利用I/O复用机制撰写的简单心跳客户端和服务器。主要包括以下工作：

设计客户端和服务器之间交互的报文格式；

设计客户端，具有发送心跳和超时重发的功能；

设计服务器，具有接收心跳和其他程序的能力，具有超时重发的能力。

编程语言：C-I/O multiplexing mechanism written the simple heartbeat client and server. Mainly include the following: design of the interaction between the client and server message format　design the client has to send the heartbeat and timeout retransmission function　design server, with the ability to receive heartbeat and other programs, with a timeout retransmission capacity. Programming languages: C++