Faculty Advisor

Elke A. Rundensteiner

Faculty Advisor

Robert E. Kinicki


"Complex Event Processing (CEP) has become increasingly important for tracking and monitoring anomalies and trends in event streams emitted from business processes such as supply chain management to online stores in e-commerce. These monitoring applications submit complex event queries to track sequences of events that match a given pattern. While the state-of-the-art CEP systems mostly focus on the execution of flat sequence queries, we instead support the execution of nested CEP queries specified by the (NEsted Event Language) NEEL. However the iterative execution often results in the repeated recomputation of similar or even identical results for nested sub- expressions as the window slides over the event stream. This work proposes to optimize NEEL execution performance by caching intermediate results. In particular a method of applying selective caching of intermediate results called Continuous Sliding Caching technique has been designed. Then a further optimization of the previous technique which we call the Semantic Caching and the Continuous Semantic Caching have been proposed. Techniques for incrementally loading, purging and exploiting the cache content are described. Our experimental study using real- world stock trades evaluates the performance of our proposed caching strategies for different query types."


Worcester Polytechnic Institute

Degree Name



Computer Science

Project Type


Date Accepted





caching, Complex Event Processing, nested