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++)
如何实现一个客户端
*初始化ROS客户端;
*创建一个Client实例;
*发布服务请求数据;
*等待Server处理之后的应答结果

/**
 * 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service
	ros::service::waitForService("/spawn");//阻塞型函数
	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); //阻塞型函数

	// 显示服务调用结果
	ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str());

	return 0;
};

配置客户端代码编译规则
如何配置CMakeLists.txt中的编译规则
*设置需要编译的代码和生成的可执行文件
*设置链接库

//配置CMakeLists.txt
add_executable(turtle_spawn src/turtle_spawn.cpp)
target_link_libraries(turtle_spawn ${catkin_LIBRARIES})

编译并运行客户端

//编译并运行
cd ~/catkin_ws
catkin_make
source devel/setup.bash
roscore
//新开一个终端,开启turtlesim
rosrun turtlesim turtlesim_node
//新开一个终端,运行发布者cpp程序
rosrun learning_service turtle_spawn

创建客户端代码(python)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 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())