RDF Statements

RDF is based on statements made about resources. A resource is anything with an associated URI, and a statement describes the properties of resources. A property in RDF is a special kind of resource, which describes a relationship between resources.

RDF uses a triple to link a subject to an object via a predicate. Note that RDF only allows statements consisting of a single subject and a single object.

Subject: The resource that the statement describes (e.g. a person, place, object, document, etc.). Represented in diagrams as an oval.

Predicate: The property of the subject (e.g. name, city, colour, characteristic). Represented in diagrams as an arrow.

Object: The value for the property of the subject (e.g. John, red, 64, etc.). Can be either a resource or a literal value. Represented in diagrams as a rectangle.

For example, the statement "The MacBookAir has an IntelCore2Duo processor" can be split into its three components:

This can then be represented diagrammatically as:

Each triple is defined by a single rdf:Description element, and the subject is defined by the rdf:about attribute. Within the tags is the property-value pair, corresponding to the predicate and object of the triple. The predicate in this example is identified by the name of the element computer:hasProcessor, and the object IntelCore2Duo appears inside the element. e.g.

<rdf:Description rdf:about="MacBookAir">
	<computer:hasProcessor>IntelCore2Duo</computer:hasProcessor>
</rdf:Description>