The OAI-ORE meeting is coming up, and in general I’ve been really impressed with the alpha specs that have come out. It’s not clear that there’s an established vocabulary for talking about aggregated resources on the web, so the Data Model and Vocabulary documents were of particular interest to me.
One thing I didn’t quite understand, and which I think may have some significance for implementors, is some language in the Discovery document on the subject of URI conflation:
The Data Model document [ORE Model] explicitly prohibits a URI of a ReM (URI-R) ever returning anything other than a ReM. This allows multiple representations to be associated with URI-R, such as using content negotiation to return ReMs in different languages, character sets, or compression encodings. But it does not allow URI-R to return a human readable “splash page”, either by HTTP content negotiation or redirection. For example, clients MUST NOT merge with content negotiation the following URI pair that would correspond to a ReM and a “splash page” for an object:
If I’m understanding right this would prohibit using technologies like microformats, eRDF, RDFa and GRDDL in a “splash page” to represent the resource map. It seems odd to me that you can represent a resource map in Atom, but not in HTML.
To illustrate what this might look like I took a splash page off of arXiv (hope that was ok!) and marked it up with oai-ore RDFa.
Take a look. So all I did is modify the existing XHTML at arxiv.org, and I’ve been able to represent an ORE Resource Map. This seems like a relatively simple, and powerful way for existing repositories to make their aggregated resources available.
RDFa just entered Last Call, but there are already multiple implementations. Try out the GetN3 bookmarklet on the splash page, and you should see some triples come back. I ran them through the validator at w3c and got the following graph (kinda too big to include here inline).
This kind of issue seem to be at the heart of what Ian Davis refers to when he asks “Is the Semantic Web Destined to be a Shadow?“. Andy Powell and Pete Johnston have also been strong voices for integrating digital library repositories and the web–and they are also involved with the oai-ore effort. It feels like some of the oia-ore language could be loosened a bit to allow machine readable and human readable information to commingle a bit more.
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Hi,
I agree with you that things could be loosened. The Discovery document position tends to arise when it is assumed that it must be possible to tell the difference between a resource and an information resource, perhaps by performing an HTTP request. (This is something I know that Ian has argued in the past.)
In my view this is an over-literal reading of the situation, something various people have tried to tackle. My own comments are in Once more on information resources and RDFa. I also have an older post from a couple of years ago, which was originally intended to be a critical look at the whole discussion from the same standpoint as the Discovery document that you quote, but in the course of working it through I discovered that my own view was wrong. It may be of interest to others who are as confused as I was, and it’s called The Information Resource Debate, and RDFa.
Interesting work, though. And a great use of RDFa.
All the best,
Mark Birbeck
http://webBackplane.com/mark-birbeck
Ed,
Good point.
Speaking only for myself here(!), I completely agree that an XHTML/RDFa document would make a good representation of an ORE Resource Map; and that such a document could/would probably look very much like what we think of as a “splash page”.
Of course if you want to talk about both
(i) the Resource Map (with an XHTML/RDFa representation and possibly other representations via conneg) and
(ii) a “splash page”
as two distinct resources, which I guess we might want to do in some circumstances, then we need two distinct URIs for those two distinct resources.
But that’s still perfectly do-able. One could probably even serve the _same_ XHTML/RDFa doc as a representation of _both_ of those _distinct_ resources (pace taking care with base URIs etc).
I would like to see this be the case, most of the new DSpace UI (Manakin specifically) technology will support including RDFa and microformats into the Item page generation and this would be an ideal use-case for it.
Cheers,
Mark Diggory
DSpace Systems Manager
MIT Libraries
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