7、客户端Client的编程实现
- 创建功能包
cd ~/catkin_ws/src catkin_create_pkg learning_service roscpp rospy std_msgs geometry_msgs turtlesim
- 创建客户端代码(C++) ——文件名为turtle_spawn.cpp
/*********************************************************************** Copyright 2020 GuYueHome (www.guyuehome.com). ***********************************************************************/ /** * 该例程将请求/spawn服务,服务数据类型turtlesim::Spawn */ #include <ros/ros.h> #include <turtlesim/Spawn.h> int main(int argc, char** argv) { // 初始化ROS节点 ros::init(argc, argv, "turtle_spawn"); // 创建节点句柄 ros::NodeHandle node; // 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的serviceros::service::waitForService("/spawn"); ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn> ("/spawn"); // 初始化turtlesim::Spawn的请求数据 turtlesim::Spawn srv; srv.request.x = 2.0; srv.request.y = 2.0; srv.request.name = "turtle2"; // 请求服务调用 ROS_INFO("Call service to spwan turtle[x:%0.6f, y:%0.6f, name:%s]", srv.request.x, srv.request.y, srv.request.name.c_str()); add_turtle.call(srv); // 显示服务调用结果 ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str()); return 0; };
总结上面的代码,实现一个客户端的步骤为:
初始化ROS节点
创建一个Client实例
发布服务请求数据
等待Server处理后的应答结果
python代码如下:
#!/usr/bin/env python # -*- coding: utf-8 -*- ######################################################################## #### Copyright 2020 GuYueHome (www.guyuehome.com). ### ######################################################################## # 该例程将请求/spawn服务,服务数据类型turtlesim::Spawn import sys import rospy from turtlesim.srv import Spawn def turtle_spawn(): # ROS节点初始化 rospy.init_node('turtle_spawn') # 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的service rospy.wait_for_service('/spawn') try: add_turtle = rospy.ServiceProxy('/spawn', Spawn) # 请求服务调用,输入请求数据 response = add_turtle(2.0, 2.0, 0.0, "turtle2")return response.name except rospy.ServiceException, e: print "Service call failed: %s"%e if __name__ == "__main__": #服务调用并显示调用结果 print "Spwan turtle successfully [name:%s]" %(turtle_spawn())
- 配置客户端代码编译规则
设置需要的编译的代码和生成的可执行文件
add_executable(turtle_spawn src/turtle_spawn.cpp)
设置链接库
target_link_libraries(turtle_spawn ${catkin_LIBRARIES})
- 编译并运行客户端
cd ~/catkin_ws catkin_make roscore rosrun turtlesim turtlesim_node rosrun learning_service turtle_spawn
运行结果如下,在坐标(2,2)处产生了一只新的乌龟。
8、服务端Server的编程实现
- 创建服务器代码(C++) ——文件名为turtle_command_server.cpp
/*********************************************************************** Copyright 2020 GuYueHome (www.guyuehome.com). ***********************************************************************/ /** * 该例程将执行/turtle_command服务,服务数据类型std_srvs/Trigger */ #include <ros/ros.h> #include <geometry_msgs/Twist.h> #include <std_srvs/Trigger.h> ros::Publisher turtle_vel_pub; bool pubCommand = false; // service回调函数,输入参数req,输出参数res bool commandCallback(std_srvs::Trigger::Request &req, std_srvs::Trigger::Response &res) { pubCommand = !pubCommand; // 显示请求数据 ROS_INFO("Publish turtle velocity command [%s]", pubCommand==true?"Yes":"No"); // 设置反馈数据 res.success = true; res.message = "Change turtle command state!"; return true; } int main(int argc, char **argv) { // ROS节点初始化 ros::init(argc, argv, "turtle_command_server"); // 创建节点句柄 ros::NodeHandle n; // 创建一个名为/turtle_command的server,注册回调函数commandCallback ros::ServiceServer command_service = n.advertiseService("/turtle_command", commandCallback); // 创建一个Publisher,发布名为/turtle1/cmd_vel的topic,消息类型为 geometry_msgs::Twist,队列长度10 turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10); // 循环等待回调函数 ROS_INFO("Ready to receive turtle command."); // 设置循环的频率 ros::Rate loop_rate(10); while(ros::ok()) {// 查看一次回调函数队列 ros::spinOnce(); // 如果标志为true,则发布速度指令 if(pubCommand) { geometry_msgs::Twist vel_msg; vel_msg.linear.x = 0.5; vel_msg.angular.z = 0.2; turtle_vel_pub.publish(vel_msg); } //按照循环频率延时 loop_rate.sleep(); } return 0; }
