Value-Based Predicate Filtering of XML Documents

Publish-subscribe systems based on XML filtering have received much attention in ubiquitous computing environments and Internet applications. The main challenge is to process a large number of content against millions of user subscriptions. Several XML filtering systems focus on the efficient processing of structural matching of user subscriptions represented as XPath twig patterns. However, existing techniques provide limited or no support for twig patterns that contain various operators in the value-based predicates. This paper presents the pFiST system that filters XML documents by transforming twig patterns into sequences based on Prufer's method.