Exposing databases as linked data using clojure, compojure and R2RML
From the post:
Some of these problems could be solved using some of the technologies developed as part of the semantic web initiative in the past decade. People have started referring to this pragmatic approach to the semantic web with a new title: Linked Data. The pragmatic approach here means putting less emphasis in the inference and ontological layers of the semantic web and just focusing in offer a simple way to expose data in the web linking resources across different web application and data sources.
Many interesting technologies are being developed under the linked data monicker or are commonly associated to it, RDFa for instance. Another of these technologies is R2RML: RDB to RDF Mapping Language.
R2RML describes a standard vocabulary to lift relational data to a RDF graph. It also provides a standard mapping for the relational data. This RDF graph can be serialized to some transport format: RDFa, Turtle, XML and then retrieved by the client. The client can store the triples in the graph locally and use the standard query language SPARQL to retrieve the information. Data from different applications using the same vocabulary (FOAF, GoodRelations) can be easily mixed and manipulated by the client in the same triple store. Furthermore, links to other resources can be inserted inside the RDF graph leading to the discovery of additional information.
Exposing data, even as an RDF graph, is a good thing.
Discovering additional information is also a good thing.
But they fall short of specifying the semantics of data, which is necessary to enable reliable identification of data with the same semantics.