Research On Optimal Data Transport Mechanism In Real-Time Collaborative Pattern Designing System

With the deep development of information industry, CSCW (Computer Supported Cooperative Work) is exploited combining application software and network and becoming a hot research topic. Real-time Collaborative Designing System (RCDS) is one of the most popular CSCW applications. There are many key issues in designing a RCDS system, such as consistency maintenance, conflicting resolution, mutual awareness, undo/redo algorithm, data transport mechanism, etc. Among these, how to keey efficient mutual data transport is an important and thus essential part to build a robust CSCW application. In addition, mutual awareness is an important technique to enable collaborators understanding with other collaborators, achieving real-time information about others, thus can effectively reduce conflicting and improve the system efficiency remarkably. This dissertation focus on following three aspects: network infrastructure, multi-protocol data transport mechanism and self-adaptive mutual awareness model. The ultimate goal of our research is to improve the smoothness of the collaborating process and improve the collaborating efficiency.The background of the development of CSCW applications is presented in the review part and the classification of popular CSCW systems is introduced. Then some key issues in designing a real-time collaborative system are introduced. We focus on the research work on mutual data transport and mutual awareness technique and the issues are presented according to the merits and flaws of these approaches.In Chapter 3, some characteristics of the heterogeneous data network are introduced, and the impact it may bring to collaborative systems is analyzed. Aims to make better performance in heterogeneous network environment, a P2P-based collaborative network infrastructure is presented. This infrastructure eliminates the central server functionality from the traditional CSCW system and distributes this functionality into all the collaborative sites, depending on the directly collaboration among the collaborative sites to improve the availability of system resources and to improve the wholly system performance by resource balance mechanism.In chapter 4, a multi-protocol data transmission mechanism is proposed. By using this method, interaction data are divided into some preassigned transmission types, then different protocol is selected to complete the data transmission process. It utilizes the different perfonnance advantage of distinct network protocols to achieve better performance on data transmission according to the intrinsic data characteristic.A self-adaptive mutual awareness model SAMSM is also designed. This modelcalculates awareness strength between each two collaborators according to their collaborative relation, using multi-rate coding mechanism to provide different granularity awareness data. In addition, it also adopts a receiver-based network bandwidth estimation algorithm to capture the real-time network condition, and adapts the awareness strength to make the transport of awareness data appropriate to current network condition. Each collaborator can also make some voluntary adaptation to protect her/his privacy. This self-adaptive awareness model can make a trade-off between the awareness quality and wholly performance, thus enhance the robustness and the efficiency of the collaborative application.Some practical examples are presented by applying the forenamed three proposed mechanisms. Analytical results on the performance of the practical experiments demonstrate that it has significant advantages over traditional methods in term of making the system automatically adapting to the real-time collaborative condition.