TAILIEUCHUNG - Efficient Pattern Matching over Event Streams 

Well-Defined Currency. Almost all previously de- ployed computational markets have used a virtual cur- rencies instead of real cash. The low barrier to utiliza- tion and low stakes in case of deployment error make simple closed virtual currencies attractive to developers. In these scenarios, it is all too easy to skip the monetary policy considerations that make currencies work. For all of their bootstrapping advantages, virtual cur- rencies require initial thought and ongoing care to func- tion properly. Virtual currencies often suffer from a lack of liquidity, making it difficult to convert into or out of the virtual currency. As a result, these ersatz currencies are quite limited; certain usersmight be willing. | Efficient Pattern Matching over Event Streams Jagrati Agrawal Yanlei Diao Daniel Gyllstrom and Neil Immerman Department of Computer ScienCe University of Massachusetts Amherst Amherst MA USA jagrati yanlei dpg immermang@ ABSTRACT Pattern matching over event streams is increasingly being employed in many areas including financial services RFIDbased inventory management click stream analysis and electronic health systems. While regular expression matching is well studied pattern matching over streams presents two new challenges Languages for pattern matching over streams are significantly richer than languages for regular expression matching. Furthermore efficient evaluation of these pattern queries over streams requires new algorithms and optimizations the conventional wisdom for stream query processing . using selection-join-aggregation is inadequate. In this paper we present a formal evaluation model that offers precise semantics for this new class of queries and a query evaluation framework permitting optimizations in a principled way. We further analyze the runtime complexity of query evaluation using this model and develop a suite of techniques that improve runtime efficiency by exploiting sharing in storage and processing. Our experimental results provide insights into the various factors on runtime performance and demonstrate the significant performance gains of our sharing techniques. Categories and Subject Descriptors H. 2 Database Management Systems General Terms Algorithms Design Performance Theory Keywords Event streams pattern matching query optimization I. INTRODUCTION Pattern matching over event streams is a new processing paradigm where continuously arriving events are matched This work has been supported in part by NSF grants CCF 0541018 and CCF 0514621 and a gift from Cisco. Authors of this paper are listed alphabetically. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted .

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