DDC 23 released as linked data at dewey.info

As announced on Monday at the seminar "Global Interoperability and Linked Data in Libraries" in beautiful Florence, an exciting new set of linked data has been added to dewey.info. All assignable classes from DDC 23, the current full edition of the Dewey Decimal Classification, have been released as Dewey linked data. As was the case for the Abridged Edition 14 data, we define "assignable" as including every schedule number that is not a span or a centered entry, bracketed or optional, with the hierarchical relationships adjusted accordingly. In short, these are numbers that you find attached to many WorldCat records as standard Dewey numbers (in 082 fields), as additional Dewey numbers (in 083 fields), or as number components (in 085 fields).

The classes are exposed with full number and caption information and semantic relationships expressed in SKOS, which makes the information easily accessible and parsable by a wide variety of semantic web applications.

This recent addition massively expands the data set by over 38.000 Dewey classes (or, for the linked data geeks out there, by over 1 million triples), increasing the number of classes available almost tenfold. If you like, take some time to explore the hierarchies; you might be surprised to find numbers for Maya calendar or transits of Venus (loyal blog readers will recognize these numbers).

All the old goodies are still there, of course. Depending on which type of user agent is accessing the data (e.g., a browser) a different representation is negotiated (HTML or various flavors of RDF). The HTML pages still include RDFa markup, which can be distilled into RDF by browser plug-ins and other applications without the user ever having to deal with the RDF data directly.

We have incorporated some of the "lessons learned" as gentle improvements of the Dewey URIs and the underlying RDF data model. We now implement a more complete version of the Dewey class URIs and have also switched to a new date format that should be easier to parse by user agents. Compare a sample "old" URI for a specific concept like http://dewey.info/class/539.7/2009/07/about.en with a URI that accesses a single DDC 23 class: http://dewey.info/class/539.7/e23/2012-06-14/about.en. But don't worry, URIs with the deprecated date format will still work and are automatically redirected to their new counterparts. If your starting point for constructing URIs was cataloging data (i.e., MARC 082 fields), your links to dewey.info in all likelihood have been more general anyway (and will not be affected by these changes).

I will not go into details about improvements to the data model; this is a topic for another day (along with some SPARQL query wizardry). But if you feel like diving right in, the SPARQL endpoint is of course still available for advanced queries and use as a web service.

Finally, two major features of the Dewey data deserve special mention: licensing and handling of updates. In terms of licensing, all data (including DDC 23 classes) are still reusable under the same terms (Creative Commons BY-NC-ND) and the license is carried in each record. Regarding updates, dewey.info is now fully integrated into the standard data flow of the Dewey ecosystem; updates are automatically distributed from the same source that provides data for WebDewey. Going forward, DDC 23 data in dewey.info will be updated regularly.

I hope you find this news as exciting as we do! Let us know what you think and how you plan to use Dewey linked data in your own applications or data sets. DDC 23 as linked data provides a living and breathing foundation for further ventures into the linked data space in the near future. Stay tuned!

Comments

[Adrian Gschwend]

Great example on how to use SKOS, thanks a lot!