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Introduction to RDF and RDFS BY Tushar Dongare

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RDF Concept <ul><li>RDF stands for Resource Description Framework. </li></ul><ul><li>RDF is a framework for describing resources on the web. </li></ul><ul><li>RDF is designed to be read and understood by computers. </li></ul><ul><li>RDF (i.e RDF/XML) is a W3C Recommendation (for Semantic Web). </li></ul><ul><li>RDF is written in XML </li></ul>

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RDF Concept <ul><li>How to describe resources ? </li></ul><ul><li>Decompose knowledge or fact of resource into small pieces. </li></ul><ul><li>In Method and not the format. </li></ul><ul><li>Comparing with XML </li></ul><ul><li>XML is not concerned with meaning. </li></ul><ul><li>XML standard doesn't indicate how to derive a fact from a document. </li></ul>

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<ul><li>Decomposition of knowledge into small pieces is called triple (statement). </li></ul><ul><li>Triple is made of three parts. </li></ul>Triples SUBJECT OBJECT PREDICATE

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Triple Example <ul><li>Subject and Object denotes the real world entities. </li></ul><ul><li>Predicate is relationship between them. </li></ul>amravati is_in my_house my_bed has my_house my_computer has my_house my_house own I OBJECT PREDICATE SUBJECT

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URI 2 Name Resources <ul><li>Names must be global. </li></ul><ul><li>Names for subjects, predicates, and objects must be Uniform Resource Identifiers. </li></ul><ul><li>Let tushar: abbreviate http://tushar.myhomepage.com/index.html# </li></ul><ul><li>And ex: abbreviate http://example.com/ </li></ul>

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URI 2 Name Resources RDF as a Graph

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Semantic Web : Three Rules <ul><li>A fact is expressed as a triple of the form (Subject, Predicate, Object). </li></ul><ul><li>Subjects, predicates, and objects are given as names for entities, whether concrete or abstract, in the real world. </li></ul><ul><li>Names are in the format of URIs, which are opaque and global. </li></ul>

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Reading and Writing RDF <ul><li><rdf:RDF xmlns:rdf=&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot; </li></ul><ul><li>xmlns:dc=&quot;http://purl.org/dc/elements/1.1/&quot; </li></ul><ul><li>xmlns:geo=&quot;http://www.w3.org/2003/01/geo/wgs84_pos#&quot; </li></ul><ul><li>xmlns:edu=&quot;http://www.example.org/&quot;> </li></ul><ul><li><rdf:Description rdf:about=&quot;http://www.coebadnera.com&quot;> </li></ul><ul><li><geo:lat>40.35</geo:lat> </li></ul><ul><li><geo:long>-74.66</geo:long> </li></ul><ul><li><edu:hasDept rdf:resource=&quot;http://www.coebadnera.com/IT#&quot;/> </li></ul><ul><li></rdf:Description> </li></ul><ul><li><rdf:Description rdf:about=&quot;http://www.coebadnera.com/IT#&quot;> </li></ul><ul><li><dc:title>Department of Information Technology</dc:title> </li></ul><ul><li></rdf:Description> </li></ul><ul><li></rdf:RDF> </li></ul>

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Reading and Writing RDF <ul><li>……… </li></ul><ul><li><rdf:Description rdf:about=&quot; http://www.coebadnera.com &quot;> </li></ul><ul><li><geo:lat>40.35</geo:lat> </li></ul><ul><li><geo:long>-74.66</geo:long> </li></ul><ul><li><edu:hasDept> </li></ul><ul><li><rdf:Description rdf:about=&quot;http://www.coebadnera.com/IT#&quot;> </li></ul><ul><li><dc:title> Department of Information Technology </dc:title> </li></ul><ul><li></rdf:Description> </li></ul><ul><li></edu:hasDept> </li></ul><ul><li></rdf:Description> </li></ul>

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Choosing The Right Predicates <ul><li>WHY ? </li></ul><ul><li>Piece of knowledge is not automatically interpretable. </li></ul><ul><li>If two RDF documents with no URIs in common, there is no information that can be interrelated. </li></ul><ul><li>For Example Let consider information from Google Book and Amazon.com about book in RDF Format. </li></ul>

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Choosing The Right Predicates <urn:isbn:0143034650> dc:title &quot;Pro ASP.NET 3.5&quot; <urn:isbn:0613917472> dc:title &quot;Laws of Cyberspace&quot; <urn:isbn:B00005U7WO> dc:title &quot;System Simulation&quot; From Google Book <urn:isbn:0143034650> amazon:price &quot;$20.00&quot; <urn:isbn:0613917472> amazon:price &quot;$30.00&quot; <urn:isbn:B00005U7WO> amazon:price &quot;$40.00&quot; From Amazon.com (automatically interpretable for two application)

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Meshing The Information <ul><li>Example : Product Vender and Reviewer </li></ul>Meshup of Data Vender 1 with Product_X Product_Y Product_Z Vender 2 with Product_Y Product_Z Vender 3 with Product_A Product_B Product_Z Reviewer 1 for Product_X Product_A Product_B Reviewer 2 for Product_Y Product_Z Reviewer 3 for Product_Z Product_X

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RDFS : RDF Schema <ul><li>RDFS extends RDF such that it is RDF which describe other RDF. </li></ul><ul><li>Ontologies, schemas and vocabularies which all mean roughly the same thing. </li></ul><ul><li>Purpose is to show applications how some information should be interpreted. </li></ul><ul><li>RDF Schema (RDFS) introduces the notion of a class. </li></ul><ul><li>Here a class is a type of thing. </li></ul>

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RDF Schema : Example <ul><li>rdf:type class is first higher-level predicate. </li></ul><ul><li><urn:isbn:0143034650> rdf:type general:Book </li></ul><ul><li><urn:isbn:0613917472> rdf:type general:Book </li></ul><ul><li>One interesting class is rdf:Property </li></ul><ul><li>dc:title rdf:type rdf:Property </li></ul><ul><li>amazon:price rdf:type rdf:Property </li></ul><ul><li>RDFS predicates can provide even more information like rdfs:range predicate </li></ul><ul><li>dc:title rdfs:range rdfs:Literal </li></ul>

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RDF Schema : Example <ul><li>rdfs:subClassOf relation indicates that one class is a sub-class of another. </li></ul>Animal Dog rdfs:subClassOf

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Criticism of RDF <ul><li>RDF has been criticized in 2001 on the following grounds </li></ul><ul><li>The XML syntax for RDF is too verbose. </li></ul><ul><li>The triple notation simplicity introduces reading and computation disadvantages. </li></ul><ul><li>RDF's ability to reify statements allows for uncertainty. </li></ul>

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Conclusion <ul><li>For Semantic Web interoperability: </li></ul><ul><li>All items of interest, such as information resources, real-world objects and vocabulary terms are identified by URI references. </li></ul><ul><li>URI references are dereferenceable. </li></ul><ul><li>Descriptions are provided using the RDF/XML syntax. </li></ul><ul><li>Every RDF triple is conceived as a hyperlink that links to related information from the same or a different source. </li></ul>

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Thank You! <ul><li>rdfabout.com </li></ul><ul><li>http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/ </li></ul>