Barcamprdu linkeddata

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Barcamprdu linkeddata

  1. 1. Linked Data BarCampRDU 2010 Intro slides - Dave Johnson Monday, October 25, 2010
  2. 2. Motivations Data model for machine readable web Monday, October 25, 2010
  3. 3. HTML is great for people with browsers Monday, October 25, 2010
  4. 4. Not so great for software that needs to extract meaningful data from web Monday, October 25, 2010
  5. 5. Motivations Data model for HTTP / REST based web services Monday, October 25, 2010
  6. 6. HTTP is pretty good for creating, retrieving, updating and deleting resources on the web Image by Paul Downey http://www.flickr.com/photos/psd/421186578/ Monday, October 25, 2010
  7. 7. XML and JSON based formats are pretty good for representing resources Photo by Alex Waterhouse-Hayward http://blog.alexwaterhousehayward.com/2007_11_14_archive.html Monday, October 25, 2010
  8. 8. But, just because a resource is represented in XML or JSON doesn’t mean you know how to parse it or what the data means Monday, October 25, 2010
  9. 9. Enter RDF • Resource Description Framework (RDF) • Simple data model • Resources identified by URI • Resources have property values • Property values can be literal values • Or URI links to other resources • Property value also known as triple • Subject - resource (identified by URI) • Predicate - property type (identified by URI) • Object - value of property • RDF data can be represented in XML, JSON and other formats • If it’s an RDF representation then you know how to parse it or what the data means Monday, October 25, 2010
  10. 10. Common vocabularies • RDF provides ways to specify vocabularies of properties (e.g. http://www.w3.org/TR/rdf-schema/, http://www.w3.org/TR/owl-ref/ ) • And ontologies: resource classes with agreed upon sets properties • Two of many examples: abstract, accessRights, accrualMethod, accrualPeriodicity, accrualPolicy, alternative, audience, available, bibliographicCitation, conformsTo, contributor, coverage, created, creator, date, dateAccepted, dateCopyrighted, dateSubmitted, description, educationLevel, extent, format, hasFormat, hasPart, hasVersion, identifier, instructionalMethod, isFormatOf, isPartOf, isReferencedBy, isReplacedBy, isRequiredBy, issued, isVersionOf, language, license, mediator, medium, modified, provenance, publisher, references, relation, replaces, requires, rights, rightsHolder, source, spatial, subject, tableOfContents, temporal, title, type, valid, contributor, coverage, creator, date, description, format, identifier, language, publisher, relation, rights, source, subject, title, type Classes: | Agent | Document | Group | Image | LabelProperty | OnlineAccount | OnlineChatAccount | OnlineEcommerceAccount | OnlineGamingAccount | Organization | Person | PersonalProfileDocument | Project | Properties: | account | accountName | accountServiceHomepage | age | aimChatID | based_near | birthday | currentProject | depiction | depicts | dnaChecksum | familyName | family_name | firstName | focus | fundedBy | geekcode | gender | givenName | givenname | holdsAccount | homepage | icqChatID | img | interest | isPrimaryTopicOf | jabberID | knows | lastName | logo | made | maker | mbox | mbox_sha1sum | member | membershipClass | msnChatID | myersBriggs | name | nick | openid | page | pastProject | phone | plan | primaryTopic | publications | schoolHomepage | sha1 | skypeID | status | surname | theme | thumbnail | tipjar | title | topic | topic_interest | weblog | workInfoHomepage | workplaceHomepage | yahooChatID | FOAF Monday, October 25, 2010
  11. 11. Example Blog entry in RDF / Turtle @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix dcterms: <http://purl.org/dc/terms/> . @prefix foaf: <http://http://xmlns.com/foaf/0.1/> . @prefix oslc: <http://open-services.net/ns/core#> . @prefix oslc_blog: <http://open-services.net/ns/bogus/blogs#> . <http://example.com/blogs/entry/1> rdf:type oslc_blog:Entry ; dcterms:content "Anything dirty or dingy or dusty. n Anything ragged or rotten or rusty." ; dcterms:creator [ rdf:type foaf:Person ; foaf:name "Oscar T. Grouch" ] ; dcterms:modified "2002-10-10T12:00:00-05:00" ; dcterms:title "I love trash" . URI of this resource http://example.com/blogs/entry/1 Monday, October 25, 2010
