摘要：In order to support the real-time collaboration between geographically distributed designers, the single-user application AutoCAD is required to be transformed transparently into groupware system by adopting fully replicated architecture. As the core issue to maintain the consistency of the distributed replicas, traditional consistency maintenance algorithms (such as Operation Transformation and Address Space Transformation algorithms), however, support only linear data model, and may lead to low algorithm efficiency and small operation types when adapted to the collaborative design field. In this paper, a novel layered document model is proposed to abstract the document model of AutoCAD, and the AST algorithm is adapted according to the model to achieve transparent and real-time collaboration. Moreover, the Update conflicts resolution based on child-precedence strategy, and the database listening technique used to grasp the semantics of interface operations to realize operation adaptation are also presented. Efficiency analysis of the Layer-AST algorithm is given, showing the improved performance of the algorithm. Finally, the system architecture of Co-AutoCAD using this strategy is detailed to guide the application.
关键词：conflict resolution, consistency maintenance, data model transformation, layered document model, operation adaptation
