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RE: 2.3 URI Ambiguity

From: Bullard, Claude L (Len) <clbullar@ingr.com>
Date: Tue, 2 Dec 2003 10:40:42 -0600
Message-ID: <15725CF6AFE2F34DB8A5B4770B7334EE03F9EFD8@hq1.pcmail.ingr.com>
To: 'Walden Mathews' <waldenm@optonline.net>, 'Tim Berners-Lee' <timbl@w3.org>
Cc: "'www-tag@w3.org'" <www-tag@w3.org>, "'Williams, Stuart'" <skw@hp.com>, 'Mark Baker' <distobj@acm.org>

The issue is that it doesn't 'identify one **thing**'. 
It identifies 'one resource' and the entire debate 
comes down to not being able to clarify what a 
resource is except in terms of a tautology (what 
a URI identifies).  And a resource can have multiple 
representations.  This is the willowy abstraction 
on which the web is built, by which it obtains 
membership in the set (on the Web), and the 
source of much debate but surprisingly little 
confusion.  

Implementers don't have a problem with it.

The use of the mailto URI to identify a person is 
indirect, yes, and common, yes.  But in no way 
architectural except insofar as an application 
language such as a database dictionary, a kb 
language or such is used to declare that association. 
Indirect identification is and always is just 
another assignment in some language where that 
language creates the context of use.

len

-----Original Message-----
From: Walden Mathews [mailto:waldenm@optonline.net]
Sent: Tuesday, December 02, 2003 10:31 AM
To: Tim Berners-Lee
Cc: www-tag@w3.org; Williams, Stuart; Mark Baker
Subject: Re: 2.3 URI Ambiguity



Hello Tim,

Thanks for your reply.

I believe that if you can crystallize an architectural constraint
by giving a rule, and exception, and a formalization of the
criteria for applying the exception, then you can hit a valid
goal without extending the document indefinitely or embarking
on a formalization of the universe.

The problem, as it stands, is that you have an exception to
the rule, but have not as yet distinguished the exceptional cases
from the normal ones, and so the rule is lost.

But if the consensus is that "indirect identification" is not an
important notion in Web Architecture, then can I suggest a
rewording of your text below:

"Only use URI to *directly* identify the one thing."  And
then explain that indirect identification is outside the architecture,
and give examples in hypertext of direct identification and
indirect.

The above approach allows a single sentence to settle the
issue for anyone who appreciates the meaning of "directly" in
that context, pays a little more with examples for those who
don't quite, and avoids formalisms altogether.

Not that I don't like your formalisms below, but I'm an Alloy
guy.  How do you read that stuff!? :-)

Walden



----- Original Message ----- 
From: "Tim Berners-Lee" <timbl@w3.org>
To: "Walden Mathews" <waldenm@optonline.net>
Cc: <www-tag@w3.org>; "Williams, Stuart" <skw@hp.com>; "Mark Baker"
<distobj@acm.org>
Sent: Tuesday, December 02, 2003 10:39 AM
Subject: Re: 2.3 URI Ambiguity


:
: On Dec 1, 2003, at 14:15, Walden Mathews wrote:
:
: > It seems to me that the Architecture of the World Wide Web
: > has to make a decision as to whether there is such a thing as
: > indirect identification at the architecture level, and if so formalize
: > what that is.
:
: The problem was just that when we said "only use URI to identify the
: one thing", a lot of people responded with a counter-example of the
: person "identified" by their mailbox.  So the counter-example was only
: in so as to say, "No, we don't mean that".   If we have to formalize
: everything that we don't mean, then we would end up  extending the
: architecture document indefinitely!
:
: The only way i can think of of making it clearer is to use say NTriples.
:
: Direct identification:
:
:   here the same URI is use twice to identify the same thing,
: which is a person called fred.
:
: card:i rdf:type  contact:Person.
: card:i foaf:aka  "fred".
:
: Misuse:
:
: Here the URI card <http://www.w3.org/> is used to
: identify two distinct concepts, with resulting confusion.
:
: <http://www.w3.org>  a  :Consortium.
: <http://www.w3.org>  dc:created "1994".
:
: <http://www.w3.org/> a :WebPage.
:        <http://www.w3.org>   dc:created "2003-12-01".
:
:
: Indirect "identification":
:
: _:x    rdf:type  contact:Person.
:         _:x    contact:mailbox   <mailto:foo@example.com>.
: <foo.html>   dc:creator  _:x.
:
:
: _:y    contact:givenName "Frederick".
:         _:y    contact:mailbox   <mailto:foo@example.com>.
: _:y     foaf:aka  "fred".
:
:
: contact:mailBox rdf:type owl:inverseFunctionalProperty.
:
: in this example, the fact that contact:mailbox is an inverse function
: property (erstwhile unambiguous property),  one can infer that the
: unlabeled concepts _:x and _y are the same thing.  This is equivalent of
: the way databases are typically used with keys.
:
: (I don't think that this level of detail is necessary in the
: architecture document - it would be useful maybe in a finding.)
:
: Tim
:
:
:
:
: > Otherwise, beyond saying "don't do that" about using URI to
: > identify more than one resource, I don't think there is anything
: > to say, and one shouldn't try.
: >
: > Sorry to keep chiming in...
: >
: > Walden
:
:
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Received on Tuesday, 2 December 2003 11:41:56 GMT

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