SPSC: Efficient Composition of Semantic Services in Unstructured P2P Networks

The problem of automated semantic peer-to-peer (P2P) service composition has been addressed in cross-disciplinary research of semantic web and P2P computing. Solutions for semantic web service composition in structured P2P networks benefit from the underlying distributed global index but at the cost of network traffic overhead for its maintenance. Current solutions to service composition in unstructured P2P networks with selective flooding can be more robust against changes but suffer from redundant messaging, lack of efficient semanticsempowered search heuristics and proven soundness. In this paper, we present a novel approach, called SPSC, for efficient semantic service composition planning in unstructured P2P networks. SPSC peers conduct a guarded heuristics-based composition to jointly plan complex workflows of semantic services in OWL-S. The semantic service query branching method based on local observations by peers about the semantic overlay alleviates the problem of reaching dead-ends in the not fully observable and heuristically pruned search space. We theoretically prove that the SPSC approach is sound and provide a lower bound of its completeness. Finally, our experimental evaluation shows that SPSC achieves high cumulative recall with relatively low traffic overhead.