Concurrency Control In Collaborative Design Based Feature Dependency

Collaboration among departments or enterprises is becoming more and more frequent with the increasing development of global economy. To meet various market requirement and shorten product design cycle, collaborative design, which can enable designers distributed in global areas share works simultaneously, is becoming an outsourcing trend of CAD area. Among all the key issues of collaborative design, concurrency control, as one of the most important, is researched in this study.Firstly, the characteristics of shared objects are analyzed and conflicts in collaborative design are classified. Based on the analyses, a concept of Feature Dependency is put forward and based on it, a new definition of concurrency conflict for collaborative design is presented.Secondly, a non-state-vector concurrency determination rule based on done-operations set is presented so as to eliminate some unreasonable judgment in some conditions. Then an operation feedback mechanism is presented to know well where the collaborative operations are and to optimize the concurrency determination previously given.Thirdly, the relationship of feature dependency of collaborative model is re-organized into a hierarchical graph. Based on the constructed graph, a new concurrency conflict detection algorithm is proposed. And then a detailed analysis is also given to the algorithm.Fourthly, two algorithms for concurrency conflict resolution are presented. One is the operation-choosing within conflict operations based on designer priority. The other is multi-version mechanism for collaborative design system, where the data structure representation and basic algorithm for it are given.At last, the proposed method of concurrency control based feature dependency is implemented so as to verify the correctness of the key rules, algorithms and mechanisms presented previously.