I have created the presentation below in response to a recent discussion about converting XML to RDF.
A person I was talking to assumed that there was a mapping process one needed to go through before a translation of XML (or relational databases, spreadsheets, etc.) into RDF could take place.
Indeed mapping often happens, but it happens after translation. First the non RDF information is represented in RDF. Any mappings that are created are also captured in RDF/OWL – either by using constructs such as rdfs:subClassOf and owl:sameAs or, for more complex mappings, by using SPIN (SPARQL rules).
I am always surprised how often people find this approach novel and need time to understand what is going on. I guess this is because RDF is so flexible – it is quite easy to represent any data structures in RDF. And because both, data and models are represented in RDF, once imported, structural transformations are very straightforward. RDF is built for change. Other data models do not have this advantage. Hence, they require mappings before importing external data.
The presentation below explains in detail how RDF import and transformations are done including a step by step example. The benefits of the approach are also discussed.