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GIven to the Edinburgh Tech Meetup on 8 July 2009. A quick introduction to how to publish linked data on the web.

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  1. 1. Getting started with the web of data Bill Roberts bill@swirrl.com http://www.swirrl.com http://webofdatablog.com
  2. 2. What is the web of data? Tom Coates: “A web of data sources, services for exploring and manipulating data, and ways that users can connect them together”
  3. 3. Linked data “a method of exposing, sharing, and connecting data via dereferenceable URIs on the Web” http://wikipedia.org/Linked_data
  4. 4. Linked data principles From Sir TimBL: 1. Use URIs as names for things 2. Use HTTP URIs so that people can look up those names 3. When someone looks up a URI, provide useful information, using the standards 4. Include links to other URIs so that they can discover more things
  5. 5. http://www.readwriteweb.com/archives/interview_with_tim_b erners-lee_part_1.php
  6. 6. Why publish linked data on the web? • Be found by your customers • Because it’s your mission • As part of academic publishing • As a paid-for service • Complement your main product or service • Build a reputation or brand
  7. 7. Who’s doing it?
  8. 8. How do you find it? • Sindice • Yahoo SearchMonkey • Google Rich Snippets • Following links • Data mashups/aggregators • SPARQL
  9. 9. How to get started? Tom Scott of the BBC: ”...for those considering the Linked Data approach we’d say that 95% of the work is work you should be doing just to build for the (non-semantic) web. Get the fundamentals right and the leap to the Semantic Web is really more of a hop.”
  10. 10. Resource Description Framework Subject/predicate/object (= Thing/attribute/value) “Bill’s e-mail address is bill@swirrl.com” Bill bill@swirrl.com e-mail address
  11. 11. Everything gets a URI http://swirrl.com/ mailto:bill@swirrl.com bill.rdf#me http://xmlns.com/foaf/0.1/mbox <rdf:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#”> <foaf:Person rdf:about="http://swirrl.com/bill.rdf#me"> <foaf:mbox rdf:resource=“mailto:bill@swirrl.com”> </foaf:Person> Don’t worry about the XML stuff: it’s just circles and arrows!
  12. 12. Everything gets a URI http://swirrl.com/ foaf:Person bill.rdf#me rdf:type <rdf:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#”> <foaf:Person rdf:about="http://swirrl.com/bill.rdf#me"> <foaf:mbox rdf:resource=“mailto:bill@swirrl.com”> </foaf:Person>
  13. 13. Ontologies • Use existing ones where possible • Extend if you have to • Make your own if you really have to – People: Friend of a Friend (FOAF) – People/companies: vCard – Dates: iCal – Authors, titles, etc: Dublin Core – E-Commerce: GoodRelations – Places: Geonames – Projects: Description of a Project (DOAP)
  14. 14. Publish for people AND machines URI for a real thing: http://dbpedia.org/resource/Edinburgh HTML representation: http://dbpedia.org/page/Edinburgh RDF representation: http://dbpedia.org/data/Edinburgh.xml
  15. 15. Content negotiation DBPedia Tell me about resource/Edinburgh (in HTML) 303 redirect to …/page/Edinburgh Ok give me …/page/Edinburgh HTML file
  16. 16. Content negotiation curl –v –H “Accept: application/rdf+xml” http://dbpedia.org/resource/Edinburgh Tell me about Edinburgh (in RDF) DBPedia 303 redirect to …/data/Edinburgh.xml Ok give me the data RDF+XML file
  17. 17. RDFa • Mix the HTML and RDF markup in one file. +ve: simpler as only one file -ve: sometimes you want to include data that doesn’t really fit the HTML structure +ve: Google and Yahoo can use it (or at least some of it)
  18. 18. Tools • Validators – w3.org/RDF/Validator • Client libraries and frameworks - Jena • RDF databases - Sesame • Platforms – Talis
  19. 19. Looking for data publishing pilot studies… <rdf:Description rdf:about="http://dbpedia.org/resourc e/Guinea_pig_breed"> <skos:subject rdf:resource="http://dbpedia.org/reso urce/Category:Guinea_pigs"/> </rdf:Description> http://www.flickr.com/photos/mjjames/2767817164/
  20. 20. Useful links Tom Coates “Native to a web of data” http://www.plasticbag.org/files/native/ Linked Data: http://www.linkeddata.org RDF primer http://www.w3.org/TR/rdf-primer/ RDFa primer http://www.w3.org/TR/xhtml-rdfa-primer/ Berners-Lee “Linked data – design issues” http://www.w3.org/DesignIssues/LinkedData.html Berners-Lee “Putting government data online” http://www.w3.org/DesignIssues/GovData.html Tom Scott “Building coherence at bbc.co.uk” http://blogs.talis.com/nodalities/2009/01/building-coherence-at-bbccouk.php RDF Validator http://www.w3.org/RDF/Validator/ Sesame RDF database http://www.openrdf.org Jena – Semantic web framework for Java http://jena.sourceforge.net/ Talis Platform http://www.talis.com/platform/ Yahoo SearchMonkey http://developer.yahoo.com/searchmonkey/ Google Rich Snippets http://www.google.com/support/webmasters/bin/answer.py?answer=99170
  21. 21. Thanks! http://www.slideshare.net/billroberts/webofdata