基于ROS 服务通信模式详解

 int64 a int64 b --- int64 sum

 /** * 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; } 

 /** * AddTwoInts Client */ #include  #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("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; } 

 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) 

   learning_communication0.0.0The learning_communication packagehcxTODOcatkingeometry_msgsroscpprospystd_msgsgeometry_msgsroscpprospystd_msgsmessage_generationmessage_runtime 

 1）config：放置功能包中的配置文件，由用户创建，文件名可以不同。 2）include：放置功能包中需要用到的头文件。 3）scripts：放置可以直接运行的Python脚本。 4）src：放置需要编译的C++代码。 5）launch：放置功能包中的所有启动文件。 6）msg：放置功能包自定义的消息类型。 7）srv：放置功能包自定义的服务类型。 8）action：放置功能包自定义的动作指令。 9）CMakeLists.txt：编译器编译功能包的规则。

 message_generation message_runtime

 find_package(catkin REQUIRED COMPONENTS geometry_msgs roscpp rospy std_msgs message_generation ) add_service_files( FILES AddTwoInts.srv ) 

 #include "learning-communication/AddTwoInts.h"

 bool add(learning_communication::AddTwoInts::Request &req,learning_communication::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); ROS_INFO("sending back response: [%ld]", (long int)res.sum); return true; }

 ros::ServiceClient client = n.serviceClient ("add_two_ints"); 

 learning_communication::AddTwoInts srv; srv.request.a = atoll(argv[1]); srv.request.b = atoll(argv[2]);

 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)

 rosservice list     输出可用服务的信息 rosservice call     调用带参数的服务 rosservice type     输出服务类型 rosservice find     依据类型寻找服务find services by service type rosservice uri     输出服务的ROSRPC uri