R2RML Processor for Materializing RDF View of Relational Data: Algorithms and Experiments

RDB2RDF mapping has been a hot topic in the Semantic Web research community. In order to standardize the mapping mechanism and then facilitate sharing and reuse of the mapping definitions, the W3C RDB2RDF Working Group published a general purpose RDB2RDF mapping language standard, R2RML, in September 2012. Several mapping tools or ongoing projects have been gradually supporting the R2RML standard. But they rarely write up and report the design and implementation techniques for the mapping algorithms. This paper presents the algorithm design of a prototype R2RML processor for materializing RDF view of relational data. Experimental tests on the effectiveness and the run-time efficiency of the algorithm were conducted with the W3C-defined R2RML mapping test cases. The experimental results show that the proposed RDB2RDF mapping approach is implementable with Java language, and the run-time of the algorithm exhibits a linear growth rate as the generated RDF triples size increases.