The Research And Implementation Of Concurrency Control Mechanism Of Collaborative CAD Based On CSCW

Collaborative CAD is based on both CSCW and CAD, and it has become a significant product design mode. Now there are a few collaborative CAD systems, but these systems are not perfect. In this paper, the concurrency control mechanism of collaborative CAD system is studied.The rules of designing concurrency control for collaborative CAD is described. By the analysis and discussion of currency control mechanism adapted in traditional databases and the now used CSCW systems, the advantages and disadvantages of these concurrency control model are discussed. After studying the characters of graphics operations, the rules of designing concurrency control mechanism in collaborative CAD are described.Based on the rules of concurrency control, a consistent concurrency control model is presented. The model includes four parts, one is identical consistency restriction, another is reason-result restriction, the other is result restriction, and the rest is intention restriction. The map of graphics ID is used to solve the identical consistency restriction. The state vector is used to reason-result restriction and result restriction. For intention restriction, color-lock way, priority way and multi-version way are applied.An access control algorithm for Doctor CAD is presented. Based on the mode of organization and the mode of collaboration, an access control bases on role is described. At last, the detailed design method of collaborative CAD system is studied. Finally a complete collaborative CAD system, collaborative Doctor CAD is developed and the concurrency control mechanism is proved to be successful.