[ros-users] [Discourse.ros.org] Suggestions for std_srvs

Georg Heppner ros.discourse at gmail.com
Tue Jan 10 13:29:33 UTC 2017

But is it really the job of the ROS topic type to carry meaning? Why not use the advertised name for that?

Don't get me wrong, I think it is often very helpful that topics and services carry semantics as you described it. It makes something easier to understand and less error prone if used correctly. But on the other hand, it requires to create a bunch of services or topics for things which are in many cases the same or very similar. I sometimes find myself "missusing" topics just to not have to introduce my own topics just for convenience.

This is especially important when thinking about one of the main strong points of ROS (in my opinion): The strong emphasis on interconnecting different parts of an application together without having to couple them specifically. When I use newly defined topics and services for that, I loose some of the flexibility I otherwise have when using just the generic types of std_msgs. Instead of having two packages perfectly on their own ( _of course they are not on their own as they referr to std\_msgs or std\_srvs but as they will be present on every ros system it is basically the same as having no specific dependency_), I will need to either have one as the dependency of the other or create a third, just to define the communication type.

Additionally there is the option of using the advertised name for semantics. Simple example would be the camera image of a stereo camera simply named camera_left and camera_right instead of using a different message type for each.

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