Resource Description Framework

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Resource Description Framework

• Seminar MultimediaHeiko NaumannSS 2004

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Table of content

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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Semantic Web 1

• Tim Berners-Lee The Semantic Web will bring
  structure to the meaningful content of Web pages,
  creating an environment where software agents
  roaming from page to page can readily carry out
  sophisticated tasks for users.

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Semantic Web 2

• Aims of Semantic Web
• Additional information about content
• Agents understand content
• Standards for uniformed storage
• Ability for automatic analysis
• Applications exchange data automatically
• Relations and hierarchy displayable

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Semantic Web 3

• RDF in a Semantic Web
• RDF as a Tool for the Semantic Web
• Older concept than Semantic Web
• Universal usage (every possible resource)
• Concept, regardless if implementation
• Addition, not substitution of technologies

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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RDF History

• Based on the work of Ora Lassila and Ralph Swick
  (Application Data Exchange)
• 1997 first draft
• 1998 W3C takes over draft
• 1999 Model- and Syntax Specification (W3C)
• 2000 RDF Schema Specification (W3C)
• Splitting of specifications
• Ongoing Process (Core Groups)

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W3C Spezifikationen

• RDF/XML Syntax Specification
• RDF Vocabulary Description Language 1.0 (RDF
  Schema)
• RDF Concepts and Abstract Syntax
• RDF Semantics
• RDF Primer (Examples Explanation)
• RDF Test Cases (Probs Discussion)

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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RDF Konzept 1

• Information as triple
• ltSourcegt ltPropertygt ltValuegt
• In RDF as compound sentence
• ltSubjectgt Predicate ltObjectgt
• Known as occurs in grammar (sentence building)

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RDF Konzept 2

• RDF Graph
• Abstract display (Tree - node)
• Human readability
• Complex graphs possible to display
• Node arc Node
• Regardless of implementation

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RDF Konzept 3

• Serialising N-Triples
• Subject Predicate Object .
• lthttp//www.beispiel.de/folder/index.htmlgt
• lthttp//purl.org/dc/elements/1.1/creatorgt
• Hans Mustermann .
• ltbbdindex.htmlgt dccreator Hans Mustermann .

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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RDF / XML 1

• Typical serialisation in XML-Syntax
• lt?xml version1.0?gt
• ltrdfRDF
• xmlnsrdfhttp//www.w3.org/1999/02/22-rdf-syntax
  -ns
• xmlnspstcnhttp//www.mydomain.de/rdf/schema/pos
  tcon/gt
• ltrdfDescription rdfabouthttp//www.mydomain.de
  /artikel/artikel1.htmlgt
• ltpstcnauthorgtHeiko Naumannlt/pstcnauthorgt
• ltpstcndatumgt01.09.1999lt/pstcndatumgt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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RDF / XML 2

• A resource as a property
• lt?xml version1.0?gt
• ltrdfRDF
• xmlnsrdfhttp//www.w3.org/1999/02/22-rdf-syntax
  -ns
• xmlnspstcnhttp//www.mydomain.de/rdf/schema/pos
  tcon/gt
• ltrdfDescription rdfabouthttp//www.mydomain.de
  /artikel/artikel1.htmlgt
• ltpstcnsubpageOf rdfresourcehttp//www.mydomain
  .de/serie1.html gt
• lt/rdfDescriptiongt
• lt/rdfRDFgt
• ltrdfDescription rdfabouthttp//www.mydomain.de
  /serie1.htmlgt
• ltpstcntitelgtEine Serielt/pstcntitelgt
• lt/rdfDescriptiongt

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RDF / XML 3

• Blank nodes with parseType
• ltpstcnauthor parseTypeLiteralgt
• ltrdfgtHeiko Naumannlt/rdfgt
• lt/pstcnauthorgt
• ltpstcnauthor parseTypeResourcegt
• ltpstcnnamegtHeiko Naumannlt/pstcnnamegt
• lt/pstcnauthorgt
• Explicit ID for Nodes with rdfnodeIDxxx

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RDF / XML 4

• Container Seq and Bag
• ltrdfDescription rdfabouthttp//www.mydomain.de
  /artikel1.htmlgt
• ltpstcnmenugt
• ltrdfSeqgt
• ltrdf_1 rdfresourcehttp//www.mydomain.de/artik
  el/sub1.html /gt
• ltrdfli rdfresourcehttp//www.mydomain.de/artik
  el/sub2.html /gt
• ltrdfli rdfresourcehttp//www.mydomain.de/artik
  el/sub3.html /gt
• lt/rdfSeqgt
• lt/pstcnmenugt
• lt/rdfDescriptiongt

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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RDF Schema 1

• Own vocabulary with Schema
• Combination of different Schemas
• Use with XML Namespaces (QNames)
• Derivates of base classes (W3C)
• Consistency

