Extensions of SPARQL towards Heterogeneous Sources and Domain Annotations
SPARQL is the W3C Recommended query language for RDF. My current work aims at extending SPARQL in two distinct ways: (i) to allow a better integration of RDF and XML; and (ii) to define a query language for RDF extended with domain specific annotations. Transforming data between XML and RDF is a much required, but not so simple, task in the Semantic Web. The aim of (i) is to enable transparent transformations between these two representation formats, relying on a new query language called XSPARQL. On a different aspect, representing and reasoning with meta-information about RDF triples has been addressed by several proposals for representing time, trust and provenance. A common extension of RDF (and RDFS inferencing rules), capable of encompassing all these proposals, with a clearly defined semantics is much desirable. Building on top of Annotated RDF, we present such an extension and an extension of the SPARQL language capable of querying triples with annotations. An open research issue remains the possibility of unifying the two, currently independent, extensions of SPARQL.