Calling a third party service on a client

edit

This is a bit of a guess, but:

However, this method needs a callback function which is implemented on the server side, which I don't have access.

Are you referring to this line in the Writing the Client Node section:

add_two_ints = rospy.ServiceProxy('add_two_ints', AddTwoInts)

and then specifically AddTwoInts?

That is not a callback method, but the type of the service.

Edit:

However the issue stands: How call I call the the service, once I don't have access to server side of code?

I don't really understand your question. Is the tutorial not clear?

You create a ServiceProxy instance. This instance is a callable by itself, so once bound, you can invoke the service by doing something like:

result = add_two_ints(1, 2)

See also wiki/rospy/Overview/Services - Service proxies on the wiki, which might be clearer than the tutorial.

If this still doesn't help you, then you'll have to explain more precisely what it is you don't understand.

Edit2: are you actually wondering how to get access to the type definitions for the remote service? If that is the case, you'll have to make sure to import the correct class from the ROS package that defines the service files.

For the hector_quadrotor collection of packages, that is probably hector_uav_msgs, so something like the following should work (after having declared a proper run_depend on the package):

from hector_uav_msgs.srv import EnableMotors

and then the ServiceProxy instance should be created like so:

motors_on = rospy.ServiceProxy('enable_motors', EnableMotors)