12.1.8. RDF Schema (RDFS)

Classes for RDF Schema and applications ¶

RDF describes resources by classes, attributes, and values.

In addition, RDF needs a way to define application-specific classes and properties. Application-specific classes and properties must be defined using an extension to RDF.

RDF Schema is such an extension.

RDF Schema (RDFS) ¶

Instead of providing actual application-specific classes and properties, RDF Schema provides a framework for describing application-specific classes and properties.

Classes in RDF Schema are very similar to classes in object-oriented programming languages. This allows resources to be defined as instances of the class and subclasses of the class.

RDFS instance ¶

The following example demonstrates some aspects of RDFS’s capabilities:

<?xml version="1.0"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xml:base="http://www.animals.fake/animals#">
<rdf:Description rdf:ID="animal">
  <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
</rdf:Description>
<rdf:Description rdf:ID="horse">
  <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
  <rdfs:subClassOf rdf:resource="#animal"/>
</rdf:Description>
</rdf:RDF>

In the above example, the resource “horse” is a subclass of the class “animal”.

An example of shorthand ¶

Since a RDFS class is a RDF resource, we can abbreviate the above example by using rdfs:Class instead of rdf:Description and removing the rdf:type information:

<?xml version="1.0"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xml:base="http://www.animals.fake/animals#">
<rdfs:Class rdf:ID="animal" />
<rdfs:Class rdf:ID="horse">
  <rdfs:subClassOf rdf:resource="#animal"/>
</rdfs:Class>
</rdf:RDF>

okay!