ros的msg和srv

功能包:chapter2_tutorials
创建一个msg和srv文件:
msg文件
首先在功能包文件夹下创建msg文件,并且创建一个新的文件chapter2_msg1.msg.
内容:
    int32 A;
    int32 B;
    int32 C;
编辑package.xml,从<build_depend>message_genneration</build_depend>和<run_depend>message_runtime</run_depend>行删除<!--------------->;

编辑CMakelist.txt:
1 按照下面表示加入message_generation:
 find_package(catkin REQUIRED COMPONENTS
        roscpp
        std_msg
        message_generation
 )
 2 找到如下行,并且取消注释,并且加入新的消息名称:
  ## Generate message in the 'msg' folder
  add_message_files(
        FILES
        chapter2_msg1.msg
  )
  
  ##Generate added messages and services with any dependencise listed here
  generate_messages(
    generate_messages(
      DEPENDENCIES
      std_msgs
    )
  )
  
  srv文件:
  创建一个srv文件夹.在chapter2_tutorials功能包下创建一个名为srv的文件夹,并创建文件chapter2_srv1.srv,并在文件中增加以下
   int32 A;
   int32 B;
   int32 C;
   ---
   int32 sum;
   
   为了编译新的msg和srv文件,必须取消package.xml和CMakelist.txt的如下的注释.
   找到下面行,并取消注释:
   <build_depend>message_generation</build_depend>
   <run_depend>message_runtime</run_depend>
   找到CMakelist.txt找到下面行,并且取消注释
   
   catkin_package(
   CATKIN_DEPENDS message_runtime
   )
   
   为了生成消息,需要在find_package中添加message_generation行:
   find_package(catkin REQUIRED COMPONENTS
   roscpp
   std_msgs
   message_generation
   )
   
   在 add_message_files(
    FILES
    chapter2_msg1.msg   //添加
   )
   
   在add_message_files(
   FILES
   chapter2_srv1.srv
   )
   
   取消generate_message部分的注释,可以使消息顺利生成;
   
   在功能包package下的src创建example2_a.cpp和example2_b.cpp为名称.
   
   example2_a.cpp代码:
   #inlcued "ros/ros.h"
   #include "chapter2_tutorials/chapter2_srv1.h"               //包含必要的头文件和创建的srv文件
   
   bool add(chapter2_tutorials::chapter2_srv1::Request  &req,  //这个函数会对三个变量求和,并将计算结果发送给给他节点.
            chapter2_tutorials::chapter2_srv1::Respons &res)
   {
      res.sum = req.A + req.B + req.c;
      ROS_INFO("request:A=%1d, B=%1d, C=%1d", (int)req.A,  (int)req.B,  (int)req.C);
      ROS_INFO("sending back response:[%1d]", (int)res.sum);
      return true;
   
   }
   
   int main(int argc,char  **argv)                              
   {
   ros::init(argc,argv, "add_3_ints_server");
   ros::NodeHandle n;
   
   ros::ServiceServer service = n.advertiseService("add_3_ints",add);  //创建服务并在ros中发布广播
   ROS_INFO("Ready to add 3 ints.");
   ros::spin();
   
   return 0;
   }
   
   example2_b.cpp
   #include "ros/ros.h"
   #include "chapter2_tutorials/chapter2_srv1.h"
   #include <cstdlib>
   
   int main(int argc, chat **argv)
   {
      ros::init(argc,argv,"add_3_ints_client");
      if(argc !=4)
      {
          ROS_INFO("usage:add_3_ints_client A B C");
          return 1;
      }
      ros::NodeHandle n;
      ros::ServiceClient client = n.serviceClient<chapter2_tutorials::chapter2_srv1>("add_3_ints");
      chapter2_tutorials::chapter2_srv1 srv;
      srv.request.A = ato11(argv[1]);
      srv.request.B = ato11(argv[2]);
      srv.request.C = ato11(argv[3]);
      if(client.call(srv))
      {
        ROS_INFO("sum:%1d",(long int)srv.response.sum);
        
      }
      else
      {
      ROS_INFO("Failed to call service add_3_ints");
      return 1;
      }
      return 0;
   }