实现一个局域网即时通讯系统的客户端，用户可自由登录，退出，采用文档-识图结构，可以很容易的扩展其功能如加入私聊等。-Implement a LAN instant messaging system of the client, the user can freely log in, quit, using documents- knowledge graph structure, can easily extend its functionality such as adding whisper