Supporting internet applications beyond browsing: Trigger processing and change notification (extended abstract)

This paper presents the design and implementation methodology of the JCQ system, a Java-based Continual Query system for update monitoring over Web information sources. A continual query is a standing query that monitors updates of interest using distributed triggers and notifies users whenever the updates reach specified thresholds. In this paper we focus on the strategies and techniques developed in JCQ for scalable and efficient trigger firing and the execution model for flexible and robust change notification. We evaluate our approach through a performance study of the most recent release of the JCQ system and a comparison with related work.