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Create ServicePair Messages

Overview

This tutorial takes you through the process of creating a package with .pair definitions and inspecting the results of the build.

Define the Pair

> catkin_create_pkg chatter
> cd chatter
> mkdir pairs
> echo "string babble" > pairs/Chatter.pair
> echo "----" >> pairs/Chatter.pair
> echo "string reply" >> pairs/Chatter.pair

In your CMakeLists.txt, you'll need a dependency on rocon_service_pair_msgs as well as the add_service_pair_files macro to trigger generation of the messages:

   1 find_package(catkin REQUIRED COMPONENTS 
   2     message_generation 
   3     rocon_service_pair_msgs
   4 )
   5 
   6 add_service_pair_files(
   7   DIRECTORY pairs
   8   FILES
   9   Chatter.pair
  10 )
  11 generate_messages(DEPENDENCIES rocon_service_pair_msgs)
  12 
  13 catkin_package(CATKIN_DEPENDS
  14   message_runtime
  15   rocon_service_pair_msgs
  16 )

Don't forget to add message_xxx and rocon_service_pair_msgs to your package.xml:

   1   <build_depend>message_generation</build_depend>
   2   <build_depend>rocon_service_pair_msgs</build_depend>
   3 
   4   <run_depend>message_runtime</run_depend>
   5   <run_depend>rocon_service_pair_msgs</run_depend>

Build

You should be able to catkin_make this package now and detect the output in the cmake step:

-- +++ processing catkin package: 'chatter'
-- ==> add_subdirectory(chatter)
-- Using these message generators: gencpp;genlisp;genpy
-- Generating .msg files for service pair chatter/Chatter
--      ... this is hard work, toss me a beer!
-- chatter: 5 messages, 0 services

The resulting pub/sub messages can be found in devel/share/chatter/msg.