創(chuàng)建功能包

cd ~/catkin_ws/src catkin_create_pkg learning_communication roscpp rospy std_msgs geometry_msgs turtlesim

定義 srv 文件

cd ~/catkin_ws/src/learning_communication mkdir srv

創(chuàng)建 AddTwoInts.srv 文件

cd ~/catkin_ws/src/learning_communication/srv touch AddTwoInts.srv

AddTwoInts.srv 文件內(nèi)容

int64 a int64 b --- int64 sum

在package.xml中添加功能包依賴

<build_depend>message_generation</build_depend> <exec_depend>message_runtime</exec_depend>

在CMakeLists.txt添加編譯選項

find_package(catkin REQUIRED COMPONENTS............message_generation )

catkin_package( # INCLUDE_DIRS include # LIBRARIES learning_topicCATKIN_DEPENDS geometry_msgs roscpp rospy std_msgs turtlesim message_runtime # DEPENDS system_lib )

add_service_files(FILES AddTwoInts.srv) generate_messages(DEPENDENCIES std_msgs)

配置完成后，對工程目錄進行編譯

cd ~/catkin_ws catkin_make

通過以下代碼去調(diào)用生成的頭文件

在 src 目錄下創(chuàng)建 兩個 cpp文件

cd ~/catkin_ws/src/learning_communication/src

創(chuàng)建 server.cpp 文件

touch server.cpp

以下是server.cpp 文件中的內(nèi)容
代碼功能：將輸入?yún)?shù)中的請求數(shù)據(jù)相加，結(jié)果放到應(yīng)答變量中

#include <ros/ros.h> #include "learning_communication/AddTwoInts.h"// service回調(diào)函數(shù)，輸入?yún)?shù)req，輸出參數(shù)res bool add(learning_communication::AddTwoInts::Request &req,learning_communication::AddTwoInts::Response &res) {// 將輸入?yún)?shù)中的請求數(shù)據(jù)相加，結(jié)果放到應(yīng)答變量中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節(jié)點初始化ros::init(argc, argv, "add_two_ints_server");// 創(chuàng)建節(jié)點句柄ros::NodeHandle n;// 創(chuàng)建一個名為/show_person的server，注冊回調(diào)函數(shù)personCallbackros::ServiceServer service = n.advertiseService("/add_two_ints", add);// 循環(huán)等待回調(diào)函數(shù)ROS_INFO("Ready to add two ints.");ros::spin();return 0; }

創(chuàng)建 client.cpp 文件

touch client.cpp

client.cpp 文件中的內(nèi)容
代碼功能：發(fā)布service請求，等待加法運算的應(yīng)答結(jié)果

#include <cstdlib> #include <ros/ros.h> #include "learning_communication/AddTwoInts.h"int main(int argc, char** argv) {// 初始化ROS節(jié)點ros::init(argc, argv, "add_two_ints_client");// 從終端命令行獲取兩個加數(shù)if (argc != 3){ROS_INFO("usage: add_two_ints_client X Y");return 1;}// 創(chuàng)建節(jié)點句柄ros::NodeHandle n;// 創(chuàng)建一個client，請求add_two_int service, service消息類型是 learning_communication::AddTwoIntsros::ServiceClient client = n.serviceClient<learning_communication::AddTwoInts>("add_two_ints");// 創(chuàng)建learning_communication::AddTwoInts類型的service消息learning_communication::AddTwoInts srv;srv.request.a = atoll(argv[1]);srv.request.b = atoll(argv[2]);// 發(fā)布service請求，等待加法運算的應(yīng)答結(jié)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; };

在CMakeLists.txt文件中添加以下代碼：

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)

編譯工程項目

cd ~/catkin_ws catkin_make

啟動ROS Master

roscore

啟動自定義的訂閱者節(jié)點

rosrun learning_communication server

啟動自定義的發(fā)布者節(jié)點

rosrun learning_communication client 7 8

Client啟動后發(fā)布服務(wù)請求，并成功接收到反饋結(jié)果。

Server接收到服務(wù)調(diào)用后完成加法求解，并將結(jié)果反饋給Client。

總結(jié)

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