用C++编写一个简单的服务端和客户端

1.首先执行roscd beginner_tutorials命令，然后创建src/add_two_ints_server.cpp服务端源码，内容如下：

  #include "ros/ros.h"
  #include"beginner_tutorials/AddTwoInts.h"

  booladd(beginner_tutorials::AddTwoInts::Request &req,
          beginner_tutorials::AddTwoInts::Response &res)
  {
      res.sum = req.a + req.b;
      ROS_INFO("request: x=%ld,y=%ld", (long int)req.a, (long int)req.b);
      ROS_INFO("sending back response:[%ld]", (long int)res.sum);
      return true;
  }

  int main(int argc, char **argv)
  {
      ros::init(argc, argv,"add_two_ints_server");
      ros::NodeHandle n;
      ros::ServiceServer service =n.advertiseService("add_two_ints", add);
      ROS_INFO("Ready to add twoints.");
      ros::spin();
      return 0;
  }

2.接下来创建src/add_two_ints_client.cpp客户端程序，源码如下：

  #include "ros/ros.h"
  #include"beginner_tutorials/AddTwoInts.h"
  #include <cstdlib>

  int main(int argc, char **argv)
  {
      ros::init(argc, argv,"add_two_ints_client");
      if (argc != 3)
      {
          ROS_INFO("Usage: add_two_ints_clientX Y");
          return 1;
      }
      ros::NodeHandle n;
      ros::ServiceClient client =n.serviceClient("add_two_ints");
      beginner_tutorials::AddTwoInts srv;
      srv.request.a = atoll(argv[1]);
      srv.request.b = atoll(argv[2]);
      if (client.call(srv))
      {
          ROS_INFO("Sum: %ld", (longint)srv.response.sum);
      }
      else
      {
          ROS_ERROR("Failed to callservice add_two_ints");
          return 1;
      }
      return 0;
  }

3.接下来修改CMakeLists.txt文件，在文件尾部添加如下内容：

  add_executable(add_two_ints_serversrc/add_two_ints_server.cpp)
  target_link_libraries(add_two_ints_server${catkin_LIBRARIES})
  add_dependencies(add_two_ints_serverbeginner_tutorials_gencpp)

  add_executable(add_two_ints_clientsrc/add_two_ints_client.cpp)
  target_link_libraries(add_two_ints_client${catkin_LIBRARIES})
  add_dependencies(add_two_ints_clientbeginner_tutorials_gencpp)

4.编译运行

  cd ~/ros/catkin_ws
  catkin_make

  执行如下命令运行服务端：

  rosrun beginner_tutorials add_two_ints_server

  执行后会有如下提示：

  [ INFO] [1497789377.150363403]: Ready to addtwo ints.

  接下来执行客户端：

  rosrun beginner_tutorialsadd_two_ints_client  1 3

  会有如下提示：

  [ INFO] [1497789453.191450800]: Sum: 4

  而刚才服务端会有如下提示：

  [ INFO] [1497789453.191038638]: request: x=1,y=3
  [ INFO] [1497789453.191116375]: sending backresponse: [4]

参考网址：http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28c%2B%2B%29