A Web based Multipoint Application Model without Real-time Constraints

This paper presents a web based multipoint communication model which differs from the multimedia conferencing model defined by ITU-T T.120 series of recommendations. The T.120 series are built on top of OSI Transport layer, and are suitable for real-time conferences. For applications that need universal access instead of stringent real-time constraints imposed by audio and video conferencing, the model presented in this paper is easier and lighter. We built our multipoint control on top of HTTP sessions or connections. This model can be easily implemented by attainable, inexpensive server side scripts like PHP. It uses refresh mechanism of the Web to facilitate periodical message exchanges between a Web server and its client, and makes web clients feel like they are sending and receiving messages in their group. Not only can text and graphic messages be exchanged in our model, but any messages that can be posted to the web server can also be exchanged. We demonstrate a go game platform. Each go game is played by a group of two people, and our model is to manage the dynamic, arbitrary groups. With DHTMI, richer contents can also be exchanged. This paper also demonstrates a whiteboard system, which can be shared by a group of people.