*ActionServer cancel implementation
I'm confused about how to implement cancelling in action servers. I'm under the impression that I'll need an ActionServer rather than a SimpleActionServer, but I'm hoping I'm wrong.
The actionlib detailed description page says that cancel request is a client action rather than a server action. It also shows a cancel request as the only way to transition to the preempting or recalling states. Yet the SimpleActionServer can recall goals upon receipt of a new goal. Is it just interpreting new goals as cancel requests and cancelling its own goals, or is a SimpleActionClient also sending a cancel message along with a new goal? Must I use a SimpleActionServer with a SimpleActionClient or could I have a specialized regular ActionServer with a SimpleActionClient?
Here's why I'm asking: I'm designing an action server. The client must be able to cancel active goals. However, no newly received goal should replace an active goal; instead the server should reject them. I'll need a special callback for cancelling goals where I stop motors and whatnot.
Thanks for your help.
