Predicate-based push-pull communication for distributed CEP

Steven Purtzel, Samira Akili, Matthias Weidlich

Abstract: Complex event processing (CEP) enables the detection of situations of interest by evaluating queries over event streams. When applied in a networked application, events generated by distributed nodes are sent over the network to evaluate CEP queries. To reduce the transmission of events, push-based communication that sends each event immediately upon generation may be complemented with a pull-based model that buffers events locally until they are requested for query evaluation. Existing approaches that leverage push-pull communication to reduce transmission costs for distributed CEP, however, exploit solely temporal constraints imposed by a query. As such, they are not applicable in scenarios, in which relevant events may occur in each time window defined by a query.In this paper, we propose predicate-based push-pull (PrePP) plans for CEP queries to overcome the above limitations. Our idea is to construct pull requests that enable fine-granular filtering at event sources based on query predicates, thereby reducing event transmission. Since the construction of optimal PrePP plans is NP-hard, we introduce a set of algorithms to speed up the plan construction by up to five orders of magnitude compared to a brute-force approach, while producing near-optimal results. In extensive experiments, we demonstrate that PrePP plans reduce event transmission by up to three orders of magnitude over baseline techniques.