Re: A structured format for dates?

Martin Thomson <mt@lowentropy.net> Thu, 16 June 2022 07:37 UTC

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Date: Thu, 16 Jun 2022 17:34:47 +1000
From: Martin Thomson <mt@lowentropy.net>
To: ietf-http-wg@w3.org
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Subject: Re: A structured format for dates?
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The resistance is probably the result of wanting to be able to read the header as it appears in logs.  I still find this to be challenging with seconds-since-epoch.

That said, I no longer believe that readable is a requirement for wire formats.  Tools can do a lot to cover any shortcomings.

On Thu, Jun 16, 2022, at 16:04, Mark Nottingham wrote:
> Personally, I tend to agree with PHK - I think that Integer (or 
> Decimal) is adquate and appropriate.
>
> However, some people seem to keep on pushing back on this - I think 
> especially for application-focused headers it's more visible. If we're 
> going to do something, retrofit is a good opportunity for it, since 
> we're defining SF-Date and friends.
>
> Cheers,
>
>
>> On 16 Jun 2022, at 3:46 pm, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
>> 
>> --------
>> Mark Nottingham writes:
>> 
>>> I'd love to hear what people think about this issue:
>>>  https://github.com/httpwg/http-extensions/issues/2162
>> 
>> I've added this comment:
>> 
>> 	I see no mention of fractional seconds ?
>> 
>> 	I think we need to ponder that, if the goal is (eventual) convergence for all timestamps in HTTP ?
>> 
>> 	Considering how much effort we spend on speeding up HTTP, I find the "human readable" argument utterly bogus.
>> 
>> 	Only a very tiny fraction of these timestamps are ever read by humans, and most are in a context where software trivially can render the number in 8601 format if so desired.
>> 
>> 	In terms of efficiency, I will concede that, in a HTTP context, it is almost always possible to perform the necessary calculations and comparisons on raw ISO-8601 timestamps, without resorting to the full calendrical conversions, but once all the necessary paranoia is included, I doubt it is an optimization.
>> 
>> 	My preference is sf-decimal seconds since epoch, (and this is largely why sf-decimal has three decimals in the first place), because it gives us fast processing, good compression and millisecond resolution.
>> 
>> 	PS: A Twitter poll with only 40 respondents, carried out on the first monday after new-years ? Really ?!
>> 
>> 
>> -- 
>> 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.
>> 
>
> --
> Mark Nottingham   https://www.mnot.net/