GRDDL

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 [http://www.w3.org/2007/07/grddl-pressrelease 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-view

The 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:

and

Use of this profile licenses RDF data extracted by hcard2rdf.xsl from 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
* [http://code.google.com/p/xmlgrddl/ XML_GRDDL] , a semi compliant PHP 5 library
* See [http://esw.w3.org/topic/GrddlImplementations 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

* [http://www.w3.org/TR/grddl/ W3C GRDDL Specification]
* [http://www.w3.org/2001/sw/grddl-wg/ W3C GRDDL Working Group]
* [http://www.w3.org/TR/grddl-primer/ W3C GRDDL Primer]
* [http://www.w3.org/TR/grddl-scenarios/ W3C GRDDL Use-Cases]
* [http://dannyayers.com/misc/grddl-reference GRDDL Quick Reference] (pdf)

*cite news
date = 2006-10-26
title = W3C Looks to GRDDL For Semantic Web Sense'
publisher = internetnews.com
author = Kerner, Sean Michael
url = http://www.internetnews.com/dev-news/article.php/3640361