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RE: EDITS for Section 13.20 (Cache Replacement for Varying Resources)

From: Paul Leach <paulle@microsoft.com>
Date: Thu, 2 May 1996 16:13:30 -0700
Message-Id: <c=US%a=_%p=msft%l=RED-77-MSG-960502231330Z-36601@tide21.microsoft.com>
To: "'koen@win.tue.nl'" <koen@win.tue.nl>
Cc: "'http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com'" <http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com>
I sent it before I added my rationale -- sorry.

It now primarily defines what a cache must not do in order to be
correct. It allows the cache to cache stuff for later use, but doesn't
require it.

>----------
>From: 	Paul Leach
>Sent: 	Thursday, May 02, 1996 4:00 PM
>To: 	'koen@win.tue.nl'
>Cc: 	'http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com'
>Subject: 	EDITS for Section 13.20 (Cache Replacement for Varying
>Resources)
>
>>
>>Replacement for 13.20
>>==================================
>>
>>   13.20 Caching Responses
>>
>>   If a new cacheable response (see sections 10.7.2, 13.11.2, 13.11.3
>>and 13.14) 
>>   is received from a non-varying resource while any existing responses
>>for the same 
>>   resource are cached, the cache MUST NOT return any of those older
>responses to any 
>   future requests for the resource.
>	
>	Note: a new response that has an older Date header value than existing
>cached 
>>      responses is not cacheable.
>>
>>   If a new cacheable response is received from a varying
>>   resource with a certain variant-ID while any old responses with the
>>same
>   variant-ID for the same resource are cached, the cache MUST NOT
>return any of 
>   those old responses to any future requests for the resource.
>>
>>	Note: In some cases, this may mean that the cache chooses to delete
>>the old
>	response(s) from cache storage to recover space. However, note that
>there will 
>	never be a new response to signal that a variant-ID is no longer in
>use. It is 
>>	expected that the 'least recently used' update heuristics employed by
>>	caches will eventually cause such old responses to be deleted.
>>
>>   The cache SHOULD use the new response to reply to the current
>request. It may insert
>   it into cache storage and may, if it meets all other requirements,
>use it to
>>   respond to any future requests that would previously have caused the
>>old response to
>>   be returned. If it inserts the new response into cache storage it
>>   should follow the rules in section 13.7.3.
>
>>|  All responses from varying resources SHOULD include variant-IDs.  If
>>|  these are not present, the resource author can expect caches to
>>|  correctly handle requests on the varying resource, but cannot expect
>>|  the caching to be efficient.
>>
>>
>>
>
>
Received on Thursday, 2 May 1996 16:20:05 EDT

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