Semantic Query Routing Experiences in a PDMS

Querying a PDMS means either flooding the network with messages to all peers or taking advantage of a routing mechanism to reformulate a query only on the best peers selected according to some given criteria. As reformulations may lead to semantic approximations, we deem that such approximations can be exploited for locating the semantically best directions to forward a query to. In this paper, we present our experiences in devising and testing a mechanism for effective query routing in a PDMS. In particular, we describe a distributed index mechanism where each peer is provided with a Semantic Routing Index (SRI) for routing queries effectively. We illustrate SRIs’ structure, their use and the framework we devised for their incremental update, then we provide an extensive evaluation of their effectiveness through a set of query routing experiments on a variety of scenarios. This work is partially supported by the PRIN WISDOM and FIRB NeP4B national projects.