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Re: #375: Most Conservative (caching and date parsing)

From: Yutaka OIWA <y.oiwa@aist.go.jp>
Date: Mon, 16 Jul 2012 23:58:53 +0900
Message-ID: <CAMeZVwuXo8L6yOKzbVWT9bXNO02oEpv4Hwu6pqFht4Ax52hXXw@mail.gmail.com>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
Dear Poul,

2012/7/16 Poul-Henning Kamp <phk@phk.freebsd.dk>:
> In message <CAMeZVwscuX986t9KMD0eXou-fgHUG8DBBkx2++AbJAt0gDs+Ng@mail.gmail.com>
> , Yutaka OIWA writes:
>>>> If an HTTP header field incorrectly carries a date value with a time zone other than GMT, it must be converted into GMT using the most conservative possible conversion.
>>> What does "most conservative" mean?
>>My personal proposal is instead of adding any examples, state it like "it may be
>>converted to GMT using whatever methods they think appropriate",
> As a time-geek, I would caution against that, because names of timezones
> are politically chosen and both their definition and naming is highly
> fragile in various parts of the world.

Yes, that's why I am proposing to remove any clauses that
morally require people to parse wrong dates "correctly".
I think my proposal is along with, not against your suggested direction.
# The original text requests people to parse these appropriately and

> Given that it is a class-A fuckup to send wrong dates, I will advocate
> that such timestamps SHOULD be ignored, but CAN be interpreted on a
> best-effort basis.

+1 on default to ignore.  That's one step further beyond my proposal and
it makes sense.
But I am not sure, are there any HTTP date-related headers for which
ignoring is more dangerous than guessing?

> Ohh, and also:  GMT is (maybe!) what parliament decides in the UK, the
> correct "independent" timescale is called UTC.

This is very historic :-)  In HTTP, GMT *is* the mnemonic for the Universal
Coordinated Time, independent from any local time standards of UK.

Yutaka OIWA, Ph.D.              Leader, Software Reliability Research Group
                             Research Institute for Secure Systems (RISEC)
   National Institute of Advanced Industrial Science and Technology (AIST)
                     Mail addresses: <y.oiwa@aist.go.jp>, <yutaka@oiwa.jp>
OpenPGP: id[440546B5] fp[7C9F 723A 7559 3246 229D  3139 8677 9BD2 4405 46B5]
Received on Monday, 16 July 2012 14:59:40 UTC

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