W3C home > Mailing lists > Public > ietf-http-wg@w3.org > October to December 2012

Re: 304 and Age

From: Thomas Fossati <TFossati@velocix.com>
Date: Tue, 9 Oct 2012 15:05:34 +0000
To: Amos Jeffries <squid3@treenet.co.nz>
CC: "<ietf-http-wg@w3.org>" <ietf-http-wg@w3.org>
Message-ID: <49DB8780-F855-4299-9262-093B70607DFB@velocix.com>
On 9 Oct 2012, at 01:01, Amos Jeffries wrote:
> On 09.10.2012 03:04, Thomas Fossati wrote:
>> Hi all,
>> 
>> maybe a dumb one, but I couldn't find any decisive anchor for the
>> following question: suppose my cache receives a conditional GET for a
>> resource for which it has a fresh representation, should Age be sent
>> back to the requester in a 304 ?
>> 
>> The two points in the current spec that got me confused are:
>> 
>> - p6, Section 4: "When a stored response is used to satisfy a request
>> without validation, a cache MUST include a single Age header field in
>> the response with a value equal to the stored response's current_age."
>> 
>> - p4, Section 4.1 after the paragraph listing the mandatory headers
>> for 304 (which do not include Age): "Since the goal of a 304 response
>> is to minimize information transfer when the recipient already has one
>> or more cached representations, the response should not include
>> representation metadata other than the above listed fields unless said
>> metadata exists for the purpose of guiding cache updates (e.g., future
>> HTTP extensions)."
>> 
>> TIA, Thomas.
> 
> 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. If the requestor does not already have a coy (was checking for existence etc) then it does not need to know Age, but only existence and future lifetime - which are included via the other 304 headers.

That seems reasonable, thanks.

The MUST about Age in Section 4 of p6 should then be amended to take care of 304, or am I missing some other point in the spec that already narrows the scope of this requirement ?
Received on Tuesday, 9 October 2012 15:06:10 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 9 October 2012 15:06:12 GMT