ROS中Client的编程实现

文章目录

• 简介
• C++
• • 1.代码
  • 2.在CMakeLists中添加编译依赖
  • 3.编译
  • 4.修改环境变量
  • 5.执行
• Python
• • 1.代码
  • 2.编译
  • 3. 设置环境变量
  • 4. 运行
• 总结

简介

编写代码控制spawn，实现添加小海龟操作

C++

1.代码

#include <ros/ros.h>
#include <turtlesim/Spawn.h>

int main(int argc, char** argv)
{
	//初始化节点
	ros::init(argc, argv, "turtle_spawn");
	//创建节点句柄
	ros::NodeHandle n;
	//发现/spawm服务后，创建一个服务客户端，连接名为/spawn的service
	//如果没有找到服务就会一直等待
	ros::service::waitForService("/spawn");
	ros::ServiceClient add_turtle = n.serviceClient<turtlesim::Spawn>("/spawn");
	
	//初始化请求数据
	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 spawn turtle[x: %0.6f, y:%0.6f, name:%s]", srv.request.x, srv.request.y, srv.request.name.c_str());
	
	add_turtle.call(srv);//调用服务，进程处于阻塞状态，直到接受到反馈
	//显示服务结果
	ROS_INFO("Spawn turtle successfully [name:%s]", srv.response.name.c_str());

	return 0;
}

2.在CMakeLists中添加编译依赖

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

注意
catkin_LIBRARIES是前小写后大写

3.编译

回到工作目录
catkin_make

4.修改环境变量

source src/setup.bash

5.执行

rosrun learning_service turtle_spawn

Python

1.代码

#!/usr/bin/env python3
#-*- coding:utf-8 -*-

import sys
import rospy
from turtlesim.srv import Spawn

def turtle_spawn():
	#初始化节点
	rospy.init_node('turtle_spawn')
	
	rospy.wait_for_service('/spawn')
	add_turtle = rospy.ServiceProxy('/spawn', Spawn)
	response = add_turtle(2.0, 2.0, 0.0, 'turtle2')
	return response.name
if __name__ == '__main__':
	print ('Spawn turtle successfully [name:%s]',turtle_spawn())

2.编译

catkin_make

3. 设置环境变量

source devel/setup.bash

4. 运行

rosrun turtlesim turtlesim_node

总结

1. 初始化节点（名字）
2. 创建一个Client实例
3. 在找到service时，发布请求数据
4. 等待service处理之后的应答结构

有2处进程阻塞
1.寻找service
2.等待service的反馈