Bi-directional Translation of Relational Data into Virtual RDF Stores

A vast majority of the world´s valuable data currently exists in relational databases and other legacy storage systems. In order for Semantic Web applications to access such legacy data without replication or synchronization of the same, the gap between the two needs to be bridged. Several efforts exist that publish relational data as Resource Description Framework (RDF) triples, however almost all current work in this arena is uni-directional, presenting the existing and new data from an underlying relational database into a corresponding virtual RDF store in a read-only manner. This paper expands on previous relational-to-RDF bridging work, by enabling the bridge to be bi-directional and allowing data updates specified as triples to be propagated back to the relational database as tuples. Algorithms to translate the triples to be updated/inserted/deleted into equivalent relational attributes/tuples whenever possible are presented. A widely embraced open-source tool called D2RQ is enhanced with these algorithms to serve as evidence of the bi-directionality of our translation process.