SPARQL Query Language

Abstract

This chapter provides a detailed introduction to the SPARQL Protocol and RDF Query Language (SPARQL 1.1): the standard query language for RDF. After some initial motivation, we delve into the features of the query language, illustrated with concrete examples. We then formally define the semantics of these query features. We next discuss how federated queries can be used to evaluate queries over multiple remote sources on the Web. We detail the SPARQL Update language, which allows for modifying the data indexed by a SPARQL query service. We introduce SPARQL Entailment Profiles, which allow for query results to consider entailments, including support for RDF, RDFS and OWL semantics. We further discuss the HTTP-based protocol by which requests can be issued to a SPARQL service over the Web, as well as the SPARQL Service Description vocabulary, which can be used to describe and advertise the features supported by such services. We conclude by discussing the importance of SPARQL for the Web of Data, the key research directions that are currently being explored, as well as open challenges.