GRDDL
From Wikipedia, the free encyclopedia
Semantic Web
Web 2.0, Web 3.0, Plain Old Semantic HTML, Search engine optimization, Open Database Connectivity, References, Information architecture, Knowledge management, Topic Maps, XML, Description logic
W3C based
RDF, OWL, URI, HTTP, SPARQL, GRDDL, RDFS
Common Vocabularies
FOAF, SIOC, Dublin Core, SKOS
Semantic Annotation
RDFa, Microformats, eRDF
Rules
Rule Interchange Format, Semantic Web Rule Language
Tim Berners-Lee, James Hendler, Ora Lassila, Nigel Shadbolt, Wendy Hall, Kingsley Idehen, Dan Brickley, Libby Miller, Dave Beckett
GRDDL (pronounced 'griddle') is a markup format for Gleaning Resource Descriptions from Dialects of Languages.
It is a W3C Recommendation, and enables users to get RDF out of XML and XHTML documents via XSLT.
It became a recommendation on September 11, 2007.
Contents
[edit] How it works
[edit] XHTML & Transformations
A document specifies associated transformations, using one of a number of ways.
For instance, an XHTML document may contain the following markup:
<head profile="http://www.w3.org/2003/g/data-view
http://dublincore.org/documents/dcq-html/
http://gmpg.org/xfn/11">
<link rel="transformation" href="grokXFN.xsl" />
Document consumers are informed that there are GRDDL transformations available in this page, by including the following in the PROFILE attribute of the HEAD element:
http://www.w3.org/2003/g/data-view
The available transformations are revealed through one or more LINK elements:
<link rel="transformation" href="grokXFN.xsl" />
[edit] Microformats & Profile Transformations
If an XHTML page contains Microformats, there is usually a specific profile.
For instance, a document with hcard information should have:
<head profile="http://www.w3.org/2003/g/data-view http://www.w3.org/2006/03/hcard">
When fetched http://www.w3.org/2006/03/hcard has:
<head profile="http://www.w3.org/2003/g/data-view">
and
<p>Use of this profile licenses RDF data extracted by
<a rel="profileTransformation" href="../vcard/hcard2rdf.xsl">hcard2rdf.xsl</a>
from <a href="http://www.w3.org/2006/vcard/ns">the 2006 vCard/RDF work</a>.
</p>
The GRDDL aware agent can then use that profileTransformation to extract all hcard data from pages that reference that link.
[edit] XML & Transformations
In a similar fashion to XHTML, GRDDL transformations can be attached to XML documents.
[edit] XML Namespace Transformations
Just like a profileTransformation, an XML namespace can have a transformation associated with it.
This allows entire XML dialects (for instance, KML or Atom) to provide meaningful RDF.
An XML document simply points to a namespace
<foo xmlns="http://example.com/1.0/"> <!-- document content here --> </foo>
and when fetched, http://example.com/1.0/ points to a namespaceTransformation.
This also allows very large amounts of the existing XML data in the wild to become RDF/XML with a very minimal effort from the namespace author.
[edit] Output
Once a document has been transformed, there is an RDF representation of that data.
This output is generally put into a database and queried via SPARQL.
