Using Semantic Mappings for Query Routing in a PDMS Environment

In this paper we present the current achievement of our research activity in the WISDOM project, whose aim is the definition of intelligent techniques enabling e®ective and e±cient information search in a distributed and decentralized PDMS scenario. We focus on the query routing problem and we define a new routing mechanism, which we call routing by mapping, in which the query is sent to the peers whose subnetworks best approximate the concepts required. In order to select the best subnetworks, the peer receiving the query exploits information about the semantic approximation of the query concepts, when moving towards each neighbour. This information is computed starting from the semantic mappings established with the peer's neighbours and it is maintained into specifically devised data structures called Semantic Routing Indices (SRIs), whose update we propose specific algorithms and protocols for. The effectiveness of the achieved results has been experimentally proved through a series of exploratory tests.