1. Publishing Linked Data Juan F. Sequeda Semantic Technology Conference June 2011

2. Thanks Heath & Bizer

3. Static RDF Files Small amount of data (personal FOAF file) Use RDF/XML because it is the most common serialization Save as a .rdf file and upload it to your webserver http://www.cs.utexas.edu/~jsequeda/foaf.rdf http://www.cs.utexas.edu/~jsequeda/foaf.rdf#me Configure MIME Types AddType application/rdf+xml .rdf AddType text/n3;charset=utf-8 .n3 Make RDF Discoverable from HTML <link rel="alternate" type="application/rdf+xml" href="company.rdf">

4. RDF Embedded in HTML Files Use RDFa RDFa is useful when you have template HTML pages Can get complicated if your HTML is complicated Drupal 7 will do this out of the box

5. Links to other URIs

6. <span rel="foaf:interest"> <a href="http://dbpedia.org/resource/Database" property="dcterms:title">Database</a>, <a href="http://dbpedia.org/resource/Data_integration" property="dcterms:title">Data Integration</a>, <a href="http://dbpedia.org/resource/Semantic_Web" property="dcterms:title">Semantic Web</a>, <a href="http://dbpedia.org/resource/Linked_Data" property="dcterms:title">Linked Data</a>, etc.</span>

7. Linked Data from Relational Databases Majority of the data on the web is stored in relational databases Enterprises are full of relational databases Use RDF as common data format for data integration RDB2RDF tools expose relational data as RDF

8. RDB2RDF Systems D2R Server http://www4.wiwiss.fu-berlin.de/bizer/d2rq/ Free University of Berlin D2RQ Mapping Language Virtuoso RDF Views http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VOSSQLRDF Openlink Proprietary mapping language Triplify http://triplify.org/Overview Universitaet Leipzig SQL/PHP

9. RDB2RDF Systems SquirrelRDF http://jena.sourceforge.net/SquirrelRDF/ Last update: 2006 R2O UPM http://mayor2.dia.fi.upm.es/oeg-upm/index.php/en/downloads/9-r2o-odempaster R2O mapping language Doesn’t support SPARQL (yet) Survey Jan 2009 http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf

10. RDB2RDF Systems Spyder http://www.revelytix.com/content/spyder Revelytix W3C RDB2RDF R2RML standard Ultrawrap http://ribs.csres.utexas.edu/ultrawrap/ University of Texas at Austin W3C RDB2RDF Direct Mapping standard

11. Current State-of-Art W3C RDB2RDF Working Group is generating two standards: R2RML: RDB to RDF Mapping Language Customized mapping A Direct Mapping of Relational Data to RDF Default mapping Spyder and Ultrawrap are the only systems that follow the standard Benchmarks comparing RDB2RDF systems with native relational database show that RDB2RDF are slow and need a lot more optimization Ultrawrap performance is almost equal to native SQL

12. Linked Data from Triplestores Commercial Oracle Garlik – 4store Systap – BigData Ontotext – BigOwlim Openlink – Virtuoso Franz – AllegroGraph Ontobroker - Ontoprise … Open Source Jena Sesame Mulgara … Pubby – Linked Data frontend for SPARQL endpoints http://www4.wiwiss.fu-berlin.de/pubby/

13. Linked Data in the Cloud Kasabi (Talis) beta.kasabi.com Dydra dydra.com …

14. Linked Data from APIs http://www4.wiwiss.fu-berlin.de/bizer/bookmashup/ http://www4.wiwiss.fu-berlin.de/flickrwrappr/ Assign HTTP URIs to resources that the API provides When a URI is dereferenced, rewrite client request to a request against the API Different types of query and retrieval interfaces Result of the API are transformed to RDF and sent back to the client Different return formats: XML, JSON, ATOM

15. Testing your Linked Data Vapour Linked Data Validator http://idi.fundacionctic.org/vapour RDF:Alerts http://swse.deri.org/RDFAlerts/ Sindice Inspector http://inspector.sindice.com/ cURL http://richard.cyganiak.de/blog/2007/02/debugging-semantic-web-sites-with-curl/ Firefox Plugins Live HTTP Headers https://addons.mozilla.org/af/firefox/addon/live-http-headers/ Modify Headers https://addons.mozilla.org/af/firefox/addon/modify-headers/ Linked Data browsers http://browse.semanticweb.org/