[LEAPSECS] Windows Server 2019

[Martin Burnicki]

Stephen Colebourne wrote:
> On 19 July 2018 at 09:44, Hal Murray <hmurray at megapathdsl.net> wrote:
>>> As a IT professional, and author of date/time libraries, I cannot stress
>>> enough how much a standard is needed here. We are going to have both UTC
>>> (with leap seconds) and systems that smear ("UT-Smear") and there is
>>> currently no agreed way to define the latter or move from one to the other. I
>>> strongly suspect that Microsoft is going to have to define a smear in order
>>> to meet old APIs, but this really should be something well defined by a
>>> standard, not invented by a company.
>>
>> I think there is a semi-standard emerging for NTP.
>>
>> There are several big companies running smearing servers.  I think they have
>> all agreed to use the same parameters.  I think that's linear over 24 hours,
>> 12 before the leap and 12 after.  I'll dig deeper if it matters.
> 
> What I'm hoping will appear is a document that can be treated as a
> standard (preferably at a formal standards body of some kind).
> 
> With the changes to Java, I used UTC-SLS (linear over 1000secs). But I
> deliberately left open the possibility for Java to adopt any future
> standard for smearing that emerged.
> https://docs.oracle.com/javase/10/docs/api/java/time/Instant.html

As far as I know, UTC-SLS is done locally on a client, and since it's
implemented in a Java runtime it is only "seen" by Java applications.

This means if you get timestamps in Java and non-Java applications on
the same machine then they may be off by up to 1000 s at the end of the
UTC-SLS smear interval, isn't it?

If you have a smearing NTP server then all clients of the same server
will have the same smeared time, which is of course off UTC during the
smear interval, but at least all Java and non-Java applications on a
particular machine will see the same system time.

I think it depends on the requirements of the applications which way is
to be preferred.

Martin
-- 
Martin Burnicki

Senior Software Engineer

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