W3C home > Mailing lists > Public > semantic-web@w3.org > August 2006

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

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Sat, 5 Aug 2006 17:45:49 -0400
To: "'Dan Connolly'" <connolly@w3.org>
Cc: <semantic-web@w3.org>, <public-xg-geo@w3.org>
Message-ID: <002b01c6b8d8$84221270$08241780@bioxiao>


> > 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).

I actually disagree this a little bit.  To save a roundtrip requires caching
on the consumer's side.  The same can/should also be done with the slash

But, in order to do so, there are a few things needs to be clarified.

First, should W3C clearly define a policy regarding what can be a legit
namespace from a URI?

The reason for me to raise this question is this.  Unlike hash URI, the
namespace URI can not be "inferred" or "guessed" from a URI itself.  For
instance, a URI of http://foo.com/bar can be constructed with namespace
http://foo.com/, http://foo.com/b or http://foo.com/ba coupled with local ID
of "bar", "ar" and "r", respectively.

Shouldn't there be a policy governed this.  For instance, to say that only
the first one is legit?

Second, should dereferencing a URI retrieve all the statements under the
same namespace?  I.e., should dereference http://foo.com/bar will retrieve
the same document as dereferencing http://foo.com/bar2, assuming they shared
the same namespace?  

Inferred from the arguments so far, the question should be "no" because
otherwise, slash URI would be no different from hash URI except the added
server side complexity.   

Then, i.e., the answer to the question 2 is "no", what is the use of the
namesapce if it is only served as a shorthand for URI?  What would I get
when I dereference the namespace of a slash URI?

Received on Saturday, 5 August 2006 21:46:09 UTC

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