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Re: HTTP URIs and authority

From: <noah_mendelsohn@us.ibm.com>
Date: Tue, 23 Oct 2007 20:10:03 -0400
To: Pat Hayes <phayes@ihmc.us>
Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, Mikael Nilsson <mikael@nilsson.name>, Richard Cyganiak <richard@cyganiak.de>, wangxiao@musc.edu, W3C-TAG Group WG <www-tag@w3.org>
Message-ID: <OF80F6D65C.59A8B44D-ON8525737E.00004F88-8525737E.0000C5F9@lotus.com>

Pat Hayes writes:

> > [Noah Mendelsohn wrote]:
> >  If I say that it's for the poem, and in a year or so someone
> >comes up with a font I like better, I see no problem with my changing 
> >page to use that.
> Neither do I: but that doesn't mean that the URI denotes anything 
> font-less, like the 'real' poem. It just means that your resource 
> here has a changing font.

Let's make the example more complicated.  I mint the URI and claim, at 
least insofar as you're willing to allow me too :-), that it represents 
the poem itself, not a particular presentation of it.  Because I'm a cool 
Web guy, I support content negotiation.  On day one, in addition to that 
fancy 25 point italic version served as text/html, I also offer 
text/plain, with each line of the poem given on one line of the returned 
text.  Now, as in the first example, I decide I've found a better font for 
the HTML, and I leave the text version unchanged.  You seem to imply that 
the resource itself has surely changed? 

Your view seems to be that the resource needs to, at least in some sense, 
be isomorphic to the representation, so you infer that when the 
representation changes the resource must have changed.  It seems to follow 
that in the case of conneg, the resource must in some sense be (or be 
isomorphic to) the union of all served representations.  My preferred view 
is that there is allowance for changing policy as to how a particular 
resource is represented, and that such changes to not necessarily imply 
that the resource itself has changed. 


Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
Received on Wednesday, 24 October 2007 00:09:03 UTC

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