Re: I-D Action: draft-ietf-httpbis-cache-08.txt

Ken Murchison <murch@fastmail.com> Sun, 14 June 2020 16:40 UTC

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To: Amos Jeffries <squid3@treenet.co.nz>, ietf-http-wg@w3.org
References: <159048066829.15360.13534615257560671669@ietfa.amsl.com> <2cd0d6c6-2ac9-5218-cf5c-068444b358aa@fastmail.com> <dc5e4d3d-c8e3-2f54-e9aa-59751bbf4f98@treenet.co.nz>
From: Ken Murchison <murch@fastmail.com>
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Date: Sun, 14 Jun 2020 12:37:24 -0400
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Subject: Re: I-D Action: draft-ietf-httpbis-cache-08.txt
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On 6/13/20 9:27 PM, Amos Jeffries wrote:
> On 14/06/20 1:32 am, Ken Murchison wrote:
>> All,
>>
>> I'm trying to verify my understanding of must-revalidate vs unqualified
>> no-cache in responses per the text in Sections 5.2.2.1 and 5.2.2.3
>> respectively.  Other than the point regarding the Authorization header
>> field and must-revalidate, is the difference that unqualified no-cache
>> requires validation for every request and must-revalidate only requires
>> validation after the response has become stale?
>>
> The specification difference is exactly that yes.


Thanks Amos.

> In practice implementations (particularly older RFC2616 based ones) may
> treat "no-cache" as if it were "no-store" and "must-revalidate" as if it
> were unqualified "no-cache".


So, given the possible ambiguity here, would a best practice for 
cacheable resources that should always be validated be for the origin 
server to return maxage: 0 or Expires in the past?

-- 
Kenneth Murchison
Senior Software Developer
Fastmail US LLC