I just came across D2RQ, a notation (plus implementation) for mapping relational databases to RDF, developed over the last four years by Chris Bizer, Richard Cyganiak and others at Freie UniversitÃ¤t Berlin. In a previous post, “digging ourselves back from the Semantic Web mire“, I worried about the ghetto-like nature of RDF and the need for “abstractions that make non-triple structures more like the Semantic Web”, D2RQ is exactly the sort of thing, allowing existing relational databases to be accessed (but not updated) as if they were and RDF triple stores, including full SPARQL queries.
As D2RQ has clearly been around for years, I tried to do a bit of a web search to find things the other way around – more programmer-friendly layers on top of RDF (or XML) allowing it to be manipulated with IDL-like or other abstractions closer to ‘normal’ programming. ECMAScript for XML (E4X) seems to be just this allowing reasonably easy access to XML (but I guess RDF would be ‘flat’ in this). E4X has been around a few years (standard since 2005), but as far as I can see not yet in IE (surprise!). I guess for really practical XML it would be JSON, and there’s a nice discussion of different RDF in JSON representation issues on the n2 wiki “RDF JSON Brainstorming“. However, both E4X and RDF in JSON still are just accessing RDF nicely not adding higher level structure.
Going back to the beginning I was wondering about any tools that represent RDF as SQL / RDMS in order to make it available to ‘old technology’ … but then remembered that SPARQL creates tuples not triples so, I guess, one could say that is exactly what it does :-/