This document summarizes techniques for publishing linked data on the web. It discusses publishing static RDF files, embedding RDF in HTML using RDFa, linking to other URIs, generating linked data from relational databases using RDB2RDF tools, publishing linked data from triplestores and APIs, hosting linked data in the cloud, and testing linked data quality.

1. Publishing Linked Data Juan F. SequedaSemantic Technology ConferenceJune 2011

2. Thanks Heath & Bizer

3. Static RDF FilesSmall amount of data (personal FOAF file)Use RDF/XML because it is the most common serializationSave as a .rdf file and upload it to your webserverhttp://www.cs.utexas.edu/~jsequeda/foaf.rdfhttp://www.cs.utexas.edu/~jsequeda/foaf.rdf#meConfigure MIME TypesAddType application/rdf+xml .rdfAddType text/n3;charset=utf-8 .n3Make RDF Discoverable from HTML<link rel="alternate" type="application/rdf+xml" href="company.rdf">

4. RDF Embedded in HTML FilesUse RDFaRDFa is useful when you have template HTML pagesCan get complicated if your HTML is complicatedDrupal 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 DatabasesMajority of the data on the web is stored in relational databasesEnterprises are full of relational databasesUse RDF as common data format for data integrationRDB2RDF tools expose relational data as RDF

8. RDB2RDF SystemsD2R Serverhttp://www4.wiwiss.fu-berlin.de/bizer/d2rq/Free University of BerlinD2RQ Mapping LanguageVirtuoso RDF Viewshttp://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VOSSQLRDFOpenlinkProprietary mapping languageTriplifyhttp://triplify.org/OverviewUniversitaet LeipzigSQL/PHP

9. RDB2RDF SystemsSquirrelRDFhttp://jena.sourceforge.net/SquirrelRDF/Last update: 2006R2OUPMhttp://mayor2.dia.fi.upm.es/oeg-upm/index.php/en/downloads/9-r2o-odempasterR2O mapping languageDoesn’t support SPARQL (yet)Survey Jan 2009http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf

10. RDB2RDF SystemsSpyderhttp://www.revelytix.com/content/spyderRevelytixW3C RDB2RDF R2RML standardUltrawraphttp://ribs.csres.utexas.edu/ultrawrap/University of Texas at AustinW3C RDB2RDF Direct Mapping standard

11. Current State-of-ArtW3C RDB2RDF Working Group is generating two standards:R2RML: RDB to RDF Mapping LanguageCustomized mappingA Direct Mapping of Relational Data to RDFDefault mappingSpyder and Ultrawrap are the only systems that follow the standardBenchmarks comparing RDB2RDF systems with native relational database show that RDB2RDF are slow and need a lot more optimizationUltrawrap performance is almost equal to native SQL

12. Linked Data from TriplestoresCommercialOracleGarlik – 4storeSystap – BigDataOntotext – BigOwlimOpenlink – VirtuosoFranz – AllegroGraphOntobroker - Ontoprise…Open SourceJenaSesameMulgara…Pubby – Linked Data frontend for SPARQL endpointshttp://www4.wiwiss.fu-berlin.de/pubby/

13. Linked Data in the CloudKasabi (Talis)beta.kasabi.comDydradydra.com…

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

15. Testing your Linked DataVapour Linked Data Validatorhttp://idi.fundacionctic.org/vapourRDF:Alertshttp://swse.deri.org/RDFAlerts/Sindice Inspectorhttp://inspector.sindice.com/cURLhttp://richard.cyganiak.de/blog/2007/02/debugging-semantic-web-sites-with-curl/Firefox PluginsLive 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/