Research On Conflict Avoidance Mechanism And Late Join In Real-time Collaborative Editing Systems

Distributed Real-time collaborative editing system allows a group of users to view and edit the same text/graphic/image/multimedia document at the same time from geographically dispersed sites connected by networks. They provide a convenient virtual workspace for collaboration and communication among people. Therefore, it is of great importance to study the real-time image cooperative editing system, especially for people to raise the working efficiency and quality under the improving Internet environment.Based on the research project "Research in the Critical Technology of Image Cooperative CAD/CAM Based on the Internet", this paper discusses the system framework model of a real-time collaborative editing system. The strategy and algorithm of Optional and Customizable Dynamic Locking (OCDL) have been improved by analyzing the mechanism of conflict avoidance in the real-time collaborative editing system. OCDL realizes separation on locking policy and locking mechanism. User can describe a specific locking policy as needed. OCDL mechanism can adapts the locking scope and locking granularity at runtime according to user's editing activities and locking policy selected. After analyzing the existing Late Join methods, the paper presents a Late Join Approach for Distributed Dynamic-locking which solves the new problem aroused in the collaborative system with dynamic locking mechanism and the error control method in the transmission and the late join algorithm are also presented. After analyzing the conflict avoidance problem in collaborative image editing system, the paper presents better methods and algorithm which improve the risk locking mechanism. At last, the paper discusses the design and the implementation of the system, the main data structures and algorithms of OCDL, and the risk locking mechanism in detail.