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RDF Schema 2

• Base classes of W3C
• rdfsResource
• rdfsClass
• rdfsLiteral
• rdfsXMLLiteral
• rdfsContainer
• rdfsContainerMembershipProperty
• rdfsDatatype
• All classes and properties are derivates

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RDF Schema 3

• Syntax for derivation
• lt?xml version1.0?gt
• ltrdfRDF
• xmlnsrdfhttp//www.w3.org/1999/02/22-rdf-syntax-
  ns
• xmlnsrdfshttp//www.w3.org/2000/01/rdf-schema
• xmlnspstcnhttp//www.mydomain.de/rdf/schema/pos
  tcon/ gt
• ltrdfsClass rdfabouthttp//www.mydomain.de/rdf/
  schema/postcon/DiaryEntrygt
• ltrdfssubClassOf rdfresourcehttp//www.w3.org/2
  000/01/rdf-schemaResource /gt
• lt/rdfsClassgt
• ltrdfProperty rdfabouthttp//www.mydomain.de/rd
  f/schema/postcon/autorgt
• ltrdfsdomain rdfresourcehttp//www.mydomain.de/
  rdf/schema/postcon/DiaryEntry /gt
• lt/rdfPropertygt
• lt/rdfRDFgt
• Comment and xmllang for readability

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RDF Schema 4

• Determination of valid values
• ltrdfsClass rdfabouthttp//www.mydomain.de/rdf/
  schema/postcon/Reviewgt
• ltrdfssubClassOf rdfresourcehttp//www.w3.org/2
  000/01/rdf-schemaResource /gt
• lt/rdfsClass gt
• ltrdfProperty rdfabouthttp//www.mydomain.de/rd
  f/schema/postcon/uebergt
• ltrdfsdomain rdfresourcehttp//www.mydomain.de/
  rdf/schema/postcon/Review /gt
• ltrdfsrange rdfresourcehttp//www.mydomain.de/r
  df/schema/postcon/Artikel /gt
• lt/rdfPropertygt
• Rdfsrange defines valid values all subclasses
• Rdfstype for single type values

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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PostCon 1
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PostCon 2

• 404 Error whats up ?
• Did that page exist at all ?
• Is page moved or deleted ?
• Why moved or deleted ?
• Redirection to another source ?

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PostCon 3

• PostContent-System can provide information
• Did or does page exist ?
• Has it been moved ? Where ?
• If so, why ?
• Is content depricated ?
• Is there a substitutional source ?
• A Schema is required

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PostCon 4

• RDF File for a documentrdf_description.doc
  (.rdf)
• RDF Schemapostcon_schema.doc (.rdfs)
• So system can give automatic information, why 404
  Error has occured.(Evtl. further information on
  the document)

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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Practical RDF 1

• Query language for RDF
• RDQL similar SQL
• Implementations in APIs
• Supports PHP, Perl, C, JAVA, ..
• SELECT ?date
• WHERE
• (?resource, ltrdftypegt, ltpstcnMovementgt),
• (?resource, ltpstcnmovementTypegt, ?value),
• (?resource, ltdcdategt, ?date)
• AND (?value eq Add)
• USING pstcn FOR http//www.mydomain.de/postcon/sch
  ema/,
• rdf FOR http///www.w3.org/1999/02/22-rdf-syntax-n
  s,
• dc FOR lthttp//purl.org/dc/elements/1.1/gt

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Practical RDF 2

• Tools to modify and work with RDF
• BrownSauce (brownsauce.sourceforge.net)
• FOAF (Friend-of-a-friend) O-Matic
• Sesame (Java Appl. RDF Repos Query)
• Jena (by HP Java API Parser Toolkit)
• ARP (Another RDF Parser)

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Practical RDF 3

• Software using RDF
• Mozilla (embedded, e.g. Bookmarks, History,..)
• RDF Gateway (DB WebServer) based on RDF
• Adobe ProductsProprietary format XMP based on
  RDFEmbedding of RDF into binary dataSupports
  Photoshop 7, Acrobat 5, Illustrator
  10..)Microsoft supports XMP Framework

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Inhalt

• Semantic Web Introduction
• RDF History Specifications
• RDF Graphs N-Triples
• RDF Serialising (Coding)
• RDF Schema
• Example RDF Vocabulary
• Practical RDF
• Summary

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Fazit 1

• About RDF
• Needs increase with the WWW
• Relevant for parts of the web only
• RDF/XML notation as a standard
• Usage für Applications, Agents and Embedded
  Systems (Portability)
• Basic concepts easily understandabel

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Fazit 2

• About seminar
• Difficult research
• Little and redundant information found
• Difficult to present, mainly embedded usage
• Very interesting and innovative
• Want to work with RDF more in the future

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The End

• Tim Berners-Lee
• Though there will still not be a machine which
  can guarantee to answer arbitrary questions, the
  power of RDF to answer real questions which
  are the stuff of our daily lives and especially
  of commerce may be quite remarkable.
  (http//www.w3.org/DesignIssues/Semantic.html)