Description

Currently there is no example for a lifecycle node that can be used as a component.

This could be a simple talker node, which only publishes messages when active.

Motivation

Currently there is no example lifecycle node component.
This is not a really critical example for how to use the API, as it is relatively straightforward; however, it is essential for testing features such as lifecycle node components in launch_ros, which currently do not behave correctly when namespaced (ros2/launch_ros#479).

Having access to such a lifecycle node component will allow for testing of related features and prevent regression from happening in the future.

Design / Implementation Considerations

The node would need to be testable such that an effect can be measured after its transition.

An alternative to a new lifecycle node component is to convert the existing lifecycle node to a node component.
However, this would complicate the basic lifecycle node example unnecessarily.

Additional Information

Related to ros2/launch_ros#479, ros2/launch_ros#480, ros2/launch_ros#481

I could write this; however, I would be unsure in which package to put it.