RDF
The Resource Description Framework (RDF, http://www.w3.org/RDF/ ) can be understood as an XML encoding for a particularly simple data model. An RDF document describes resources using triples. Each triple says that a resource has a property with a value. Resources are identified by URIs. Properties can be identified by URIs or by element-qualified names. The value can be a string of plain text, a chunk of XML, or another resource identified by a URI.
The root element of an RDF document is an RDF
element. Each resource the RDF
element describes is represented as a
Description
element whose
about
attribute contains a URI
pointing to the resource described. Each child element of the
Description
element represents a
property of the resource. The contents of that child element are the
value of that property. All RDF elements like RDF
and Description
are placed in the http://www.w3.org/1999/02/22-rdf-syntax-ns#
namespace. Property values generally come from other
namespaces.
For example, suppose we want to say that the book
XML in a Nutshell has the authors W. Scott
Means and Elliotte Rusty Harold. In other words, we want to say that
the resource identified by the URI urn:isbn:0596002920
has one author
property with the value “W. Scott Means” and another author property
with the value “Elliotte Rusty Harold.” Example 7-10 does this.
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> ...
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