[OAI-implementers] Re: Identifiers

Chris Hubick chrish@athabascau.ca
Thu, 11 Mar 2004 17:40:19 -0700

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
 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

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')?


Chris Hubick
phone:1-780-421-2533 (work)
phone:1-780-721-9932 (cell)

    This communication is intended for the use of the recipient to whom it
    is addressed, and may contain confidential, personal, and or privileged
    information. Please contact us immediately if you are not the intended
    recipient of this communication, and do not copy, distribute, or take
    action relying on it. Any communications received in error, or
    subsequent reply, should be deleted or destroyed.