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RDDL and XML Schema instances are not valid representations of namespaces

From: <Patrick.Stickler@nokia.com>
Date: Thu, 30 Jan 2003 14:58:27 +0200
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B01B90A8D@trebe006.europe.nokia.com>
To: <tbray@textuality.com>, <timbl@w3.org>
Cc: <fielding@apache.org>, <sandro@w3.org>, <www-tag@w3.org>

> 2. XML Namespace Names
> 
> Namespace names are URIs, and they were chosen this way back in 1999 
> largely (in the XML community) because of their useful syntactic 
> uniqueness properties and (in the nascent RDF community) 
> because of the 
> emerging grander ambitions for URIs.
> 
> For some years, I steadfastly argued that these URIs were 
> just names and 
> don't you worry your pretty little head about what they point 
> at.  This 
> position turned out to be untenable; the user population 
> really wanted 
> to dereference these and get something back.

Well, certainly not untenable, since systems work just fine
without having to dereference namespace URIs. The position
is simply not the most popular.

> So now we're arguing about what representations to return and the 
> various flavors of RDDL.  Well, if you consider that an XML 
> Namespace is 
> a Resource, there's no inconsistency or angst here.  The resource 
> previously was typically without representations and still worked OK; 
> and now it turns out that a RDDL document will likely be a 
> very useful 
> representation of that resource.  Dan argues hotly that an 
> XML Schema is 
> a useful representation of a namespace-name resource and despite the 
> fact that <snicker> he's clearly wrong about it being useful, it is 
> undeniably some kind of a representation.

Here's where I disagree (or would like to hear convincing arguments
establishing such a view). Neither RDDL instances nor XML Schemas
are IMO valid representations of the *namespace*. They are something
else. RDDL instances are representations of knowledge about arbitrary
resources having some relation to the namespace, but that's not the
same as a representation of a namespace no more so than a map of Europe
is a representation of London, because London happens to be related
to other places in Europe. An XML Schema (when returned by GET) is a
representation of some document model, which just happens to utilize
terms grounded in one or (usually) more namespaces. It is NOT a
representation of a single namespace.

Are RDDL instances and XML Schemas useful information? Sure.

Is it useful to be able to get such information in terms of
a given namespace URI? Sure.

Are they valid or reasonable representations of the namespace? NO!

And I encourage the TAG or anyone else to convince me otherwise.

If an HTTP GET returns a representation of a resource, and RDDL or
XML Schema instances are considered valid representations of an
XML Namespace, then I see no useful value to the concept of 
representation, since there apparently are no bounds as to what it
might be, and very well might be random.

What is required is a means to obtain such useful information in
terms of any URI in a manner that fits with intuitions about
resources and representations, rather than a hack that is simply
convenient but disregards such intuitions.

Regards,

Patrick
Received on Thursday, 30 January 2003 10:19:20 GMT

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