)¶ Guid prefix comparison operator
- Return
True if equal
- Parameters
id1: First EntityId to compareid2: Second EntityId to compare
-
bool
eprosima::fastrtps::rtps::operator!=(const EntityId_t &id1, const EntityId_t &id2)¶ Guid prefix comparison operator
- Return
True if not equal
- Parameters
id1: First EntityId to compareid2: Second EntityId to compare
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const EntityId_t &enI)¶
-
std::istream &
eprosima::fastrtps::rtps::operator>>(std::istream &input, EntityId_t &enP)¶
FragmentNumber¶
FragmentNumber_t¶
-
using
eprosima::fastrtps::rtps::FragmentNumber_t= uint32_t¶
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const FragmentNumberSet_t &fns)¶
FragmentNumberSet_t¶
-
using
eprosima::fastrtps::rtps::FragmentNumberSet_t= BitmapRange<FragmentNumber_t>¶ Structure FragmentNumberSet_t, contains a group of fragmentnumbers.
Guid¶
GUID_t¶
-
struct
eprosima::fastrtps::rtps::GUID_t¶ Structure GUID_t, entity identifier, unique in DDS-RTPS Domain.
Public Functions
-
GUID_t() noexcept¶ Default constructor.
Contructs an unknown GUID.
-
GUID_t(const GuidPrefix_t &guid_prefix, uint32_t id) noexcept¶ Construct
- Parameters
guid_prefix: Guid prefixid: Entity id
-
GUID_t(const GuidPrefix_t &guid_prefix, const EntityId_t &entity_id) noexcept¶ - Parameters
guid_prefix: Guid prefixentity_id: Entity id
-
bool
is_on_same_host_as(const GUID_t &other_guid) const¶ Checks whether this guid is for an entity on the same host as another guid.
- Return
true when this guid is on the same host, false otherwise.
- Parameters
other_guid: GUID_t to compare to.
-
bool
is_on_same_process_as(const GUID_t &other_guid) const¶ Checks whether this guid is for an entity on the same host and process as another guid.
- Return
true when this guid is on the same host and process, false otherwise.
- Parameters
other_guid: GUID_t to compare to.
-
bool
is_builtin() const¶ Checks whether this guid corresponds to a builtin entity.
- Return
true when this guid corresponds to a builtin entity, false otherwise.
-
GUID_t Operators¶
-
bool
eprosima::fastrtps::rtps::operator==(const GUID_t &g1, const GUID_t &g2)¶ GUID comparison operator
- Return
True if equal
- Parameters
g1: First GUID to compareg2: Second GUID to compare
-
bool
eprosima::fastrtps::rtps::operator!=(const GUID_t &g1, const GUID_t &g2)¶ GUID comparison operator
- Return
True if not equal
- Parameters
g1: First GUID to compareg2: Second GUID to compare
GuidPrefix¶
c_GuidPrefix_Unknown¶
-
const GuidPrefix_t
eprosima::fastrtps::rtps::c_GuidPrefix_Unknown¶
GuidPrefix_t¶
-
struct
eprosima::fastrtps::rtps::GuidPrefix_t¶ Structure GuidPrefix_t, Guid Prefix of GUID_t.
Public Functions
-
GuidPrefix_t()¶ Default constructor. Set the Guid prefix to 0.
-
bool
operator==(const GuidPrefix_t &prefix) const¶ Guid prefix comparison operator
- Return
True if the guid prefixes are equal
- Parameters
prefix: guid prefix to compare
-
bool
operator!=(const GuidPrefix_t &prefix) const¶ Guid prefix comparison operator
- Return
True if the guid prefixes are not equal
- Parameters
prefix: Second guid prefix to compare
-
bool
operator<(const GuidPrefix_t &prefix) const¶ Guid prefix minor operator
- Return
True if prefix is higher
- Parameters
prefix: Second guid prefix to compare
-
GuidPrefix_t Operators¶
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const GuidPrefix_t &guiP)¶
-
std::istream &
eprosima::fastrtps::rtps::operator>>(std::istream &input, GuidPrefix_t &guiP)¶
InstanceHandle¶
c_InstanceHandle_Unknown¶
-
const InstanceHandle_t
eprosima::fastrtps::rtps::c_InstanceHandle_Unknown¶
InstanceHandle_t¶
-
struct
eprosima::fastrtps::rtps::InstanceHandle_t¶ Struct InstanceHandle_t, used to contain the key for WITH_KEY topics.
Public Functions
-
InstanceHandle_t &
operator=(const InstanceHandle_t &ihandle)¶ Assignment operator
- Parameters
ihandle: Instance handle to copy the data from
-
InstanceHandle_t &
operator=(const GUID_t &guid)¶ Assignment operator
- Parameters
guid: GUID to copy the data from
-
bool
isDefined() const¶ Know if the instance handle is defined
- Return
True if the values are not zero.
-
InstanceHandle_t &
InstanceHandle_t Operators¶
-
bool
eprosima::fastrtps::rtps::operator==(const InstanceHandle_t &ihandle1, const InstanceHandle_t &ihandle2)¶ Comparison operator
- Return
True if equal
- Parameters
ihandle1: First InstanceHandle_t to compareihandle2: Second InstanceHandle_t to compare
-
bool
eprosima::fastrtps::rtps::operator!=(const InstanceHandle_t &ihandle1, const InstanceHandle_t &ihandle2)¶
-
bool
eprosima::fastrtps::rtps::operator<(const InstanceHandle_t &h1, const InstanceHandle_t &h2)¶
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const InstanceHandle_t &iHandle)¶ - Parameters
output:iHandle:
-
void
eprosima::fastrtps::rtps::iHandle2GUID(GUID_t &guid, const InstanceHandle_t &ihandle)¶ Convert InstanceHandle_t to GUID
- Parameters
guid: GUID to store the resultsihandle: InstanceHandle_t to copy
-
GUID_t
eprosima::fastrtps::rtps::iHandle2GUID(const InstanceHandle_t &ihandle)¶ Convert GUID to InstanceHandle_t
- Return
- Parameters
ihandle: InstanceHandle_t to store the results
Locator¶
Macro definitions (#define)¶
-
LOCATOR_INVALID(loc)¶
-
LOCATOR_KIND_INVALID¶
-
LOCATOR_ADDRESS_INVALID(a)¶
-
LOCATOR_PORT_INVALID¶
-
LOCATOR_KIND_RESERVED¶
-
LOCATOR_KIND_UDPv4¶
-
LOCATOR_KIND_UDPv6¶
-
LOCATOR_KIND_TCPv4¶
-
LOCATOR_KIND_TCPv6¶
-
LOCATOR_KIND_SHM¶
Locator_t¶
-
class
eprosima::fastrtps::rtps::Locator_t¶ Class Locator_t, uniquely identifies a communication channel for a particular transport.
Public Functions
-
Locator_t()¶ Default constructor.
-
Locator_t(uint32_t portin)¶ Port constructor.
-
Locator_t(int32_t kindin, uint32_t portin)¶ Kind and port constructor.
Public Members
-
int32_t
kind¶ Specifies the locator type.
Valid values are: LOCATOR_KIND_UDPv4 LOCATOR_KIND_UDPv6 LOCATOR_KIND_TCPv4 LOCATOR_KIND_TCPv6 LOCATOR_KIND_SHM
-
LocatorList¶
-
class
LocatorList¶ Class LocatorList, a Locator vector that doesn’t avoid duplicates.
LocatorList_t¶
-
using
eprosima::fastrtps::rtps::LocatorList_t= eprosima::fastdds::rtps::LocatorList¶
LocatorListConstIterator¶
LocatorListIterator¶
LocatorsIterator¶
-
struct
LocatorsIterator¶ Provides a Locator’s iterator interface that can be used by different Locator’s containers
Subclassed by eprosima::fastdds::rtps::Locators, eprosima::fastrtps::rtps::LocatorSelector::iterator
Locator Operators¶
-
std::ostream &
eprosima::fastdds::rtps::operator<<(std::ostream &output, const LocatorList &locList)¶
LocatorSelectorEntry¶
-
struct
eprosima::fastrtps::rtps::LocatorSelectorEntry¶ An entry for the LocatorSelector.
This class holds the locators of a remote endpoint along with data required for the locator selection algorithm. Can be easily integrated inside other classes, such as ReaderProxyData and WriterProxyData.
Public Functions
-
LocatorSelectorEntry(size_t max_unicast_locators, size_t max_multicast_locators)¶ Construct a LocatorSelectorEntry.
- Parameters
max_unicast_locators: Maximum number of unicast locators to hold.max_multicast_locators: Maximum number of multicast locators to hold.
-
void
enable(bool should_enable)¶ Set the enabled value.
- Parameters
should_enable: Whether this entry should be enabled.
-
void
reset()¶ Reset the selections.
Public Members
-
ResourceLimitedVector<Locator_t>
unicast¶ List of unicast locators to send data to the remote entity.
-
ResourceLimitedVector<Locator_t>
multicast¶ List of multicast locators to send data to the remote entity.
-
EntryState
state¶ State of the entry.
-
bool
enabled¶ Indicates whether this entry should be taken into consideration.
-
bool
transport_should_process¶ A temporary value for each transport to help optimizing some use cases.
-
struct
EntryState¶ Holds the selection state of the locators held by a LocatorSelectorEntry
Public Functions
-
EntryState(size_t max_unicast_locators, size_t max_multicast_locators)¶ Construct an EntryState object.
- Parameters
max_unicast_locators: Maximum number of unicast locators to held by parent LocatorSelectorEntry.max_multicast_locators: Maximum number of multicast locators to held by parent LocatorSelectorEntry.
-
-
LocatorSelector¶
-
class
eprosima::fastrtps::rtps::LocatorSelector¶ A class used for the efficient selection of locators when sending data to multiple entities.
Algorithm:
Entries are added/removed with add_entry/remove_entry when matched/unmatched.
When data is to be sent:
A reference to this object is passed to the message group
For each submessage:
A call to reset is performed
A call to enable is performed per desired destination
If state_has_changed() returns true:
the message group is flushed
selection_start is called
for each transport:
transport_starts is called
transport handles the selection state of each entry
select may be called
Submessage is added to the message group
Public Functions
-
LocatorSelector(const ResourceLimitedContainerConfig &entries_allocation)¶ Construct a LocatorSelector.
- Parameters
entries_allocation: Allocation configuration regarding the number of remote entities.
-
void
clear()¶ Clears all internal data.
-
bool
add_entry(LocatorSelectorEntry *entry)¶ Add an entry to this selector.
- Parameters
entry: Pointer to the LocatorSelectorEntry to add.
-
bool
remove_entry(const GUID_t &guid)¶ Remove an entry from this selector.
- Parameters
guid: Identifier of the entry to be removed.
-
void
reset(bool enable_all)¶ Reset the enabling state of the selector.
- Parameters
enable_all: Indicates whether entries should be initially enabled.
-
void
enable(const GUID_t &guid)¶ Enable an entry given its GUID.
- Parameters
guid: GUID of the entry to enable.
-
bool
state_has_changed() const¶ Check if enabling state has changed.
- Return
true if the enabling state has changed, false otherwise.
-
void
selection_start()¶ Reset the selection state of the selector.
-
ResourceLimitedVector<LocatorSelectorEntry*> &
transport_starts()¶ Called when the selection algorithm starts for a specific transport.
Will set the temporary transport_should_process flag for all enabled entries.
- Return
a reference to the entries collection.
-
void
select(size_t index)¶ Marks an entry as selected.
- Parameters
index: The index of the entry to mark as selected.
-
size_t
selected_size() const¶ Count the number of selected locators.
- Return
the number of selected locators.
-
bool
is_selected(const Locator_t locator) const¶ Check if a locator is present in the selections of this object.
- Return
True if the locator has been selected, false otherwise.
- Parameters
locator: The locator to be checked.
-
template<class
UnaryPredicate>
voidfor_each(UnaryPredicate action) const¶ Performs an action on each selected locator.
- Parameters
action: Unary function that accepts a locator as argument. The function shall not modify its argument. This can either be a function pointer or a function object.
-
class
iterator: public eprosima::fastdds::rtps::LocatorsIterator¶
-
struct
IteratorIndex¶
MatchingInfo¶
MatchingInfo¶
-
class
eprosima::fastrtps::rtps::MatchingInfo¶ Class MatchingInfo contains information about the matching between two endpoints.
Public Functions
-
MatchingInfo()¶ Default constructor.
