[[abstract]]Due to the protocol's Stateless and Client/Server property in World Wide Web(WWW),It is diffcult to develop online interactive applications such as electronic bulletin board system(BBS) and online pager software(ICQ). On the web, users are unable to interact mutually like online interactive applications. The study is to develop a real-time interactive instant messaging system to provide online interactive applications. In this system , Web can inform users or users notice others online and they can communicate with each others. Active Server Pages (ASP) and it's session object(Session) are used to develop a simulative online messaging system , and the application object of ASP is used as a temporary space for instant messages. T...