Introduction: Data and Documents

Many dialects of XML in use by documents on the web.
Encoding techniques to overlay additional semantics onto documents (e.g. RDFa, microformats)
Valuable data for many systems if they could support the wide variety of dialects
Gleaning Resource Descriptions from Dialects of Languages.
A markup for...
- ... declaring that an XML document includes gleanable data (PROFILE)
- ... linking to an algorithm (typically XSLT) for gleaning the RDF data from the document (TRANSFORMATION)

GRDDL enables you to...

... provide an inexpensive set of mechanisms for bootstrapping RDF content from uniform XML dialects
... shift the burden of formulating RDF away from the author to transformation algorithms written specifically for XML dialects.
... associate transformations with an individual document either through direct inclusion of references or indirectly through profile and namespace documents.
... express and deploy transformations (preferably in XSLT 1.0).

Examples of declarations

Simple XML:

<book xmlns="http://example.org/book/"
      xmlns:grddl='http://www.w3.org/2003/g/data-view#'
      grddl:transformation="glean_title.xsl
      http://example.org/book/getAuthor.xsl" >
<title>The man who mistook his wife for a hat</title>
...
</book>

Simple XHTML

<html xmlns="http://www.w3.org/1999/xhtml">
 <head profile="http://www.w3.org/2003/g/data-view">
  <title>The man who mistook his wife for a hat</title>
  <link rel="transformation"
   href="http://www.w3.org/2000/06/dc-extract/dc-extract.xsl" />
  <link rel="transformation" href="glean_title.xsl" />
  <meta name="DC.Subject" content="clinical tales" />
   ...
 </head>
 ...
</html>

Biblio example.

Example of a biblio description in HTML:
- Biblio description
  
  Title
  
  RDF Semantics - W3C Recommendation 10 February 2004
  
  Author
  
  Patrick Hayes see homepage

HTML code for this description

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
      xmlns:dc="http://purl.org/dc/elements/1.1/"
      xmlns:foaf="http://xmlns.com/foaf/0.1/" >
      
  <head profile="http://www.w3.org/2003/g/data-view" >
    <link rel="transformation" href="RDFa2RDFXML.xsl"/>
    <title>Biblio description</title>
  </head>
  
  <body>
    <h2>Biblio description</h2>
    <dl about="http://www.w3.org/TR/2004/REC-rdf-mt-20040210/">

      <dt>Title</dt>
       <dd property="dc:title">RDF Semantics - W3C Recommendation 10 February 2004</dd>
       
      <dt>Author</dt>
       <dd rel="dc:creator" href="#a1">
        <span id="a1">
        
          <link rel="rdf:type" href="[foaf:Person]" />
          
          <span property="foaf:name">Patrick Hayes</span>
          see <a rel="foaf:homepage"
          href="http://www.ihmc.us/users/user.php?UserID=42">homepage</a>
          
        </span>
       </dd>
    </dl>
  </body>
</html>l>

RDF that can be extracted from it:

PREFIX dc: <http://purl.org/dc/elements/1.1/>
 
  <http://www.w3.org/TR/2004/REC-rdf-mt-20040210/>
    dc:title "RDF Semantics - W3C Recommendation 10 February 2004"
    
  <http://www.w3.org/TR/2004/REC-rdf-mt-20040210/>
    dc:creator <#a1>
  
  <#a1> rdf:type <http://xmlns.com/foaf/0.1/Person"/>
  
  <#a1> foaf:name "Patrick Hayes"
  
  <#a1> foaf:homepage <http://www.ihmc.us/users/user.php?UserID=42/>

Scheduling

Jane is trying to coordinate a meeting.

Jane is trying to coordinate a meeting with friends. She uses GRDDL to extract data from each of their calendar pages and combine it in a single model. She then writes a query to filter the events down to those dates when all of them are in the same city.

Health Care

Kayode wants to query clinical data.

Kayode uses a single-purpose XML vocabulary as the main representation format for a computer-based patient record. He uses GRDDL to be able to query these records both in their XML vocabulary and as RDF, without managing a dual representation.

Aggregating data

Stephan wants a synthetic review before buying a guitar.

Stephan wishes to buy a guitar and visits a site offering a review service. He uses GRDDL to aggregate reviews and profiles of the reviewers in order to select the reviews he can trust.

Querying sites and digital libraries

DC4Plus Corp. wants to automate the publication of its electronic documents.

