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Towards D2RQ Mappings

We have previously discussed RDB2RDF technology and found some information about available implementations.  Now we have further explored some of the implementation options.  In our survey, we found that there are basically two viable production-level tools for making SPARQL queries against a relational database: the Virtuoso server and the D2R server.

NGS Beta 3 release includes RDFa

The recent release of the MusicBrainz NGS Beta 3 server includes RDFa courtesy of the LinkedBrainz project.  This release is now live on the MusicBrainz test server so grab your favorite RDFa consumption tools and try it out.  A wiki page about consuming RDFa has also been added to help the uninitiated get into RDFa.

RDFa test server online

 We are happy to announce a new RDFa test server for those interested in what the RDFa we're embedding in MusicBrainz will look like.  This effort is far from complete, if you find something missing or incorrect we'd love to hear about it on the Music Ontology specification mailing list.  One notable omission is that of the Advanced Relationships which we hope to cover eventually.  But all the core entity types should include some valid RDFa.  Also, there is some RDFa for the entities that have pagination (xhv:next, xhv:prev) and tabs (rdfs:seeAlso).

You can consume the RDFa with your favorite RDFa parser.  For testing, we've been using the rapper command line tool and  If you have rapper installed, you can execute the following command to see the embedded RDFa for the release "Sex Machine" by James Brown as Turtle RDF:

rapper -i rdfa -o turtle

This should work for any core entity.  Give it a go and let us know!

RDFa ok - adding structured data to MusicBrainz HTML to commence

Last week during the MusicBrainz developer meeting, we presented some experiments about including RDFa in MusicBrainz HTML pages.  The results suggest that the page size (just the HTML file) will increase by between 5% and 30%.

Learning from RDB2RDF at W3C

The LinkedBrainz project is primarily about mapping a relation database (the MusicBrainz DB) into RDF. The W3C RDB2RDF Working Group is focused on use cases just like this. The mission of the working group is to standardize a language for mapping relational data and relational database schemas into RDF and OWL. Richard Cyganiak recommended a video of the working group's recent panel discussion.

From Relational Databases to the Semantic Web: New W3C Standards and Directions Part One from Semantic Universe on Vimeo.

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