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Re: no-transform

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Thu, 06 Jun 96 10:40:15 MDT
Message-Id: <9606061740.AA18467@acetes.pa.dec.com>
To: jg@w3.org
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
One last rewrite:

 14.9.5 No-Transform Directive

  Intermediate caches (proxies) have found it useful to convert the
  media type of certain entity bodies.  A proxy might, for example,
  convert between image formats in order to save cache space or
  to reduce the amount of traffic on a slow link.  HTTP has to date
  been silent on these transformations.  

  Serious operational problems have already occured, however, when these 
  transformations have been applied to entity bodies intended for certain 
  kinds of applications.  For example, applications for  medical imaging, 
  scientific data analysis and those using end-to-end authentication, 
  all require that the original entity-body be reproduced exactly bit for bit.
  Therefore, an intermediate cache MUST NOT change the
  media type of an entity-body if the response includes the no-transform
  directive.

I would change that last sentence to

  Therefore, an intermediate cache or proxy MUST NOT change the
  media type of an entity-body if the response includes the no-transform
  directive.

since we don't want non-caching proxies to violate this, do we?

I suppose it might make Roy happier if this were part of a Proxy-Control:
header, instead of Cache-Control, since that's really what it is.  But
I don't see that much harm in including it in Cache-Control, if it's
clear to implementors of non-caching proxies that it applies to them,
too.

-Jeff
Received on Thursday, 6 June 1996 10:53:43 EDT

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