Adeline designs a system to allow here company to streamline the publication of Technical Reports. The system relies on shared templates for publishing documents and a GRDDL transformation to build an up-to-date RDF index used to create an authoritative repository..

Wikis and e-learning

The Technical University of Marcilly decided to use wikis to foster knowledge exchanges between lecturers and students.

The Technical University of Marcilly decides to use a wiki with metadata embedded in its pages to tag, structure, navigate and query the resources of the wiki. GRDDL is used to extract these metadata as RDF to feed the different tools of the system.

Web syndication

Extracting form descriptions to push entries to Voltaire's blog.

Voltaire has setup a weblog engine that utilizes XForms for editing entries. He also provides a GRDDL transformation that extracts an RDF description of the XForms that other client applications can use to update existing entries using the identified service URIs, and perform other such services.

Validated Documents

the OAI would like to be able to specify document licenses in the schema they share.

The Open Archives Initiative (OAI) publishes an XML schema that universities can use to publish their archived documents. This schema also identifies a GRDDL transform to apply to all its instance documents in order to extract their Creative Commons license.

Pulling Data from the Web

Steffen wants to build a directory of the people he works with.

Whenever he gets in touch with someone, Steffen starts a simple script that aims at gathering as much metadata about this person as possible. Because most of these web pages are not even valid HTML, the script calls an HTML-tidying tool and if the tidying is complex some of the metadata is likely to be no longer coherent.

Pushing a transformation

Oceanic Consortium wants to provide transformations for their files without altering them or their schema.

Oceanic wishes to also publish RDF descriptions of their parts reusing the AirPartML documents produced for an arrangement with a consortium of airlines. The AirPartML schemas are strict and therefore Oceanic cannot alter their XML documents to specify a transformation. Yet using the HTTP Headers, Oceanic can specify link and profiles for transformation when serving their AirPartML documents.

Direct referencing of GRDDL transformations

GRDDL introduces markup based on existing standards for:
1. declaring that an XML document includes data compatible with the Resource Description Framework (RDF).
2. linking to algorithms (typically represented in XSLT), for extracting this data from the document.

The markup includes:

a namespace-qualified attribute for use in general-purpose XML documents.

xmlns:grddl='http://www.w3.org/2003/g/data-view#' grddl:transformation="glean_title.xsl"

a profile-qualified link relationship for use in valid XHTML documents.

<head profile="http://www.w3.org/2003/g/data-view">
  <link rel="transformation" href="glean_title.xsl" />

Profile-based referencing of GRDDL transformations

XML namespace document (or XHTML profile document)

to declare that every document associated with that namespace (or profile) includes gleanable data.
```
<head profile="http://purl.org/NET/erdf/profile">
```

for linking to an algorithm for gleaning the data.

<a rel="profileTransformation" 
   href="http://purl.org/NET/erdf/extract-rdf">GRDDL transform</a>

A namespace document or a profile document also provide a means for their authors to explain in prose the purpose of the transformation or any policy statements.

Provide a faithful rendition

By specifying a GRDDL transformation, the author of a document states that the transformation will provide a faithful rendition in RDF of at least some portion of the information expressed through the XML dialect used in the source document.
By specifying a GRDDL namespace transformation or profile transformation, the creator of that namespace or profile states that the transformation will provide a faithful RDF rendition of a class of source documents which relate to that namespace or profile.

Example with Microformats

Example referencing GRDDL transformations directly in the head of the HTML.

Example of a calendar in HTML:
- 1. 2007
    1. Web Design Conference in Edinburgh, UK: Jan 8 to 10
    2. Board Review in New York, USA: Feb 23 to 24

HTML code for this calendar with microformats

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <title>Robin's Schedule</title>
  </head>
  <body>
    <ol class="schedule">
      <li>2007
        <ol>
          <li class="vevent">
            <strong class="summary">Web Design Conference</strong> in 
            <span class="location">Edinburgh, UK</span>:
            <abbr class="dtstart"
              title="2007-01-08">Jan 8</abbr> to 
            <abbr class="dtend"
              title="2007-01-11">10</abbr>
          </li>
          <li class="vevent">
            <strong class="summary">Board Review</strong> in 
            <span class="location">New York, USA</span>:
            <abbr class="dtstart"
              title="2007-02-23">Feb 23</abbr> to 
            <abbr class="dtend"
              title="2007-02-25">24</abbr>
          </li>
        </ol>
      </li>
    </ol>
  </body>
</html>

Add a profile attribute to the head element to denote that the document contains GRDDL metadata:

<html xmlns="http://www.w3.org/1999/xhtml"
    xml:lang="en" lang="en">
  <head profile="http://www.w3.org/2003/g/data-view" >
    <title>Robin's Schedule</title>
  </head>
  <body>& ...

