内含服务的和客户端，运行服务端后可实时监听客户端是否有用户上下线。客户端通过连接服务端可与各个客户端之间进行信息联系。-Containing the service and the client, after running the server if there is a user can real-time monitor the client up and down the line.The client by connecting to the server can contact in