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Re: 13.1.2 Warnings

From: Koen Holtman <koen@win.tue.nl>
Date: Fri, 18 Oct 1996 00:28:20 +0200 (MET DST)
Message-Id: <199610172228.AAA08048@wsooti04.win.tue.nl>
To: ben@algroup.co.uk
Cc: mogul@pa.dec.com, luotonen@netscape.com, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Ben Laurie:
>Jeffrey Mogul wrote:
>> 
>> You've made a convincing case that the existing design for Warning
>> can yield bogus Warnings when HTTP/1.0 and HTTP/1.1 caches are
>> combined.  (I believe we wrote the HTTP/1.1 caching rules so that
>> an HTTP/1.1 cache in the position of your cache "B" would remove
>> the Warning after doing a successful validation from cache "A",
>> but of course it's too late to apply that to the HTTP/1.0 caches
>> out there.)
>> 
>> So please suggest a solution!
>> 
>> I can see three options:
>>       (1) Live with it.  This can only happen when an HTTP/1.0
>>       cache is a client of an HTTP/1.1 cache, and presumably
>>       in somewhat unusual cases, so maybe it's a temporary
>>       problem.
>
>Something you'd have to live with for a long time, I suspect. Not an
>acceptable option, IMHO.

I think (1) is the most acceptable solution of the three.  At some
time, we need to add a note to the spec telling that 1.1 clients
should be aware that 1.0 caches could send erroneous staleness related
Warnings. The note should outline a method to deal with this.

It is not very bad if that method causes a few cache misses.  Even if
chains with 1.0 caches in them will become common, responses with
Warnings won't, so the impact on overall efficiency should be small.

Koen.
Received on Thursday, 17 October 1996 15:36:51 EDT

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