（十一）创建一个简单的service和client

参考网址：

http://www.ros.org/wiki/ROS/Tutorials/WritingServiceClient(c++)

1，编写一个简单的service节点

创建add_two_ints_server节点，作用是接受2个ints，和返回sum.

$ roscdbeginner_tutorials

$ touchsrc/add_two_ints_server.cpp －－－创建add_two_ints_server.cpp文件在src文件夹内。

$ emacssrc/add_two_ints_server.cpp     －－－用emacs编辑

输入：

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

bool add(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 two ints.");
  ros::spin();

  return 0;
}

2，编写client节点

$ touchsrc/add_two_ints_client.cpp   －－－创建client文件

$ emacssrc/add_two_ints_client.cpp －－－用emacs编辑修改

输入：

#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_client X Y");
    return 1;
  }

  ros::NodeHandle n;
  ros::ServiceClient client = n.serviceClient<beginner_tutorials::AddTwoInts>("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", (long int)srv.response.sum);
  }
  else
  {
    ROS_ERROR("Failed to call service add_two_ints");
    return 1;
  }

  return 0;
}

3，编译节点

$ rosedbeginner_tutorials CMakeLists.txt    －－－编辑CMakeLists.txt文件

在最后添加：

rosbuild_add_executable(add_two_ints_server src/add_two_ints_server.cpp)
rosbuild_add_executable(add_two_ints_client src/add_two_ints_client.cpp)

$make