"?> Re: WGLC p6 4.2.1 from Poul-Henning Kamp on 2013-03-18 (ietf-http-wg@w3.org from January to March 2013)

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Re: WGLC p6 4.2.1

From: Poul-Henning Kamp <phk@phk.freebsd.dk>
Date: Mon, 18 Mar 2013 06:58:32 +0000
To: "Adrien W. de Croy" <adrien@qbik.com>
cc: "IETF HTTP Working Group" <ietf-http-wg@w3.org>
Message-ID: <10364.1363589912@critter.freebsd.dk>
In message <em2a931273-ea65-4c5c-83d3-2d9698e19de0@bombed>, "Adrien W. de Croy" writes:

>I see there were some changes made to the 3rd bullet point in 4.2.1 
>about selection of representations to update with a 304.
>
>The new text hints that dates other than those received in a previous 
>Last-Modified can be used to generate a conditional request with 
>If-Modified-Since.

There are several uses I know of, where IMS is used by clients
without having an older object, as a way to say "Is a recent version
of this object available ?".

One such usage is "Are there any severe weather warnings published
in the last 24 hours ?" which avoids pulling the "no warnings"
boilerplate most of the year.

I will fully agree, that using only values originally received from
the server is a lot more water-tight, and is to be strongly recommended
(at the SHOULD level), but trying to outlaw other values is a waste
of everybodys time, given that such a ban cannot be sensibly enforced
by us.

If the server for some reason insists on not receiving arbitrary
timestamps in IMS, it can use E-tags, which by definition are
impossible to synthesize anywhere else.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
Received on Monday, 18 March 2013 06:58:56 GMT

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