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RDF Schema

 
Computer Desktop Encyclopedia: RDF
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(Resource Description Framework) A recommendation from the W3C for creating meta-data structures that define data on the Web. RDF is designed to provide a method for classification of data on Web sites in order to improve searching and navigation (see Semantic Web).

An RDF Schema (RDFS) is a construct that describes the structure of the RDF vocabulary, including the terms used and their interrelationships and properties.

Based on XML

RDF is implemented in XML (RDF/XML) and adds new rules to XML as well as reducing some constraints. For example, it supports flat structures, eliminating the need to have data nested in a hierarchy. RDF is structured as one or more Triples: (1) the subject (what the data are about), (2) the property (an attribute of the subject) and (3) the actual value.

A Common Denominator

RDF serves as a common denominator that allows different sets of vocabulary to be recognized. For example, using the RDF descriptor for zip code would let systems exchange zip code data that use "ZIP" and "ZIPCODE. See SPARQL, OWL, XDI and RSS.

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Wikipedia: RDF Schema
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Home > Library > Miscellaneous > Wikipedia
RDF Schema
Current Status Published
Year Started 1998
Editors Dan Brickley, Ramanathan V. Guha
Base Standards RDF
Related Standards OWL
Domain Semantic Web
Abbreviation RDFS
Website RDF Schema

RDF Schema (various abbreviated as RDFS, RDF(S), RDF-S, or RDF/S) is an extensible knowledge representation language, providing basic elements for the description of ontologies, otherwise called Resource Description Framework (RDF) vocabularies, intended to structure RDF resources. The first version[1] was published by the World-Wide Web Consortium (W3C) in April 1998, and the final[2] W3C recommendation was released in February 2004. Many RDFS components are included in the more expressive language Web Ontology Language (OWL).

Contents

Main RDFS constructs

Classes and subclasses

  • rdfs:Class allows to declare a resource as a class for other resources.

Typical example of an rdfs:Class is foaf:Person in the Friend of a Friend (FOAF) vocabulary. An instance of foaf:Person is a resource linked to the class using an rdf:type predicate, such as in the following formal expression of the natural language sentence : 'John is a Person'.

ex:John rdf:type foaf:Person

The definition of rdfs:Class is recursive: rdfs:Class is the rdfs:Class of any rdfs:Class.

  • rdfs:subClassOf allows to declare hierarchies of classes.

For example, the following declares that 'Every Person is an Agent':

foaf:Person rdfs:subClassOf foaf:Agent

Hierarchies of classes support inheritance of a property domain and range (see definitions in next section) from a class to its subclasses.

Property

The RDF Schema specification describes rdf:Property as the class of RDF properties. Each member of the class is an RDF predicate.

  • rdfs:domain of an rdf:predicate declares the class of the subject in a triple whose second component is the predicate.
  • rdfs:range of an rdf:predicate declares the class or datatype of the object in a triple whose second component is the predicate.

For example the following declarations are used to express that the property ex:employer is linking a subject which is a foaf:Person, to an object which is a foaf:Organization

ex:employer rdfs:domain foaf:Person

ex:employer rdfs:range foaf:Organization

Given the previous declarations, in the following triple, ex:John is necessarily a foaf:Person, and ex:CompanyX is necessarily a foaf:Organization

ex:John ex:employer ex:CompanyX

  • rdfs:subPropertyOf is an instance of rdf:Property that is used to state that all resources related by one property are also related by another.

Utility Properties

  • rdfs:seeAlso is an instance of rdf:Property that is used to indicate a resource that might provide additional information about the subject resource.
  • rdfs:isDefinedBy is an instance of rdf:Property that is used to indicate a resource defining the subject resource. This property may be used to indicate an RDF vocabulary in which a resource is described.

Others

  • rdfs:label is an instance of rdf:Property that may be used to provide a human-readable version of a resource's name.
  • rdfs:comment is an instance of rdf:Property that may be used to provide a human-readable description of a resource.
  • rdfs:Literal is the class of literal values such as strings and integers.property values such as textual strings are examples of RDF literals. Literals may be plain or typed.
  • rdfs:Datatype is the class of datatypes. All instances of rdfs:Datatype correspond to the RDF model of a datatype described in the RDF Concepts specification. rdfs:Datatype is both an instance of and a subclass of rdfs:Class. Each instance of rdfs:Datatype is a subclass of rdfs:Literal.

See also

  • SPARQL Query Language for RDF

References

  1. ^ RDFS first version
  2. ^ Final W3C recommendation

External links

v • d • e
Semantic Web
Background
Sub-topics
Applications
Related Topics
Standards
Syntax & Supporting Technologies : RDF (Notation 3  · Turtle  · N-Triples)  · SPARQL  · URI  · HTTP  · XML

Schemas, Ontologies & Rules : RDFS  · OWL  · Rule Interchange Format  · Semantic Web Rule Language

Semantic Annotation : RDFa  · eRDF  · GRDDL  · Microformats

Common Vocabularies : FOAF  · SIOC  · Dublin Core  · SKOS

Others: Plain Old Semantic HTML
People
Key Semantic
Web Organizations
v • d • e
Standards of the World Wide Web Consortium
Recommendations
Canonical XML · CDF · CSS · DOM · HTML · MathML · OWL · P3P · PLS · RDF · RDF Schema · SISR · SMIL · SOAP · SRGS · SSML · SVG · SPARQL · Timed Text · VoiceXML · WSDL · XForms · XHTML · XLink · XML · XML Base · XML Encryption · XML Events · XML Information Set · XML Schema · XML Signature · XPath · XPointer · XQuery · XSL · XSL-FO · XSLT
Notes
Working Drafts
CCXML · CURIE · HTML 5 · InkML · WICD · XFDL · XFrames · XBL · XHTML+MathML+SVG · XMLHttpRequest · XProc · OWL 2
Guidelines
Deprecated
C-HTML · HDML · JSSS · PGML · VML
W3C Device Description Working Group

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