string name
int32 age
---
string feedback

// 加载必要文件，注意Service_demo的加载方式
# include "ros/ros.h"
# include "service_demo/Greeting.h"
# include "string"

// 定义请求处理函数
bool handle_function(service_demo::Greeting::Request &req,
                                        service_demo::Greeting::Response &res)
{
        // 此处我们对请求直接输出
        ROS_INFO("Request from %s with age %d ", req.name.c_str(), req.age);

        // 返回一个反馈，将response设置为"..."
        res.feedback = "Hi " + req.name + ". I'm server!";
        return true;
}

int main(int argc, char **argv)
{
        // 初始化节点，命名为"greetings_server"
        ros::init(argc, argv, "greetings_server");

        // 定义service的server端，service名称为“greetings”，收到request请求之后>传递给handle_function进行处理
        ros::NodeHandle nh;
        ros::ServiceServer service = nh.advertiseService("greetings", handle_function);
        
        ros::spin();
        return 0;
}

# include "ros/ros.h"
# include "service_demo/Greeting.h"

int main(int argc, char **argv)
{
        // 初始化，节点命名为"greetings_client"
        ros::init(argc, argv, "greetings_client");

        // 定义service客户端，service名字为“greetings”，service类型为Service_demo
        ros::NodeHandle nh;
        ros::ServiceClient client = nh.serviceClient<service_demo::Greeting>("greetings");

        // 实例化srv，设置其request消息的内容，这里request包含两个变量，name和age，见Greeting.srv
        service_demo::Greeting srv;
        srv.request.name = "HAN";
        srv.request.age = 20;
        if (client.call(srv))
        {
                // 注意我们的response部分中的内容只包含一个变量response，另，注>意将其转变成字符串
                ROS_INFO("Response from server: %s", srv.response.feedback.c_str());
        }
        else
        {
                ROS_ERROR("Failed to call service Service_demo");
                return 1;
        }
        return 0;
}