[OAI-implementers] Re: Identifiers

[Chris Hubick]

On Thu, 2004-03-11 at 16:58, Andy Powell wrote:
> On Thu, 11 Mar 2004, Chris Hubick wrote:
> 
> > In a repository that harvests from a number of different systems through
> > a variety of protocols, and has identifiers from many catalog types (not
> > necessarily URI's)...
> >
> > How does one map an arbitrary catalog/entry *pair*, to a *single*
> > identifier string?
> >
> > My answer was to use a URN:
> >
> > 'urn:' + <catalog> + ':' + <entry>
> 
> It seems to me that the 'catalog'/'entry' pairing in LOM is a bit broken
> - because it really requires a global registry of 'catalog' names to work
> properly.  (At least, without a global registry I can have no way of
> knowing if your 'catalog' is the same as my 'catalog').  URIs already
> provide a global space within which new identifier schemes can be created
> - why not use it, rather than building a LOM-specific registry.

First, can we assume, for the sake of my problem discussion, that all
those who create some new identifier format do in fact manage to choose
a truly unique catalog name, just as if there were in fact a registry
(that's a tangental discussion :).

> In partricular, the proposed 'info' URI scheme
> 
> http://info-uri.info/registry/docs/misc/faq.html
> 
> provides an open mechanisn for assigning URIs to information assets that
> have identifiers in public namespaces but have no representation within
> URI space.

Oooh, that's new, thanks for that :)

Ok, so, if I use that, then the algorithm would be:

IF (LOM.Identifier.Catalog == 'URI')
 THEN export LOM.Identifier.Entry unmodified
ELSE
 export info URI as:
 'info:' + <catalog> + '/' + <entry>

I will read more about these info URI's to see if that's a valid use
(?).

> > Has anyone else tackled this problem?
> 
> Not really, but you might be interested in
> 
> Guidelines for encoding identifiers in Dublin Core and IEEE LOM metadata
> http://www.ukoln.ac.uk/metadata/dcmi-ieee/identifiers/
> 
> which basically suggests that URIs should *always* be used.

Hrm, that's interesting too, thanks.  Though it's basically the reverse
problem.

One thing that does bring to light is using 'URI' as your LOM Catalog
whenever your entries are in URI format.  I have been using our URN's
Namespace Identifier (NID) as our Catalog, when I perhaps should be
using 'URI' instead (or the more specific 'URN')?

Thanks!

-- 
Chris Hubick
mailto:chrish@athabascau.ca
mailto:chris@hubick.com
phone:1-780-421-2533 (work)
phone:1-780-721-9932 (cell)
http://www.hubick.com/


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