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Re: Summary: Section 2: What does a URI identify?

From: Mark Baker <distobj@acm.org>
Date: Mon, 18 Mar 2002 11:14:00 -0500 (EST)
Message-Id: <200203181614.LAA00654@markbaker.ca>
To: connolly@w3.org (Dan Connolly)
Cc: www-archive@w3.org
> [-cc www-tag; +cc www-archive; i.e. there's
> not enough substance here to bother everybody
> with, but you're free to show it to anybody
> you like.]
> 
> On Mon, 2002-03-18 at 09:45, Mark Baker wrote:
> > > If we use the same identifier for the organization and its
> > > homepage, we can't tell them apart; i.e. we can't say
> > > that the page was last revised at time T without
> > > saying the organization was last revised at time T.
> > 
> > Last-Modified is defined to be a property of the representation,
> > not the resource itself, no?
> > 
> >  "The Last-Modified entity-header field indicates the date and time at
> >   which the origin server believes the variant was last modified."
> 
> that's contradictory... if a representation is a
> bag-o-bits, then it's immutable, and last-modified
> makes little sense.

The nomenclature in this space is so fuzzy that I've found it difficult
to discuss in the past.  But I have run into this before, in trying to
describe the difference between the bag-o-bits, and the resource
identified by the Content-Location URI describing that bag-o-bits.  For
example, if I had a clock;

GET /time HTTP/1.1
Host: clock.example.org
Accept: text/plain

response;

HTTP/1.1 200 Ok
Content-Type: text/plain
Content-Location: /time/text
[blank]
12:34:56

If I reinvoked GET on that Content-Location URI, I wouldn't expect
to receive "12:34:56" 10 minutes later, I'd expect to see "12:44:56".

So in this case,

http://www.w3.org could identify the W3C, but
http://www.w3.org/index.html (or whatever it is that you use) could
identify the HTML representation of the W3C.  But I would expect that
each would reflect the current state of the W3C organization.

> But I'll try to think of a better example.

Looking forward to it.

MB
-- 
Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Monday, 18 March 2002 11:09:17 GMT

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