Accessing relational data on the web with SparqlMap

Abstract

The vast majority of the structured data of our age is stored in relational databases. In order to link and integrate this data on the Web, it is of paramount importance to make relational data available according to the RDF data model and associated serializations. In this article we present SparqlMap, a SPARQL-to-SQL rewriter based on the specifications of the W3C R2RML working group. The rationale is to enable SPARQL querying on existing relational databases by rewriting a SPARQL query to exactly one corresponding SQL query based on mapping definitions expressed in R2RML. The SparqlMap process of rewriting a query on a mapping comprises the three steps (1) mapping candidate selection, (2) query translation, and (3) query execution. We showcase our SparqlMap implementation and benchmark data that demonstrates that SparqlMap outperforms the current state-of-the-art. © Springer-Verlag 2013.