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Re: URIs for Concept & ConceptScheme - best practice?

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Tue, 18 May 2010 12:28:36 +0200
Message-ID: <4BF26BD4.60803@few.vu.nl>
To: public-esw-thes@w3.org
Hi everyone,

> On Fri, May 14, 2010 at 02:41:39PM +0200, Simon Cox wrote:
>> I'm thinking about identifier policies for ontologies and concept-schemes.
>> In work that I have done previously on identifier policies for Open
>> Geospatial Consortium and for Commission for Geoscience Information we used
>> the identifier scheme largely as a way to enforce certain governance
>> arrangements for resource publication. The general principle is that a URI
>> is composed of a number of fields. A new URI can only be minted if the
>> values in all the fields are valid; the allowable value for each field must
>> come from a specific register; and different parties are authorized to
>> modify different registers. So we end up with a delegation system. This kind
>> of scheme uses the URI structure for internal governance purposes, within
>> the community.
>> But http URIs have a 'path-like' structure which can be interpreted as a
>> tree. Read in this way, the URI scheme impies certain relationships between
>> resources, in particular 'ownership' of children by their parents.
>> Notwithstanding the REST principle that information is in the representation
>> and not the identifier, Cool URIs can be interpreted by users, and typically
>> support navigation through tweaking the URI (many refs).  This kind of
>> scheme is aimed at external users.
>> Following this approach: is it smart to have the URI for a SKOS concept to
>> be just an extension of the URI for the SKOS concept scheme?
>> e.g.
>> <http://resource.geosciml.org/concept/
>> <http://resource.geosciml.org/concept/unit-rank/bed>  unit-rank/bed>
>> skos:inScheme<http://resource.geosciml.org/concept/
>> <http://resource.geosciml.org/concept/unit-rank>  unit-rank>.
>> I'm assuming slash URIs, since I want the server to do most of the work,
>> supporting content-negotiation, etc.
>> The advantage in this approach is that a casual user can navigate between
>> parent and child by URI twiddling.
>> But possible gotchas are
>> (1) it assumes exactly one parent
>>     - it requires every concept to be in a scheme
>>     - it privileges one scheme above any others (though I think there is no
>> limit on the number of inScheme properties a Concept can have?)
>> (2) there must be some others
> I don't see any problem with this, as long as the scheme is the
> definitive (i.e., authoritative) scheme for that concept.
> Slightly tangential, but you might also be interested in:
> http://www.cabinetoffice.gov.uk/media/308995/public_sector_uri.pdf
> http://www.ivoa.net/Documents/latest/Vocabularies.html

Very good guidelines, indeed!

About Simon's questions.
+1 for Alistair and Johan's comments on using some concept scheme "label" in the path for for the concepts that they originally coined.
And I would advise against using the parent concepts in the path, unless your scheme has a strict tree structure. Otherwise you'll have to make some hard choices at some places...

And of course any cool URI tricks should not replace proper representation of knowledge about the resources! As Rob has pointed out, the data for some resources may change, making obsolete even the best patterns of the moment...



>> I'd be interested in comments.
>> --------------------------------------------------------
>> Simon Cox
>> European Commission, Joint Research Centre
>> Institute for Environment and Sustainability
>> Spatial Data Infrastructures Unit, TP 262
>> Via E. Fermi, 2749, I-21027 Ispra (VA), Italy
>> Tel: +39 0332 78 3652
>> Fax: +39 0332 78 6325
>>   <mailto:simon.cox@jrc.ec.europa.eu>  mailto:simon.cox@jrc.ec.europa.eu
>>   <http://ies.jrc.ec.europa.eu/simon-cox>
>> http://ies.jrc.ec.europa.eu/simon-cox
>> SDI Unit:<http://sdi.jrc.ec.europa.eu/>  http://sdi.jrc.ec.europa.eu/
>> IES Institute:<http://ies.jrc.ec.europa.eu/>  http://ies.jrc.ec.europa.eu/
>> JRC:<http://www.jrc.ec.europa.eu/>  http://www.jrc.ec.europa.eu/
>> --------------------------------------------------------
>> Any opinions expressed are personal unless otherwise indicated.
Received on Tuesday, 18 May 2010 12:14:04 UTC

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