Research On Group Communication Mechanism In Cooperative Editing System

The Cooperative Editing System is an important research subject of Computer Supported Cooperation Work(CSCW),Like other CSCW systems, it relies on group communication. But there are still some shortages in existing group communication systems' architectures and mechanisms, so a novel system InterGCS is proposed.Firstly,based on the analysis of the previous group communication system's architecture and combined the Cooperative Editing System's running environment, the paper presents a hierarchic group communication model which is designed derectly to the WAN,and the client/server architecture is introduced into this model. By this architecture, the system can provide the services for any users with good scalability and wide applicability. Based on the new communication model,the paper point out that reliable and ordered message transmission and group membership management are two main parts of group communication system.in the aspect of reliable and ordered message transmission,a set of management mechanisms is designed for supporting reliable and ordered message transmission. In the management of group membership managerment, unlike predefining algorithm setting the failure detection TIMEOUT value in advance,the Adaptive Failure Detector algorithm based pull model is proposed to makeit adaptive to the variable transmission states of WANs. Based on this novel algorithm, a new Failure Detector is designed to avoid making wrong failure decisions in unstable member states and network states. In addition,the membership process mechanism is used to tranfer member state change information timely. The awareness of the collaborators is enhanced. To guarantee the message's synchronization processing,the Virtual synchronization mechanism is introduced to the system, and the paper designs an synchronization algorithm to solve the group members state synchronization.Finally,all above methods are realized as the function components. The adaptor interface is provided to construct the cooperative Editing System on InterGCS system seamlessly.