总结上面的代码,实现一个服务器的步骤为:
初始化ROS节点
创建Serveer实例
循环等待服务请求,进入回调函数
在回调函数中完成服务功能的处理,并反馈应答数据
python代码如下:
#!/usr/bin/env python # -*- coding: utf-8 -*- ######################################################################## #### Copyright 2020 GuYueHome (www.guyuehome.com). ### ######################################################################## # 该例程将执行/turtle_command服务,服务数据类型std_srvs/Trigger import rospy import thread,time from geometry_msgs.msg import Twist from std_srvs.srv import Trigger, TriggerResponse pubCommand = False; turtle_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10) def command_thread(): while True: if pubCommand: vel_msg = Twist() vel_msg.linear.x = 0.5 vel_msg.angular.z = 0.2 turtle_vel_pub.publish(vel_msg) time.sleep(0.1) def commandCallback(req):global pubCommand pubCommand = bool(1-pubCommand) # 显示请求数据 rospy.loginfo("Publish turtle velocity command![%d]", pubCommand) # 反馈数据 return TriggerResponse(1, "Change turtle command state!") def turtle_command_server(): # ROS节点初始化 rospy.init_node('turtle_command_server') # 创建一个名为/turtle_command的server,注册回调函数commandCallback s = rospy.Service('/turtle_command', Trigger, commandCallback) # 循环等待回调函数 print "Ready to receive turtle command." thread.start_new_thread(command_thread, ()) rospy.spin() if __name__ == "__main__": turtle_command_server()
- 配置服务器代码编译规则
设置需要编译的代码和生成可执行文件
add_executable(turtle_command_server src/turtle_command_server.cpp)
设置链接库
target_link_libraries(turtle_command_server ${catkin_LIBRARIES})
- 编译并运行服务器
cd ~/catkin_ws catkin_make roscore rosrun turtlesim turtlesim_node rosrun learning_service turtle_command_server rosservice call /turtle_command "{}"
运行结果如下,可以发现可以通过客户端发送请求,然后达到控制海龟的运动和停止。
9、自定义服务数据
- 自定义服务数据
定义srv文件
//在learning_service目录下创建srv文件夹 cd ~/catkin_ws/src/learning_topic mkdir srv //创建Penson.srv文件 touch Person.srv
创建好Person.srv文件后,在文件中写入以下内容:
string name uint8 sex uint8 age uint8 unknown = 0 uint8 male = 1 uint8 female = 2 --- string result
在package.xml中添加功能包依赖
<build_depend>message_generation</build_depend> <exec_depend>message_runtime</exec_depend>
在CMakeLists.txt中添加编译选项
find_package( ...... message_generation)add_service_files(FILES Person.srv) generate_messages(DEPENDENCIES std_msgs) catkin_package(...... message_runtime)
add_service_files(FILES Person.srv) generate_messages(DEPENDENCIES std_msgs)
catkin_package(…… message_runtime)
编译生成语言相关文件
cd ~/catkin_ws catkin_make
- 创建服务器代码(C++)——文件名为person_server.cpp
/*********************************************************************** Copyright 2020 GuYueHome (www.guyuehome.com). ***********************************************************************/ /** * 该例程将执行/show_person服务,服务数据类型learning_service::Person */ #include <ros/ros.h> #include "learning_service/Person.h" // service回调函数,输入参数req,输出参数res bool personCallback(learning_service::Person::Request &req, learning_service::Person::Response &res) {// 显示请求数据 ROS_INFO("Person: name:%s age:%d sex:%d", req.name.c_str(), req.age, req.sex); // 设置反馈数据 res.result = "OK"; return true; } int main(int argc, char **argv) { // ROS节点初始化 ros::init(argc, argv, "person_server"); // 创建节点句柄 ros::NodeHandle n; // 创建一个名为/show_person的server,注册回调函数personCallback ros::ServiceServer person_service = n.advertiseService("/show_person", personCallback); // 循环等待回调函数 ROS_INFO("Ready to show person informtion."); ros::spin(); return 0; }
