创建使用msg,srv和topic注意事项

creat .msg后，

（1）必须在package.xml中添加依赖项：

<build_depend>message_generation</build_depend>
<run_depend>message_runtime</run_depend>

（2）在CMakeLists.txt中添加message_generation：

find_package(catkin REQUIRED COMPONENTS
   roscpp
   rospy
   std_msgs
   message_generation
)
[code]catkin_package(
  ...
  CATKIN_DEPENDS message_runtime ...
  ...)

and uncomment :

add_message_files(
  FILES
  Num.msg    ### msg which you create
)
[code]generate_messages(   
  DEPENDENCIES  
  std_msgs  
)

If you have a previously compiled workspace and you add a new package inside it, you can tell catkin to add this new package to the already-compiled binaries by adding this parameter:

$ catkin_make --force-cmake
$ source

NOTES：

a， ***.h文件不是自己写的，

#include "beginner_tutorials/AddTwoInts.h"   ##  it is a header file generated from the srv file that we created earlier.

b， 新建**.c ， **.py文件后，必须修改对应的CMakeLists.txt。

c , rosbag info <your bagfile> 查看bag信息。

d, rosdep install turtlesim 下载turtlesim包的依赖项。

WORKFLOW：

<pre name="code" class="cpp">$ cd ~/catkin_ws/src/beginner_tutorials/src
# Add/Edit source files
$ cd ~/catkin_ws/src/beginner_tutorials
# Update CMakeFiles.txt to reflect any changes to your sources
$ cd ~/catkin_ws
$ catkin_make -DCMAKE_BUILD_TYPE=Release

参考： http://wiki.ros.org/ROS/Tutorials/CreatingMsgAndSrv