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Full Paper AbstractsContent Distribution for Publish/Subscribe ServicesMao Chen, Andrea LaPaugh and Jaswinder Pal Singh (Princeton U.) Publish/subscribe systems have focused primarily on matching events to subscriptions and routing them based on the results. However, caching and content delivery are very important for publish/subscribe applications in which the objects of interest have large sizes. In this paper, we propose several content distribution approaches that combine match-based pushing and access-based caching, based on users' subscription information and access patterns. To study the performance of the proposed approaches, we built a simulator and developed a workload to mimic the content and access dynamics of a busy news site. We use two request traces: the trace NEWS uses a large homogeneity parameter for a Zipf-like page popularity distribution based on the observations at the news site, and the ALTERNATIVE trace represents more general scenarios. The experimental results using our best approaches demonstrate about 50% relative improvement in the hit ratio in local caches for NEWS and about 140% for ALTERNATIVE over the baseline algorithm that uses access-based caching only. Even when the subscription information is assumed not to reflect users' accesses perfectly (a more realistic scenario), our best approaches still have about 40% and 90% relative improvement for the two traces. In all cases, our best approaches introduce only traffic overhead that is comparable to the access-based caching-only approach. To the best of our knowledge, this work is the first effort to investigate content distribution under the publish/subscribe paradigm. Based on it, we believe that not only can publish/subscribe systems incorporate content distribution effectively, but that general caching and content distribution systems can be substantially enhanced by using publish/subscribe information judiciously when it is available. |
Latest update: 28 May 2003 - Questions and Comments about the Site: fmc@inf.ufg.br |