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Re: URIs for Concepts: Best Practices

From: David Menendez <zednenem@psualum.com>
Date: Mon, 19 Apr 2004 17:22:14 -0400
To: "Miles, AJ (Alistair) " <A.J.Miles@rl.ac.uk>
Cc: "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>, "'public-esw@w3.org'" <public-esw@w3.org>
Message-id: <r02000200-1033-A1717AA0924711D891D0000393758032@[10.0.1.5]>

Miles, AJ (Alistair)  writes:

> I wanted to consult you all on this matter.  I have agreement from
> the EEA to publish the GEMET environmental thesaurus in the SKOS/RDF
> format.  The next step is to work out with them the URIs they wish to
> assign to their thesaurus and concepts.  I'm not sure what to
> recommend to them on this matter.

Dan Brickley's Wordnet vocabulary service[1] at xmlns.com seems like a
useful model. Essentially, each concept is given a (non-fragmentary) URI
which, if dereferenced, returns a description of the concept. Mr
Brickley's system only returns RDF/XML presently, but there's no reason
it couldn't also return HTML or something else via content negotiation.

[1] http://xmlns.com/2001/08/wordnet/

> I thought to use an http:// based URI base (e.g.
> http://www.eionet.eu.int/GEMET) and then add the id number of each
> concept (e.g. http://www.eionet.eu.int/GEMET#204).

That works, but my preference would be for something like
<http://eionet.eu.int/GEMET/204>. In practice, using a fragment ID means
that an HTTP request to a term's URI will return nothing or else a
description of the entire vocabulary, which I'm guessing is pretty
large.

> A first question is, is it OK to use http: URIs for concepts?  Sorry
> to drag this old chestnut up again, but I need some clear answer on
> best practices for this.  Are we not at all concerned that the same
> URI may identify both a thesaurus concept and a resolveable network
> resource (i.e. the file containing the RDF data)?

It would be confusing for a URI to identify a thesaurus concept and an
RDF file. The key, as I see it, is the idea that the response to an HTTP
Get is a representation of the resource, not the resource itself. The
fact that <http://xmlns.com/wordnet/1.6/Dog> returns an RDF/XML
document, doesn't mean that it identifies that particular document. If,
for some reason, you wanted to talk about that RDF/XML document instead
of the word "Dog", you would need to use a blank node or a different
URI.

Not everyone agrees with this position.

> What do you think of info: based URIs for concepts?

>From an RDF perspective, it's just as good. From a web perspective, it's
less useful because it can't be dereferenced.
-- 
David Menendez <zednenem@psualum.com> <http://www.eyrie.org/~zednenem/>
Received on Monday, 19 April 2004 17:22:32 GMT

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