The Resource Description Framework

1
The Resource Description Framework

• And its application to thegateway.org

For the IIAP Jon Jablonski, jonjab_at_u.washington.e
du Research Assistant The Information
School University of Washington. May 18, 2001
2
Current work on theGateway

• Designing RDF based record structures
• Converting old data to RDF
• Establishing standards for expressing Dublin Core
  metadata

3
www.thegateway.org

• A consortial effort to provide a directory to
  quality educational materials on the web.

4
Behind the scenes

• Content providers and consortium members catalog
  and embed metadata
• Register URIs with GEM
• Harvester crawls the metadata, builds database.

• GEM1 data is html meta tags.
• Descriptors based on Dublin Core GEM
  qualifiers
• www.geminfo.org/Workbench/Metadata

5
What is RDF?

• An evolving XML application.
• A model for representing metadata
• A syntax for encoding and transporting this
  metadata.
• A real-life beginning of the semantic web

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So what does it look like?

• ltrdfDescription
• rdfabout "http//someplace.edu"gt
• ltinterest_levelgt
• Really Interesting
• lt/interest_levelgt
• lt/rdfDescriptiongt

Subject
Predicate
Object
And that is the entire model.
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Dublin Core in RDF

• ltrdfDescription rdfabout"http//some_URIgt
• ltdctitlegtExpressing Dublin Core with
  RDFlt/dctitlegt
• ltdccreatorgt Eric Miller lt/dccreatorgt
  ltdcsubjectgt Dublin Core RDF XML lt/dcsubjectgt
• ltdcpublishergt Dublin Core Metadata Initiative
  lt/dcpublishergt
• ltdccontributorgtDublin Core Data Model Working
  Group lt/dccontributorgt
• ltdcdategt 1999-07-01 lt/dcdategt
• ltdcformatgt text/html lt/dcformatgt ltdclanguagegt
  en lt/dclanguagegt lt/rdfDescriptiongt

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Well, there are complications

• Structured entities

ltrdfDescription rdfabout "http//some_uri"gt
ltdccreatorgt ltrdfDescriptiongt
ltgemperson value"Jon Jab" /gt ltgememail
value"jonjab_at_u.wash.edu" /gt
lt/rdfDescriptiongt lt/dccreatorgt lt/rdfDescript
iongt
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Same approach for Statements about Statements

• ltdcrelationgt
• ltgemisChildOfgt
• ltrdfvaluegt
• http//www.nytimes.com/learning/
• lt/rdfvaluegt
• ltrdfslabelgt
• Lesson Plan Archive
• lt/rdfslabelgt
• lt/gemisChildOfgt
• lt/dcrelationgt

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Schemas define classes and properties.

• Written in RDF
• Describes the relationships between properties
  and their resources.
• Analogous to ERDs.
• Can be used to control vocabulary.

• Core Classes
• rdfsResource
• rdfProperty
• rdfsClass
• Core Properties
• rdftype
• rdfssubClassOf
• rdfssubPropertyOf
• rdfsseeAlso
• rdfsisDefinedBy

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Schemas declare standard compliance.

• ltrdfsClass rdfID "LanguageScheme"gt
• ltrdfslabelgtLanguage Encoding Schemeslt/rdfslabel
  gt
• ltrdfscommentgtA set of language encoding schemes
  and/or formats.lt/rdfscommentgt
• ltrdfsisDefinedBy rdfresource "" /gt
• lt/rdfsClassgt
• ltrdfsClass rdfID "RFC1766"gt
• ltrdfslabelgtRFC1766lt/rdfslabelgt
• ltrdfscommentgtInternet RFC 1766 'Tags for the
  identification of Language' specifies a two
  letter code taken from ISO 639, followed
  optionally by a two letter country code taken
  from ISO 3166.lt/rdfscommentgt
• ltrdftype rdfresource "LanguageScheme" /gt
• ltrdfsseeAlso rdfresource "http//www.ietf.org
  /rfc/rfc1766.txt" /gt
• ltrdfsisDefinedBy rdfresource "" /gt
• lt/rdfsClassgt
• ltdclanguagegt
• ltdcqRFC1766gt
• ltrdfvaluegtENlt/rdfvaluegt
• ltrdfslabelgtEnglishlt/rdfslabelgt

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Schemas are also namespaces

• lt?xml version"1.0" encoding"ISO-8859-1" ?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns" xmlnsrdfs"http//www.w3.org/2000/
  01/rdf-schema" xmlnsdc"http//purl.org/dc/eleme
  nts/1.1/" xmlnsdcq"http//dublincore.org/2000/03
  /13/dcq" xmlnsdctype"http//dublincore.org/2000
  /03/13/dctype" xmlnsgemq"http//gemstar.ischool
  .wasington.edu/2.0/gemq"gt
• ltrdfDescription rdfabout""gt
• ltdctitlegtThe GEM Element Set v2.0lt/dctitlegt
• ltdcpublishergtThe GEM Consortiumlt/dcpublishergt
  
• ltdcdescriptiongtThe GEM metadata vocabulary is
  a simple vocabulary intended to facilitate
  discovery of educational resources.lt/dcdescriptio
  ngt
• ltdclanguagegtEnglishlt/dclanguagegt
• ltdcdategt2001-03-16lt/dcdategt
• lt/rdfDescriptiongt

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Controlled language values in RDF wordlists

• ltrdfDescription rdfabout"s3"gt
• ltgemERIC
• rdfabout"http//128.208.100.148/
  thesauri/eric?Secondary_Education"gt
• ltrdfvaluegtSecondary Educationlt/rdfvaluegt
• lt/gemERICgt
• lt/rdfDescriptiongt

Thesaurus is one type of word list stored in
rdf ltrdfDescription about"http//raven.ischool.
washington.edu/thesauri/eric?programs"gt 
ltrdfvaluegtprogramslt/rdfvaluegt  
ltns2SCOPEgtschedules or plans of procedure under
which a series of intended activities is directed
toward desired results (note use a more specific
term if possbile)lt/ns2SCOPEgt ltns2RT
resource"http//raven.ischool.washington.edu/thes
auri/eric?program_administration" /gt   ltns2RT
resource"http//raven.ischool.washington.edu/thes
auri/eric?program_attitudes" /gt   ltns2RT
resource"http//raven.ischool.washington.edu/thes
auri/eric?program_budgeting" /gt   ltns2RT
resource"http//raven.ischool.washington.edu/thes
auri/eric?program content" /gt
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Links

• rdf parser from w3.orghttp//www.w3.org/RDF/Imple
  mentations/SiRPAC/
• RDF Model and Syntax Specificationhttp//www.w3.o
  rg/TR/REC-rdf-syntax/
• RDF Schema Specification 1.0http//www.w3.org/TR/
  2000/CR-rdf-schema-20000327/
• RDF homepagehttp//www.w3c.org/RDF
• Expressing Qualified Dublin Core in
  RDFhttp//www.mathematik.uni-osnabrueck.de/projec
  ts/dcqual/qual21.3.1/qual21-3-1.html
• The Gateway to Educational Materialshttp//www.th
  egateway.org/
• GEMinfo (about the Gateway)http//www.geminfo.org
  /