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Re: #430 / #268 - definition of "public"

From: Roy T. Fielding <fielding@gbiv.com>
Date: Fri, 8 Feb 2013 01:04:10 -0800
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <37BEE4A8-AE9B-4F2F-BA7D-D0452D4FC402@gbiv.com>
To: David Morris <dwm@xpasc.com>
Actually, I was wrong about the precedence rule on cache-control.
It turns out that only applies to extension directives that
specifically override existing directives.

RFC2616 does have a general rule for precedence in section 13.1.3
that I just found only after researching the history of Cache-Control
back to the original drafts:

   The Cache-Control header allows a client or server to transmit a
   variety of directives in either requests or responses. These
   directives typically override the default caching algorithms. As a
   general rule, if there is any apparent conflict between header
   values, the most restrictive interpretation is applied (that is, the
   one that is most likely to preserve semantic transparency). However,
   in some cases, cache-control directives are explicitly specified as
   weakening the approximation of semantic transparency (for example,
   "max-stale" or "public").

so the opposite rule that exists for directive extensions (extensions can
override more restrictive standard directives) does not apply when we are
considering two standard directives. Hence, no-store and no-cache should
still override public except for the one case that is explicitly specified.
Or at least it would if something like the above text is restored in p6.

Received on Friday, 8 February 2013 09:04:34 UTC

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