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Re: Major errors in Caching and Cache-Control

From: <jg@w3.org>
Date: Wed, 05 Jun 96 16:16:25 -0400
Message-Id: <9606052016.AA13547@zorch.w3.org>
To: Koen Holtman <koen@win.tue.nl>
Cc: Jeffrey Mogul <mogul@pa.dec.com>, fielding@liege.ICS.UCI.EDU, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com, jg@w3.org
>From: koen@win.tue.nl (Koen Holtman)
>Message-Id: <199606041332.PAA08780@wsooti06.win.tue.nl>
>Subject: Re: Major errors in Caching and Cache-Control
>To: mogul@pa.dec.com (Jeffrey Mogul)
>Date: Tue, 4 Jun 1996 15:32:19 +0200 (MET DST)
>Cc: fielding@liege.ics.uci.edu, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
>In-Reply-To: <9606032143.AA05153@acetes.pa.dec.com> from "Jeffrey Mogul" at Jun 3, 96 02:43:40 pm
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>Jeffrey Mogul:
>>
>>Since Roy has complained several times about the Cache-control
>>section, I guess I owe him a response ... even though I agree
>>with Larry that the timing is a little odd,
>
>It is much more odd that the only-if-cached etc stuff was introduced
>in the 02 draft without any discussion on the mailing lists in the
>first place.
>

There was a face-to-face design meeting in Palo Alto, that many of us
involved in the caching work (myself included) attended.  It is
therefore NOT odd that not everything was discussed on the mailing
list.  We relied on the editor to reflect our discussions in the
draft; overall the editor of the caching spec (Jeff) did a good job.
Also note there have been MULTIPLE drafts available for
anyone to read and comment on. There was time (measured in months) for
these sections to be read by anyone.

I believe most of this was discussed at that meeting, but memory
of that meeting is going dim.

At this date, all discussions of what should or should not be
in the draft are moot, and we should all STOP.  

If there are technical problems in this draft (04), we should discuss
those, and fix them.  I am not going to make any changes to the draft
at this date on strictly procedural grounds; technical arguments/for
or against the document as it currently exists are all that will count
in my book.

>Discussions about what is more odd aside, I share Roy's opinion that
>no-transform is fatal:
>
>    [Roy:]
>>   "no-transform"
>>      is completely wrong because it talks about content codings
>>      in a way that only transfer codings are allowed to behave, and
>>      thus CONTRADICTS other sections.  THIS IS FATAL (and isn't needed).
>>
>[Jeff:]
>>Please discuss the wording with the Digest Authentication folks,
>>who believed that this was a necessary feature.
>

>I commented on this one earlier, in 
>http://www-uk.hpl.hp.com/people/ange/archives/http-wg-archive/1013.html:
>
>  10.7.6 Miscellaneous restrictions
>
>[This is 14.9.5 in the current draft]
>
>  In certain circumstances, an intermediate cache (proxy) may find it
>  useful to convert the encoding of an entity body. For example, a proxy
>   ^^^^^^^^^^^^^^^^^          
>  might use a compressed content-coding to transfer the body to a client
>  on a slow link.
>
> This implicitly allows conversion of entity bodies by proxy caches.  I
> don't think this was ever allowed before, and in any case it breaks
> range retrieval (afaik, range requests work on the entity data in the
> response, not on the unencoded version of this data.)
>
>I think Roy has the same problem with no-transform that I have: it
>disallows a conversion that should never be allowed in the first
>place.  14.9.5 is fatal and must be deleted. Along with it,
>"no-transform" must be deleted.
>

And others disagree; see my message of today for other opinions.  I remember
quite a discussion with Paul Leach and Jeff Mogul on transformations at one point
in time; I've put at least some of the technical rational into that message,
to capture some of what went into an extensive oral discussion of the time.
There are others, but I think two examples should suffice.

					- Jim
Received on Wednesday, 5 June 1996 13:19:40 EDT

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