说明：  其实很简单，就是利用ajax中updatepanel实现无刷新显示 然后利用timer实现重复的调用 application保存聊天信息 session保存登陆人信息
(In fact very simple, it is using the ajax in the realization of a updatepanel refresh display and then use the call timer to repeat realize Save chat application information session preservation landing Information)