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Unformatted text preview: Efficient Probabilistic Subsumption Checking for Content-based Publish/Subscribe Systems Aris M. Ouksel ? 1 , Oana Jurca 2 , Ivana Podnar 2 , and Karl Aberer ?? 2 1 The University of Illinois at Chicago Depts. Of Information and Decision Sciences and Computer Science [email protected] 2 School of Computer and Communication Sciences Ecole Polytechnique F´ed´erale de Lausanne (EPFL) CH-1015 Lausanne, Switzerland { oana.jurca, ivana.podnar, karl.aberer } @epfl.ch Abstract. Efficient subsumption checking, deciding whether a subscription or publication is covered by a set of previously defined subscriptions, is of para- mount importance for publish/subscribe systems. It provides the core system functionality—matching of publications to subscriber needs expressed as sub- scriptions—and additionally, reduces the overall system load and generated traffic since the covered subscriptions are not propagated in distributed environments. As the subsumption problem was shown previously to be co-NP complete and existing solutions typically apply pairwise comparisons to detect the subsump- tion relationship, we propose a ‘Monte Carlo type’ probabilistic algorithm for the general subsumption problem. It determines whether a publication/subscription is covered by a disjunction of subscriptions in O ( k m d ) , where k is the number of subscriptions, m is the number of distinct attributes in subscriptions, and d is the number of tests performed to answer a subsumption question. The prob- ability of error is problem specific and typically very small, and sets an upper bound on d . Our experimental results show significant gains in term of subscrip- tion set reduction which has favorable impact on the overall system performance as it reduces the total computational costs and networking traffic. Furthermore, the expected theoretical bounds underestimate algorithm performance because it performs much better in practice due to introduced optimizations, and is adequate for fast forwarding of subscriptions in case of high subscription rate. 1 Introduction Content-based publish/subscribe systems are receiving growing interest with a large number of relevant applications such as stock tickers, RSS news feeds, network moni- toring, traffic monitoring, and electronic commerce requiring selective information dis- ? Research supported in part by the National Science Foundation grant IIS-0326284. ?? Research supported in part by the National Competence Center in Research on Mobile Infor- mation and Communication Systems (NCCR-MICS), a center supported by the Swiss National Science Foundation under grant number 5005-67322 and carried out (partly) in the framework of the EPFL Center for Global Computing. semination. Traditional content-based publish/subscribe systems usually employ high- performance servers to handle high rates of publications and serve millions of sub- scribers in static environments. They have been optimized for fast matching of publi- cations to subscriptions [1–4] and typically maintain a special subscription index that...
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This note was uploaded on 12/08/2011 for the course CS 525 taught by Professor Gupta during the Spring '08 term at University of Illinois, Urbana Champaign.

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getDocum - Efficient Probabilistic Subsumption Checking for...

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