Blog

We’ve been asked a few times if it is possible to determine whether or not a particular domain name belongs to a Crossref member. To address this we’re launching another small service that performs something like a “reverse look-up” of URLs and domain names to DOIs and Crossref member status.

The service provides an API that will attempt to reverse look-up a URL to a DOI and return the membership status (member or non-member) of the root domain of the URL. In practice resolving URLs to DOIs has substantial limitations - many publishers redirect the resolution URL of DOIs to other online content and URLs become clogged up with session IDs and other cruft appearing in their query parameters. All of this means it is unlikely that the URLs that appear to be the end result of DOI resolution are actually the URLs pointed to.

In April In April for its DOIs. At the time I cheekily called-out DataCite to start supporting content negotiation as well.

Edward Zukowski (DataCite’s resident propellor-head) took up the challenge with gusto and, as of September 22nd DataCite has also been supporting content negotiation for its DOIs. This means that one million more DOIs are now linked-data friendly. Congratulations to Ed and the rest of the team at DataCite.

We hope this is a trend. Back in June Knowledge Exchange organized a seminar on Persistent Object Identifiers. One of the outcomes of the meeting was “Den Haag Manifesto” a document outlining five relatively simple steps that different persistent identifier systems could take in order to increase interoperability. Most of these steps involved adopting linked data principles including support for content negotiation. We look forward to hearing about other persistent identifiers adopting these principles over the next year.

Today I’m announcing a small web API that wraps a family name database here at Crossref R&D. The database, built from Crossref’s metadata, lists all unique family names that appear as contributors to articles, books, datasets and so on that are known to Crossref. As such the database likely accounts for the majority of family names represented in the scholarly record.

The web API comes with two services: a family name detector that will pick out potential family names from chunks of text and a family name autocompletion system.

So does anybody remember the posting DOIs and Linked Data: Some Concrete Proposals?

Well, we went with option “D.”

From now on, DOIs, expressed as HTTP URIs, can be used with content-negotiation.

Let’s get straight to the point. If you have curl installed, you can start playing with content-negotiation and Crossref DOIs right away:

curl -D - -L -H   “Accept: application/rdf+xml” “http://dx.doi.org/10.1126/science.1157784” 

curl -D - -L -H   “Accept: text/turtle” “http://dx.doi.org/10.1126/science.1157784”

Announcements regarding Crossref system status or changes are posted in an Announcements forum on our support portal (http://support.crossref.org). We recommend that someone from your organization monitor this forum to stay informed about Crossref system status, schema changes, or other issues affecting deposits and queries. Subscribe to this forum via RSS feed (https://support.crossref.org/hc/en-us) or select the ‘Subscribe’ option in the forum to subscribe by email.

The TWG Discussion forum replaces the TWG mailing list and can be accessed by members of the Crossref community who log in to our support portal. Intended topics include technical matters related to Crossref’s services, DOI issues and Crossref system operation.

While working on an internal project, we developed “pdfstamp“, a command-line tool that allows one to easily apply linked images to PDFs. We thought some in our community might find it useful and have released it on github. Some more PDF-related tools will follow soon.

Just a quick heads-up to say that we’ve had a go at incorporating InChIs and ontology terms into our PDFs with XMP. There isn’t a lot of room in an XMP packet so we’ve had to be a bit particular about what we include.

• InChIs: the bigger the molecule the longer the InChI, so we’ve standardized on the fixed-length InChIKey. This doesn’t mean anything on its own, so we’ve gone the Semantic Web route of including an InChI resolver HTTP URI. Alternatively you can extract the InChIKeys with a regular expression.
• Ontology terms: we’re using HTTP URIs again and pointing to either Open Biomedical Ontology URIs (biology, biomedicine; slashy) or RSC ontology terms (chemistry; hashy). Often the OBO URIs resolve to a specific web page, but for the moment the RSC URIs just point to a large OWL file. Slashy URIs are quite a bit more involved so we’ll have to see what the demand is like.

There’s only about 4K to play with, so it’s only ever going to be a best-of. More detailed article metadata has to go in either a sidecar file, as Tony has pointed out before, or ideally on the article landing page. The example files are here and I’ve posted something with a different slant on the RSC technical blog.

Since I’ve already blogged about this a number of times before here, I thought I ought to include a link to a fuller writeup in this month’s D-Lib Magazine of our nature.com OpenSearch service which serves as a case study in OpenSearch and SRU integration:

doi:10.1045/july2010-hammond

(Click image for full size graphic.)

I thought I could take this opportunity to demonstrate one evolution path from traditional record-based search to a more contemporary triple-based search. The aim is to show that these two modes of search do not have to be alternative approaches but can co-exist within a single workflow.

Let me first mention a couple of terms I’m using here: ‘graphs’ and ‘properties’. I’m using ‘property’ loosely to refer to the individual RDF statement (or triple) containing a property, i.e. a triple is a ‘(subject, property, value)’ assertion. And a ‘graph’ is just a collection of ‘properties’ (or, more properly, triples). Oh, and I’ll also use the term ‘records’ when considering ‘graphs’ as pre-fabricated objects returned within a result set.

Since last month’s threads (here, here, here and here) talking about the issues involved in making the DOI a first-class identifier for linked data applications, I’ve had the chance to actually sit down with some of the thread’s participants (Tony Hammond, Leigh Dodds, Norman Paskin) and we’ve been able sketch-out some possible scenarios for migrating the DOI into a linked data world.

I think that several of us were struck by how little actually needs to be done in order to fully address virtually all of the concerns that the linked data community has expressed about DOIs. Not only that- but in some of these scenarios we would put ourselves in a position to be able to semantically-enable over 40 million DOIs with what amounts to the flick of a switch.