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An Introduction to RDF: The Resource Description Framework Ian GRAHAM Centre for Academic Technology Tel: 978-4548 Talk:

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Presentation on theme: "An Introduction to RDF: The Resource Description Framework Ian GRAHAM Centre for Academic Technology Tel: 978-4548 Talk:"— Presentation transcript:

1 An Introduction to RDF: The Resource Description Framework Ian GRAHAM Centre for Academic Technology Tel: 978-4548 Email: Talk: http://www.utoronto.ca/ian/talks/

2 Overview zThe problems and issues zResources and Metadata yModularizability yExample: The Dublin Core Set zExpression: RDF and XML  Examples This talk is based on material presented at WWW8 by Carl Lagoze, Eric Miller and Stu Weibel

3 The Problems: zToo much Web information yaround 1,000,000,000 (1  10 9 ) resources yMany different types of resources xtext, images, graphics, xaudio, video, multimedia, xdatabases, Web applications, … xresource metadata (pointers to media servers)

4 The Problems (cont.): zInformation not indexable yNo common “scheme” for doing so yShort-lived, dynamic resources yDiffering relationships between authors, publishers, info intermediaries, users xEach community uses their own approach

5 The Problems (cont.): zInformation not shareable yDifficult to share information yDifficult to share information about information xno common cataloging schemes

6 Talk outline: zThe problems and issues zResources and Metadata yModularizability yExample: The Dublin Core Set zExpression: RDF and XML zExamples

7 Main Issues: zMetadata yInformation about information yStructured data about data zMany types/forms of metadata, dependent on role:

8 Types of Metadata: Web Resource discovery Content ratings (PICS) Product & Services Descriptions Document management administration Security & User authentication (Intellectual) property rights management Database / data schemas Archival information / status Process description & control

9 Second Issue: zLanguage for expressing metadata. zMust be: yuniversal (so all can understand) yflexible (to incorporate different types) yextensible (flexible to custom types) ysimple (to encourage adoption) ymodular (so that schemes can be mixed, extended)

10 Third Issue: zShared Metadata Architectures: yTo share names, and meanings (shared semantics) zExample: Dublin Core Metadata

11 Example : Dublin Core zNot a weapons system from Star Trek zSimple semantics for describing resources -- I.e., metadata ysimple, intuitive, ycross-disciplinary, flexible

12 DC Element Set zTitle zAuthor/creator zSubject/keywords zDescription zPublisher zOther Contributor zDate z Resource type z Format z Resource Identifier z Source z Language z Relation z Coverage z Rights management

13 Creator Extensibility zSubstructure to define more detail Given name Surname Affiliation Contact Info Phone Fax Email

14 Use of Extensibility: zDC: a high-level framework yDescribe features common to “all” resources zExtensible to domain-specific schemes yRefine semantics of keywords yAdd special vocabularies for data (e.g., LC), or for encodings (e.g., 7/11/99 or 11/7/99)

15 Other Metadata Models zDublin core zvCard (business-card data) zvCalendar (calendar/scheduling data) zLCNA (Library of Congress Name Authority File)

16 Describing Resources zMany things to describe z Need flexible scheme that supports yDifferent metadata schemes … yat the same time yExpress in some useful syntax x(e.g., XML)

17 Talk Outline zThe problems and issues zResources and Metadata yModularizability yExample: The Dublin Core Set zExpression: RDF and XML zExamples

18 RDF zResource Description Framework yMachine understandable format yFramework for many classes of resource descriptions xcatalog, accessibility, Intellectual property rights

19 RDF Components zModel for the framework (graphical): yResources yProperties yValues yStatements yContainers zSyntax for interchange (XML dialect)

20 Simple RDF Example http://foo.org/g “RDF talk” dc:Title dc:Creator “Ian Graham” ResourcePropertyValue

21 Expression as XML http://foo.org/g “RDF talk” dc:Title dc:Creator “Ian Graham” RDF Talk Ian Graham

22 Less Simple RDF Example http://foo.org/g “RDF talk” “me” http://utoronto.ca dc:Title dc:Creator bib:Aff “Ian Graham” “ian@goo.org” bib:Name bib:Email

23 Written in XML as: < RDF xmlns=“http://www.w3.org/TR/..” xmlns:dc=“http://purl.org/dc/…” xmlns:bib=http://www.bibby…” > RDF Talk Ian Graham ian@goo.org http://foo.org/g “RDF talk” “me” http://utoronto.ca dc:Title dc:Creator bib:Aff “Ian Graham” “ian@goo.org” bib:Name bib:Email

24 Other Important Concepts zBags -- groups of things zSequences -- ordered group of things zAlternates -- Alternate things/values yFirst value is the default yMust be at least one

25 Bags, Sequences zBag: index categories Category 1 Cat. 2 Bleel z Seq: Sequence Category 1 Cat. 2 Bleel

26 Talk Outline zThe problems and issues zResources and Metadata yModularizability yExample: The Dublin Core Set zExpression: RDF and XML zExamples

27 Netscape Open Directory zhttp://www.dmoz.org yDirectory of Web-accessible resources yHuman-maintained (people add resources zUses RDF to: yDescribe category structure yDescribe resources in each category

28 Top.... Arts... .... CategoryStructure

29 ... Arts John phillips Blown glass A small display of glass by John Phillips Computers Resources

30 2. Netscape Navigator 5 zUses RDF to describe data used in browser y(mailbox contents, directory contents) zAs a way of adding dynamic data access

31 { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/12/3415701/slides/slide_31.jpg", "name": " wat@netscape.com helga@netcenter.net wing.mcom.com Recipe for Yam Soup.", "description": "http://www.mozilla.org/smart-mail/get-body.cgi ... wat@netscape.com w2@pbox.ohio-state.edu x-wing.mcom.com We won our ultimate game http://www.mozilla.org/smart-mail/get-body.cgi ... MailboxEntries.", "width": "800" }

32 Some References: zRDF yhttp://www.w3.org/RDF/ (Overview) yhttp://www.w3.org/Press/1999/RDF-REC (RDF model and syntax spec.) yhttp://www.w3.org/TR/PR-rdf-schema/ (RDF schema specification) z Dublin Core yhttp://purl.org/dc/ yftp://ftp.ietf.org/rfc/rfc2413.txt

33 An Introduction to RDF The Resource Description Framework Ian GRAHAM Centre for Academic Technology Tel: 978-4548 Email: Talk: http://www.utoronto.ca/ian/talks/


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