An RDF-based P2P overlay network supporting range and wildcard queries

In recent years, a new branch of the P2P research called the semantic-based system has been emerged. The semantic-based P2P overlay network uses metadata to describe resources so that complex queries can be implemented. Although systems such as RDFPeers and RDF-Chord support complex queries including the range query, none of these systems in the literature supports the wildcard query. In this paper, we propose a RDF-based P2P overlay network, called RDFChord-W, which supports all atomic queries, conjunctive and disjunctive queries, the range query, and the wildcard query. In RDFChord-W, nodes are arranged into multiple layers where each layer is organized as a Chord-like ring. Resources are described by their RDF triples. Hence, the indices of resources can be generated by hashing their RDF triples and then distributed to corresponding nodes. Based on our survey in the P2P literature, RDFChord-W is the first RDF-based P2P overlay network that supports the wildcard query. Although RDFChord-W supports various types of queries, its performance is much superior to traditional P2P overlay networks such as RDFPeers and Squid through intensive experiments, which are executed by the well-known simulator PeerSim.