-
MatchingInfo(MatchingStatus stat, const GUID_t &guid)¶ - Parameters
stat: Statusguid: GUID
-
MatchingStatus¶
-
enum
eprosima::fastrtps::rtps::MatchingStatus¶ , indicates whether the matched publication/subscription method of the PublisherListener or SubscriberListener has been called for a matching or a removal of a remote endpoint.
Values:
-
enumerator
MATCHED_MATCHING¶ MATCHED_MATCHING, new publisher/subscriber found.
-
enumerator
REMOVED_MATCHING¶ REMOVED_MATCHING, publisher/subscriber removed.
-
enumerator
PortParameters¶
-
class
eprosima::fastrtps::rtps::PortParameters¶ Class PortParameters, to define the port parameters and gains related with the RTPS protocol.
Public Functions
-
uint32_t
getMulticastPort(uint32_t domainId) const¶ Get a multicast port based on the domain ID.
- Return
Multicast port
- Parameters
domainId: Domain ID.
-
uint32_t
getUnicastPort(uint32_t domainId, uint32_t RTPSParticipantID) const¶ Get a unicast port based on the domain ID and the participant ID.
- Return
Unicast port
- Parameters
domainId: Domain ID.RTPSParticipantID: Participant ID.
Public Members
-
uint16_t
portBase¶ PortBase, default value 7400.
-
uint16_t
domainIDGain¶ DomainID gain, default value 250.
-
uint16_t
participantIDGain¶ ParticipantID gain, default value 2.
-
uint16_t
offsetd0¶ Offset d0, default value 0.
-
uint16_t
offsetd1¶ Offset d1, default value 10.
-
uint16_t
offsetd2¶ Offset d2, default value 1.
-
uint16_t
offsetd3¶ Offset d3, default value 11.
-
uint32_t
Property¶
RemoteLocators¶
RemoteLocators Operators¶
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const RemoteLocatorList &remote_locators)¶
RemoteLocatorList¶
-
struct
eprosima::fastrtps::rtps::RemoteLocatorList¶ Holds information about the locators of a remote entity.
Public Functions
-
RemoteLocatorList()¶ Default constructor of RemoteLocatorList for deserialize.
-
RemoteLocatorList(size_t max_unicast_locators, size_t max_multicast_locators)¶ Construct a RemoteLocatorList.
- Parameters
max_unicast_locators: Maximum number of unicast locators to hold.max_multicast_locators: Maximum number of multicast locators to hold.
-
RemoteLocatorList(const RemoteLocatorList &other)¶ Copy-construct a RemoteLocatorList.
- Parameters
other: RemoteLocatorList to copy data from.
-
RemoteLocatorList &
operator=(const RemoteLocatorList &other)¶ Assign locator values from other RemoteLocatorList.
- Remark
Using the assignment operator is different from copy-constructing as in the first case the configuration with the maximum number of locators is not copied. This means that, for two lists with different maximum number of locators, the expression
(a = b) == bmay not be true.- Parameters
other: RemoteLocatorList to copy data from.
-
SampleIdentity¶
-
class
eprosima::fastrtps::rtps::SampleIdentity¶ This class is used to specify a sample.
Public Functions
-
SampleIdentity()¶ Default constructor.
Constructs an unknown SampleIdentity.
-
SampleIdentity(const SampleIdentity &sample_id)¶ Copy constructor.
-
SampleIdentity(SampleIdentity &&sample_id)¶ Move constructor.
-
SampleIdentity &
operator=(const SampleIdentity &sample_id)¶ Assignment operator.
-
SampleIdentity &
operator=(SampleIdentity &&sample_id)¶ Move constructor.
-
bool
operator<(const SampleIdentity &sample) const¶ To allow using SampleIdentity as map key.
- Return
- Parameters
sample:
-
SequenceNumber¶
c_SequenceNumber_Unknown¶
-
const SequenceNumber_t eprosima::fastrtps::rtps::c_SequenceNumber_Unknown (-1, 0)
SequenceNumber_t Operators¶
-
bool
eprosima::fastrtps::rtps::operator==(const SequenceNumber_t &sn1, const SequenceNumber_t &sn2) noexcept¶ Compares two SequenceNumber_t.
- Return
True if equal
- Parameters
sn1: First SequenceNumber_t to comparesn2: Second SequenceNumber_t to compare
-
bool
eprosima::fastrtps::rtps::operator!=(const SequenceNumber_t &sn1, const SequenceNumber_t &sn2) noexcept¶ Compares two SequenceNumber_t.
- Return
True if not equal
- Parameters
sn1: First SequenceNumber_t to comparesn2: Second SequenceNumber_t to compare
-
bool
eprosima::fastrtps::rtps::operator>(const SequenceNumber_t &seq1, const SequenceNumber_t &seq2) noexcept¶ Checks if a SequenceNumber_t is greater than other.
- Return
True if the first SequenceNumber_t is greater than the second
- Parameters
seq1: First SequenceNumber_t to compareseq2: Second SequenceNumber_t to compare
-
bool
eprosima::fastrtps::rtps::operator<(const SequenceNumber_t &seq1, const SequenceNumber_t &seq2) noexcept¶ Checks if a SequenceNumber_t is less than other.
- Return
True if the first SequenceNumber_t is less than the second
- Parameters
seq1: First SequenceNumber_t to compareseq2: Second SequenceNumber_t to compare
-
bool
eprosima::fastrtps::rtps::operator>=(const SequenceNumber_t &seq1, const SequenceNumber_t &seq2) noexcept¶ Checks if a SequenceNumber_t is greater or equal than other.
- Return
True if the first SequenceNumber_t is greater or equal than the second
- Parameters
seq1: First SequenceNumber_t to compareseq2: Second SequenceNumber_t to compare
-
bool
eprosima::fastrtps::rtps::operator<=(const SequenceNumber_t &seq1, const SequenceNumber_t &seq2) noexcept¶ Checks if a SequenceNumber_t is less or equal than other.
- Return
True if the first SequenceNumber_t is less or equal than the second
- Parameters
seq1: First SequenceNumber_t to compareseq2: Second SequenceNumber_t to compare
-
SequenceNumber_t
eprosima::fastrtps::rtps::operator-(const SequenceNumber_t &seq, const uint32_t inc) noexcept¶ Subtract one uint32_t from a SequenceNumber_t
- Return
Result of the subtraction
- Parameters
seq: Base SequenceNumber_tinc: uint32_t to subtract
-
SequenceNumber_t
eprosima::fastrtps::rtps::operator+(const SequenceNumber_t &seq, const uint32_t inc) noexcept¶ Add one uint32_t to a SequenceNumber_t
- Return
Result of the addition
- Parameters
[in] seq: Base sequence numberinc: value to add to the base
-
SequenceNumber_t
eprosima::fastrtps::rtps::operator-(const SequenceNumber_t &minuend, const SequenceNumber_t &subtrahend) noexcept¶ Subtract one SequenceNumber_t to another
- Return
Result of the subtraction
- Parameters
minuend: Minuend. Has to be greater than or equal to subtrahend.subtrahend: Subtrahend.
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const SequenceNumber_t &seqNum)¶ - Return
- Parameters
output:seqNum:
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const std::vector<SequenceNumber_t> &seqNumSet)¶
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const SequenceNumberSet_t &sns)¶ Prints a sequence Number set
- Return
OStream.
- Parameters
output: Output Streamsns: SequenceNumber set
SequenceNumber_t¶
-
struct
eprosima::fastrtps::rtps::SequenceNumber_t¶ Structure SequenceNumber_t, different for each change in the same writer.
Public Functions
-
SequenceNumber_t() noexcept¶ Default constructor.
-
SequenceNumber_t(int32_t hi, uint32_t lo) noexcept¶ - Parameters
hi:lo:
-
SequenceNumber_t(uint64_t u) noexcept¶ - Parameters
u:
-
uint64_t
to64long() const noexcept¶ Convert the number to 64 bit.
- Return
64 bit representation of the SequenceNumber
-
SequenceNumber_t &
operator++() noexcept¶ Increase SequenceNumber in 1.
-
SequenceNumber_t &
operator+=(int inc) noexcept¶ Increase SequenceNumber.
- Parameters
inc: Number to add to the SequenceNumber
-
SequenceNumberHash¶
-
struct
SequenceNumberHash¶ Defines the STL hash function for type SequenceNumber_t.
SequenceNumberSet_t¶
-
using
eprosima::fastrtps::rtps::SequenceNumberSet_t= BitmapRange<SequenceNumber_t, SequenceNumberDiff, 256>¶ Structure SequenceNumberSet_t, contains a group of sequencenumbers.
sort_seqNum¶
-
bool
eprosima::fastrtps::rtps::sort_seqNum(const SequenceNumber_t &s1, const SequenceNumber_t &s2) noexcept¶ Sorts two instances of SequenceNumber_t
- Return
True if s1 is less than s2
- Parameters
s1: First SequenceNumber_t to compares2: First SequenceNumber_t to compare
SerializedPayload¶
SerializedPayload_t¶
-
struct
eprosima::fastrtps::rtps::SerializedPayload_t¶ Structure SerializedPayload_t.
Public Functions
-
SerializedPayload_t()¶ Default constructor.
-
SerializedPayload_t(uint32_t len)¶ - Parameters
len: Maximum size of the payload
-
bool
copy(const SerializedPayload_t *serData, bool with_limit = true)¶ Copy another structure (including allocating new space for the data.)
- Return
True if correct
- Parameters
[in] serData: Pointer to the structure to copywith_limit: if true, the function will fail when providing a payload too big
-
bool
reserve_fragmented(SerializedPayload_t *serData)¶ Allocate new space for fragmented data.
- Return
True if correct
- Parameters
[in] serData: Pointer to the structure to copy
-
void
empty()¶ Empty the payload.
Public Members
-
uint16_t
encapsulation¶ Encapsulation of the data as suggested in the RTPS 2.1 specification chapter 10.
-
uint32_t
length¶ Actual length of the data.
-
uint32_t
max_size¶ Maximum size of the payload.
-
uint32_t
pos¶ Position when reading.
Public Static Attributes
-
constexpr size_t
representation_header_size= 4u¶ Size in bytes of the representation header as specified in the RTPS 2.3 specification chapter 10.
-
Time_t¶
Const values¶
-
const Time_t
eprosima::fastrtps::c_TimeInfinite(TIME_T_INFINITE_SECONDS, TIME_T_INFINITE_NANOSECONDS)¶ Time_t (Duration_t) representing an infinite time. DONT USE IT IN CONSTRUCTORS.
-
const Time_t eprosima::fastrtps::c_TimeZero (0, 0) Time_t (Duration_t) representing a zero time. DONT USE IT IN CONSTRUCTORS.
-
const Time_t eprosima::fastrtps::c_TimeInvalid (-1, TIME_T_INFINITE_NANOSECONDS) Time_t (Duration_t) representing an invalid time. DONT USE IT IN CONSTRUCTORS.
eprosima::fastrtps::Time_t¶
-
struct
eprosima::fastrtps::Time_t¶ Structure Time_t, used to describe times.
Public Functions
-
Time_t()¶ Default constructor. Sets values to zero.
-
Time_t(int32_t sec, uint32_t nsec)¶ - Parameters
sec: Secondsnsec: Nanoseconds
-
Time_t(long double sec)¶ - Parameters
sec: Seconds. The fractional part is converted to nanoseconds.
-
int64_t
to_ns() const¶ Returns stored time as nanoseconds (including seconds)
-
Time_t Operators¶
-
bool
eprosima::fastrtps::rtps::operator==(const Time_t &t1, const Time_t &t2)¶ Comparison assignment
-
bool
eprosima::fastrtps::rtps::operator!=(const Time_t &t1, const Time_t &t2)¶ Comparison assignment
-
bool
eprosima::fastrtps::rtps::operator<(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is less than other.
-
bool
eprosima::fastrtps::rtps::operator>(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is greater than other.
-
bool
eprosima::fastrtps::rtps::operator<=(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is less or equal than other.
-
bool
eprosima::fastrtps::rtps::operator>=(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is greater or equal than other.
-
Time_t
eprosima::fastrtps::rtps::operator-(const Time_t &ta, const Time_t &tb)¶ Subtracts two Time_t.
-
bool
eprosima::fastrtps::operator<(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is less than other.
-
bool
eprosima::fastrtps::operator>(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is greater than other.
-
bool
eprosima::fastrtps::operator<=(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is less or equal than other.
