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Re: On transparency

From: Shel Kaphan <sjk@amazon.com>
Date: Sun, 25 Feb 1996 11:26:28 -0800
Message-Id: <199602251926.LAA08743@bert.amazon.com>
To: koen@win.tue.nl (Koen Holtman)
Cc: fielding@avron.ICS.UCI.EDU (Roy T. Fielding), http-caching@pa.dec.com
Koen Holtman writes:
 
 > Roy T. Fielding:
	...
 > >  Why not just send a
 > >Warning header in a response to any request containing max-stale?
 > 
 > My proposed header is basically a refined version of max-stale.  
 > I would be happy with max-stale
 > 
 >  1) if it can express any kind of `never check' mode we can imagine
 >     now
 >  2) if clients are required to send it if they may be planning to 
 >     weaken caching rules.
 > 
 > I don't know if both these requirements are met by max-stale, that is
 > why I made a new header definition.
 > 
	...

 > So again: If you insist that HTTP/1.1 must make it legal for user
 > agents and proxy caches to ignore a Cache-Control response header,
 > then I insist that HTTP/1.1 requires user agents and proxies to always
 > warn origin servers if they may do so.
 > 
 > > ...Roy T. Fielding
 > 
 > Koen.

It seems pretty clear to me that Koen is on the right track with this.
(I take back some confused comments earlier today on the subject
max-stale -- sorry, I should eat some breakfast before answering mail...).

Koen: do you think the warnings that users see should just be in
documents sent by the origin server, or do think that there should be
any kind of general facility for warning users when the server wants
to issue such a warning?  If there were a general facility, it might
be simpler for users to turn off the "never check" option (e.g. if a
dialog box pops up at the appropriate time).  It is theoretically
possible for browsers to offer such a facility if (1) they are in
"never check" mode, and (2) they receive a response from a server that
indicates cache-control or expiration options that would be overridden
by the browser's current mode.

--Shel
Received on Sunday, 25 February 1996 19:54:14 UTC

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