standard messages?
I'm a noob. I've installed ROS on my beagle bone and just worked through the tutorials (I ran the tutorial on the ROS VM).
Now I want to use ROS to control my custom robot. The first thing I want to write is a driver/node/package to control the motor drivers. But, I'm not sure what kind of interface my driver should expose.
Firstly, do I just subscribe to a message type (topic?), or do I create a service? What messages do I use to make my robot move? The turtle tutorial used turtlesim/Velocity to move the robot. I've browsed the code of some other packages, art_servo for example, has throttle, brake and acceleration messages. It looks like these drivers can only work with nodes that specifically know what message to send, that is, there is no standard motion messages.
Is that correct? How reusable are packages written by others if they create their own messages each time?
Or am I missing something?