在Windows下编写基于消息的网络应用程序，掌握阻塞与非阻塞网络程序的编写，理解在Windows平台下，采用异步选择机制可以提高网络应用程序的性能。-Master blocking and non-blocking network program to write message-based network applications, understanding the the the asynchronous selection mechanism can improve the perfo