RDF Resource Description Framework

1
RDFResource Description Framework
2
Rückblick

• HTML
• Auszeichnung, vorgegeben
• XML, XHTML, SGML
• Auszeichnung, eigene
• RDF, OWL
• Auszeichnung, inhaltliche Einordnung

3
RDF-Model

• RDF-Konzept (Tripel)
• RDF-Graph
• RDF-Syntax
• RDF-Schema

4
RDF-Konzept

• Subjekte
• Prädikate
• Objekte

• Resources
• Properties
• Values

Statements Sätze
5
Basistypen

• Ressource
• komplexe, abstrakte oder konkrete Entität
• eindeutig durch URI charakterisiert (global)
• Literal
• Datentyp (definiert, undefiniert)
• Blank Node
• Anonyme Ressource (ohne Bezeichner, URI)
• nur innerhalb der Definition einer Ressource
  eindeutig

6
Subjekte

• Beispiele
• Web-Seiten
• Teile von Web-Seiten (HTML-/ XML-Element)
• Sammlungen von Web-Seiten
• Typen
• Resource
• Blank Node

7
Prädikate

• Beispiele
• Specific aspect,
• characteristic,
• attribute, or
• relation
• Typen
• Resource

8
Objekte

• Typen
• Resources
• Blank Nodes
• Literals

9
RDF-Syntax

• Tripel
• RDF-Graph
• In XML eingebunden
• Notation 3 (N3), Tim BernersLee

10
RDF-Graph -Beispiel

• Subject http//www.w3.org/Home/Lassila
• Predicate Creator
• Object "Ora Lassila"

11
RDF-Syntax (XML) -Beispiel

• ltrdfRDFgt
• ltrdfDescription about"http//www.w3.org/Home/La
  ssila"gt
• ltsCreatorgtOra Lassilalt/sCreatorgt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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Container

• Bag
• Seq (Sequence)
• Alt (Alternative)

13
Bag

• a group of part numbers in which the order of
  entry or processing of the part numbers does not
  matter.

14
Bag (2)

• lt?xml version"1.0"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns"
• xmlnss"http//example.org/students/voca
  b"gt
• ltrdfDescription rdfabout"http//example.org/
  courses/6.001"gt
• ltsstudentsgt
• ltrdfBaggt
• ltrdfli rdfresource"http//example.o
  rg/students/Amy"/gt
• ltrdfli rdfresource"http//example.o
  rg/students/Mohamed"/gt
• ltrdfli rdfresource"http//example.o
  rg/students/Johann"/gt
• ltrdfli rdfresource"http//example.o
  rg/students/Maria"/gt
• ltrdfli rdfresource"http//example.o
  rg/students/Phuong"/gt
• lt/rdfBaggt
• lt/sstudentsgt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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Seq (Sequence)

• a group of resources or literals, possibly
  including duplicate members, where the order of
  the members is significant

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Alt (Alternative)

• a group of resources or literals that are
  alternatives (typically for a single value of a
  property)

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Alt (2)

• lt?xml version"1.0"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns"
• xmlnss"http//example.org/packages/voca
  b"gt
• ltrdfDescription rdfabout"http//example.org/
  packages/X11"gt
• ltsDistributionSitegt
• ltrdfAltgt
• ltrdfli rdfresource"ftp//ftp.exampl
  e.org"/gt
• ltrdfli rdfresource"ftp//ftp1.examp
  le.org"/gt
• ltrdfli rdfresource"ftp//ftp2.examp
  le.org"/gt
• lt/rdfAltgt
• lt/sDistributionSitegt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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RDF Collections

• An RDF collection is a group of things
  represented as a list structure in the RDF
  graph.
• This list structure is constructed using a
  predefined collection vocabulary consisting of
• the predefined type rdfList,
• the predefined properties rdffirst
• and rdfrest, and
• the predefined resource rdfnil.