Add link element containing the reference to the specific transformation for converting HTML containing hCalendar patterns into RDF:

<html xmlns="http://www.w3.org/1999/xhtml"
    xml:lang="en" lang="en">
  <head profile="http://www.w3.org/2003/g/data-view" >
    <title>Robin's Schedule</title>
    <link rel="transformation" href="http://www.w3.org/2002/12/cal/glean-hcal"/>
  </head>
  <body>& ...

Example with embedded RDF

Example referencing GRDDL transformations in a profile document referenced in the head of the HTML.

Example of a calendar in HTML
- From 7 October, 2006 to 12 October, 2006 I will be attending the National Tiddlywinks Championship in Bognor Regis, UK.

HTML code for this calendar with embedded RDF

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <title>Where Am I</title>
    <link rel="schema.cal" href="http://www.w3.org/2002/12/cal#" />
  </head>

  <body>
    <p class="-cal-Vevent" id="tiddlywinks">
      From <span class="cal-dtstart" title="2006-10-07">7 October, 2006</span>
      to <span class="cal-dtend"  title="2006-10-13">12 October, 2006</span> 
      I will be attending the <span class="cal-summary">National Tiddlywinks
      Championship</span> in 
      <span class="cal-location">Bognor Regis, UK</span>.
    </p>
  </body>
</html>

Reference a GRDDL profile:

<head profile="http://purl.org/NET/erdf/profile">
  <title>Where Am I</title>
  <link rel="schema.cal" href="http://www.w3.org/2002/12/cal#" />
</head>

This references the standard profile URI for Embedded RDF which does contain the GRDDL metadata:

<html xmlns="http://www.w3.org/1999/xhtml"
    xml:lang="en" lang="en">
 <head profile="http://www.w3.org/2003/g/data-view">
   <title>Embedded RDF HTML Profile</title>
   <link rel="transformation" href="http://www.w3.org/2003/g/glean-profile" />
 </head>
 <body>
   <p>
     <a rel="profileTransformation" 
        href="http://purl.org/NET/erdf/extract-rdf">GRDDL transform</a>
   </p>
 </body>
</html>

Example XML

Example referencing GRDDL transformations in an XML document.

Example of a clinical file in XML

<ClinicalDocument
  xmlns="urn:hl7-org:v3"
  xmlns:voc="urn:hl7-org:v3/voc"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  templateId="2.16.840.1.113883.3.27.1776">
...
 <author>
  <time value="20000407"/>
  <assignedAuthor>
  <id extension="KP00017" root="2.16.840.1.113883.3.933"/>
  <assignedPerson>
   <name>
       <given>Robert</given>
   <family>Dolin</family>
   <suffix>MD</suffix>
   </name>
  </assignedPerson>
  <recordTarget>
   <patientRole>
    <patientPatient>
     <name>
      <given>Henry</given>
      <family>Levin</family>
      <suffix>the 7th</suffix>
     </name>
     <administrativeGenderCode code="M" codeSystem="2.16.840.1.113883.5.1"/>
     <birthTime value="19320924"/>
    </patientPatient>
   </patientRole>
  </recordTarget>
   </author>
</ClinicalDocument>

Add a link to a transformation:

<ClinicalDocument
     xmlns="urn:hl7-org:v3"
     xmlns:voc="urn:hl7-org:v3/voc"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     templateId="2.16.840.1.113883.3.27.1776"
     xmlns:grddl="http://www.w3.org/2003/g/data-view#" 
     grddl:transformation="glean-HL7-CDA.xslt">

Complete example in RDFa

Document from RDFa test case:
http://www.w3.org/2006/07/SWD/RDFa/testsuite/testcases/000002.html

<html xmlns="http://www.w3.org/1999/xhtml"
  xmlns:dc="http://purl.org/dc/elements/1.1/">
<body>
  This photo was taken by
  <span class="author"
  about="photo1.jpg"
  property="dc:creator">Mark Birbeck</span>.
</body>
</html>

Rendered: This photo was taken by Mark Birbeck.