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ISSUE: transformations

From: <rlgray@acm.org>
Date: Wed, 12 Aug 1998 17:28:46 EST
Message-Id: <199808122128.RAA28590@rtpmail01.raleigh.ibm.com>
To: HTTP Working Group <http-wg@hplb.hpl.hp.com>
The wordage around application of transformations to entities [by
proxies] seems to deal only with what headers can be changed
(presumably interoperability issues are thought to only be possible 
in that case).

However, imagine for a moment that my proxy applies a transformation
that neither changes the Content-Type nor the Content-Encoding (for the
sake of argument, call it the "ee cummings" transform: on text types
only, lowercase and remove punctuation).
Even for the example used in the spec, if one were to change the
resolution of a medical image, it would be a potentially bad thing.

Now, for the questions:

1. Content-MD5, for example, is an end-to-end header (which, according
to 13.5.1, MUST be stored and forwarded, and according to 14.15 MUST
NOT be generated by proxies.  If I leave it in, it will be wrong.  If I
remove it, I run the risk of breaking an application.  Gaaack.

2. This would lead me to think that I should add a "Warning: 214" even
if I do not change the Content-Type or Content-Encoding (and that
perhaps the spec should be changed to require this).

Richard L. Gray
will code for chocolate
Received on Wednesday, 12 August 1998 14:31:02 EDT

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