Re: Predictable Internet Time

Stewart Bryant <stewart.bryant@gmail.com> Tue, 03 January 2017 18:55 UTC

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Subject: Re: Predictable Internet Time
To: Cyrus Daboo <cyrus@daboo.name>, Phillip Hallam-Baker <phill@hallambaker.com>
References: <CAMm+LwgfQJ8aG5wB=d3fRbbeje3J9o7Z4_DCuP8DL88ouDeKzw@mail.gmail.com> <504e2cea0d1668c31486b05fec0a967a4446aefe@webmail.weijax.net> <CAMm+Lwi_jU6gjdtdM6a2n_9_89tUvWBNXxnMtSjTEA++h1D4Ew@mail.gmail.com> <e0a43370-751f-808c-3719-9716f9cd57d1@isi.edu> <alpine.DEB.2.11.1701031348430.7102@grey.csi.cam.ac.uk> <0bbfcd7c-11a7-0e7f-56f7-eee959b7a947@gmail.com> <CAMm+Lwi0sQyRE_2dMCkwTk7xTiK2JbHhHSPYMkdG2FeBw_6CNA@mail.gmail.com> <7BDE58D23ADF3BC046F8942D@caldav.corp.apple.com> <b27515e2-a36a-7bf2-0ca4-1fae31a9dc21@gmail.com> <04DD5DFCB528DCD404C81F78@caldav.corp.apple.com>
From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Tue, 3 Jan 2017 18:55:33 +0000
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On 03/01/2017 18:38, Cyrus Daboo wrote:
> Hi Stewart,
>
> --On January 3, 2017 at 6:30:19 PM +0000 Stewart Bryant 
> <stewart.bryant@gmail.com>; wrote:
>
>> Only the UI needs the TZ information, the machine can operate just fine
>> with any timescale. That is you present the time in local time, but
>> operate in global time, and this is definitely an application that will
>> not care about leap seconds.
>
> No that simply does not work. Repeating events or alarms may not 
> involve any UI at all, but the device may need to trigger those at a 
> specific local time - that means time zone information has to be taken 
> into account somewhere. This is a crucial fact of any calendaring and 
> scheduling system that those of us who have been using iCalendar 
> (RFC5545) fully appreciate.
>

Hi Cyrus,

I think that depends on what you consider to be the infrastructure and 
what you consider the application. I would like to see the CPU clocks, 
and in particular  the time transfer protocols just work on non-jumpy 
constant-duration-second time since that has to scale from 
sub-femtoseconds to millennia with sub-femtosecond accuracy without 
glitching and with unambiguous duration measurements.

If we distribute time in the infrastructure as  non-jumpy 
constant-duration-second time , then the iCal system can surely do the 
conversion to/from whatever format the human needs? Whether it talks to 
itself in human time or machine time is for those of you that design 
iCal to determine, but it sounds from what you say that it talks to 
itself in human time. Whether it does the conversion from machine time 
to human time, or whether the OS does it for outside the scope of the 
point I am making.

- Stewart