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Re: I-D ACTION:draft-reschke-http-etag-on-write-00.txt

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 11 Aug 2006 08:29:56 +0200
Message-ID: <44DC23E4.6080301@gmx.de>
To: Jeffrey Mogul <Jeff.Mogul@hp.com>
CC: HTTP Working Group <ietf-http-wg@w3.org>

Jeffrey Mogul schrieb:

> I thought about this a little more.  There's a potential problem
> with simply specifying the grammar as
> 
>      Entity-Transform    = "Entity-Transform" ":" 1#transform-info
> 
> The problem is that this (1) allows multiple transforms, and
> (2) doesn't explicitly specify what order they were applied in.
> 
> But one could easily imagine that, if a server does apply
> multiple transforms, they are not commutative.  For example
> (not that you would ever expect this combination), "uuencode"
> followed by "remove-nasty-words" is not the same as
> "remove-nasty-words" followed by "uuencode".
> 
> See the language in RFC2616 for Content-Encoding as an example
> for how to solve this problem:
> 
>    If multiple encodings have been applied to an entity, the content
>    codings MUST be listed in the order in which they were applied.
> 
> Without such an explicit requirement, one could imagine
> implementations that use other orders (such as: alphabetical,
> or reverse-order).
> 
> This is another case of where an incautious over-application
> of the KISS principle could lead to ambiguity and hence
> complexity.

Jeff,

I think this is indeed an example where the KISS example should apply, 
at least for now. The purpose of the proposal is to resolve the conflict 
between various proposals for applications of HTTP, currently under IESG 
evaluation.

The nature of the problem is how the ETag can be used, not whether or 
not a server can indicate what kinds of transforms have been applied. 
Thus, the discussion about the actual contents of the Entity-Transform 
header for now is distracting us from the base problem it intends to 
solve. Thus I would prefer to discuss the format only after the base the 
document (the discussion of the problem, and that path how to resolve 
it) has some kind of consensus.

Best regards, Julian
Received on Friday, 11 August 2006 06:30:10 GMT

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