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XML Optimistic Concurrency Control Protocol for DOM API

XML concurrency control protocol ensures that transactions execute atomically in a XML database system. Existing concurrency control methods for XML are mainly based on locking. In this paper, we propose two optimistic concurrency control protocols for XML that use snapshot-based approach. OptiXDOM extends traditional backward-oriented optimistic concurrency control protocol while FOCCXDOM is based on forward-oriented approach. Both protocols are optimized for XML data and can be used in XML DOM API. Experiments show that both OptiXDOM and FOCCXDOM have better performance than that of lock-based approach when conflicts are few. Furthermore, FOCCXDOM has the larger throughput and higher abort rate than that of OptiXDOM in most cases.