ROS Compatiblity Node

The ROS compatibility node is an interface that allows packages to be used seamlessly with both ROS 1 and ROS 2. Depending on the environment variable ROS_VERSION, the same API will call either ROS 1 or ROS 2 functions. It is used by creating classes that inherit from the CompatibleNode.

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ROS parameters

Parameters need to be declared before being set or accessed in ROS 2 by default. This is not the case in ROS 1. In order to keep both ROS 1 and ROS 2 modes working in a similar way, the parameter allow_undeclared_parameters is set to True in the ROS 2 version of the CompatibleNode, allowing the use of parameters without declaring them beforehand.

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Services

In ROS 2, services can be called asynchronously. This is not the case in ROS 1. Consequently, the call_service() method of the ROS 2 version waits for the server's response after calling it asynchronously, in order to mimic the ROS 1 synchronous behavior.