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RE: Summary of the QName to URI Mapping Problem

From: <Patrick.Stickler@nokia.com>
Date: Thu, 16 Aug 2001 14:22:55 +0300
Message-ID: <2BF0AD29BC31FE46B78877321144043114B50C@trebe003.NOE.Nokia.com>
To: pkaminsk@home.com, www-rdf-logic@w3.org

Thanks Piotr for the additional examples. Hopefully more folks will
begin to see that this issue is not just "fluff"...

Cheers,

Patrick

--
Patrick Stickler                      Phone:  +358 3 356 0209
Senior Research Scientist             Mobile: +358 50 483 9453
Software Technology Laboratory        Fax:    +358 7180 35409
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Visiokatu 1, 33720 Tampere, Finland   Email:  patrick.stickler@nokia.com
 

> -----Original Message-----
> From: ext Piotr Kaminski [mailto:pkaminsk@home.com]
> Sent: 16 August, 2001 03:07
> To: www-rdf-logic@w3.org
> Subject: Re: Summary of the QName to URI Mapping Problem
> 
> 
> Dan Connolly said:
> > The RDF spec includes an unambiguous QName -> URI mapping:
> > uri(qname) = concat(nsname(qname), localname(qname))
> 
> The mapping mechanism is indeed unambiguously defined.  It 
> can, however,
> lead to invalid results.
> 
> Let's start from the following axioms.
> 1.  A QName identifies a (single) resource.
> 2.  A URI identifies a (single) resource.
> 3.  The goal of a QName -> URI mapping is to transform a 
> QName into a URI
> that identifies the *same* resource.
> 
> The above mapping doesn't achieve the goal.  An example 
> follows that is
> essentially equivalent to Patrick's, but I have a feeling 
> that most of the
> contention will be about the axioms above, especially (1).  
> One could take
> the position that a QName is a purely syntactic construct, and doesn't
> identify anything in and of itself.  I believe such an interpretation
> contradicts the XML Namespaces recommendation, in spirit if 
> not in letter.
> 
> Informal example to demonstrate why the mapping is flawed 
> according to the
> axioms:
> 
> xmlns:foo="http://ideanest.com/foo"
> xmlns:bar="http://ideanest.com/foobar"
> 
> Then the following two QNames identify distinct resources; they do so
> because they are different names, the namespace URI is mine, 
> and I say that
> the resources they identify are different.
> 
> foo:barcat
> bar:cat
> 
> Yet, using the standard concatenation mapping, both QNames 
> are mapped to the
> same URI:
> 
> http://example.com/foobarcat
> 
> While this URI identifies some resource (by definition), it 
> cannot identify
> both of the (distinct!) resources identified by the two QNames
> simultaneously.  Hence the mapping is deficient.
> 
>         -- P.
> 
> --
>   Piotr Kaminski <piotr@ideanest.com>  http://www.ideanest.com/
>   "It's the heart afraid of breaking that never learns to dance."
> 
> 
> 
Received on Thursday, 16 August 2001 07:23:06 GMT

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