2. Semantic representation of content

2.1 Basic model

The tasks set for the WS are first made possible by the creation of a semantic layer for describing resources. The basic model for formalizing these descriptions is proposed by the W3C under the name of RDF (Resource Data Framework). RDF is to data semantics what HTML is to document presentation and XML is to tagged document description. It enables these representations to be constructed in the form of a set of "subject/property/object" triplets. These triplets form what are known as RDF graphs (see figure 1 ). A subject is a resource as defined above. The object, in the sense of the RDF triplets, is generally also a resource, or possibly a literal, the value of a simple data type...