Computer Supported Cooperative Work(CSCW) is the result of the modern development of computer technology, multimedia tech, computer networks and the people's requirement of cooperative work in long-distance. Differ from traditional computer tech., CSCW not only provide the interface between man and machine, but also provide the interface between man and man. Video- conferencing system is one of offshoot of CSCW. It combines the interaction of computer tech., the distribution of networks tech and the authenticity of TV tech. As a result, it changes the use of computer from traditionally isolated application to cooperative work. This project realizes a video conferencing system based on personal computer and common networks. It includes video subsystem, audio subsystem, white- board subsystem and manager subsystem. Furthermore, every subsystem can run independently on a certain extent. This paper introduces some basic knowledge about conferencing system. Then according to the experience of our realization of white-board, we discuss some key technique about white-board emphatically, such as the design for application-layer protocol, the maintenance of awareness between multi-users, the conflict in parallel process, the transfer of large quantities of data on networks. the management of conference data-base and so on. In the paper, we discuss the conference convoking subsystem, server subsystem and the modules in white-board client in detail In the end, we summarize the shortage of the system and give some advice for more developments. |