W3C home > Mailing lists > Public > uri@w3.org > October 2003

Re: Announcement: The "info" URI Scheme

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 02 Oct 2003 15:39:41 +0300
To: ext John Cowan <cowan@mercury.ccil.org>
Cc: ext Garret Wilson <garret@globalmentor.com>, "ext Hammond, Tony (ELSLON)" <T.Hammond@elsevier.com>, <www-rdf-interest@w3.org>, <uri@w3.org>
Message-ID: <BBA1F73D.1BD2%patrick.stickler@nokia.com>

On 2003-10-02 14:44, "ext John Cowan" <cowan@mercury.ccil.org> wrote:

> Patrick Stickler scripsit:
>> It is an understandable common misconception that what an HTTP
>> server actually returns is what is denoted by the URI. The fact
>> is that we can never be absolutely sure what resource a URI
>> denotes based on what is returned by a server. In some cases
>> it's easier to guess than other cases, but typically you can't
>> ever be sure. Hence the car/document problem.
> This characterization of the problem is far
> too mild.  Consider the resource whose URI is
> http://www.tagyerit.com/images/adopted/shakespeare.jpg .
> You can't do a direct GET on this any more, but it's
> still available (for now) in the Google cache at
> http://images.google.com/images?q=tbn:IbW4adfRGVkC:www.tagyerit.com/images/ado
> pted/shakespeare.jpg
> If you retrieve this resource, you will get a sequence of bits labeled
> image/jpeg.  But what is the resource?  Is it Shakespeare?  Is it a
> (generic) picture of Shakespeare?  Is it this *particular* image of
> Shakespeare?  Or is it something else altogether?  Nobody can say,
> probably not even the person who posted the picture to the Web.

Insofar as a cache reflects what was/could be retrievable from
a particular web authority, I don't see that the above case needs
any special interpretation. One could fairly presume an implicit
equivalence relation between the denotation of cache URIs and
the original URI. I.e.

      <http://www.tagyerit.com/images/adopted/shakespeare.jpg> .

But the ambiguity of what resource is actually denoted by either
URI (regardless of the nature of the representation itself) remains.
>> And hence the reason for URIQA. To be able to obtain an authoritative
>> answer to the questions "What does this URI denote, and what is
>> that thing like?". A representation of the resource might be able
>> to give a human some clues, but being able to obtain a formal,
>> precise description of the resource is much better.
> A fine thing indeed.  How would you formally characterize the relationship
> of the above URI to Shakespeare?

Well, if the above URI actually does denote Shakespeare (rather than
a portrait of Shakespeare, etc.) then it really is a matter of
vocabulary. If a more commonly used URI denoting Shakespeare exists,
you could make an owl:sameIndividualAs assertion, but in the end,
a URI is a URI is a URI and its actual denotation is meta-knowledge
that is (at least presently) defined by social means, not formal.

Still, if the server www.tagyerit.com was URIQA enlightened, then
one could hope for a description of the resource denoted by the
URI in question, stating that it denotes a historical person, who's
name is William Shakespeare, who was a poet/playwright, was born
on a given date, in a given place, died on a give date, etc. etc.
with statements relating the person to his works, yada yada yada.

Perhaps a google cache (in the future) would also contain the
formal concise bounded description of the resource denoted by the
URI, in addition to one or more representations that are/were
accessible via that URI.

Received on Thursday, 2 October 2003 08:40:42 UTC

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