W3C home > Mailing lists > Public > http-caching-historical@w3.org > February 1996

Re: where we stand on caching

From: Koen Holtman <koen@win.tue.nl>
Date: Wed, 21 Feb 1996 13:29:17 +0100 (MET)
Message-Id: <199602211229.MAA01556@wsooti09.win.tue.nl>
To: mogul@pa.dec.com (Jeffrey Mogul)
Cc: http-caching@pa.dec.com, masinter@parc.xerox.com
Jeffrey Mogul:
>Anyway, what follows are two rather terse lists.  The first is "stuff
>we agree on" and the second is "stuff we disagree on or haven't really
>tackled yet."  I'm sure I have left stuff off of both lists, and
>perhaps I've put something on the "agree" list that doesn't deserve to
>be there.

I will make some additions to some points of the list.

[...]
>----------------------------------------------------------------
>"Agreed:"
>
>	A user or cache administrator may override that "MUST NOT"
>	with an explicit request, and if the resulting known-stale
>	response is explicitly flagged to the user as being stale.

Add the text:

 No agreement has been reached on syntax for the overriding facility,
 and no agreement has been reached on how explicit the staleness flag
 must be.  The opinions range from 'you have to do the equivalent of
 signing a waiver form [when you want to override max-age=0 or
 no-cache].' (caching meeting) to 'Requiring a visible/noticeable
 warning be presented when semantic transparency is disabled [i.e. when
 overriding is enabled] is reasonable, provided that it does not
 actively interfere with people's work.' (Roy).

>Age calculations:
[...]
>		age = max(now - Date:, Age:)
>	Note that this correction can be applied at each HTTP/1.1 cache
                                  ^^^
change 'can' into 'can (but is not required to)'.

>	along the path, so that if there is an HTTP/1.0 cache in the path,


>Cache-control: stale-max=NNN, fresh-min=NNN
>	Necessary for user-centric control over freshness parameters.

Delete this.  As noted above, there has been no agreement on syntax.
(Note: I still have some 30 unread messages, so I may be wrong on this,
but I think not.)

Add two new agreement items:

 Vary:
        We agree that a Vary header is necessary.

 Caching section:
        We agree that the HTTP/1.1 specification must have a caching
        section that explains all caching issues in a central place,
        and that prevents some possible misinterpretations of the
        of the caching-related text elsewhere.

>----------------------------------------------------------------
>
>"Not agreed"
>
>(8) Volume validation: yes or no

I think we already agreed on 'no for 1.1, maybe yes later', because it
would be too big a step.

Add one more disagreement item:

  (n) Use 'max-age' and 'private' directives in both request and response 
  Cache-Control headers, or use four different directive names?

Koen.
Received on Wednesday, 21 February 1996 13:07:06 UTC

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