Note: This tutorial assumes that you have completed the previous tutorials: Create ServicePair Messages.
(!) Please ask about problems and questions regarding this tutorial on answers.ros.org. Don't forget to include in your question the link to this page, the versions of your OS & ROS, and also add appropriate tags.

Writing a ServicePair Server (Python)

Description: Simple example of a service pair server in python.

Keywords: servicepair, rocon

Tutorial Level: INTERMEDIATE

Next Tutorial: Writing a ServicePair Client (Python)

Overview

This tutorial demonstrates how to write a service pair server in python. There are two ways to do this but in both all you need is a callback function to provide to the ServicePairServer class. In the first method this callback will run directly, and in the second method, this callback will be put into a thread.

Non-Threaded

   1 #!/usr/bin/env python
   2 
   3 import rospy
   4 from chatter.msg import ChatterRequest, ChatterResponse, ChatterPair
   5 from rocon_python_comms import ServicePairServer
   6 
   7 class ChatterServer(object):
   8 
   9     def __init__(self):
  10         self.server = ServicePairServer('chatter', self.callback, ChatterPair)
  11         
  12     def callback(self, request_id, msg):
  13         rospy.loginfo("Server : I heard %s" % msg.babble)
  14         response = ChatterResponse()
  15         response.reply = "I heard %s" % msg.babble
  16         self.server.reply(request_id, response) 
  17 
  18 if __name__ == '__main__':
  19     rospy.init_node('chatter_server', anonymous=True)
  20     chatter_server = ChatterServer()
  21     rospy.spin()    

Threaded

Use this when your callback will take either an indeterminate amount of time to resolve or it requires non-negligible work. To configure the server, just toggle the use_threads variable to True:

   1     self.server = ServicePairServer('chatter', self.callback, ChatterPair, use_threads=True)

Wiki: rocon_python_comms/Tutorials/indigo/Writing a ServicePair Server (Python) (last edited 2015-08-01 04:40:57 by MarcusLiebhardt)