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Re: Representation consistency and content negotiation

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 15 Jan 2009 17:10:31 -0500
To: wangxiao@musc.edu
Cc: Drummond Reed <drummond.reed@cordance.net>, "elharo@metalab.unc.edu" <elharo@metalab.unc.edu>, "'www-tag'" <www-tag@w3.org>
Message-ID: <OF21AEE9F3.832D73FE-ON8525753F.0077B8FC-8525753F.0079D0C9@lotus.com>

With respect to the overall subject of this thread:  I have felt for years 
that the question of variability between conneg'd representations is one 
that is confusing in Web architecture.  Not only would clarification be 
useful in some particular scenarios, I think that attempting a 
clarification would force us to think hard about what it means for 
something to be a representation in the first place, how much fidelity is 
required or appropriate (and that's presuming we could articulate 
"fidelity to what?"), etc.  Indeed, I think that discussion of this would, 
for better or worse, take us back to httpRange-14 [1] and to why we care 
whether something is an Information Resource.  Specifically, I've always 
assumed that the reason we allow 200 for an IR but not for another 
resource is that the representation of an IR can in some sense be truer to 
conveying the state of the resource itself (if I may call it that), while 
a representation of some more tangible object, for example, tends to be 
more "about" the object.  Indeed, that's why I've always been more 
comfortable than some seem to be with the AWWW definition of an IR, I.e. 
that its essence can be conveyed in a message.  Therefore, a 
representation can (and presumably should) in some way convey all (most? 
some?) of the state of the object with good (pretty good? reasonable? best 
possible under the circumstances?) fidelity.  Nonetheless, we seem to 
accept that jpegs of varying degrees of compression are acceptable means 
of conveying a photograph, and even that translations of a text into a 
different language may be suitable as representations, all of the same 
generic resource.

I wonder whether now is the time for the TAG to consider these questions 
in a more focussed way?  Not sure.  Maybe we have more urgent things to 


Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
Received on Thursday, 15 January 2009 22:11:25 UTC

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