Pragma: header and preventing caching in general

reinpost@info.win.tue.nl (Reinier Post)

Mail folder: WWW Talk Apr 94-present
Next message: Michael Mealling: "An Anchor attribute question:"
Previous message: Daniel W. Connolly: "Re: An Anchor attribute question: "
Reply: Reinier Post: "Re: Pragma: header and preventing caching in general"

Errors-To: listmaster@www0.cern.ch
Date: Wed, 1 Jun 1994 16:01:41 +0200
Errors-To: listmaster@www0.cern.ch
Message-id: <199406011142.NAA03426@wsinis10.info.win.tue.nl>
Errors-To: listmaster@www0.cern.ch
Reply-To: reinpost@info.win.tue.nl
Originator: www-talk@info.cern.ch
Sender: www-talk@www0.cern.ch
Precedence: bulk
From: reinpost@info.win.tue.nl (Reinier Post)
To: Multiple recipients of list <www-talk@www0.cern.ch>
Subject: Pragma: header and preventing caching in general
X-Listprocessor-Version: 6.0c -- ListProcessor by Anastasios Kotsikonas
Content-Type: text/plain; charset=US-ASCII
Content-Type: text/plain; charset=US-ASCII
Mime-Version: 1.0
Mime-Version: 1.0
X-Mailer: ELM [version 2.4 PL23]
X-Mailer: ELM [version 2.4 PL23]

Two questions to those (Ari et al.) who are working on proxy and caching:

Recently, a new HTTP request header was introduced (Pragma: no-cache)
to make it possible for clients to ask intermediaries to refrain from caching
a document.  As I gathered from the discussion, its main purpose was to make
the Refresh function of clients actually refresh the document by causing it
to refresh any intermediate caches also.

Apparently, the name of this header doesn't match its intended
usage.  What you want is a request for the cache server to refresh the
document in cache, instead of bypassing the cache altogether.  My question:
don't we rather need a Pragma: refresh header?

The second question: several occasions have arisen in which it would be useful
for the remote server (not the client) to explicitly indicate that
the document sent must not be cached.  (For example, the case of WIRED,
where fragments of copyrighted material are cached, but copyright is not
on the individual fragments.)  Can I suggest that the Pragma: no-cache header
is added to the valid HTTP response headers?  (It's not yet there on

  http://info.cern.ch/hypertext/WWW/Protocols/HTTP/Object_Headers.html

).  Maybe with an HTML equivalent, too.

-- 
Reinier Post						 reinpost@win.tue.nl
a.k.a. <A HREF="http://www.win.tue.nl/win/cs/is/reinpost/reinier.E.html">me</A>