Decentralized infrastructure for knowledge discovery in the Semantic Web

An enormous volume of well-structured data with explicit semantics, in accordance with W3C's standards, becomes a reality in the Web of Linked Data. However, the Semantic Web promise to turn it into a machine-process able global graph of knowledge still encounters numerous impediments. Efficient access and discovery along with the semantic heterogeneity have been identified as major stumbling blocks. Following the design principles for Semantic Web and Linked Data, we present ActiveDiscovery, a decentralized infrastructure for distributed SPARQL query evaluation based on its terminological entities, namely the ontologies used in a query. ActiveDiscovery's main goal is to facilitate distributed and transparent semantic search based on structural rather than keyword-based querying in the Semantic Web. Key architectural extensions regarding metadata, indexing and ontology alignment are proposed to achieve transparency for federated query execution in a decentralized manner. The rewriting procedure for extensional SPARQL query is considered regarding the proposed components and SERVICE clause as a standard recommendation for query federation. We investigate the feasibility of our approach and present preliminary results of initial evaluation. We conclude by indicating questions which need to be addressed in future work.