-
bool
eprosima::fastrtps::operator>=(const Time_t &t1, const Time_t &t2)¶ Checks if a Time_t is greater or equal than other.
Time_t¶
-
class
eprosima::fastrtps::rtps::Time_t¶ Structure Time_t, used to describe times at RTPS protocol.
Public Functions
-
Time_t()¶ Default constructor. Sets values to zero.
-
Time_t(int32_t sec, uint32_t frac)¶ - Parameters
sec: Secondsfrac: Fraction of second
-
Time_t(long double sec)¶ - Parameters
sec: Seconds. The fractional part is converted to nanoseconds.
-
Time_t(const eprosima::fastrtps::Time_t &time)¶ - Parameters
time: fastrtps::Time_t, aka. Duration_t.
-
int64_t
to_ns() const¶ Returns stored time as nanoseconds (including seconds)
-
void
from_ns(int64_t nanosecs)¶ - Parameters
nanosecs: Stores given time as nanoseconds (including seconds)
-
int32_t
seconds() const¶ Retrieve the seconds field.
-
int32_t &
seconds()¶ Retrieve the seconds field by ref.
-
void
seconds(int32_t sec)¶ Sets seconds field.
-
uint32_t
nanosec() const¶ Retrieve the nanosec field.
-
void
nanosec(uint32_t nanos)¶ Sets nanoseconds field and updates the fraction.
-
uint32_t
fraction() const¶ Retrieve the fraction field.
-
void
fraction(uint32_t frac)¶ Sets fraction field and updates the nanoseconds.
-
Token¶
AuthenticatedPeerCredentialToken¶
DataHolderSeq¶
-
typedef std::vector<DataHolder>
eprosima::fastrtps::rtps::DataHolderSeq¶
Token¶
-
typedef DataHolder
eprosima::fastrtps::rtps::Token¶
Types¶
Const values¶
-
const ProtocolVersion_t eprosima::fastrtps::rtps::c_ProtocolVersion_2_0 (2, 0)
-
const ProtocolVersion_t eprosima::fastrtps::rtps::c_ProtocolVersion_2_1 (2, 1)
-
const ProtocolVersion_t eprosima::fastrtps::rtps::c_ProtocolVersion_2_2 (2, 2)
-
const ProtocolVersion_t eprosima::fastrtps::rtps::c_ProtocolVersion_2_3 (2, 3)
-
const ProtocolVersion_t
eprosima::fastrtps::rtps::c_ProtocolVersion¶
-
const VendorId_t
eprosima::fastdds::rtps::c_VendorId_Unknown= {0x00, 0x00}¶
-
const VendorId_t
eprosima::fastdds::rtps::c_VendorId_eProsima= {0x01, 0x0F}¶
DurabilityKind_t¶
-
typedef enum eprosima::fastrtps::rtps::DurabilityKind_t
eprosima::fastrtps::rtps::DurabilityKind_t¶ Durability kind
Endianness_t¶
EndpointKind_t¶
-
typedef enum eprosima::fastrtps::rtps::EndpointKind_t
eprosima::fastrtps::rtps::EndpointKind_t¶ Endpoint kind
ProtocolVersion_t¶
-
struct
ProtocolVersion_t¶ Structure ProtocolVersion_t, contains the protocol version.
-
std::ostream &
eprosima::fastrtps::rtps::operator<<(std::ostream &output, const ProtocolVersion_t &pv)¶ Prints a ProtocolVersion
- Return
OStream.
- Parameters
output: Output Streampv: ProtocolVersion
ReliabilityKind_t¶
-
typedef enum eprosima::fastrtps::rtps::ReliabilityKind_t
eprosima::fastrtps::rtps::ReliabilityKind_t¶ Reliability enum used for internal purposes
TopicKind_t¶
-
typedef enum eprosima::fastrtps::rtps::TopicKind_t
eprosima::fastrtps::rtps::TopicKind_t¶ Topic kind.
WriteParams¶
-
class
eprosima::fastrtps::rtps::WriteParams¶ This class contains additional information of a CacheChange.
Public Functions
-
WriteParams() = default¶ Default constructor.
-
WriteParams(const WriteParams &wparam)¶ Copy constructor.
-
WriteParams(WriteParams &&wparam)¶ Move constructor.
-
WriteParams &
operator=(const WriteParams &wparam)¶ Assignment operator.
-
WriteParams &
operator=(WriteParams &&wparam)¶ Assignment operator.
-
Endpoint¶
-
class
eprosima::fastrtps::rtps::Endpoint¶ Class Endpoint, all entities of the RTPS network derive from this class. Although the RTPSParticipant is also defined as an endpoint in the RTPS specification, in this implementation the RTPSParticipant class does not inherit from the endpoint class. Each Endpoint object owns a pointer to the RTPSParticipant it belongs to.
Subclassed by eprosima::fastrtps::rtps::RTPSReader, eprosima::fastrtps::rtps::RTPSWriter
Exceptions¶
Exception¶
-
class
eprosima::fastrtps::rtps::Exception: public exception¶ This abstract class is used to create exceptions.
Subclassed by eprosima::fastrtps::rtps::security::SecurityException
Public Functions
-
~Exception()¶ Default destructor.
-
const int32_t &
minor() const¶ This function returns the number associated with the system exception.
- Return
The number associated with the system exception.
-
void
minor(const int32_t &minor)¶ This function sets the number that will be associated with the system exception.
- Parameters
minor: The number that will be associated with the system exception.
-
void
raise() const = 0¶ This function throws the object as exception.
-
const char *
what() const¶ This function returns the error message.
- Return
The error message.
-
Flow control¶
History¶
History¶
-
class
eprosima::fastrtps::rtps::History¶ Class History, container of the different CacheChanges and the methods to access them.
Subclassed by eprosima::fastrtps::rtps::ReaderHistory, eprosima::fastrtps::rtps::WriterHistory
Public Functions
-
bool
reserve_Cache(CacheChange_t **change, const std::function<uint32_t()> &calculateSizeFunc)¶ Reserve a CacheChange_t from the CacheChange pool.
- Return
True if reserved
- Warning
This method has been deprecated and will be removed on v3.0.0
- Parameters
[out] change: Pointer to pointer to the CacheChange_t to reserve[in] calculateSizeFunc: Function to calculate the size of the payload.
-
bool
reserve_Cache(CacheChange_t **change, uint32_t dataSize)¶ Reserve a CacheChange_t from the CacheChange pool.
- Return
True if reserved
- Warning
This method has been deprecated and will be removed on v3.0.0
- Parameters
[out] change: Pointer to pointer to the CacheChange_t to reserve[in] dataSize: Required size for the payload.
-
void
release_Cache(CacheChange_t *ch)¶ release a previously reserved CacheChange_t.
- Warning
This method has been deprecated and will be removed on v3.0.0
- Parameters
ch: Pointer to the CacheChange_t.
-
const_iterator
find_change_nts(CacheChange_t *ch)¶ Find a specific change in the history using the matches_change method criteria. No Thread Safe
- Return
an iterator if a suitable change is found
- Parameters
ch: Pointer to the CacheChange_t to search for.
-
iterator
remove_change_nts(const_iterator removal, bool release = true)¶ Remove a specific change from the history. No Thread Safe
- Return
iterator to the next CacheChange_t or end iterator.
- Parameters
removal: iterator to the CacheChange_t to remove.release: defaults to true and hints if the CacheChange_t should return to the pool
-
bool
remove_all_changes()¶ Remove all changes from the History
- Return
True if everything was correctly removed.
-
bool
remove_change(CacheChange_t *ch)¶ Remove a specific change from the history.
- Return
True if removed.
- Parameters
ch: Pointer to the CacheChange_t.
-
const_iterator
find_change(CacheChange_t *ch)¶ Find a specific change in the history using the matches_change method criteria.
- Return
an iterator if a suitable change is found
- Parameters
ch: Pointer to the CacheChange_t to search for.
-
bool
matches_change(const CacheChange_t *ch_inner, CacheChange_t *ch_outer)¶ Verifies if an element of the changes collection matches a given change Derived classes have more info on how to identify univocally a change and should override.
- Return
true if the iterator identifies this change.
- Parameters
ch_inner: element of the collection to compare with the given changech_outer: Pointer to the CacheChange_t to identify.
-
iterator
remove_change(const_iterator removal, bool release = true)¶ Remove a specific change from the history.
- Return
iterator to the next CacheChange_t or end iterator.
- Parameters
removal: iterator to the CacheChange_t to remove.release: defaults to true and hints if the CacheChange_t should return to the pool
-
iterator
changesBegin()¶ Get the beginning of the changes history iterator.
- Return
Iterator to the beginning of the vector.
-
iterator
changesEnd()¶ Get the end of the changes history iterator.
- Return
Iterator to the end of the vector.
-
bool
get_min_change(CacheChange_t **min_change)¶ Get the minimum CacheChange_t.
- Return
True if correct.
- Parameters
min_change: Pointer to pointer to the minimum change.
-
bool
get_max_change(CacheChange_t **max_change)¶ Get the maximum CacheChange_t.
- Return
True if correct.
- Parameters
max_change: Pointer to pointer to the maximum change.
-
uint32_t
getTypeMaxSerialized()¶ Get the maximum serialized payload size
- Return
Maximum serialized payload size
-
RecursiveTimedMutex *
getMutex()¶ Get the mutex.
- Return
Mutex
-
bool
get_earliest_change(CacheChange_t **change)¶ A method to get the change with the earliest timestamp.
- Return
True on success
- Parameters
change: Pointer to pointer to earliest change
Public Members
-
HistoryAttributes
m_att¶ Attributes of the History.
-
bool
IChangePool¶
-
class
eprosima::fastrtps::rtps::IChangePool¶ An interface for classes responsible of cache changes allocation management.
Public Functions
-
bool
reserve_cache(CacheChange_t *&cache_change) = 0¶ Get a new cache change from the pool.
- Return
whether the operation succeeded or not
- Pre
cache_changeisnullptr- Post
cache_changeis not nullptr*cache_changeequalsCacheChange_t()except for the contents ofserializedPayload
- Parameters
[out] cache_change: Pointer to the new cache change.
-
bool
release_cache(CacheChange_t *cache_change) = 0¶ Return a cache change to the pool.
- Return
whether the operation succeeded or not
- Pre
cache_changeis notnullptrcache_changepoints to a cache change obtained from a call tothis->reserve_cache
- Parameters
[in] cache_change: Pointer to the cache change to release.
-
bool
IPayloadPool¶
-
class
eprosima::fastrtps::rtps::IPayloadPool¶ An interface for classes responsible of serialized payload management.
Public Functions
-
bool
get_payload(uint32_t size, CacheChange_t &cache_change) = 0¶ Get a serialized payload for a new sample.
This method will usually be called in one of the following situations:
When a writer creates a new cache change
When a reader receives the first fragment of a cache change
In both cases, the received
sizewill be for the whole serialized payload.- Return
whether the operation succeeded or not
- Pre
Fields
writerGUIDandsequenceNumberofcache_changeare either:Both equal to
unknown(meaning a writer is creating a new change)Both different from
unknown(meaning a reader has received the first fragment of a cache change)
- Post
Field
cache_change.payload_ownerequals thisField
serializedPayload.datapoints to a buffer of at leastsizebytesField
serializedPayload.max_sizeis greater than or equal tosize
- Parameters
[in] size: Number of bytes required for the serialized payload. Should be greater than 0.[inout] cache_change: Cache change to assign the payload to
-
bool
get_payload(SerializedPayload_t &data, IPayloadPool *&data_owner, CacheChange_t &cache_change) = 0¶ Assign a serialized payload to a new sample.
This method will usually be called when a reader receives a whole cache change.
- Return
whether the operation succeeded or not
- Note
dataanddata_ownerare received as references to accommodate the case where several readers receive the same payload. If the payload has no owner, it means it is allocated on the stack of a reception thread, and a copy should be performed. The pool may decide in that case to pointdata.datato the new copy and take ownership of the payload. In that case, when the reception thread is done with the payload (after all readers have been informed of the received data), methodrelease_payloadwill be called to indicate that the reception thread is not using the payload anymore.- Warning
data_ownercan only be changed fromnullptrtothis. If a value different fromnullptris received it should be left unchanged.- Warning
datafields can only be changed whendata_ownerisnullptr. If a value different fromnullptris received all fields indatashould be left unchanged.- Pre
Field
cache_change.writerGUIDis notunknownField
cache_change.sequenceNumberis notunknown
- Post
Field
cache_change.payload_ownerequals thisField
cache_change.serializedPayload.datapoints to a buffer of at leastdata.lengthbytesField
cache_change.serializedPayload.lengthis equal todata.lengthField
cache_change.serializedPayload.max_sizeis greater than or equal todata.lengthContent of
cache_change.serializedPayload.datais the same asdata.data
- Parameters
[inout] data: Serialized payload received[inout] data_owner: Payload pool owning incoming data[inout] cache_change: Cache change to assign the payload to
-
bool
release_payload(CacheChange_t &cache_change) = 0¶ Release a serialized payload from a sample.
