Research On Consistency Maintenance Based On Graphic Object

Collaborative Graphics Editing System supports a group of designers who are spread regionally to browse, operate and modify a shared graphics file through Internet in real-time. And studying the consistency maintenance in the collaborative process is one of the key problems in a collaborative design system with a replicated architecture.Based on the summarization of related research achievements at home and abroad, this paper designs and realizes a concurrent control method for consistency maintenance based on graphic objects, and discusses the operation semantic problem with predefined relationships between multiple graphic objects. The main research contents and achievement is summarized as follows:1. Starting from the CCI consistency maintenance model, this paper has a deep research and analysis on the causes and forms of the three consistency problem. And after study of three commonly used consistency maintenance method, an improved concurrent control algorithm based on Operation Transformation has been proposed. The algorithm can meet the three necessary conditions for consistency model, and effectively process the operation conflict detection and resolution on graphics object attribute level, so the consistency has been maintained.2. After analysis and discussing several common semantic maintenance models, a semantic rule library based semantic maintenance model has been designed in this paper. On this basis we also propose a predefined constraint condition semantic method. And the relationship of multiple graphics object in the space position in our system is fully considered in this method and User semantic has been effectively maintained.All of the algorithms presented above have been implemented in a prototypical system and tested. Results of these examples indicate the correctness of the algorithms in this thesis.