The Design And Implementation Of SIP Based Tree Conference System Control Model

With convenient, fast, efficient and economic characteristics to save a lot of time and cost, multimedia conference system has become an important symbol for the informatizations of government and company. Since the feature of NGN and 3G is well supporting for multimedia, multimedia conference system will have a fast development with the coming of NGN and 3G.Multimedia conference system is a typical computer supported collaborative work (CSCW)system, which can build a work environment of "face to face" and "what you see is what I see" to conference participants. By combining communication,computer and multimedia technologies together, multimedia conference system supports discussions or other various collaborations among groups of users in different areas.As a mechanism to co-ordinate and to manage multiple users using different media in different conferences, conference control is the key part of multimedia conference system, it is the basis and core in conference system. It is requires not just by traditional audio or video conference, but also for multi-part network gaming. Since the conference control requirements of different conferences (tightly coupled or loosely coupled) vary, for SIP based multimedia conference system, the most important is how to design a scalable conference control model according the conference type and application, and how to implement a conference framework considering the security and reliability.This dissertation makes a research on design and implementation of SIP based tree conference system control model, includes following outcomes:Firstly, after analysis and comparisons of various conference models, a tree-based multimedia conference framework-TCF using SIP as controlling signaling, has been proposed in this article. TCF have constructed a distributed server tree (DST) for distributing tasks such as floor management and media operation to sub conference servers, which avoided the bottle-neck of single-server conference, and could support server transfer when a sub conference server crashed.Secondly, base on the studies on conference control model and conference control protocols, given a conference control model of TCF, including session management,conference management,floor control,user management and DST management and so on, which completed the whole control functions.Thirdly, according the conference control model, software architecture of the control module has been presented, and a couple of solutions to the key module or key questions during the design and implementation have been studied, such as session control, floor control.Finally, discussed the implementation of control message, and classed the message into conference command and conference notification while implemented command message with SOAP and implemented notification message with SIP.