This method will be called when a cache change is removed from a history.
- Return
whether the operation succeeded or not
- Pre
Field
payload_ownerofcache_changeequals this
- Post
Field
payload_ownerofcache_changeisnullptr
- Parameters
[inout] cache_change: Cache change to assign the payload to
-
bool
ReaderHistory¶
-
class
eprosima::fastrtps::rtps::ReaderHistory: public eprosima::fastrtps::rtps::History¶ Class ReaderHistory, container of the different CacheChanges of a reader
Public Functions
-
ReaderHistory(const HistoryAttributes &att)¶ Constructor of the ReaderHistory. It needs a HistoryAttributes.
-
bool
received_change(CacheChange_t *change, size_t)¶ Virtual method that is called when a new change is received. In this implementation this method just calls add_change. The user can overload this method in case he needs to perform additional checks before adding the change.
- Return
True if added.
- Parameters
change: Pointer to the change
-
bool
add_change(CacheChange_t *a_change)¶ Add a CacheChange_t to the ReaderHistory.
- Return
True if added.
- Parameters
a_change: Pointer to the CacheChange to add.
-
iterator
remove_change_nts(const_iterator removal, bool release = true) override¶ Remove a specific change from the history. No Thread Safe
- Return
iterator to the next change if any
- Parameters
removal: iterator to the change for removalrelease: specifies if the change must be returned to the pool
-
bool
matches_change(const CacheChange_t *inner, CacheChange_t *outer) override¶ Criteria to search a specific CacheChange_t on history
- Return
true if inner matches outer criteria
- Parameters
inner: change to compareouter: change for comparison
-
bool
remove_changes_with_guid(const GUID_t &a_guid)¶ Remove all changes from the History that have a certain guid.
- Return
True if successful, even if no changes have been removed.
- Parameters
a_guid: Pointer to the target guid to search for.
-
bool
remove_fragmented_changes_until(const SequenceNumber_t &seq_num, const GUID_t &writer_guid)¶ Remove all fragmented changes from certain writer up to certain sequence number.
- Return
True if successful, even if no changes have been removed.
- Parameters
seq_num: First SequenceNumber_t not to be removed.writer_guid: GUID of the writer for which changes should be looked for.
-
WriterHistory¶
-
class
eprosima::fastrtps::rtps::WriterHistory: public eprosima::fastrtps::rtps::History¶ Class WriterHistory, container of the different CacheChanges of a writer
Public Functions
-
WriterHistory(const HistoryAttributes &att)¶ Constructor of the WriterHistory.
-
bool
add_change(CacheChange_t *a_change)¶ Add a CacheChange_t to the WriterHistory.
- Return
True if added.
- Parameters
a_change: Pointer to the CacheChange_t to be added.
-
bool
add_change(CacheChange_t *a_change, WriteParams &wparams)¶ Add a CacheChange_t to the WriterHistory.
- Return
True if added.
- Parameters
a_change: Pointer to the CacheChange_t to be added.wparams: Extra write parameters.
-
iterator
remove_change_nts(const_iterator removal, bool release = true) override¶ Remove a specific change from the history. No Thread Safe
- Return
iterator to the next change if any
- Parameters
removal: iterator to the change for removalrelease: specifies if the change should be return to the pool
-
bool
matches_change(const CacheChange_t *inner, CacheChange_t *outer) override¶ Criteria to search a specific CacheChange_t on history
- Return
true if inner matches outer criteria
- Parameters
inner: change to compareouter: change for comparison
-
bool
remove_min_change()¶ Remove the CacheChange_t with the minimum sequenceNumber.
- Return
True if correctly removed.
-
RTPSParticipant¶
ParticipantDiscoveryInfo¶
ParticipantAuthenticationInfo¶
-
struct
eprosima::fastrtps::rtps::ParticipantAuthenticationInfo¶
-
bool
eprosima::fastrtps::rtps::operator==(const ParticipantAuthenticationInfo &l, const ParticipantAuthenticationInfo &r)¶
ParticipantDiscoveryInfo¶
-
struct
eprosima::fastrtps::rtps::ParticipantDiscoveryInfo¶ Class ParticipantDiscoveryInfo with discovery information of the Participant.
Public Types
Public Members
-
DISCOVERY_STATUS
status¶ Status.
-
const ParticipantProxyData &
info¶ Participant discovery info.
-
DISCOVERY_STATUS
ParticipantProxyData¶
-
class
eprosima::fastrtps::rtps::ParticipantProxyData¶ ParticipantProxyData class is used to store and convert the information Participants send to each other during the PDP phase.
Public Functions
-
bool
updateData(ParticipantProxyData &pdata)¶ Update the data.
- Return
True on success
- Parameters
pdata: Object to copy the data from
-
uint32_t
get_serialized_size(bool include_encapsulation) const¶ Get the size in bytes of the CDR serialization of this object.
- Return
size in bytes of the CDR serialization.
- Parameters
include_encapsulation: Whether to include the size of the encapsulation info.
-
bool
writeToCDRMessage(CDRMessage_t *msg, bool write_encapsulation)¶ Write as a parameter list on a CDRMessage_t
- Return
True on success
-
bool
readFromCDRMessage(CDRMessage_t *msg, bool use_encapsulation, const NetworkFactory &network, bool is_shm_transport_available)¶ Read the parameter list from a received CDRMessage_t
- Return
True on success
-
void
clear()¶ Clear the data (restore to default state).
-
void
copy(const ParticipantProxyData &pdata)¶ Copy the data from another object.
- Parameters
pdata: Object to copy the data from
-
void
set_persistence_guid(const GUID_t &guid)¶ Set participant persistent GUID_t
- Parameters
guid: valid GUID_t
-
GUID_t
get_persistence_guid() const¶ Retrieve participant persistent GUID_t
- Return
guid persistent GUID_t or c_Guid_Unknown
-
void
set_sample_identity(const SampleIdentity &sid)¶ Set participant client server sample identity
- Parameters
sid: valid SampleIdentity
-
SampleIdentity
get_sample_identity() const¶ Retrieve participant SampleIdentity
- Return
Public Members
-
ProtocolVersion_t
m_protocolVersion¶ Protocol version.
-
VendorId_t
m_VendorId¶ Vendor ID.
-
bool
m_expectsInlineQos¶ Expects Inline QOS.
-
BuiltinEndpointSet_t
m_availableBuiltinEndpoints¶ Available builtin endpoints.
-
RemoteLocatorList
metatraffic_locators¶ Metatraffic locators.
-
RemoteLocatorList
default_locators¶ Default locators.
-
string_255
m_participantName¶ Participant name.
-
bool
-
BUILTIN_PARTICIPANT_DATA_MAX_SIZE¶
-
TYPELOOKUP_DATA_MAX_SIZE¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_DETECTOR¶
-
DISC_BUILTIN_ENDPOINT_PUBLICATION_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PUBLICATION_DETECTOR¶
-
DISC_BUILTIN_ENDPOINT_SUBSCRIPTION_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_SUBSCRIPTION_DETECTOR¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_PROXY_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_PROXY_DETECTOR¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_STATE_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_STATE_DETECTOR¶
-
BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_DATA_WRITER¶
-
BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_DATA_READER¶
-
BUILTIN_ENDPOINT_TYPELOOKUP_SERVICE_REQUEST_DATA_WRITER¶
-
BUILTIN_ENDPOINT_TYPELOOKUP_SERVICE_REQUEST_DATA_READER¶
-
BUILTIN_ENDPOINT_TYPELOOKUP_SERVICE_REPLY_DATA_WRITER¶
-
BUILTIN_ENDPOINT_TYPELOOKUP_SERVICE_REPLY_DATA_READER¶
-
DISC_BUILTIN_ENDPOINT_PUBLICATION_SECURE_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PUBLICATION_SECURE_DETECTOR¶
-
DISC_BUILTIN_ENDPOINT_SUBSCRIPTION_SECURE_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_SUBSCRIPTION_SECURE_DETECTOR¶
-
BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_DATA_WRITER¶
-
BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_DATA_READER¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_ANNOUNCER¶
-
DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_DETECTOR¶
ReaderDiscoveryInfo¶
-
struct
eprosima::fastrtps::rtps::ReaderDiscoveryInfo¶ Class ReaderDiscoveryInfo with discovery information of the reader.
Public Types
Public Members
-
DISCOVERY_STATUS
status¶ Status.
-
const ReaderProxyData &
info¶ Participant discovery info.
-
DISCOVERY_STATUS
ReaderProxyData¶
-
class
eprosima::fastrtps::rtps::ReaderProxyData¶ Class ReaderProxyData, used to represent all the information on a Reader (both local and remote) with the purpose of implementing the discovery.
Public Functions
-
void
set_sample_identity(const SampleIdentity &sid)¶ Set participant client server sample identity
- Parameters
sid: valid SampleIdentity
-
SampleIdentity
get_sample_identity() const¶ Retrieve participant SampleIdentity
- Return
-
uint32_t
get_serialized_size(bool include_encapsulation) const¶ Get the size in bytes of the CDR serialization of this object.
- Return
size in bytes of the CDR serialization.
- Parameters
include_encapsulation: Whether to include the size of the encapsulation info.
-
bool
writeToCDRMessage(CDRMessage_t *msg, bool write_encapsulation) const¶ Write as a parameter list on a CDRMessage_t
- Return
True on success
-
bool
readFromCDRMessage(CDRMessage_t *msg, const NetworkFactory &network, bool is_shm_transport_available)¶ Read the information from a CDRMessage_t. The position of the message must be in the beginning on the parameter list.
- Return
true on success
- Parameters
msg: Pointer to the message.network: Reference to network factory for locator validation and transformationis_shm_transport_available: Indicates whether the Reader is reachable by SHM.
-
void
clear()¶ Clear (put to default) the information.
-
bool
is_update_allowed(const ReaderProxyData &rdata) const¶ Check if this object can be updated with the information on another object.
- Return
true if this object can be updated with the information on rdata.
- Parameters
rdata: ReaderProxyData object to be checked.
-
void
update(ReaderProxyData *rdata)¶ Update the information (only certain fields will be updated).
- Parameters
rdata: Pointer to the object from which we are going to update.
-
void
copy(ReaderProxyData *rdata)¶ Copy ALL the information from another object.
- Parameters
rdata: Pointer to the object from where the information must be copied.
-
void
WriterDiscoveryInfo¶
-
struct
eprosima::fastrtps::rtps::WriterDiscoveryInfo¶ Class WriterDiscoveryInfo with discovery information of the writer.
Public Types
Public Members
-
DISCOVERY_STATUS
status¶ Status.
-
const WriterProxyData &
info¶ Participant discovery info.
-
DISCOVERY_STATUS
WriterProxyData¶
-
class
eprosima::fastrtps::rtps::WriterProxyData¶ Public Functions
-
void
set_sample_identity(const SampleIdentity &sid)¶ Set participant client server sample identity
- Parameters
sid: valid SampleIdentity
-
SampleIdentity
get_sample_identity() const¶ Retrieve participant SampleIdentity
- Return
-
void
clear()¶ Clear the information and return the object to the default state.
-
bool
is_update_allowed(const WriterProxyData &wdata) const¶ Check if this object can be updated with the information on another object.
- Return
true if this object can be updated with the information on wdata.
- Parameters
wdata: WriterProxyData object to be checked.
-
void
update(WriterProxyData *wdata)¶ Update certain parameters from another object.
- Parameters
wdata: pointer to object with new information.
-
void
copy(WriterProxyData *wdata)¶ Copy all information from another object.
-
uint32_t
get_serialized_size(bool include_encapsulation) const¶ Get the size in bytes of the CDR serialization of this object.
- Return
size in bytes of the CDR serialization.
- Parameters
include_encapsulation: Whether to include the size of the encapsulation info.
