Notions sur la sérialisation RDFS/XML

RDFS permet de définir un schéma (sémantique) d'une application spécifique. RDF Schema est défini par l'URI :

http://www.w3.org/2000/01/rdf-schema#, et le préfixe est rdfs.

Pour le vocabulaire introduit dans ce cours, on utilise la notation des triplets RDF pour définir plusieurs classes de documents comme suit :

cs:Publication

cs:Book

cs:JournalPaper

cs:ConfPaper

cs:ShortPaper

cs:Book

cs:JournalPaper

cs:ConfPaper

cs:ShortPaper

cs:ShortPaper

rdf:type

rdf:type

rdf:type

rdf:type

rdf:type

rdfs:subClassOf

rdfs:subClassOf

rdfs:subClassOf

rdfs:subClassOf

rdfs:subClassOf

rdfs:Class

rdfs:Class

rdfs:Class

rdfs:Class

rdfs:Class

cs:Publication

cs:Publication

cs:Publication

cs:JournalPaper

cs :ConfPaper

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<?xml version="1.0"?>
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<rdf:RDF	xml:base="http://www.cat.com/schema/"
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 			xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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 			xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
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 			xmlns:dc="http://purl.org/dc/elements/1.1/">
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 <rdf:Description rdf:about="Publication">
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 	   <rdf:type 	rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
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 </rdf:Description>
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 <rdf:Description rdf:about="Book">
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 	  <rdf:type	  rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
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	  <rdfs:subClassOf rdf:resource="Publication"/>
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 </rdf:Description>
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 <rdf:Description rdf:about="JournalPaper">
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 	    <rdf:type   rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
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 	    <rdfs:subClassOf rdf:resource="Publication"/>
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 </rdf:Description>
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 <rdf:Description rdf:about="ConfPaper">
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 	    <rdf:type  rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
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 	    <rdfs:subClassOf rdf:resource="Publication"/>
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 </rdf:Description>
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 <rdf:Description rdf:about="ShortPaper">
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 	    <rdf:type   rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
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 	    <rdfs:subClassOf rdf:resource="JournalPaper"/>
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 	    <rdfs:subClassOf rdf:resource="ConfPaper"/>
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 </rdf:Description>
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 </rdf:RDF>

Syntaxe abrégée

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<?xml version="1.0"?>
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<rdf:RDF	xml:base="http://www.cat.com/schema/"
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 			xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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 			xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
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 			xmlns:dc="http://purl.org/dc/elements/1.1/">
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	<rdfs:Class	 rdf:about="Publication"/>
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   <rdfs:Class   rdf:about="Book">
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 		  <rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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	<rdfs:Class rdf:about="JournalPaper">
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 	 	<rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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 	<rdfs:Class rdf:about="ConfPaper">
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 	 	<rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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	<rdfs:Class rdf:about="ShortPaper">
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 	 	  <rdfs:subClassOf rdf:resource="JournalPaper"/>
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 		  <rdfs:subClassOf rdf:resource="ConfPaper"/>
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	 </rdfs:Class>
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 </rdf:RDF>
Propriétés dans RDFS
Le prédicat (propriété) est une instance de la classe Property .
Exemple :
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<?xml version="1.0"?>
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<!DOCTYPE rdf:RDF  [<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#">]>
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<rdf:RDF		xml:base="http://www.cat.com/schema/"
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 			xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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 			xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
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 			xmlns:dc="http://purl.org/dc/elements/1.1/">
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	<rdfs:Class    rdf:about="Publication"/>
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 	<rdfs:Class   rdf:about="Book">
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 		  <rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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 	<rdfs:Class rdf:about="JournalPaper">
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 	 	<rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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 	<rdfs:Class rdf:about="ConfPaper">
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 	 	<rdfs:subClassOf rdf:resource="Publication"/>
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 	</rdfs:Class>
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	<rdfs:Class rdf:about="ShortPaper">
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 	 	<rdfs:subClassOf rdf:resource="JournalPaper"/>
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 		<rdfs:subClassOf rdf:resource="ConfPaper"/>
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	 </rdfs:Class>
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<rdf:Property rdf:about="noPages">
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 		<rdfs:domain rdf:resource="Publication"/>
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		<rdfs:range rdf:resource="&xsd;positiveInteger"/>
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 	</rdf:Property>
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	<rdf:Property rdf:about="placeOfPublication">
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		 <rdfs:domain rdf:resource="ConfPaper"/>
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 		<rdfs:range rdf:resource="&xsd;string"/>
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 	</rdf:Property>
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</rdf:RDF>
Instanciation d'un schéma RDF
Dans l'exemple de sérialisation, le catalogue des métadonnées des documents est basé sur 3 vocabulaires (espaces de noms)
  • http://www.cat.com/schema/ ==> schéma du catalogue (ensemble de classes et de propriétés)
  • http://www.cat.com/docs ==> ensemble des instances des classes et des propriétés définies dans le schéma du catalogue
  • http://www.cat.com/auth ==> liste des auteurs, publishers, ...
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<?xml version= "1.0"?>
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 <!DOCTYPE rdf:RDF   [<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#">]>
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<rdf:RDF  	xml:base="http://www.cat.com/docs"
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 			xmlns:cs="http://www.cat.com/schema/"
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 			xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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 			xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
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 			xmlns:dc="http://purl.org/dc/elements/1.1/">
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	<cs:Book 	 rdf:about="#R20301">
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 		<dc:creator  rdf:resource="http://www.cat.com/auth#R051156"/>
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 		<dc:title>  SEMANTIC WEB: CONCEPTS AND TECHNOLOGIES
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 				   FOR THE GEOGRAPHIC INFORMATION SCIENCES  </dc:title>
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 		<dc:date rdf:datatype="&xsd;date">  2021-01-20  </dc:date>
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 		<cs:noPages>  324  </cs:noPages>
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 	</cs:Book>
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<cs:ConfPaper   rdf:about="#R20302">
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 <dc:creator   rdf:resource="http://www.cat.com/auth#R051156"/>
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 <dc:title>  USING GAZETTEERS TO ANNOTATE GEOGRAPHIC
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 			CATALOGUE ENTRIES
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 </dc:title>
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 <dc:date rdf:datatype="&xsd;date">  2021-01-21  </dc:date>
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 <cs:noPages>  6  </cs:noPages>
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 <cs:placeOfPublication>  Chipre  </cs:placeOfPublication>
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 </cs:ConfPaper>
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 </rdf:RDF>