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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://0-dx-doi-org.libus.csd.mu.edu/10.1126/science.1157784” curl -D - -L -H “Accept: text/turtle” “http://0-dx-doi-org.libus.csd.mu.edu/10.1126/science.1157784”

In order to encourage publishers and other content producers to embed metadata into their PDFs, we have released an experimental tool called “pdfmark”, This open source tool allows you to add XMP metadata to a PDF. What’s really cool, is that if you give the tool a Crossref DOI, it will lookup the metadata in Crossref and then apply said metadata to the PDF. More detail can be found on the pdfmark page on the Crossref Labs site.

We’re pleased to announce that a Crossref working group has released a set of best practice recommendations for scholarly publishers producing RSS feeds. Variations in practice amongst publisher feeds can be irritating for end-users, but they can be insurmountable for automated processes. RSS feeds are increasingly being consumed by knowledge discovery and data mining services. In these cases, variations in date formats, the practice of lumping all authors together in one <dc:creator> element, or generating invalid XML can render the RSS feed useless to the service accessing it.

I was happy to read David Shotton’s recent Learned Publishing article, Semantic Publishing: The Coming Revolution in scientific journal publishing, and see that he and his team have drafted a Citation Typing Ontology.* Anybody who has seen me speak at conferences knows that I often like to proselytize about the concept of the “typed link”, a notion that hypertext pioneer, Randy Trigg, discussed extensively in his 1983 Ph.D. thesis.. Basically, Trigg points out something that should be fairly obvious- a citation (i.

I was playing around recently and ran across this little metadata hack. At first, I thought somebody was doing something new. But no, nothing so forward apparently. (Heh! 🙂 I was attempting to grab the response headers from an HTTP request on an article page and was using by default the Perl LWP library. For some reason I was getting metadata elements being spewed out as response headers - at least from some of the sites I tested.

Once structured metadata is added to a file then retrieving a given metadata element is usually a doddle. For example, for PDFs with embedded XMP one can use Phil Harvey’s excellent Exiftool utility. Exiftool is a Perl library and application which I’ve blogged about here earlier which is available as a ‘.zip‘ file for Windows (no Perl required) or ‘.dmg‘ for MacOS. Note that Phil maintains this actively and has done so over the last five years.

The guidelines for Crossref publishers (“DOI Name Information and Guidelines” - [PDF, 210K][1]) has this to say in “Sect. 6.3 The response page” regarding the response page for a DOI:

“A minimal response page must contain a full bibliographic citation displayed to the user. A response page without bibliographic information should never be presented to a user.”

which would seem to be all fine and dandy. But if that user is a machine (or an agent acting for a user) they’ll likely be out of luck as the metadata in the bibliographic citation is generally targeted at human users.

So here’s a quick and dirty implementation of what a machine readable page could look like using RDFa. (The demo uses Jeni Tennison’s wonderful [rdfQuery][2] plugin which I [blogged][3] about earlier.)

Clicking the DOI link below will bring up in a sub-window a bibliographic citation which might be found in a typical DOI repsonse page. If you now click the “Read Me” link you should see an alert message which presents the bibliographic metadata as a complete RDF document (in a simple N3 – or Notation3 – format). This document is assembled on the fly by rdfQuery using the RDFa markup embedded in the page.

See the “View Source” link to list the actual XHTML markup and the RDFa properties which have been added. And note also that some of the properties are partially “hidden” to the human reader, e.g. a publication date is given in year form only whereas the machine record has the date in full, and some of the properties are fully “hidden”: print and electronic ISSNs, issue number, ending page, etc.

(Continues below.)

Whaddya know? I was just on the point of blogging about the real nice demo given by Jeni Tennison at last week’s SWIG UK meeting at HP Labs in Bristol of rdfQuery (an RDF plugin for jQuery - the zip file is here). And there today on her blog I see that she has a full writeup on rdfQuery, so I’ll defer to the expert. :~) All I can really add to that is that rdfQuery is a pretty darn cool way to add and manipulate RDFa using jQuery.

Yesterday a new PRISM spec (v2.1) was released for public comment. (Comment period lasts up to Dec. 3, ’08.) Changes are listed in pages 8 and 9 of the Introduction document. Some highlights: New PRISM Usage Rights namespace Accordingly usage of prism:copyright, prism:embargoDate, and prism:expirationDate no longer recommended New element prism:isbn introduced for book serials An updated mod_prism RSS 1.0 module is available which lists all versions of PRISM specs including the forthcoming v2.

Andy Powell has published on Slideshare this talk about metadata - see his eFoundations post for notes. It’s 130 slides long and aims “to cover a broad sweep of history from library cataloguing, thru the Dublin Core, Web search engines, IEEE LOM, the Semantic Web, arXiv, institutional repositories and more.” Don’t be fooled by the length though. This is a flip through and is a readily accessible overview on the importance of metadata.