Re: Predictable Internet Time
Joe Touch <touch@isi.edu> Tue, 28 March 2017 21:37 UTC
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Subject: Re: Predictable Internet Time
To: Nico Williams <nico@cryptonector.com>, Stewart Bryant <stewart.bryant@gmail.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> <f94415b6-d9f7-0a03-cf5b-ce39c109aa71@isi.edu> <f9429571-b9d5-75d4-9b46-b877a189a7bf@gmail.com> <20170328173916.GE7490@localhost>
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From: Joe Touch <touch@isi.edu>
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Date: Tue, 28 Mar 2017 14:36:54 -0700
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Hi, all, Please take this discussion to ART (art@ietf.org) Joe On 3/28/2017 10:39 AM, Nico Williams wrote: > On Tue, Jan 03, 2017 at 06:35:03PM +0000, Stewart Bryant wrote: >> Yes, the system should use a leap-second-free constant-duration-seconds time >> for everything. It is only humans that need the variable jumpy version of >> time presented to them, and that is a UI issue. > I don't think that's quite right. > > Unix time is canonically a count of seconds since an epoch and admits no > leap seconds. A conversion of Unix time to adjusted (i.e., with leap > seconds added) time since the same epoch would be nice, as well as: > > - conversion from either to broken down time > - with seconds count up to 60 when converting from seconds-with-leaps > - formatting of dates from either as well as from broken down time > - but when converting from seconds-with-leaps the formatted string > can show seconds-in-minute values of 60 > - whereas when converting from Unix seconds the formatted string can > never show seconds-in-minute values of 60 > - parsing to broken down time and to seconds-since-epoch types > - ignoring leap seconds when converting to Unix time > - correctly accounting for all leap seconds prior to that time when > converting to seconds-with-leaps-since-epoch > > It's all about data typing. In POSIX C API terms, we need new functions > to deal with seconds-with-leaps-since-epoch, and obviously a lot of > prayer because there's no way in C to distinguish one integer type from > the other (well, the new type could be wrapped in a struct..). > > We will have to deal with multiple kinds of time as long as different > applications/users need different definitions of time. Astronomers may > need corrected time, while bankers may want to ignore leap seconds -- > all on the same systems (same OSes, same code libraries). > > Functionally this is about data typing -- preferably strong data typing. > > Smearing is a third time representation that also needs conversion to > the other types (more opportunity for bugs!); it leaves a bad taste. It > may work for some apps though, but all nodes had better smear in exactly > the same way -- within your tolerances -- if your app depends on time > for synchronization. > > Nico
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Toerless Eckert
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Izaac
- Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time sandy
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Eliot Lear
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Eliot Lear
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Cyrus Daboo
- Re: Predictable Internet Time Jared Mauch
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Cyrus Daboo
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Cyrus Daboo
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Ted Lemon
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Eliot Lear
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time John C Klensin
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Pete Resnick
- Re: Predictable Internet Time Cyrus Daboo
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Paul Eggert
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Philip Homburg
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Eliot Lear
- Re: Predictable Internet Time Harald Alvestrand
- Re: Predictable Internet Time Stewart Bryant
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Leif Johansson
- Re: Predictable Internet Time Eliot Lear
- Re: Predictable Internet Time Leif Johansson
- Re: Predictable Internet Time Phillip Hallam-Baker
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Michael Breuer
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Tony Finch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Patrik Fältström
- Re: Predictable Internet Time Joe Touch
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Nico Williams
- Re: Predictable Internet Time Harald Alvestrand