该部分和之前的步骤基本一致,这里不再进行总结。
python代码如下:
#!/usr/bin/env python # -*- coding: utf-8 -*- ######################################################################## #### Copyright 2020 GuYueHome (www.guyuehome.com). ### ######################################################################## # 该例程将执行/show_person服务,服务数据类型learning_service::Person import rospy from learning_service.srv import Person, PersonResponse def personCallback(req): # 显示请求数据 rospy.loginfo("Person: name:%s req.sex) # 反馈数据 return PersonResponse("OK") def person_server(): age:%d sex:%d", req.name, req.age,# ROS节点初始化 rospy.init_node('person_server') # 创建一个名为/show_person的server,注册回调函数personCallback s = rospy.Service('/show_person', Person, personCallback) # 循环等待回调函数 print "Ready to show person informtion." rospy.spin() if __name__ == "__main__": person_server()
- 创建客户端代码(C++)——文件名为person_client.cpp
/*********************************************************************** Copyright 2020 GuYueHome (www.guyuehome.com). ***********************************************************************/ /** * 该例程将请求/show_person服务,服务数据类型learning_service::Person */ #include <ros/ros.h> #include "learning_service/Person.h" int main(int argc, char** argv) { // 初始化ROS节点 ros::init(argc, argv, "person_client"); // 创建节点句柄 ros::NodeHandle node; // 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的service ros::service::waitForService("/show_person"); ros::ServiceClient person_client = node.serviceClient<learning_service::Person>("/show_person"); // 初始化learning_service::Person的请求数据 learning_service::Person srv; srv.request.name = "Tom"; srv.request.age = 20; srv.request.sex = learning_service::Person::Request::male; // 请求服务调用 ROS_INFO("Call service to show person[name:%s, age:%d, sex:%d]", srv.request.name.c_str(), srv.request.age, srv.request.sex); person_client.call(srv); // 显示服务调用结果 ROS_INFO("Show person result : %s", srv.response.result.c_str());return 0; };
python代码如下:
#!/usr/bin/env python # -*- coding: utf-8 -*- ######################################################################## #### Copyright 2020 GuYueHome (www.guyuehome.com). ### ######################################################################## # 该例程将请求/show_person服务,服务数据类型learning_service::Person import sys import rospy from learning_service.srv import Person, PersonRequest def person_client(): # ROS节点初始化 rospy.init_node('person_client') # 发现/spawn服务后,创建一个服务客户端,连接名为/spawn的service rospy.wait_for_service('/show_person') try: person_client = rospy.ServiceProxy('/show_person', Person) # 请求服务调用,输入请求数据 response = person_client("Tom", 20, PersonRequest.male) return response.result except rospy.ServiceException, e: print "Service call failed: %s"%e if __name__ == "__main__": #服务调用并显示调用结果 print "Show person result : %s" %(person_client())
- 配置服务器/客户端代码编译规则
设置需要编译的代码和可执行文件
设置链接库
添加依赖项
add_executable(person_server src/person_server.cpp) target_link_libraries(person_server ${catkin_LIBRARIES}) add_dependencies(person_server ${PROJECT_NAME}_gencpp) add_executable(person_client src/person_client.cpp) target_link_libraries(person_client ${catkin_LIBRARIES}) add_dependencies(person_client ${PROJECT_NAME}_gencpp)
- 编译并运行客户端和服务器
cd ~/catkin_ws catkin_make roscore rosrun learning_service person_server rosrun learning_service person_client
运行结果如下,可以发现每次客户端发送请求后,服务器做出响应。
