Abstract:

We study the problem of evaluating RDF queries over structured overlay networks.We consider the publish/subscribe scenario where nodes subscribewith long-standing queries and receive notifications whenever triples matching their queries are inserted in the network. In this paper we focus on conjunctive multi-predicate queries. We demonstrate that these queries are useful in various modern applications e.g., distributed digital libraries or Grid resource discovery. Conjunctive multipredicate queries are hard to answer since multiple triples are necessary for their evaluation, and these triples will usually be inserted in the network asynchronously. We present and evaluate query processing algorithms that are scalable and distribute the query processing load evenly.