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Re: INSEE releases OWL ontology and RDF data for geographical entities

From: Dan Connolly <connolly@w3.org>
Date: Fri, 04 Aug 2006 09:32:51 -0500
To: Eric van der Vlist <vdv@dyomedea.com>
Cc: Bernard Vatant <bernard.vatant@mondeca.com>, semantic-web@w3.org, public-xg-geo@w3.org, Franck Cotton <franck.cotton@insee.fr>
Message-Id: <1154701972.30621.3.camel@dirk.w3.org>

On Fri, 2006-08-04 at 09:28 +0200, Eric van der Vlist wrote: 
> Hi,

Hi Eric,

> Le jeudi 03 août 2006 à 23:26 +0200, Bernard Vatant a écrit :
> > 
> > Dan
> > > did you consider using # rather than /? i.e.
> > >   http://rdf.insee.fr/geo#code_commune
> > > rather than
> > >   http://rdf.insee.fr/geo/code_commune
> > > especially for ontologies, it's a lot easier to manage.
> > >   
> > We did consider. Actually my first version of the ontology used a #
> > namespace. Eric (in cc)  was the one who suggested a / namespace,
> > especially for the data and somehow convinced the rest of us. That was
> > six months ago, but if I remember correctly, the idea was that at some
> > point, each instance URI would  be (should be, hopefully will be)
> > associated  with, and access to, a  separate resource, which is not
> > the case now. 
> Yes, that was the first comment I did on your first proposal end of
> January.
> The idea was that to identify a city, http://rdf.insee.fr/geo/COM_80078
> is better than http://rdf.insee.fr/geo#COM_80078.

You might also consider http://rdf.insee.fr/geo/COM_80078#city for
the city itself and http://rdf.insee.fr/geo/COM_80078 for a document
about the city.

If the cities come in natural chunks, perhaps
for the city and http://rdf.insee.fr/geo/COM_800 for a document about
the cities in some region.

>  Of course, these URIs
> are only identifiers but who konws, we might want some day to publish
> some kind of documentation (like we do in RDDL to document namespaces)
> at these URIs. 

"only identifiers"? sigh. I got the impression you wanted to publish
information about them in the Semantic Web.

> If we do so, the first URI makes each city a standalone entity while the
> second one means that they need to be fragments in a huge document which
> can cause a lot of issues (we don't know which media types we might want
> to publish and the definition of fragments is inconsistent between media
> types

It's within your control to choose media types where the definition
of fragments is consistent. The easiest way is to just use one
media type: application/rdf+xml .

>  (some of them don't even support fragments), the document might
> grow very large, ...). 
> Now, the thing that we've not considered is to have a namespace URI
> different from the RDF base.
> > Agreed, we could have kept the # namespace for the ontology at least.
> Dan, can you elaborate why that makes ontologies a lot easier to manage?

Because with a # namespace, publishing the ontology just involves
sticking one static file on a web server. (the URI looks nicer
if the web server can handle leaving the .rdf or .owl off, but
that's not completely essential).

And then to look up http://rdf.insee.fr/geo#code_commune , a consumer
just GETs http://rdf.insee.fr/geo as usual; then when they want
to look up another term such as http://rdf.insee.fr/geo#subdivision,
they can save a round trip because they already have it.

Using a / namespace has a higher cost for the producer (redirects)
and for the consumer (one GET per term rather than one GET
for the ontology).

> Thanks;
> Eric
> > 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Friday, 4 August 2006 14:33:08 UTC

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