协同CAD系统图档数据库并发控制研究

Research on concurrency control for drawing database in collaborative CAD system

为了解决传统图档事务并发控制中存在的数据一致性不高、文件复制量大和中间版本不易维护等问题,构建了面向对象的图档数据库存储结构,协同用户通过相关索引可以快捷、准确地共享数据资源。提出了基于事务语义的图档数据库并发控制策略,分析了并发控制机制中事务结构、事务提交、锁机制和冲突协调等关键性问题。协同设计者可以同时在一张图纸上进行修改,数据同步时只需更新部分对象,大大减轻了网络数据传输的负担,并保证图档数据的实时一致性。

To resolve problems such as low data consistence, excessive figures replication and inconvenient drawing management in the traditional concurrency control, a new object--oriented drawing database storage structure was constructed. Collaborative users could share data resources quickly and accurately through index. A concurrency control strategy based on semantic drawing database was proposed and some critical issues such as nested transaction, transaction submission, precautionary locking and conflict resolution were discussed. Collaborative users could synchronously modify the same blueprint while just part object was needed to be update on data synchronization to reduce network data--transmission load and maintain the consistence of drawing data.