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Note: This tutorial assumes that you have completed the previous tutorials: What are Service Pairs?.
(!) 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.

Create ServicePair Messages

Description: Create msgs from .pair definitions.

Keywords: servicepairs, rocon

Tutorial Level: BEGINNER

Next Tutorial: Writing a ServicePair Server (Python)

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.


2019-11-30 13:09