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RDF Collections (2)
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RDF Collections (3)

• lt?xml version"1.0"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns"
• xmlnss"http//example.org/students/voca
  b"gt
• ltrdfDescription rdfabout"http//example.org/
  courses/6.001"gt
• ltsstudents rdfparseType"Collection"gt
• ltrdfDescription rdfabout"http//exa
  mple.org/students/Amy"/gt
• ltrdfDescription rdfabout"http//exa
  mple.org/students/Mohamed"/gt
• ltrdfDescription rdfabout"http//exa
  mple.org/students/Johann"/gt
• lt/sstudentsgt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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RDF Collections (4)
lt?xml version"1.0"?gt ltrdfRDF xmlnsrdf"http//w
ww.w3.org/1999/02/22-rdf-syntax-ns"
xmlnss"http//example.org/students/vocab"gt
ltrdfDescription rdfabout"http//example.org/c
ourses/6.001"gt ltsstudents rdfnodeID"sch1"/gt
lt/rdfDescriptiongt ltrdfDescription
rdfnodeID"sch1"gt ltrdffirst
rdfresource"http//example.org/students/Amy"/gt
ltrdfrest rdfnodeID"sch2"/gt
lt/rdfDescriptiongt ltrdfDescription
rdfnodeID"sch2"gt ltrdffirst
rdfresource"http//example.org/students/Mohamed"
/gt ltrdfrest rdfnodeID"sch3"/gt
lt/rdfDescriptiongt ltrdfDescription
rdfnodeID"sch3"gt ltrdffirst
rdfresource"http//example.org/students/Johann"/
gt ltrdfrest rdfresource"http//www.w3.org/199
9/02/22-rdf-syntax-nsnil"/gt lt/rdfDescriptiongt lt
/rdfRDFgt
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Reification
exproductstriple12345 rdftype
rdfStatement . exproductstriple12345
rdfsubject exproductsitem10245 .
exproductstriple12345 rdfpredicate
extermsweight . exproductstriple12345
rdfobject "2.4"xsddecimal
. exproductstriple12345 dccreator
exstaff85740 .
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RDFS (RDF Schema)

• Types
• Classes
• Subclasses
• Properties
• Subpropperties

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Classes -Beispiel
exMotorVehicle rdftype rdfsClass
. exPassengerVehicle rdftype
rdfsClass . exVan rdftype
rdfsClass . exTruck
rdftype rdfsClass . exMiniVan
rdftype rdfsClass
. exPassengerVehicle rdfssubClassOf
exMotorVehicle . exVan
rdfssubClassOf exMotorVehicle . exTruck
rdfssubClassOf exMotorVehicle
. exMiniVan rdfssubClassOf
exVan . exMiniVan
rdfssubClassOf exPassengerVehicle .
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RDF-Syntax in XML
1 RDF 'ltrdfRDFgt'
description 'lt/rdfRDFgt' 2 description
'ltrdfDescription' idAboutAttr? 'gt'
propertyElt 'lt/rdfDescriptiongt' 3
idAboutAttr idAttr aboutAttr 4
aboutAttr 'about"' URI-reference '"'
5 idAttr 'ID"' IDsymbol '"'
6 propertyElt 'lt' propName 'gt' value
'lt/' propName 'gt' 'lt' propName
resourceAttr '/gt' 7 propName Qname
8 value description string
9 resourceAttr 'resource"'
URI-reference '"' 10 Qname
NSprefix '' name 11 URI-reference
string, interpreted per URI 12 IDsymbol
(any legal XML name symbol) 13 name
(any legal XML name symbol) 14
NSprefix (any legal XML namespace
prefix) 15 string (any XML text,
with "lt", "gt", and "" escaped)
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Notation 3 (N3) -Ziele

• to optimize expression of data and logic in the
  same language,
• to allow RDF to be expressed,
• to allow rules to be integrated smoothly with
  RDF,
• to allow quoting so that statements about
  statements can be made, and
• to be as readable, natural, and symmetrical as
  possible.

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Notation 3 (N3) -Features

• URI abbreviation using prefixes which are bound
  to a namespace (using _at_prefix) a bit like in XML,
• Repetition of another object for the same subject
  and predicate using a comma ","
• Repetition of another predicate for the same
  subject using a semicolon ""
• Bnode syntax with a certain properties just put
  the properties between and
• Formulae allowing N3 graphs to be quoted within
  N3 graphs using and
• Variables and quantification to allow rules, etc
  to be expressed
• A simple and consistent grammar.

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RDF Query

• W3C
• SPARQL Query Language

29
Quellen

• Grigoris Antoniou, Frank van Harmelen, "A
  Semantic Web Primer", MIT Press , 2004 , Kapitel
  3
• http//www.w3.org/TR/rdf-primer/
• http//www.w3.org/TR/2003/WD-rdf-primer-20031010/
• http//www.w3.org/TR/1999/REC-rdf-syntax-19990222/
  
• http//www.w3.org/DesignIssues/Notation3.html