Querying RDF graphs stored in a relational database using SPARQL and R2RML

The RDF framework is becoming a popular framework for presenting data. It makes the data easily accessible and queryable. But the most common way how to store structured data is to use a relational database systems. The relational databases benefit from their long theoretical and practical history, however the relational database does not offer any convenient way how to publish the data. It is essential to create a mapping between these two worlds, to publish the data stored in a relational database in the RDF format. In the presented work we study the SPARQL algebra and create a transformation algorithm that enable us to create a virtual SPARQL endpoint over the relational data. We apply the acquired knowledge in implementation of a tool which uses the algorithm to proof the concept. Powered by TCPDF (www.tcpdf.org