【RK3399Pro学习笔记】九、ROS客户端Client的编程实现

如何实现一个客户端

初始化ROS节点；
创建一个Client实例；
发布服务请求数据；
等待Server处理之后的应答结果。

C++

创建功能包

cd ~/catkin_workspace/src
catkin_create_pkg learning_service roscpp rospy std_msgs geometry_msgs turtlesim

编写程序

nano ~/catkin_workspace/src/learning_service/src/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;
};

配置CMakeLists.txt

nano ~/catkin_workspace/src/learning_service/CMakeLists.txt

添加

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

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编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun turtlesim turtlesim_node 
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_service turtle_spawn

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python

创建并编写脚本

cd ~/catkin_workspace/src/learning_service
mkdir scripts
cd ~/catkin_workspace/src/learning_service/scripts
nano turtle_spawn.py

#!/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::Spawnimport sys
import rospy
from turtlesim.srv import Spawndef 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servicerospy.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.nameexcept rospy.ServiceException, e:print "Service call failed: %s"%eif __name__ == "__main__":#服务调用并显示调用结果print "Spwan turtle successfully [name:%s]" %(turtle_spawn())

运行

sudo chmod +x ~/catkin_workspace/src/learning_service/scripts/turtle_spawn.py# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun turtlesim turtlesim_node 
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_service turtle_spawn.py

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