Publishing Linked Data 3/5 Semtech2011

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Publishing Linked Data 3/5 Semtech2011

  1. 1. Publishing Linked Data <br />Juan F. Sequeda<br />Semantic Technology Conference<br />June 2011<br />
  2. 2. Thanks Heath & Bizer<br />
  3. 3. Static RDF Files<br />Small amount of data (personal FOAF file)<br />Use RDF/XML because it is the most common serialization<br />Save as a .rdf file and upload it to your webserver<br />http://www.cs.utexas.edu/~jsequeda/foaf.rdf<br />http://www.cs.utexas.edu/~jsequeda/foaf.rdf#me<br />Configure MIME Types<br />AddType application/rdf+xml .rdf<br />AddType text/n3;charset=utf-8 .n3<br />Make RDF Discoverable from HTML<br /><link rel="alternate" type="application/rdf+xml" href="company.rdf"><br />
  4. 4. RDF Embedded in HTML Files<br />Use RDFa<br />RDFa is useful when you have template HTML pages<br />Can get complicated if your HTML is complicated<br />Drupal 7 will do this out of the box<br />
  5. 5. Links to other URIs<br />
  6. 6. <span rel="foaf:interest"><br /><a href="http://dbpedia.org/resource/Database" property="dcterms:title">Database</a>,<br /><a href="http://dbpedia.org/resource/Data_integration" property="dcterms:title">Data Integration</a>,<br /><a href="http://dbpedia.org/resource/Semantic_Web" property="dcterms:title">Semantic Web</a>,<br /><a href="http://dbpedia.org/resource/Linked_Data" property="dcterms:title">Linked Data</a>,<br />etc.</span><br />
  7. 7. Linked Data from Relational Databases<br />Majority of the data on the web is stored in relational databases<br />Enterprises are full of relational databases<br />Use RDF as common data format for data integration<br />RDB2RDF tools expose relational data as RDF<br />
  8. 8. RDB2RDF Systems<br />D2R Server<br />http://www4.wiwiss.fu-berlin.de/bizer/d2rq/<br />Free University of Berlin<br />D2RQ Mapping Language<br />Virtuoso RDF Views<br />http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VOSSQLRDF<br />Openlink<br />Proprietary mapping language<br />Triplify<br />http://triplify.org/Overview<br />Universitaet Leipzig<br />SQL/PHP<br />
  9. 9. RDB2RDF Systems<br />SquirrelRDF<br />http://jena.sourceforge.net/SquirrelRDF/<br />Last update: 2006<br />R2O<br />UPM<br />http://mayor2.dia.fi.upm.es/oeg-upm/index.php/en/downloads/9-r2o-odempaster<br />R2O mapping language<br />Doesn’t support SPARQL (yet)<br />Survey Jan 2009<br />http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf<br />
  10. 10. RDB2RDF Systems<br />Spyder<br />http://www.revelytix.com/content/spyder<br />Revelytix<br />W3C RDB2RDF R2RML standard<br />Ultrawrap<br />http://ribs.csres.utexas.edu/ultrawrap/<br />University of Texas at Austin<br />W3C RDB2RDF Direct Mapping standard<br />
  11. 11. Current State-of-Art<br />W3C RDB2RDF Working Group is generating two standards:<br />R2RML: RDB to RDF Mapping Language<br />Customized mapping<br />A Direct Mapping of Relational Data to RDF<br />Default mapping<br />Spyder and Ultrawrap are the only systems that follow the standard<br />Benchmarks comparing RDB2RDF systems with native relational database show that RDB2RDF are slow and need a lot more optimization<br />Ultrawrap performance is almost equal to native SQL<br />
  12. 12. Linked Data from Triplestores<br />Commercial<br />Oracle<br />Garlik – 4store<br />Systap – BigData<br />Ontotext – BigOwlim<br />Openlink – Virtuoso<br />Franz – AllegroGraph<br />Ontobroker - Ontoprise<br />…<br />Open Source<br />Jena<br />Sesame<br />Mulgara<br />…<br />Pubby – Linked Data frontend for SPARQL endpoints<br />http://www4.wiwiss.fu-berlin.de/pubby/<br />
  13. 13. Linked Data in the Cloud<br />Kasabi (Talis)<br />beta.kasabi.com<br />Dydra<br />dydra.com<br />…<br />
  14. 14. Linked Data from APIs<br />http://www4.wiwiss.fu-berlin.de/bizer/bookmashup/<br />http://www4.wiwiss.fu-berlin.de/flickrwrappr/ <br />Assign HTTP URIs to resources that the API provides<br />When a URI is dereferenced, rewrite client request to a request against the API<br />Different types of query and retrieval interfaces<br />Result of the API are transformed to RDF and sent back to the client<br />Different return formats: XML, JSON, ATOM<br />
  15. 15. Testing your Linked Data<br />Vapour Linked Data Validator<br />http://idi.fundacionctic.org/vapour<br />RDF:Alerts<br />http://swse.deri.org/RDFAlerts/<br />Sindice Inspector<br />http://inspector.sindice.com/<br />cURL<br />http://richard.cyganiak.de/blog/2007/02/debugging-semantic-web-sites-with-curl/<br />Firefox Plugins<br />Live HTTP Headers https://addons.mozilla.org/af/firefox/addon/live-http-headers/<br />Modify Headers https://addons.mozilla.org/af/firefox/addon/modify-headers/<br />Linked Data browsers <br />http://browse.semanticweb.org/<br />

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