XML or RDF?

By | 2003/10/09

A proposal of mine was recently accepted by the RDF Core WG which IMO, will help explain what RDF is for to a lot of people who don’t yet understand the important role it plays in the World Wide Web project. I believe this because I’ve used the RDF it permits, to successfully explain what RDF adds over vanilla XML to Exec types.

Consider the following. Is it XML or RDF?

<Person xmlns="http://example.org/foofoo/">
  <name>Mark Smith</name>
  <age>55</age>
</Person>

Answer? It’s both. Depending upon which media type it’s described with, it means different things.

To an XML application that isn’t hardcoded to know about that language, it’s an almost entirely opaque blob, except for the namespace.

To an RDF/XML application that isn’t hardcoded to know about that language, it knows what the XML app knows, plus;

  • that there exists a resource of type “http://example.org/foofoo/Person” someplace, with properties “http://example.org/foofoo/name” and “http://example.org/foofoo/age” with those values
  • that additional properties can be added without impacting the meaning of the former interpretation, i.e. potentially breaking some application somewhere. An XML app can’t assume this; it might be breaking its validity against some schema someplace
  • various other possible syntactic additions or modifications which can be used to extend the current semantics in a backwards compatible way, if desired.

This is the value of partial understanding.

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