Creative Commons GRDDL story / demonstration

Eric Miller, C. M. Sperberg-McQueen

15 October 2004, rev. 2 February 2005

This page illustrates the use of GRDDL and schema annotation to capture the semantics of information in a multi-namespace document.

We show a sample record using the vocabulary of the Open Archives Initiative (taken directly from the OAI documentation), both in its original form and in a form augmented to include Creative Commons rights information. We also show how to augment the schema documents as necessary to allow the augmented record to be validated.

Using Creative Commons Rights Data With OAI Records

• OAI sample record 1 - ( validate instance data against XML Schema)

• Schema documents for

  • the main OAI vocabulary http://www.openarchives.org/OAI/2.0/

  • the OAI wrapper for Dublic Core data, http://www.openarchives.org/OAI/2.0/oai_dc/

  • the OAI wrapper for rights information, http://www.openarchives.org/OAI/2.0/rights/

  • the OAI vocabulary for metadata provenance information, http://www.openarchives.org/OAI/2.0/provenance

  • the Dublin Core vocabulary, http://purl.org/dc/elements/1.1/

  • a subset of RDF (N.B. unofficial schema, drafted by EM and MSM), http://www.w3.org/1999/02/22-rdf-syntax-ns#

  • the Creative Commons rights vocabulary (N.B. unofficial schema, drafted by EM and MSM), http://web.resource.org/cc/

• OAI modified sample record 1 - (validate instance data against XML Schema with annotation, grddl instance data)

  When we ask the schema validator to provide access to the entire post-schema-validation infoset (PSVI) and format it for display in HTML, we can see that the results depend in part on what schema the validator has available.

  If we invoke the validator with instructions to find schema documents by checking the namespace URI and following schema-location hints in the XML document and in schema documents, then it can validate all of the OAI and Dublin Core elements. An HTML display shows those elements as green (valid) on white background (if they are fully validated) or light-blue background (if they are partially validated).

  Note that there are no schema documents available at the namespace URIs for the RDF and Creative Commons namespaces. And the relevant schema documents are not pointed to by the instance document. So the validator cannot find any declarations for the elements and attributes in those namespaces. So the rdf:RDF element is not validated at all, as the display illustrates: it's shown as amber (validity unknown) on gray (not validated at all).

  If we instruct the validator first to load the schema document for the RDF namespace linked above, and then to continue as before, the PSVI display shows that the rdf:RDF element is valid (green), but only partially validated (light blue background), because the validator cannot find any schema document for the Creative Commons vocabulary at the namespace URI.

  If we tell the validator to load the Creative Commons and RDF schema documents (from the local schema documents we have drafted), and then proceed as before, it will find schema components for all the elements and attributes in the document. The PSVI display shows the entire document valid (green) and fully validated (white background).

Workplan

• Done: Identify sample OAI record, and validate this against XML schema
• Done: Modified sample OAI record to include CC metadata.
• Canceled: Modified sample OAI record to point to local XML Schema and validate. Canceled because there is no need for it to point to a local copy of any schema document, in order to validate. The existing OAI schema can already be combined with RDF and CC schema components.
• To do: make modified sample OAI record to point to local XML Schema document, for GRDDL's sake
• Done: Create CC XML Schema for Licenses
• Canceled: modify OAI XML Schema to include CC XML Schema License. Canceled because unnecessary: the XML Schema document for OAI defines about as containing any elements not in the main OAI namespace. The RDF element is already valid against the OAI schema.
• Done. Modified OAI instance data to include license information and validate
• To do: Modified OAI XML Schema to include schema annotation
• Create XSLT script for exracting CC information from OAI records
• GRDDL sample OAI instance data
• add prototype descriptive text to demo.html
• display the data, include description and explanation, in this document