服务端

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import time, thread
import rospy
from geometry_msgs.msg import Twist
from std_srvs.srv import Trigger, TriggerResponse

pubcommand = False
tpub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)


def command_thread():
    while True:
        if pubcommand:
            v = Twist()
            v.linear.x = 0.5
            v.angular.z = 0.5
            tpub.publish(v)
        time.sleep(0.1)


def callback(req):
    global pubcommand
    pubcommand = bool(1 - pubcommand)
    rospy.loginfo("call the callback! %s", pubcommand)
    return TriggerResponse(1, "change!")


def simpleservice():
    rospy.init_node('sxcservice')
    s = rospy.Service('/turtle_command', Trigger, callback)
    print 'wait!!'
    thread.start_new_thread(command_thread, ())
    rospy.spin()


if __name__ == '__main__':
    simpleservice()

客户端

#!/usr/bin/env python
# coding=utf-8
import rospy
from turtlesim.srv import Spawn


def turtle_spawn():
    # ROS节点初始化，生成节点addturtle
    rospy.init_node('addturtle')
    # 等待'/spawn'服务，若无一直等待
    rospy.wait_for_service('/spawn')
    try:
        # 创建一个连接名为'/spawn'的服务，数据类型为Spawn
        add_turtle = rospy.ServiceProxy('/spawn', Spawn)
        # 调用请求服务，输入请求参数，并得到服务端返回结果
        response = add_turtle(2, 2, 0, 'sxc')
        return response.name
    except rospy.ServiceException, e:
        print e


if __name__ == '__main__':
    rospy.loginfo("creat turtle,name: %s", (turtle_spawn()))