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
How it works
XHTML & Transformations
A document specifies associated transformations, using one of a number of ways.For instance, an XHTML document may contain the following markup:
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-viewThe available transformations are revealed through one or more LINK elements:
Microformats & Profile Transformations
If an XHTML page contains Microformats, there is usually a specific profile.For instance, a document with hcard information should have:
When fetched http://www.w3.org/2006/03/hcard has:
andUse of this profile licenses RDF data extracted by
hcard2rdf.xslfrom the 2006 vCard/RDF work.The GRDDL aware agent can then use that profileTransformation to extract all hcard data from pages that reference that link.
XML & Transformations
In a similar fashion to XHTML, GRDDL transformations can be attached to XML documents.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
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.
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.
Implementations
GRDDL Consumers (also known as GRDDL Aware Agents)
- OpenLink Virtuoso through its Sponger cartridge system
- XML_GRDDL, a semi compliant PHP 5 library
- See other implementations
See also
- microformats, a simplified approach to semantically annotate data in websites
- RDFa, a W3C proposal for annotating websites with RDF data
- eRDF, an alternative to RDFa
External links
- W3C GRDDL Specification
- W3C GRDDL Working Group
- W3C GRDDL Primer
- W3C GRDDL Use-Cases
- GRDDL Quick Reference (pdf)
- Kerner, Sean Michael "W3C Looks to GRDDL For Semantic Web Sense'". internetnews.com, .
This article is licensed under the GNU Free Documentation License.
Last updated on Monday July 21, 2008 at 02:58:05 PDT (GMT -0700)
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