  12. 12. Example Change Request in RDF / XML <?xml version="1.0" encoding="UTF-8"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:oslc="http://open-services.net/ns/core#" xmlns:oslc_cm="http://open-services.net/ns/cm#" xmlns:ex="http://example.com/bugtracker"> <rdf:Description rdf:about="http://example.com/bugs/2314"> <rdf:type rdf:resource="http://open-services.net/ns/cm#ChangeRequest" /> <dcterms:identifier> 00002314 </dcterms:identifier> <oslc:shortTitle>Bug 2314</oslc:shortTitle> <dcterms:title> Invalid installation instructions </dcterms:title> <dcterms:type> Defect </dcterms:type> <oslc:instanceShape rdf:resource="http://example.com/shapes/defect" /> <dcterms:description> Invalid installation instructions indicating invalid patches to be applied. </dcterms:description> ... </rdf:RDF> URI of this resource http://example.com/bugs/2314 Monday, October 25, 2010
  13. 13. Example RDFa embedded in HTML <div about="/alice/posts/trouble_with_bob" xmlns:dc="http://purl.org/dc/elements/1.1/"> <h2 property="dc:title">The trouble with Bob</h2> The trouble with Bob is that he takes much better photos than I do: ! <div about="http://example.com/bob/photos/sunset.jpg"> <img src="http://example.com/bob/photos/sunset.jpg" /> <span property="dc:title">Beautiful Sunset</span> by <span property="dc:creator">Bob</span>. </div> </div> Monday, October 25, 2010
  14. 14. Linked Data Tim Berners-Lee outlined four principles of Linked Data in his Design Issues: Linked Data note, paraphrased along the following lines: 1. Use URIs to identify things. 2. Use HTTP URIs so that these things can be referred to and looked up ("dereferenced") by people and user agents. 3. Provide useful information about the thing when its URI is dereferenced, using standard formats such as RDF/XML. 4. Include links to other, related URIs in the exposed data to improve discovery of other related information on the Web. Monday, October 25, 2010
  15. 15. Problems with RDF • Representations • RDF/XML is a nightmare of complexity • RDF/JSON not really there yet • Perceptions of complexity • RDF/XML doesn’t help • Weird terminology: blank nodes, triples and reification, etc. • I need a triple-store and a SPARQL query engine? • Slow adoption, has it crossed the chasm? But... RDF is not RDF/XML, you can use other formats But... there are some JSON representations out there Yes, there is some learning curve but the underlying data model is simple: resources with property values You might need an RDF parser but not a full stack of RDF technology to benefit Who knows? We’ll review some evidence of momentum later... Monday, October 25, 2010
  16. 16. Linked Data momentum Linked Data major part of upcoming Drupal 7 release http://sf2010.drupal.org/conference/sessions/story-rdf-drupal7-and-what-it-means-web-large Monday, October 25, 2010
  17. 17. Linked Data momentum US government using Linked Data to provide access to government data Monday, October 25, 2010
  18. 18. Linked Data momentum UK government using Linked Data to provide access to government data Monday, October 25, 2010
  19. 19. Linked Data momentum http://www.readwriteweb.com/archives/how_best_buy_is_using_the_semantic_web.php Best Buy using Linked Data and RDFa to increase traffic and provide better service to customers Monday, October 25, 2010
  20. 20. Linked Data momentum http://www.youtube.com/watch?v=B2vqL8fujgE http://open-services.net OSLC specs build on Linked Data to enable integration of software development tools Monday, October 25, 2010
  21. 21. How to benefit • Web site designers and operators • Use RDFa to mark-up data in your web pages • Benefits: • Search engines can index your data more effectively • Software can more easily parse and make sense of your data Monday, October 25, 2010
  22. 22. How to benefit • REST API developers • Use RDF as the data model for your REST web services • Define your resources in terms of RDF properties • Provide RDF representations of your resources • Benefits: • You don’t have to invent a new data model or a new XML or JSON format • You can use standard property types • And common vocabulary means easier inter-op with other web apps Monday, October 25, 2010
  23. 23. Learn more • O’Reilly Programming the Semantic Web • http://oreilly.com/catalog/9780596153823 • W3C Linked Data initiative • http://esw.w3.org/LinkedData • Tim Berners-Lee:The next web of open linked data • http://www.youtube.com/watch?v=OM6XIICm_qo • Tim Berners-Lee: Linked Data is Blooming:WhyYou Should Care • http://www.readwriteweb.com/archives/ linked_data_is_blooming_why_you_should_care.php Monday, October 25, 2010

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