-
bool
writeToCDRMessage(CDRMessage_t *msg, bool write_encapsulation) const¶ Write as a parameter list on a CDRMessage_t.
-
bool
readFromCDRMessage(CDRMessage_t *msg, const NetworkFactory &network, bool is_shm_transport_possible)¶ Read a parameter list from a CDRMessage_t.
-
void
RTPSParticipant¶
-
class
eprosima::fastrtps::rtps::RTPSParticipant¶ Class RTPSParticipant, contains the public API for a RTPSParticipant.
Public Functions
-
const GUID_t &
getGuid() const¶ Get the GUID_t of the RTPSParticipant.
-
void
announceRTPSParticipantState()¶ Force the announcement of the RTPSParticipant state.
-
void
stopRTPSParticipantAnnouncement()¶ Stop the RTPSParticipant announcement period. //TODO remove this method because is only for testing.
-
void
resetRTPSParticipantAnnouncement()¶ Reset the RTPSParticipant announcement period. //TODO remove this method because is only for testing.
-
bool
newRemoteWriterDiscovered(const GUID_t &pguid, int16_t userDefinedId)¶ Indicate the Participant that you have discovered a new Remote Writer. This method can be used by the user to implements its own Static Endpoint Discovery Protocol
- Return
True if correctly added.
- Parameters
pguid: GUID_t of the discovered Writer.userDefinedId: ID of the discovered Writer.
-
bool
newRemoteReaderDiscovered(const GUID_t &pguid, int16_t userDefinedId)¶ Indicate the Participant that you have discovered a new Remote Reader. This method can be used by the user to implements its own Static Endpoint Discovery Protocol
- Return
True if correctly added.
- Parameters
pguid: GUID_t of the discovered Reader.userDefinedId: ID of the discovered Reader.
-
uint32_t
getRTPSParticipantID() const¶ Get the Participant ID.
- Return
Participant ID.
-
bool
registerWriter(RTPSWriter *Writer, const TopicAttributes &topicAtt, const WriterQos &wqos)¶ Register a RTPSWriter in the builtin Protocols.
- Return
True if correctly registered.
- Parameters
Writer: Pointer to the RTPSWriter.topicAtt: Topic Attributes where you want to register it.wqos: WriterQos.
-
bool
registerReader(RTPSReader *Reader, const TopicAttributes &topicAtt, const ReaderQos &rqos)¶ Register a RTPSReader in the builtin Protocols.
- Return
True if correctly registered.
- Parameters
Reader: Pointer to the RTPSReader.topicAtt: Topic Attributes where you want to register it.rqos: ReaderQos.
-
bool
updateWriter(RTPSWriter *Writer, const TopicAttributes &topicAtt, const WriterQos &wqos)¶ Update writer QOS
- Return
true on success
- Parameters
Writer: to updatetopicAtt: Topic Attributes where you want to register it.wqos: New writer QoS
-
bool
updateReader(RTPSReader *Reader, const TopicAttributes &topicAtt, const ReaderQos &rqos)¶ Update reader QOS
- Return
true on success
- Parameters
Reader: to updatetopicAtt: Topic Attributes where you want to register it.rqos: New reader QoS
-
std::vector<std::string>
getParticipantNames() const¶ Returns a list with the participant names.
- Return
list of participant names.
-
const RTPSParticipantAttributes &
getRTPSParticipantAttributes() const¶ Get a copy of the actual state of the RTPSParticipantParameters
- Return
RTPSParticipantAttributes copy of the params.
-
uint32_t
getMaxMessageSize() const¶ Retrieves the maximum message size.
-
uint32_t
getMaxDataSize() const¶ Retrieves the maximum data size.
-
WLP *
wlp() const¶ A method to retrieve the built-in writer liveliness protocol.
- Return
Writer liveliness protocol
-
bool
get_new_entity_id(EntityId_t &entityId)¶ Fills a new entityId if set to unknown, or checks if a entity already exists with that entityId in other case.
- Return
True if filled or the entityId is available.
- Parameters
entityId: to check of fill. If filled, EntityKind will be “vendor-specific” (0x01)
-
void
set_check_type_function(std::function<bool(const std::string&)> &&check_type)¶ Allows setting a function to check if a type is already known by the top level API participant.
-
fastdds::dds::builtin::TypeLookupManager *
typelookup_manager() const¶ Retrieves the built-in typelookup service manager.
- Return
-
void
set_listener(RTPSParticipantListener *listener)¶ Modifies the participant listener.
- Parameters
listener:
-
uint32_t
get_domain_id() const¶ Retrieves the DomainId.
-
void
enable()¶ This operation enables the RTPSParticipantImpl.
-
bool
is_security_enabled_for_writer(const WriterAttributes &writer_attributes)¶ Checks whether the writer has security attributes enabled.
- Parameters
writer_attributes: Attributes of the writer as given to the RTPSParticipantImpl::create_writer
-
bool
is_security_enabled_for_reader(const ReaderAttributes &reader_attributes)¶ Checks whether the reader has security attributes enabled.
- Parameters
reader_attributes: Attributes of the reader as given to the RTPSParticipantImpl::create_reader
-
const GUID_t &
RTPSParticipantListener¶
-
class
eprosima::fastrtps::rtps::RTPSParticipantListener¶ Class RTPSParticipantListener with virtual method that the user can overload to respond to certain events.
Public Functions
-
void
onParticipantDiscovery(RTPSParticipant *participant, ParticipantDiscoveryInfo &&info)¶ This method is called when a new Participant is discovered, or a previously discovered participant changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote participant.info: Remote participant information. User can take ownership of the object.
-
void
onReaderDiscovery(RTPSParticipant *participant, ReaderDiscoveryInfo &&info)¶ This method is called when a new Reader is discovered, or a previously discovered reader changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote reader.info: Remote reader information. User can take ownership of the object.
-
void
onWriterDiscovery(RTPSParticipant *participant, WriterDiscoveryInfo &&info)¶ This method is called when a new Writer is discovered, or a previously discovered writer changes its QOS or is removed.
- Parameters
participant: Pointer to the Participant which discovered the remote writer.info: Remote writer information. User can take ownership of the object.
-
void
on_type_discovery(RTPSParticipant *participant, const SampleIdentity &request_sample_id, const string_255 &topic, const types::TypeIdentifier *identifier, const types::TypeObject *object, types::DynamicType_ptr 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.
The field “topic” it is only available if the type was discovered using “Discovery-Time Data Typing”, in which case the field request_sample_id will contain INVALID_SAMPLE_IDENTITY. If the type was discovered using TypeLookup Service then “topic” will be empty, but will have the request_sample_id of the petition that caused the discovery. For example: fastrtps::types::TypeIdentifier new_type_id = *identifier;
-
void
on_type_dependencies_reply(RTPSParticipant *participant, const SampleIdentity &request_sample_id, const types::TypeIdentifierWithSizeSeq &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.
-
void
on_type_information_received(RTPSParticipant *participant, const string_255 &topic_name, const string_255 &type_name, const types::TypeInformation &type_information)¶ This method is called when a participant receives a TypeInformation while discovering another participant.
-
void
RTPSReader¶
ReaderListener¶
-
class
eprosima::fastrtps::rtps::ReaderListener¶ Class ReaderListener, to be used by the user to override some of is virtual method to program actions to certain events.
Subclassed by eprosima::fastdds::dds::builtin::TypeLookupReplyListener, eprosima::fastdds::dds::builtin::TypeLookupRequestListener, eprosima::fastrtps::rtps::PDPListener, eprosima::fastrtps::rtps::WLPListener
Public Functions
-
void
onReaderMatched(RTPSReader *reader, MatchingInfo &info)¶ This method is invoked when a new reader matches
- Parameters
reader: Matching readerinfo: Matching information of the reader
-
void
onReaderMatched(RTPSReader *reader, const fastdds::dds::SubscriptionMatchedStatus &info)¶ This method is invoked when a new reader matches
- Parameters
reader: Matching readerinfo: Subscription matching information
-
void
onNewCacheChangeAdded(RTPSReader *reader, const CacheChange_t *const change)¶ This method is called when a new CacheChange_t is added to the ReaderHistory.
- Parameters
reader: Pointer to the reader.change: Pointer to the CacheChange_t. This is a const pointer to const data to indicate that the user should not dispose of this data himself. To remove the data call the remove_change method of the ReaderHistory. reader->getHistory()->remove_change((CacheChange_t*)change).
-
void
on_liveliness_changed(RTPSReader *reader, const LivelinessChangedStatus &status)¶ Method called when the liveliness of a reader changes.
- Parameters
reader: The readerstatus: The liveliness changed status
-
void
on_requested_incompatible_qos(RTPSReader *reader, eprosima::fastdds::dds::PolicyMask qos)¶ This method is called when a new Writer is discovered, with a Topic that matches that of a local reader, but with an offered QoS that is incompatible with the one requested by the local reader
- Parameters
reader: Pointer to the RTPSReader.qos: A mask with the bits of all incompatible Qos activated.
-
void
RTPSReader¶
-
class
eprosima::fastrtps::rtps::RTPSReader: public eprosima::fastrtps::rtps::Endpoint¶ Class RTPSReader, manages the reception of data from its matched writers.
Subclassed by eprosima::fastrtps::rtps::StatefulReader, eprosima::fastrtps::rtps::StatelessReader
Public Functions
-
bool
matched_writer_add(const WriterProxyData &wdata) = 0¶ Add a matched writer represented by its attributes.
- Return
True if correctly added.
- Parameters
wdata: Attributes of the writer to add.
-
bool
matched_writer_remove(const GUID_t &writer_guid, bool removed_by_lease = false) = 0¶ Remove a writer represented by its attributes from the matched writers.
- Return
True if correctly removed.
- Parameters
writer_guid: GUID of the writer to remove.removed_by_lease: Whether the writer is being unmatched due to a participant drop.
-
bool
matched_writer_is_matched(const GUID_t &writer_guid) = 0¶ Tells us if a specific Writer is matched against this reader.
- Return
True if it is matched.
- Parameters
writer_guid: GUID of the writer to check.
-
bool
processDataMsg(CacheChange_t *change) = 0¶ Processes a new DATA message. Previously the message must have been accepted by function acceptMsgDirectedTo.
- Return
true if the reader accepts messages from the.
- Parameters
change: Pointer to the CacheChange_t.
-
bool
processDataFragMsg(CacheChange_t *change, uint32_t sampleSize, uint32_t fragmentStartingNum, uint16_t fragmentsInSubmessage) = 0¶ Processes a new DATA FRAG message.
- Return
true if the reader accepts message.
- Parameters
change: Pointer to the CacheChange_t.sampleSize: Size of the complete, assembled message.fragmentStartingNum: Starting number of this particular message.fragmentsInSubmessage: Number of fragments on this particular message.
-
bool
processHeartbeatMsg(const GUID_t &writerGUID, uint32_t hbCount, const SequenceNumber_t &firstSN, const SequenceNumber_t &lastSN, bool finalFlag, bool livelinessFlag) = 0¶ Processes a new HEARTBEAT message.
- Return
true if the reader accepts messages from the.
- Parameters
writerGUID:hbCount:firstSN:lastSN:finalFlag:livelinessFlag:
-
bool
processGapMsg(const GUID_t &writerGUID, const SequenceNumber_t &gapStart, const SequenceNumberSet_t &gapList) = 0¶ Processes a new GAP message.
- Return
true if the reader accepts messages from the.
- Parameters
writerGUID:gapStart:gapList:
-
bool
change_removed_by_history(CacheChange_t *change, WriterProxy *prox = nullptr) = 0¶ Method to indicate the reader that some change has been removed due to HistoryQos requirements.
- Return
True if correctly removed.
- Parameters
change: Pointer to the CacheChange_t.prox: Pointer to the WriterProxy.
-
ReaderListener *
getListener() const¶ Get the associated listener, secondary attached Listener in case it is of compound type
- Return
Pointer to the associated reader listener.
-
bool
setListener(ReaderListener *target)¶ Switch the ReaderListener kind for the Reader. If the RTPSReader does not belong to the built-in protocols it switches out the old one. If it belongs to the built-in protocols, it sets the new ReaderListener callbacks to be called after the built-in ReaderListener ones.
- Return
True is correctly set.
- Parameters
target: Pointed to ReaderLister to attach
-
bool
reserveCache(CacheChange_t **change, uint32_t dataCdrSerializedSize)¶ Reserve a CacheChange_t.
