ROS学习笔记（九）：客户端与服务端

1.创建一个服务节点

首先进入工作空间

roscd beginner_tutorials 创建一个add_two_ints_server.cpp，代码如下

1 #include "ros/ros.h" 2 #include "beginner_tutorials/AddTwoInts.h" 3 4 bool add(beginner_tutorials::AddTwoInts::Request &req, 5 beginner_tutorials::AddTwoInts::Response &res) 6 { 7 res.sum = req.a + req.b; 8 ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (long int)req.b); 9 ROS_INFO("sending back response: [%ld]", (long int)res.sum); 10 return true; 11 } 12 13 int main(int argc, char **argv) 14 { 15 ros::init(argc, argv, "add_two_ints_server"); 16 ros::NodeHandle n; 17 18 ros::ServiceServer service = n.advertiseService("add_two_ints", add); 19 ROS_INFO("Ready to add two ints."); 20 ros::spin(); 21 22 return 0; 23 } 这个cpp创建了一个将两个整型数相加的函数，调用在srv文件夹下定义的request和response，

2.创建一个客户端节点

创建add_two_ints_client.cpp

1 #include "ros/ros.h" 2 #include "beginner_tutorials/AddTwoInts.h" 3 #include <cstdlib> 4 5 int main(int argc, char **argv) 6 { 7 ros::init(argc, argv, "add_two_ints_client"); 8 if (argc != 3) 9 { 10 ROS_INFO("usage: add_two_ints_client X Y"); 11 return 1; 12 } 13 14 ros::NodeHandle n; 15 ros::ServiceClient client = n.serviceClient<beginner_tutorials::AddTwoInts>("add_two_ints"); 16 beginner_tutorials::AddTwoInts srv; 17 srv.request.a = atoll(argv[1]); 18 srv.request.b = atoll(argv[2]); 19 if (client.call(srv)) 20 { 21 ROS_INFO("Sum: %ld", (long int)srv.response.sum); 22 } 23 else 24 { 25 ROS_ERROR("Failed to call service add_two_ints"); 26 return 1; 27 } 28 29 return 0; 30 } 编辑CMakeList.txt

https://raw.github.com/ros/catkin_tutorials/master/create_package_srvclient/catkin_ws/src/beginner_tutorials/CMakeLists.txt

并在最后加上

27 add_executable(add_two_ints_server src/add_two_ints_server.cpp) 28 target_link_libraries(add_two_ints_server ${catkin_LIBRARIES}) 29 add_dependencies(add_two_ints_server beginner_tutorials_gencpp) 30 31 add_executable(add_two_ints_client src/add_two_ints_client.cpp) 32 target_link_libraries(add_two_ints_client ${catkin_LIBRARIES}) 33 add_dependencies(add_two_ints_client beginner_tutorials_gencpp) 创建两个可执行文件，并添加库和依赖项。

3.编译运行

# In your catkin workspace cd ~/catkin_ws catkin_make 运行服务端程序

rosrun beginner_tutorials add_two_ints_server

Ready to add two ints.

运行客户端程序

rosrun beginner_tutorials add_two_ints_client 1 3 Requesting 1+3 1 + 3 = 4