关键词: 实时协同系统, 锁机制, 操作转换, 一致性维护, 并发控制

Abstract: Locking is a traditional technique for concurrency control in distributed computing and databases systems by empowering the only user to update shared data objects during a certain time.Operation transformation is an innovative technique for consistency maintenance in real-time cooperative systems.Both techniques fail to resolve all the inconsistency problems.In this paper，we will demonstrate the complementary roles of locking and operation transformation in consistency maintenance.A user-customized locking approach is presented and integrated with operation transformation for consistency maintenance in fully-replicated and collaborative environment.The user-customized locking approach integrating operation transformation is considerably reliable，highly responsive，non-blocking.The user-customized granularity of locking can ensure highest concurrency.The approach can ensure generic consistency and context-based consistency.

Key words: real-time collaborative system, locking mechanism, operation transformation, consistency maintenance, concurrency control