- Return
True if correctly reserved.
- Parameters
change: Pointer to pointer to the Cache.dataCdrSerializedSize: Size of the Cache.
-
void
releaseCache(CacheChange_t *change)¶ Release a cacheChange.
-
bool
nextUnreadCache(CacheChange_t **change, WriterProxy **wp) = 0¶ Read the next unread CacheChange_t from the history
- Return
True if read.
- Parameters
change: Pointer to pointer of CacheChange_twp: Pointer to pointer to the WriterProxy
-
bool
nextUntakenCache(CacheChange_t **change, WriterProxy **wp) = 0¶ Get the next CacheChange_t from the history to take.
- Return
True if read.
- Parameters
change: Pointer to pointer of CacheChange_t.wp: Pointer to pointer to the WriterProxy.
-
bool
expectsInlineQos()¶ - Return
True if the reader expects Inline QOS.
-
ReaderHistory *
getHistory()¶ Returns a pointer to the associated History.
-
bool
isInCleanState() = 0¶ Returns there is a clean state with all Writers.
It occurs when the Reader received all samples sent by Writers. In other words, its WriterProxies are up to date.
- Return
There is a clean state with all Writers.
-
void
assert_writer_liveliness(const GUID_t &writer) = 0¶ Assert the liveliness of a matched writer.
- Parameters
writer: GUID of the writer to assert.
-
bool
begin_sample_access_nts(CacheChange_t *change, WriterProxy *&wp, bool &is_future_change) = 0¶ Called just before a change is going to be deserialized.
- Return
Whether the change is still valid or not.
- Parameters
[in] change: Pointer to the change being accessed.[out] wp: Writer proxy thechangebelongs to.[out] is_future_change: Whether the change is in the future (i.e. there are earlier unreceived changes from the same writer).
-
void
end_sample_access_nts(CacheChange_t *change, WriterProxy *&wp, bool mark_as_read) = 0¶ Called after the change has been deserialized.
- Parameters
[in] change: Pointer to the change being accessed.[in] wp: Writer proxy thechangebelongs to.[in] mark_as_read: Whether thechangeshould be marked as read or not.
-
void
change_read_by_user(CacheChange_t *change, const WriterProxy *writer, bool mark_as_read = true) = 0¶ Called when the user has retrieved a change from the history.
- Parameters
change: Pointer to the change to ACKwriter: Writer proxy of thechange.mark_as_read: Whether thechangeshould be marked as read or not
-
bool
is_sample_valid(const void *data, const GUID_t &writer, const SequenceNumber_t &sn) const¶ Checks whether the sample is still valid or is corrupted
- Return
true if the sample is valid
- Parameters
data: Pointer to the sample data to checkwriter: GUID of the writer that sentdatasn: Sequence number related todata
Public Members
-
LivelinessChangedStatus
liveliness_changed_status_¶ The liveliness changed status struct as defined in the DDS.
-
bool
Resources¶
MemoryManagementPolicy¶
-
enum
eprosima::fastrtps::rtps::MemoryManagementPolicy¶ Enum MemoryuManagementPolicy_t, indicated the way memory is managed in terms of dealing with CacheChanges
Values:
-
enumerator
PREALLOCATED_MEMORY_MODE¶ Preallocated memory.
Size set to the data type maximum. Largest memory footprint but smallest allocation count.
-
enumerator
PREALLOCATED_WITH_REALLOC_MEMORY_MODE¶ Default size preallocated, requires reallocation when a bigger message arrives.
Smaller memory footprint at the cost of an increased allocation count.
-
enumerator
DYNAMIC_RESERVE_MEMORY_MODE¶
-
enumerator
DYNAMIC_REUSABLE_MEMORY_MODE¶
-
enumerator
RTPSDomain¶
-
class
eprosima::fastrtps::rtps::RTPSDomain¶ Class RTPSDomain,it manages the creation and destruction of RTPSParticipant RTPSWriter and RTPSReader. It stores a list of all created RTPSParticipant. Is has only static methods.
Public Static Functions
-
void
stopAll()¶ Method to shut down all RTPSParticipants, readers, writers, etc. It must be called at the end of the process to avoid memory leaks. It also shut downs the DomainRTPSParticipant.
-
RTPSParticipant *
createParticipant(uint32_t domain_id, const RTPSParticipantAttributes &attrs, RTPSParticipantListener *plisten = nullptr)¶ Create a RTPSParticipant.
- Return
Pointer to the RTPSParticipant.
- Parameters
domain_id: DomainId to be used by the RTPSParticipant (80 by default).attrs: RTPSParticipant Attributes.plisten: Pointer to the ParticipantListener.
-
RTPSParticipant *
createParticipant(uint32_t domain_id, bool enabled, const RTPSParticipantAttributes &attrs, RTPSParticipantListener *plisten = nullptr)¶ Create a RTPSParticipant.
- Return
Pointer to the RTPSParticipant.
- Parameters
domain_id: DomainId to be used by the RTPSParticipant (80 by default).enabled: True if the RTPSParticipant should be enabled on creation. False if it will be enabled later with RTPSParticipant::enable()attrs: RTPSParticipant Attributes.plisten: Pointer to the ParticipantListener.
-
RTPSWriter *
createRTPSWriter(RTPSParticipant *p, WriterAttributes &watt, WriterHistory *hist, WriterListener *listen = nullptr)¶ Create a RTPSWriter in a participant.
- Return
Pointer to the created RTPSWriter.
- Parameters
p: Pointer to the RTPSParticipant.watt: Writer Attributes.hist: Pointer to the WriterHistory.listen: Pointer to the WriterListener.
Create a RTPSWriter in a participant using a custom payload pool.
- Return
Pointer to the created RTPSWriter.
- Parameters
p: Pointer to the RTPSParticipant.watt: Writer Attributes.payload_pool: Shared pointer to the IPayloadPoolhist: Pointer to the WriterHistory.listen: Pointer to the WriterListener.
-
bool
removeRTPSWriter(RTPSWriter *writer)¶ Remove a RTPSWriter.
- Return
True if correctly removed.
- Parameters
writer: Pointer to the writer you want to remove.
-
RTPSReader *
createRTPSReader(RTPSParticipant *p, ReaderAttributes &ratt, ReaderHistory *hist, ReaderListener *listen = nullptr)¶ Create a RTPSReader in a participant.
- Return
Pointer to the created RTPSReader.
- Parameters
p: Pointer to the RTPSParticipant.ratt: Reader Attributes.hist: Pointer to the ReaderHistory.listen: Pointer to the ReaderListener.
Create a RTPSWriter in a participant using a custom payload pool.
- Return
Pointer to the created RTPSReader.
- Parameters
p: Pointer to the RTPSParticipant.ratt: Reader Attributes.payload_pool: Shared pointer to the IPayloadPoolhist: Pointer to the ReaderHistory.listen: Pointer to the ReaderListener.
-
bool
removeRTPSReader(RTPSReader *reader)¶ Remove a RTPSReader.
- Return
True if correctly removed.
- Parameters
reader: Pointer to the reader you want to remove.
-
bool
removeRTPSParticipant(RTPSParticipant *p)¶ Remove a RTPSParticipant and delete all its associated Writers, Readers, resources, etc.
- Return
True if correct.
- Parameters
[in] p: Pointer to the RTPSParticipant;
-
void
setMaxRTPSParticipantId(uint32_t maxRTPSParticipantId)¶ Set the maximum RTPSParticipantID.
- Parameters
maxRTPSParticipantId: ID.
-
RTPSParticipant *
clientServerEnvironmentCreationOverride(uint32_t domain_id, bool enabled, const RTPSParticipantAttributes &attrs, RTPSParticipantListener *listen)¶ Creates a RTPSParticipant as default server or client if ROS_MASTER_URI environment variable is set.
- Return
Pointer to the RTPSParticipant.
- Parameters
domain_id: DDS domain associatedenabled: True if the RTPSParticipant should be enabled on creation. False if it will be enabled later with RTPSParticipant::enable()attrs: RTPSParticipant Attributes.listen: Pointer to the ParticipantListener.
-
void
RTPSWriter¶
LivelinessData¶
-
struct
eprosima::fastrtps::rtps::LivelinessData¶ A struct keeping relevant liveliness information of a writer.
Public Functions
-
LivelinessData(GUID_t guid_in, LivelinessQosPolicyKind kind_in, Duration_t lease_duration_in)¶ Constructor.
- Parameters
guid_in: GUID of the writerkind_in: Liveliness kindlease_duration_in: Liveliness lease duration
-
bool
operator==(const LivelinessData &other) const¶ Equality operator.
- Return
True if equal
- Parameters
other: Liveliness data to compare to
-
bool
operator!=(const LivelinessData &other) const¶ Inequality operator.
- Return
True if different
- Parameters
other: Liveliness data to compare to
Public Members
-
LivelinessQosPolicyKind
kind¶ Writer liveliness kind.
-
Duration_t
lease_duration¶ The lease duration.
-
unsigned int
count= 1¶ The number of times the writer is being counted.
-
WriterStatus
status¶ The writer status.
-
std::chrono::steady_clock::time_point
time¶ The time when the writer will lose liveliness.
-
RTPSWriter¶
-
class
eprosima::fastrtps::rtps::RTPSWriter: public eprosima::fastrtps::rtps::Endpoint, public eprosima::fastrtps::rtps::RTPSMessageSenderInterface¶ Class RTPSWriter, manages the sending of data to the readers. Is always associated with a HistoryCache.
Subclassed by eprosima::fastrtps::rtps::StatefulWriter, eprosima::fastrtps::rtps::StatelessWriter
Public Functions
-
template<typename
T>
CacheChange_t *new_change(T &data, ChangeKind_t changeKind, InstanceHandle_t handle = c_InstanceHandle_Unknown)¶ Create a new change based with the provided changeKind.
- Return
Pointer to the CacheChange or nullptr if incorrect.
- Parameters
data: Data of the change.changeKind: The type of change.handle: InstanceHandle to assign.
-
bool
release_change(CacheChange_t *change)¶ Release a change when it is not being used anymore.
- Return
whether the operation succeeded or not
- Pre
changeis notnullptrchangepoints to a cache change obtained from a call tothis->new_change
- Post
memory pointed to by
changeis not accessed- Parameters
change: Pointer to the cache change to be released.
-
bool
matched_reader_add(const ReaderProxyData &data) = 0¶ Add a matched reader.
- Return
True if added.
- Parameters
data: Pointer to the ReaderProxyData object added.
-
bool
matched_reader_remove(const GUID_t &reader_guid) = 0¶ Remove a matched reader.
- Return
True if removed.
- Parameters
reader_guid: GUID of the reader to remove.
-
bool
matched_reader_is_matched(const GUID_t &reader_guid) = 0¶ Tells us if a specific Reader is matched against this writer.
- Return
True if it was matched.
- Parameters
reader_guid: GUID of the reader to check.
-
bool
is_acked_by_all(const CacheChange_t*) const¶ Check if a specific change has been acknowledged by all Readers. Is only useful in reliable Writer. In BE Writers returns false when pending to be sent.
- Return
True if acknowledged by all.
-
bool
wait_for_all_acked(const Duration_t&)¶ Waits until all changes were acknowledged or max_wait.
- Return
True if all were acknowledged.
-
void
updateAttributes(const WriterAttributes &att) = 0¶ Update the Attributes of the Writer.
- Parameters
att: New attributes
-
void
send_any_unsent_changes() = 0¶ This method triggers the send operation for unsent changes.
- Return
number of messages sent
-
SequenceNumber_t
get_seq_num_min()¶ Get Min Seq Num in History.
- Return
Minimum sequence number in history
-
SequenceNumber_t
get_seq_num_max()¶ Get Max Seq Num in History.
- Return
Maximum sequence number in history
-
uint32_t
getTypeMaxSerialized()¶ Get maximum size of the serialized type
- Return
Maximum size of the serialized type
-
uint32_t
getMaxDataSize()¶ Get maximum size of the data.
-
uint32_t
calculateMaxDataSize(uint32_t length)¶ Calculates the maximum size of the data.
-
WriterListener *
getListener()¶ Get listener
- Return
Listener
-
bool
isAsync() const¶ Get the publication mode
- Return
publication mode
-
bool
remove_older_changes(unsigned int max = 0)¶ Remove an specified max number of changes
- Return
at least one change has been removed
- Parameters
max: Maximum number of changes to remove.
