15. Typical Use-CasesΒΆ

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:

  • 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:

  • 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.

  • Statistics module. This use case explains how to enable the Statistics module within the monitored application, and how to create a statistics monitoring application.

  • ROS 2 using Fast DDS middleware. Since Fast DDS is the default middleware implementation in 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.