Chapter 3. The Basic Elements Within the RDF/XML Syntax

The usability of RDF is heavily dependent on the portability of the data defined in the RDF models and its ability to be interchanged with other data. Unfortunately, recording the RDF data in a graph?the default RDF documentation format?is not the most efficient means of storing or retrieving this data. Instead, transporting RDF data, a process known as serialization, usually occurs with RDF/XML.

Originally, the RDF model and the RDF/XML syntax were incorporated into one document, the Resource Description Framework (RDF) Model and Syntax Specification. However, when the document was updated, the RDF model was separated from the document detailing the RDF/XML syntax. Chapter 2 covered the RDF abstract model, graph, and semantics; this chapter provides a general introduction to the RDF/XML model and syntax (RDF M&S).

The original RDF M&S Specification can be found at http://www.w3.org/TR/REC-rdf-syntax/. The updated RDF/XML Syntax Specification (revised) can be found at http://www.w3.org/TR/rdf-syntax-grammar/.

Some RDF-specific aspects of RDF/XML at first make it seem overly complex when compared to non-RDF XML. However, keep in mind that RDF/XML is nothing more than well-formed XML, with an overlay of additional constraints that allow for easier interchange, collection, and mergence of data from multiple models. In most implementations, RDF/XML is parsable with straight XML technology and can be manipulated manually if you so choose. It's only when the interchangeability of the data is important and the data can be represented only by more complex data structures and relationships that the more formalized elements of RDF become necessary. And in those circumstances, you'll be glad that you have the extra capability.

All examples listed in the chapter are validated using the W3C's RDF Validator, located at http://www.w3.org/RDF/Validator/.