Optimistic path-based concurrency control over XML documents

We present a new approach for concurrency control over XML documents. Unlike most of other approaches, we use an optimistic scheme, since we believe that it is better suited for Web applications. The originality of our solution resides in the fact that we use path expressions associated with operations to detect conflicts between transactions. This makes our approach scalable since conflict detection except in few cases does not depend on the database size nor on the amount of modified fragments. In this paper, we describe and motivate our concurrency mechanism architecture, we describe the conflict detection algorithm which is the core of our proposal and exhibit first experimental results.