A multimedia collaborative workspace system using the object-oriented design approach

摘要

With the personalization of computers and the advances of communications technology, it becomes possible for people to work together productively in new ways. One such outcome is the electronic collaborative workspace--an organization-wide system that integrates information processing and communication activities. The recent advances of the multimedia technology along with the availability of the high-speed, high-bandwidth network, such as ATM network, make it possible to develop and deploy the distributed collaborative workspace systems which use the multimedia informations. We call the system as a Multimedia Collaborative Workspace System (MCWS). Its features include the multimedia teleconferencing and other useful functions from e-mail, whiteboards, group decision support system and Web browsers. In this research, MCWS is designed using the object-oriented approach and design, and implemented using C++ language. Among the many benefits of the object-oriented programming, the inheritance is explored to design and implement the multimedia devices and communications devices. The flexibility of the system was achieved by the use of the dynamic binding at the run time, and the abstract data type and inheritance made it to be more reliable and reusable. The overall maintenance and modification of the collaborative system became easier with the object-oriented programming approach. The multimedia synchronization mechanism has been also developed for the synchronization of the multimedia streams in the collaborative workspace system, which suffered a different transmission delay over the network. By using time-stamping, Network Time Protocol, and shared memory with semaphore, three different algorithms were developed for three different system environments. The synchronized memory, inherited from the shared memory and semaphore, was also implemented by the object-oriented programming method. The synchronization mechanism was tested by the human subjective test and also by the network simulation using the real Internet data. The object-oriented programming in many aspects of the MCWS makes it flexible and reusable, and extensible. Also it will facilitate the prototyping and an iterative approach to software development of the next version of the system.