-
bool
try_remove_change(const std::chrono::steady_clock::time_point &max_blocking_time_point, std::unique_lock<RecursiveTimedMutex> &lock) = 0¶ Tries to remove a change waiting a maximum of the provided microseconds.
- Return
at least one change has been removed
- Parameters
max_blocking_time_point: Maximum time to wait for.lock: Lock of the Change list.
-
bool
wait_for_acknowledgement(const SequenceNumber_t &seq, const std::chrono::steady_clock::time_point &max_blocking_time_point, std::unique_lock<RecursiveTimedMutex> &lock) = 0¶ Waits till a change has been acknowledged.
- Return
true when change was acknowledged, false when timeout is reached.
- Parameters
seq: Sequence number to wait for acknowledgement.max_blocking_time_point: Maximum time to wait for.lock: Lock of the Change list.
-
RTPSParticipantImpl *
getRTPSParticipant() const¶ Get RTPS participant
- Return
RTPS participant
-
void
set_separate_sending(bool enable)¶ Enable or disable sending data to readers separately NOTE: This will only work for synchronous writers
- Parameters
enable: If separate sending should be enabled
-
bool
get_separate_sending() const¶ Inform if data is sent to readers separately
- Return
true if separate sending is enabled
-
bool
process_acknack(const GUID_t &writer_guid, const GUID_t &reader_guid, uint32_t ack_count, const SequenceNumberSet_t &sn_set, bool final_flag, bool &result)¶ Process an incoming ACKNACK submessage.
- Return
true when the submessage was destinated to this writer, false otherwise.
- Parameters
[in] writer_guid: GUID of the writer the submessage is directed to.[in] reader_guid: GUID of the reader originating the submessage.[in] ack_count: Count field of the submessage.[in] sn_set: Sequence number bitmap field of the submessage.[in] final_flag: Final flag field of the submessage.[out] result: true if the writer could process the submessage. Only valid when returned value is true.
-
bool
process_nack_frag(const GUID_t &writer_guid, const GUID_t &reader_guid, uint32_t ack_count, const SequenceNumber_t &seq_num, const FragmentNumberSet_t fragments_state, bool &result)¶ Process an incoming NACKFRAG submessage.
- Return
true when the submessage was destinated to this writer, false otherwise.
- Parameters
[in] writer_guid: GUID of the writer the submessage is directed to.[in] reader_guid: GUID of the reader originating the submessage.[in] ack_count: Count field of the submessage.[in] seq_num: Sequence number field of the submessage.[in] fragments_state: Fragment number bitmap field of the submessage.[out] result: true if the writer could process the submessage. Only valid when returned value is true.
-
const LivelinessQosPolicyKind &
get_liveliness_kind() const¶ A method to retrieve the liveliness kind.
- Return
Liveliness kind
-
const Duration_t &
get_liveliness_lease_duration() const¶ A method to retrieve the liveliness lease duration.
- Return
Lease duration
-
const Duration_t &
get_liveliness_announcement_period() const¶ A method to return the liveliness announcement period.
- Return
The announcement period
-
bool
destinations_have_changed() const override¶ Check if the destinations managed by this sender interface have changed.
- Return
true if destinations have changed, false otherwise.
-
GuidPrefix_t
destination_guid_prefix() const override¶ Get a GUID prefix representing all destinations.
- Return
When all the destinations share the same prefix (i.e. belong to the same participant) that prefix is returned. When there are no destinations, or they belong to different participants, c_GuidPrefix_Unknown is returned.
-
const std::vector<GuidPrefix_t> &
remote_participants() const override¶ Get the GUID prefix of all the destination participants.
- Return
a const reference to a vector with the GUID prefix of all destination participants.
-
const std::vector<GUID_t> &
remote_guids() const override¶ Get the GUID of all destinations.
- Return
a const reference to a vector with the GUID of all destinations.
-
bool
send(CDRMessage_t *message, std::chrono::steady_clock::time_point &max_blocking_time_point) const override¶ Send a message through this interface.
- Parameters
message: Pointer to the buffer with the message already serialized.max_blocking_time_point: Future timepoint where blocking send should end.
-
bool
is_datasharing_compatible() const¶ - Return
Whether the writer is data sharing compatible or not
Public Members
-
LivelinessLostStatus
liveliness_lost_status_¶ Liveliness lost status of this writer.
-
template<typename
WriterListener¶
-
class
eprosima::fastrtps::rtps::WriterListener¶ Class WriterListener with virtual method so the user can implement callbacks to certain events.
Public Functions
-
void
onWriterMatched(RTPSWriter *writer, MatchingInfo &info)¶ This method is called when a new Reader is matched with this Writer by the builtin protocols
- Parameters
writer: Pointer to the RTPSWriter.info: Matching Information.
-
void
onWriterMatched(RTPSWriter *writer, const eprosima::fastdds::dds::PublicationMatchedStatus &info)¶ This method is called when a new Reader is matched with this Writer by the builtin protocols
- Parameters
writer: Pointer to the RTPSWriter.info: Publication matching information.
-
void
on_offered_incompatible_qos(RTPSWriter *writer, eprosima::fastdds::dds::PolicyMask qos)¶ This method is called when a new Reader is discovered, with a Topic that matches that of a local writer, but with a requested QoS that is incompatible with the one offered by the local writer
- Parameters
writer: Pointer to the RTPSWriter.qos: A mask with the bits of all incompatible Qos activated.
-
void
onWriterChangeReceivedByAll(RTPSWriter *writer, CacheChange_t *change)¶ This method is called when all the readers matched with this Writer acknowledge that a cache change has been received.
- Parameters
writer: Pointer to the RTPSWriter.change: Pointer to the affected CacheChange_t.
-
void
on_liveliness_lost(RTPSWriter *writer, const LivelinessLostStatus &status)¶ Method called when the liveliness of a writer is lost.
- Parameters
writer: The writerstatus: The liveliness lost status
-
void
LOG¶
Data Distribution Service (DDS) Data-Centric Publish-Subscribe (DCPS) Platform Independent Model (PIM) API
FileConsumer¶
-
class
eprosima::fastdds::dds::FileConsumer: public eprosima::fastdds::dds::OStreamConsumer¶ Public Functions
-
FileConsumer()¶ Default constructor: filename = “output.log”, append = false.
-
FileConsumer(const std::string &filename, bool append = false)¶ Constructor with parameters.
- Parameters
filename: path of the output file where the log will be wrote.append: indicates if the consumer must append the content in the filename.
-
Log¶
-
class
eprosima::fastdds::dds::Log¶ Logging utilities. Logging is accessed through the three macros above, and configuration on the log output can be achieved through static methods on the class. Logging at various levels can be disabled dynamically (through the Verbosity level) or statically (through the LOG_NO_[VERB] macros) for maximum performance.
Public Types
-
enum
Kind¶ Types of log entry.
Error: Maximum priority. Can only be disabled statically through LOG_NO_ERROR.
Warning: Medium priority. Can be disabled statically and dynamically.
Info: Low priority. Useful for debugging. Disabled by default on release branches.
Values:
-
enumerator
Error¶
-
enumerator
Warning¶
-
enumerator
Info¶
Public Static Functions
-
void
RegisterConsumer(std::unique_ptr<LogConsumer> &&consumer)¶ Registers an user defined consumer to route log output. There is a default stdout consumer active as default.
- Parameters
consumer: r-value to a consumer unique_ptr. It will be invalidated after the call.
-
void
ClearConsumers()¶ Removes all registered consumers, including the default stdout.
-
void
ReportFilenames(bool)¶ Enables the reporting of filenames in log entries. Disabled by default.
-
void
ReportFunctions(bool)¶ Enables the reporting of function names in log entries. Enabled by default when supported.
-
void
SetVerbosity(Log::Kind)¶ Sets the verbosity level, allowing for messages equal or under that priority to be logged.
-
void
SetCategoryFilter(const std::regex&)¶ Sets a filter that will pattern-match against log categories, dropping any unmatched categories.
-
void
SetFilenameFilter(const std::regex&)¶ Sets a filter that will pattern-match against filenames, dropping any unmatched categories.
-
void
SetErrorStringFilter(const std::regex&)¶ Sets a filter that will pattern-match against the provided error string, dropping any unmatched categories.
-
void
Reset()¶ Returns the logging engine to configuration defaults.
-
void
Flush()¶ Waits until no more log info is available.
-
void
KillThread()¶ Stops the logging thread. It will re-launch on the next call to a successful log macro.
-
struct
Context¶
-
struct
Entry¶
-
enum
LogConsumer¶
-
class
LogConsumer¶ Consumes a log entry to output it somewhere.
Subclassed by eprosima::fastdds::dds::OStreamConsumer
logInfo¶
-
logInfo(cat, msg)¶ Logs an info message. Disable it through Log::SetVerbosity, define LOG_NO_INFO, or being in a release branch.
eProsima log layer. Logging categories and verbosity can be specified dynamically at runtime. However, even on a category not covered by the current verbosity level, there is some overhead on calling a log macro. For maximum performance, you can opt out of logging any particular level by defining the following symbols:
define LOG_NO_ERROR
define LOG_NO_WARNING
define LOG_NO_INFO
Additionally. the lowest level (Info) is disabled by default on release branches.
logWarning¶
-
logWarning(cat, msg)¶ Logs a warning. Disable reporting through Log::SetVerbosity or define LOG_NO_WARNING.
OStreamConsumer¶
-
class
OStreamConsumer: public eprosima::fastdds::dds::LogConsumer¶ Subclassed by eprosima::fastdds::dds::FileConsumer, eprosima::fastdds::dds::StdoutConsumer, eprosima::fastdds::dds::StdoutErrConsumer
StdoutConsumer¶
-
class
StdoutConsumer: public eprosima::fastdds::dds::OStreamConsumer¶
StdoutErrConsumer¶
-
class
eprosima::fastdds::dds::StdoutErrConsumer: public eprosima::fastdds::dds::OStreamConsumer¶ Public Functions
-
void
stderr_threshold(const Log::Kind &kind)¶ Set the stderr_threshold to a Log::Kind. This threshold decides which log messages are output on STDOUT, and which are output to STDERR. Log messages with a Log::Kind equal to or more severe than the stderr_threshold are output to STDERR using std::cerr. Log messages with a Log::Kind less severe than the stderr_threshold are output to STDOUT using std::cout.
- Parameters
kind: The Log::Kind to which stderr_threshold is set.
-
void
Statistics¶
eProsima Fast DDS Statistics Module extension API.
DomainParticipant¶
-
class
eprosima::fastdds::statistics::dds::DomainParticipant: public eprosima::fastdds::dds::DomainParticipant¶ Class DomainParticipant: extends standard DDS DomainParticipant class to include specific methods for the Statistics module
Public Functions
-
ReturnCode_t
enable_statistics_datawriter(const std::string &topic_name, const eprosima::fastdds::dds::DataWriterQos &dwqos)¶ This operation enables a Statistics DataWriter.
- Return
RETCODE_UNSUPPORTED if the FASTDDS_STATISTICS CMake option has not been set, RETCODE_BAD_PARAMETER if the topic name provided does not correspond to any Statistics DataWriter, RETCODE_INCONSISTENT_POLICY if the DataWriterQos provided is inconsistent, RETCODE_OK if the DataWriter has been created or if it has been created previously, and RETCODE_ERROR otherwise
- Parameters
topic_name: Name of the topic associated to the Statistics DataWriterdwqos: DataWriterQos to be set
-
ReturnCode_t
disable_statistics_datawriter(const std::string &topic_name)¶ This operation disables a Statistics DataWriter.
- Return
RETCODE_UNSUPPORTED if the FASTDDS_STATISTICS CMake option has not been set, RETCODE_BAD_PARAMETER if the topic name provided does not correspond to any Statistics DataWriter, RETCODE_OK if the DataWriter has been correctly deleted or does not exist, and RETCODE_ERROR otherwise
- Parameters
topic_name: Name of the topic associated to the Statistics DataWriter
Public Static Functions
-
DomainParticipant *
narrow(eprosima::fastdds::dds::DomainParticipant *domain_participant)¶ This operation narrows the DDS DomainParticipant to the Statistics DomainParticipant.
- Return
Reference to the Statistics DomainParticipant if successful. nullptr otherwise.
- Parameters
domain_participant: Reference to the DDS DomainParticipant
-
const DomainParticipant *
narrow(const eprosima::fastdds::dds::DomainParticipant *domain_participant)¶ This operation narrows the DDS DomainParticipant to the Statistics DomainParticipant.
