1、功能包下新建src文件:
srv下编写一.srv文件:
内容如下:
int64 a
int64 b
---
int64 sum
package.xml里面最后面加上功能包依赖:
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>
CMakeLists.txt下添加编译选项3处:
(1)find_package( …… message_generation)
(2)catkin_package(CATKIN_DEPENDS rospy std_msgs message_runtime)
(3)add_service_files(FILES AddTwoInts.srv)
2、实现服务器
/**
* AddTwoInts Server
*/
#include "ros/ros.h"
#include "learning_communication/AddTwoInts.h"
// service回调函数,输入参数req,输出参数res
bool add(learning_communication::AddTwoInts::Request &req,
learning_communication::AddTwoInts::Response &res)
{
// 将输入参数中的请求数据相加,结果放到应答变量中
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节点初始化
ros::init(argc, argv, "add_two_ints_server");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个名为add_two_ints的server,注册回调函数add()
ros::ServiceServer service = n.advertiseService("add_two_ints", add);
// 循环等待回调函数
ROS_INFO("Ready to add two ints.");
ros::spin();
return 0;
}
3、客户端
/**
* AddTwoInts Client
*/
#include <cstdlib>
#include "ros/ros.h"
#include "learning_communication/AddTwoInts.h"
int main(int argc, char **argv)
{
// ROS节点初始化
ros::init(argc, argv, "add_two_ints_client");
// 从终端命令行获取两个加数
if (argc != 3)
{
ROS_INFO("usage: add_two_ints_client X Y");
return 1;
}
// 创建节点句柄
ros::NodeHandle n;
// 创建一个client,请求add_two_int service,service消息类型是learning_communication::AddTwoInts
ros::ServiceClient client = n.serviceClient<learning_communication::AddTwoInts>("add_two_ints");
// 创建learning_communication::AddTwoInts类型的service消息
learning_communication::AddTwoInts srv;
srv.request.a = atoll(argv[1]);
srv.request.b = atoll(argv[2]);
// 发布service请求,等待加法运算的应答结果
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;
}
4、编译
打开CMakeLists.txt编辑,添加一下代码:
add_executable(server src/server.cpp)
target_link_libraries(server ${catkin_LIBRARIES})
add_dependencies(server ${PROJECT_NAME}_gencpp)
add_executable(client src/client.cpp)
target_link_libraries(client ${catkin_LIBRARIES})
add_dependencies(client ${PROJECT_NAME}_gencpp)
工作空间根目录下编译:
$ catkin_make
5、执行
$ rosrun learning_communication client 3 4
$ rosrun learning_communication server
显示: