Research On The Core Mechanism Of ITU-T T.120-Based Multimedia Data Conference System & Its Implementation Techniques Over Internet

Conference is an important mean of communication and organization of the world. So it's quite meaningful especially in today's over-information world. As one of the modalities of the conference system's development, Computer multimedia conference system is a typical application of modern information technology, which has improved the quality of the long-distance conference and widened the function of traditional conference. Also it makes those who attend the conference can act as in one room, no matter where they are and how far they are away from each othe. All they heed is just a multimedia computer.As an important tool for cooperation, the products of computer multimedia conference system should be in accordance with international standards to meet the need of interconnection, interflow and interoperation. To promote the standardization of computer multimedia conference system, ITU (International Telecommunications Union) has made a series of standards such as H series and T series protocols. These protocols have become the mainstream in the field of developing the conference system since they are featured with high quality of system arrangement; uniform data form exchange; good code reusability; and product interconnection, interflow and interoperation.Nowadays, there're some correspondingly mature products of computer multimedia conference system, such as the Netmeeting of Microsoft and the Sametime of IBM. However, there are still some critical problems to be solved, including the aspects of interconnection, interflow, interoperation and the network topology structure. Inland, although there exists the keen need of the computer multimedia conference system's application, Chinese enterprises have conducted little research on this subject, and what most of them do is to do the secondary development based on the exotic conference system. As the result, great gap of technology has been created between the advanced countries and us in this area. Therefore, for right now, it's urgent to conduct the research on international standards of the computer multimedia conference system,,and develop our own products under those standards to keep up with the international research of multimedia conference system. Hence, Designing, developing and implementing the multimedia data conference according to international standards, becomes the foundation and critical tasks in the computer conference system's development.One of the primary research areas of the MMIT laboratory in which the author has worked for a couple of years is the T.120 protocol based multimedia data conference. We have made advances in implementing a multimedia data conference system over the Internet, and published papers on the leading journals. As one of members of MMIT, I have been actively involved in this research and contributed a lot to it.The main contribution in this thesis can be concluded as followings:1. According to the T.120 characteristic and taking account of the feasibility and expansibility of implementation, put forward a development scheme of data conference system in accordance with T.120 protocol on Internet; define its system structure and function module.2. Bring forward a model named T120 MCU over Internet, and give the detailed implementation in which the conferece topology has been changed from star model to tree model, thus making it possible for more users participating.3. Analyze the security of the data conferece according to T.120 protocols, and give a primaryscenario on its implementation.4. Analyze the under stratum of T. 120 including T. 123, T. 122/T. 125, T. 124, base on the research of MMIT, perfect the implementation of the T.120 software stack in each layer, make the stack more integrate.5. Implement all applications including text-chat, binary file-transefer shared, e-board, application-shared, and meeting-vote, check the validity and make the proof on the correctness of the overall implementation of the T.120 software stack and the analysi...