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description: >- For the inter-process communication between FMU and apps or app to app, AOS applies DDS/ROS2 as a middleware/framework. This page describes default configurations and possible points of modification.

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DDS / ROS2 Configuration

{% hint style="info" %} This API requires at least auterion-api-version: 4 to be available {% endhint %}

For the inter-process communication between FMU and apps or app to app, AOS applies DDS/ROS2 as a middleware/framework. While there are multiple implementations of DDS, Auterion applies FastDDS as the recommended middleware to use. DDS can apply the usage of shared memory and even realizes zero-copying to make the communication most efficient and resource-saving. In order to obtain such a setup, the configuration of DDS has to be setup properly for every application using it.

This setup is done automatically on app installation. A proper configuration file is mounted to each containers and the referring environment variables are set, depending on your app's settings (running in a full access network mode host or more closed bridge network).

For example, the environment variables may be defined as:

FASTRTPS_DEFAULT_PROFILES_FILE=/usr/share/dds/fastdds/fastdds-host-mode.xml RMW_IMPLEMENTATION=rmw_fastrtps_cpp RMW_FASTRTPS_USE_QOS_FROM_XML=1

FASTRTPS_DEFAULT_PROFILES_FILE is a common FastDDS configuration file used for pure DDS communication. The two latter variables are used by ROS2 applications.

{% hint style="info" %} In case a developer intends to use zero-copy messaging, the network mode host has to be set in the auterion-app.yml. {% endhint %}

{% hint style="info" %} In case a developer intends to override the configurations, it needs to be done in the entrypoint of the application. Changes to the auterion-app.yml might not have any effect, as they may be overwritten in the automatic configuration process. {% endhint %}