基于对象复制的协同绘图并发控制算法

全复制模式下的基于对象的实时协同图形编辑系统支持不同地域的设计人员通过网络同步高效地浏览、操作和修改共享文档和文档中的各种对象，包括图形、图象和文本等，其中操作意愿保证及其并发控制成为复杂而又关键的问题之一，其研究具有挑战性．文中讨论了基于图形对象的并发操作的冲突，提出直接依赖和对象状态概念确定操作的候选对象和相容集合，并改进了对象复制算法．基于此，给出了一个有效的并发控制算法。

A Concurrent Control Algorithm for Collaborative Graphics Editing Systems Based on Object Replication

Collaborative Graphics Editing System(CGES) ,which allows multiple designers from different fields connected by communication networks synchronously or asynchronously to view or edit the same graphical object in the shared document at the same time. The operational intention preservation is one of the important and complicated problems from CGES in a replicated architecture, and it has the most significant challenges in designing and implementing such a real-time cooperative system. In this paper, we first discuss the conflict between concurrent operations of the graphics object-based. Then a new concept of direct-dependent relationship and object state are proposed, which are used to determine the candidate group of the operation and the compatible group of the object, so as to improve the algorithm of object replication. Finally, based on the above discussion, an effective concurrent control algorithm is presented to preserve the operation intention.