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Re: 304 and Age

From: Amos Jeffries <squid3@treenet.co.nz>
Date: Wed, 10 Oct 2012 11:16:42 +1300
To: <ietf-http-wg@w3.org>
Message-ID: <182c654db700219cdf9321dd7959cda1@treenet.co.nz>
On 10.10.2012 08:42, Eric J. Bowman wrote:
> Amos Jeffries wrote:
>>
>> IMO, the Age header is not useful in this case. Since the requestor
>> already appears to have a copy of the representation, thus already
>> has or can calculate its Age.
>>
>
> Sure, if the cache validates with the origin, but what if that isn't
> the case?
>
> Client has representation, reloads.  Cache also has representation,
> but responds 304 without validating to the origin.  Without Age, how
> does client know if the cache's 304 is referring to a newer or older
> representation than the one the client already has?
>

Consider how the cache knew to send 304 instead of a 200 with cached 
representation in response to that GET.

The client has to have sent conditional headers to receive that 304, 
which conditionals outlined some form of parameters for the cache to 
select representation and the above statement applies. If the client 
omitted conditional headers on a GET the cache is in error sending a 304 
status - for exactly the reason you point out.

Amos
Received on Tuesday, 9 October 2012 22:17:09 GMT

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