At the 7th World Archaeological Congress in Jordan, Martin Doerr raised a concern about the Linked Open Data world that was being advocated in our session. In particular he mentioned worry over the assumption that all of this Linked Open Data was going to be persistently and indefinitely accessible, and he suggested that people keep RDF or other serializations of the Linked Open Data they were using, particularly vocabularies or thesauri. This seemed like a good idea to us given the fragility of the web, and we have been informally promoting this idea at conferences and workshops.
Reason to heed Martin’s advice/concern has just presented itself, in the form of the recent US Government shutdown. This subsequently has brought down the Library of Congress website, including the id.loc.gov domain, which hosts their linked data records.
We have aligned a lot of our archive metadata with the Library of Congress Subject Headings, which means all of our archive Linked Data includes links to the id.loc.gov domain. With the Library of Congress servers being shut off those links currently hang. This doesn’t “break” our Linked Open Data, and our archive metadata is still coherent and sensible. However users of our Linked Open Data will find link rot which is never good, particularly within a technology that is predicated on persistent links. Its telling when even a seemingly rock-solid organisation such as the Library of Congress can have their website taken down from poor “management”.
We maintain our own copy of the Library of Congress Subject Heading Linked Data, which we downloaded 6 months ago and keep in a triple store. Not only does that give us security if anything gets turned off again, but we are also able to interrogate the dataset with ease from within our own network, regardless of political wranglings 3000 miles away. Again, even without resolvable URLs for those Library of Congress Subject Heading concepts, our Linked Open Data is still valid and makes sense, but this event certainly adds support to Martin Doerr’s recommendations in Jordan.