Hi. I am attempting to create a variation of a camera plugin, which I want to publish some additional messages on it's topic. To achieve this, we have to create a completely new Plugin and Sensor modules, which are mostly a full copy of the original code, I am basing my work on.

What are the current tasks expected from a Plugin and from a Sensor?
Why isn't the Sensor module responsible for collecting and converting data, while Plugin module, would be responsible for communications with ROS?