[LEAPSECS] Windows Server 2019

Martin Burnicki martin.burnicki at meinberg.de
Thu Jul 19 06:48:53 EDT 2018

Stephen Colebourne wrote:
> On 19 July 2018 at 11:24, Martin Burnicki <martin.burnicki at meinberg.de> wrote:
>> 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.
> True, but the point is that we have already, and are likely to have
> more in the future, boundaries that want different representations.
> Specifically, cases where a low level system understands and models
> leap seconds, but a high level system does not want to (for various
> perfectly good reasons). Once it is accepted that there are two
> representations, and both are valid, there is a need to convert
> between the two.
> For the plan to work fully it needs to be possible for any of these
> setups to be valid (and maybe more options too):
> - network clock returns UTC, OS handles UTC, application/framework handles UTC
> - network clock returns UTC, OS handles UTC, application/framework smears
> - network clock returns UTC, OS smears, application/framework unaware
> - network clock smears, OS unaware, application/framework unaware
> Getting the smear off the network and into the OS will undoubtably be
> useful in some use cases, but they are not the only use cases.

I fully agree, and that's what I meant by "it depends on the
requirements of the applications". ;-)

Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: martin.burnicki at meinberg.de
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