一種全球網多點通訊模型

Abstract

本文提出一種基於全球網的多點通訊模型，與ITU-T T.120系列標準不同的是T.120系列是建構於OSI傳輸層上面，而我們的模型是在Web上頭利用cookie加上一層多點控制層。T.120系列主要用於視訊及語音會議，有很強的即時性需求限制。如果不需要即時性限制，本文所提的模型相較之下，顯得輕巧許多，而且此模型可以利用PHP這類免費且常用的工具加以實作，用途更廣。本模型利用更新網頁的方式，作為網頁使用者相互傳遞訊息的方法，使用者間不僅可以互傳文字訊息，也可以傳遞圖形或其他可以上傳到伺服器的訊息。我們也實作了動態聊天室、圍碁及電子白板等應用，以展現此模型對於傳輸內容的處理能力。

The thesis 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 here is easier and lighter. We built a layer of multipoint control on top of HTTP sessions or connections by use of cookies. 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 clients. Not only text messages can be exchanged in our model, but graphic and any messages that can be posted to the web server can also be exchanged. A few applications, such as go games, dynamic chat rooms, and whiteboards are also presented to demonstrate the rich contents that this model is able to handle.