- Return
Constant reference to the Statistics DomainParticipant if successful. nullptr otherwise.
- Parameters
domain_participant: Constant reference to the DDS DomainParticipant
-
ReturnCode_t
DataWriterQos¶
-
class
eprosima::fastdds::statistics::dds::DataWriterQos: public eprosima::fastdds::dds::DataWriterQos¶ Class DataWriterQos: extends standard DDS DataWriterQos class to include specific default constructor for the recommended DataWriterQos profile.
Public Functions
-
DataWriterQos()¶ Constructor.
-
-
const eprosima::fastdds::statistics::dds::DataWriterQos
eprosima::fastdds::statistics::dds::STATISTICS_DATAWRITER_QOS¶ Constant to access default Statistics DataWriter Qos.
DataReaderQos¶
-
class
eprosima::fastdds::statistics::dds::DataReaderQos: public eprosima::fastdds::dds::DataReaderQos¶ Class DataReaderQos: extends standard DDS DataReaderQos class to include specific default constructor for the recommended DataReaderQos profile.
Public Functions
-
DataReaderQos()¶ Constructor.
-
-
const eprosima::fastdds::statistics::dds::DataReaderQos
eprosima::fastdds::statistics::dds::STATISTICS_DATAREADER_QOS¶ Constant to access default Statistics DataReader Qos.
Topic names¶
-
constexpr const char *
eprosima::fastdds::statistics::HISTORY_LATENCY_TOPIC= "_fastdds_statistics_history2history_latency"¶ Statistic topic that reports the write-to-notification latency between any two pairs of matched DataWriter-DataReader histories
-
constexpr const char *
eprosima::fastdds::statistics::NETWORK_LATENCY_TOPIC= "_fastdds_statistics_network_latency"¶ Statistics topic that reports the network latency (message group to message receiver) between any two communicating locators
-
constexpr const char *
eprosima::fastdds::statistics::PUBLICATION_THROUGHPUT_TOPIC= "_fastdds_statistics_publication_throughput"¶ Statistic topic that reports the publication’s throughput (amount of data sent) for every DataWriter.
-
constexpr const char *
eprosima::fastdds::statistics::SUBSCRIPTION_THROUGHPUT_TOPIC= "_fastdds_statistics_subscription_throughput"¶ Statistics topic that reports the subscription’s throughput (amount of data received) for every DataReader.
-
constexpr const char *
eprosima::fastdds::statistics::RTPS_SENT_TOPIC= "_fastdds_statistics_rtps_sent"¶ Statistics topic that reports the number of RTPS packets and bytes sent to each locator.
-
constexpr const char *
eprosima::fastdds::statistics::RTPS_LOST_TOPIC= "_fastdds_statistics_rtps_lost"¶ Statistics topic that reports the number of RTPS packets and bytes that have been lost in the network.
-
constexpr const char *
eprosima::fastdds::statistics::RESENT_DATAS_TOPIC= "_fastdds_statistics_resent_datas"¶ Statistics topic that reports the number of DATA/DATAFRAG sub-messages resent.
-
constexpr const char *
eprosima::fastdds::statistics::HEARTBEAT_COUNT_TOPIC= "_fastdds_statistics_heartbeat_count"¶ Statistics topic that reports the number of HEARTBEATs that each non discovery DataWriter sends.
-
constexpr const char *
eprosima::fastdds::statistics::ACKNACK_COUNT_TOPIC= "_fastdds_statistics_acknack_count"¶ Statistics topic that reports the number of ACKNACKs that each non discovery DataReader sends.
-
constexpr const char *
eprosima::fastdds::statistics::NACKFRAG_COUNT_TOPIC= "_fastdds_statistics_nackfrag_count"¶ Statistics topic that reports the number of NACKFRAGs that each non discovery DataReader sends.
-
constexpr const char *
eprosima::fastdds::statistics::GAP_COUNT_TOPIC= "_fastdds_statistics_gap_count"¶ Statistics topic that reports the number of GAPs that each non discovery DataWriter sends.
-
constexpr const char *
eprosima::fastdds::statistics::DATA_COUNT_TOPIC= "_fastdds_statistics_data_count"¶ Statistics topic that reports the number of DATA/DATAFRAG sub-messages that each non discovery DataWriter sends.
-
constexpr const char *
eprosima::fastdds::statistics::PDP_PACKETS_TOPIC= "_fastdds_statistics_pdp_packets"¶ Statistics topic that reports the number of PDP discovery traffic RTPS packets transmitted by each DDS participant.
-
constexpr const char *
eprosima::fastdds::statistics::EDP_PACKETS_TOPIC= "_fastdds_statistics_edp_packets"¶ Statistics topic that reports the number of EDP discovery traffic RTPS packets transmitted by each DDS participant.
-
constexpr const char *
eprosima::fastdds::statistics::DISCOVERY_TOPIC= "_fastdds_statistics_discovered_entity"¶ Statistics topic that reports when new entities are discovered.
-
constexpr const char *
eprosima::fastdds::statistics::SAMPLE_DATAS_TOPIC= "_fastdds_statistics_sample_datas"¶ Statistics topic that reports the number of DATA/DATAFRAG sub-messages needed to send a single sample.
-
constexpr const char *
eprosima::fastdds::statistics::PHYSICAL_DATA_TOPIC= "_fastdds_statistics_physical_data"¶ Statistics topic that reports the host, user and process where the module is running.
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 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).
For installing Fast DDS-Gen, please refer to Linux installation of Fast DDS-Gen or to Window 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:
$ fastrtpsgen
Windows:
> fastrtpsgen.bat
Note
In case the PATH has not been modified, these scripts can be found in the <fastrtpsgen_directory>/scripts
directory.
Supported options¶
The expected argument list of the application is:
fastrtpsgen [<options>] <IDL file> [<IDL file> ...]
Where the option choices are:
Option |
Description |
|---|---|
-help |
Shows the help information. |
-version |
Shows the current version of eProsima Fast DDS-Gen. |
-d <directory> |
Sets the output directory where the generated files are created. |
-I <directory> |
Add directory to preprocessor include paths. |
-t <directory> |
Sets a specific directory as a temporary directory. |
-example <platform> |
Generates an example and a solution to compile the generated source code for a specific |
-replace |
Replaces the generated source code files even if they exist. |
-ppDisable |
Disables the preprocessor. |
-ppPath |
Specifies the preprocessor path. |
-typeobject |
Generates TypeObject files for the IDL provided and modifies MyType constructor to |
Please refer to Dynamic Topic Types 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.
.
└── workspace_DDSHelloWorld
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── HelloWorld
│ ├── libHelloWorld_lib.a
│ └── Makefile
├── CMakeLists.txt
├── HelloWorld.cxx
├── HelloWorld.h
├── HelloWorld.idl
├── HelloWorldPublisher.cxx
├── HelloWorldPublisher.h
├── HelloWorldPubSubMain.cxx
├── HelloWorldPubSubTypes.cxx
├── HelloWorldPubSubTypes.h
├── HelloWorldSubscriber.cxx
└── HelloWorldSubscriber.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/fastrtps/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\fastrtps 2.0.0\include\fastrtpsandC:\Program Files\eProsima\fastrtps 2.0.0\include\fastcdr\for Fast DDS and Fast CDR respectively. The compiled libraries of both can be found in the directoryC:\Program Files\eProsima\fastrtps 2.0.0\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 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/fastrtpsgen/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/fastrtpsgen/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:
fastrtpsgen.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/fastrtpsgen
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 receiver 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
publisher->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.
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¶
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 |
char |
octet |
uint8_t |
short |
int16_t |
unsigned short |
uint16_t |
long |
int32_t |
unsigned long |
uint32_t |
long long |
int64_t |
unsigned long long |
uint64_t |
float |
float |
double |
double |
long double |
long double |
boolean |
bool |
string |
std::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] |
std::array<char,5> a |
octet a[5] |
std::array<uint8_t,5> a |
short a[5] |
std::array<int16_t,5> a |
unsigned short a[5] |
std::array<uint16_t,5> a |
long a[5] |
std::array<int32_t,5> a |
unsigned long a[5] |
std::array<uint32_t,5> a |
long long a[5] |
std::array<int64_t,5> a |
unsigned long long a[5] |
std::array<uint64_t,5> a |
float a[5] |
std::array<float,5> a |
double a[5] |
std::array<double,5> a |
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> |
std::vector<char> |
sequence<octet> |
std::vector<uint8_t> |
sequence<short> |
std::vector<int16_t> |
sequence<unsigned short> |
std::vector<uint16_t> |
sequence<long> |
std::vector<int32_t> |
sequence<unsigned long> |
std::vector<uint32_t> |
sequence<long long> |
std::vector<int64_t> |
sequence<unsigned long long> |
std::vector<uint64_t> |
sequence<float> |
std::vector<float> |
sequence<double> |
std::vector<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> |
std::map<char, uint64_T> |
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;
};
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, int> 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 int, 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.
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.
#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 4.2 specification.
User annotations will be passed to TypeObject generated code if the -typeobject argument was used.
@annotation MyAnnotation
{
long value;
string name;
};
Additionally, the following standard annotations are builtin (recognized and passed to TypeObject when unimplemented).
Annotation |
Implemented behavior |
|---|---|
@id |
Unimplemented. |
@autoid |
Unimplemented. |
@optional |
Unimplemented. |
@extensibility |
Unimplemented. |
@final |
Unimplemented. |
@appendable |
Unimplemented. |
@mutable |
Unimplemented. |
@position |
Used by bitmasks. |
@value |
Allows to set a constant value to any element. |
@key |
Alias for eProsima’s @Key annotation. |
@must_understand |
Unimplemented. |
@default_literal |
Allows selecting one member as the default within a collection. |
@default |
Allows specifying the default value of the annotated element. |
@range |
Unimplemented. |
@min |
Unimplemented. |
@max |
Unimplemented. |
@unit |
Unimplemented. |
@bit_bound |
Allows setting a size to a bitmasks. |
@external |
Unimplemented. |
@nested |
Unimplemented. |
@verbatim |
Unimplemented. |
@service |
Unimplemented. |
@oneway |
Unimplemented. |
@ami |
Unimplemented. |
@non_serialized |
The annotated member will be omitted from serialization. |
Most unimplemented annotations are related to Extended Types.
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 two 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 |
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).
How to run¶
On a shell, execute:
fastdds discovery -i {0-255} [optional parameters]
Where the parameters are:
Option |
Description |
|---|---|
|
Mandatory unique server identifier. Specifies zero based server position in |
|
Produce help message. |
|
IP address chosen to listen the clients. Defaults to any (0.0.0.0). |
|
UDP port chosen to listen the clients. Defaults to ‘11811’. |
|
Creates a BACKUP server (see Discovery Protocol) |
The output is:
### Server is running ###
Participant Type: <SERVER|BACKUP>
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>
UDPv4:[<ip-address>]:<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)
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 0Output:
### Server is running ### Participant Type: SERVER 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 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
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 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
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 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
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. |
Version 2.3.0¶
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.
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.
Previous versions¶
Version 2.2.0¶
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.
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 2.1.0¶
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.
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 fastrtpsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.2¶
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 fastrtpsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.1¶
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 fastrtpsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 2.0.0¶
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 1.10.0¶
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 fastrtpsgen. If you are upgrading from a version older than 1.10.0, regenerating the code is recommended.
Version 1.9.4¶
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 fastrtpsgen.
Version 1.9.3¶
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 fastrtpsgen.
Version 1.9.2¶
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 fastrtpsgen.
Version 1.9.1¶
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 fastrtpsgen.
Version 1.9.0¶
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 fastrtpsgen.
Version 1.8.4¶
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 fastrtpsgen
Version 1.8.3¶
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 fastrtpsgen
Version 1.8.2¶
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 fastrtpsgen 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 fastrtpsgen
Version 1.8.1¶
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 fastrtpsgen.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 fastrtpsgen.
Version 1.8.0¶
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 fastrtpsgen.
Version 1.7.2¶
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 fastrtpsgen.
Version 1.7.1¶
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 fastrtpsgen.
Version 1.7.0¶
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 fastrtpsgen.
Version 1.6.0¶
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 fastrtpsgen.
Version 1.5.0¶
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 fastrtpsgen.
Version 1.4.0¶
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 fastrtpsgen.
Version 1.3.1¶
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¶
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 1.2.0¶
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.