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From Alexey Kukushkin <kukushkinale...@gmail.com>
Subject Re: Interoperable Ignite.NET Dates
Date Tue, 03 Nov 2020 11:51:45 GMT
Hi Val,

Our proposal does not overlap with IEP-54
<https://cwiki.apache.org/confluence/display/IGNITE/IEP-54%3A+Schema-first+Approach>,
which proposes changing Ignite date storage format. Our proposal is
enhancing Ignite to handle .NET dates in a truly portable way instead of
requiring the application developers to repeat this task every time:

   - Write .NET dates as Ignite dates (today .NET dates are written as
   generic Ignite objects)
   - Convert Local .NET dates to UTC inside Ignite and to it using Java
   calendars.


вт, 3 нояб. 2020 г. в 11:10, Valentin Kulichenko <
valentin.kulichenko@gmail.com>:

> Hi Alexey,
>
> The IEP-54 [1] describes the data layout proposed for Ignite 3.0, it
> includes various date/time types. Can you please take a look and check if
> this addresses your concerns? We can then discuss further if needed.
>
>
> https://cwiki.apache.org/confluence/display/IGNITE/IEP-54%3A+Schema-first+Approach
>
> -Val
>
> On Tue, Nov 3, 2020 at 12:05 AM Alexey Kukushkin <
> kukushkinalexey@gmail.com>
> wrote:
>
> > Pavel,
> >
> > We propose changing public API so this is for Ignite 3.0.
> >
> > Thanks!
> >
> > вт, 3 нояб. 2020 г. в 02:17, Pavel Tupitsyn <ptupitsyn@apache.org>:
> >
> > > Alexey,
> > >
> > > Just to clarify before we start the discussion:
> > > this proposal seems to introduce some breaking changes, so we are
> talking
> > > about Ignite 3.0, correct?
> > >
> > > Pavel
> > >
> > > On Tue, Nov 3, 2020 at 12:13 AM Alexey Kukushkin <
> > > kukushkinalexey@gmail.com>
> > > wrote:
> > >
> > > > Igniters,
> > > >
> > > > What do you think about changing .NET API to read/write portable
> dates
> > by
> > > > default and making that really portable?
> > > >
> > > > *The Problem*
> > > > Presently .NET API writes dates as composite Ignite objects. Only
> .NET
> > > > clients can read such dates: any other client (JDBC, Java, etc) does
> > not
> > > > understand it without custom deserialization.
> > > >
> > > > It is still possible to configure .NET serialization to write dates
> as
> > > > Ignite dates - see DateTime Serialization note
> > > > <
> > > >
> > >
> >
> https://ignite.apache.org/docs/latest/net-specific/net-platform-interoperability#types-compatibility
> > > > >.
> > > > But then Ignite accepts only UTC dates, requiring the application
> > > > developers to convert local dates to UTC dates and back. This task is
> > not
> > > > trivial: DateTime.ToUniversalTime
> > > > <
> > > >
> > >
> >
> https://docs.microsoft.com/en-us/dotnet/api/system.datetime.touniversaltime?view=netcore-3.1
> > > > >
> > > > uses
> > > > calendars different from Java (and the .NET calendars are the invalid
> > > ones
> > > > - especially for pre-1990 dates).
> > > >
> > > > The motivation for the current default behavior was probably the
> desire
> > > to
> > > > keep the Time Zone information: Ignite dates do not store time zones.
> > > >
> > > > In our experience interoperability is more important than storing
> time
> > > zone
> > > > info.
> > > >
> > > > *The Proposal*
> > > >
> > > >    1. Always write .NET dates as portable Ignite dates: get rid of
> the
> > > >    BinaryReflectiveSerializer.ForceTimestamp flag that currently
> > triggers
> > > > this
> > > >    behavior.
> > > >       - We could still keep the ForceTimestamp flag if saving .NET
> > dates
> > > as
> > > >       transparent objects seems a useful case. We do not think it is
> > > > useful.
> > > >    2. Automatically convert Local dates to UTC and back *inside*
> > > >    Ignite.NET.
> > > >       - In this case we lose the DateTime.Kind of UTC dates: we
> write a
> > > UTC
> > > >       date but we would read a Local date since Ignite would always
> > > > convert UTC
> > > >       to Local when reading.
> > > >       We could add a UtcDate date flag to QuerySqlFieldAttribute
> > > >       and BinaryReflectiveSerializer to control the deserialization
> > > > behavior if
> > > >       keeping dates in UTC format use case seems important.
> > > >    3. Use NodaTime <https://nodatime.org/> for UTC<->Local
> > conversions.
> > > >    Noda time uses Java calendars making the conversion truely
> portable.
> > > >
> > > > *The Benefits*
> > > >
> > > >    1. We think portable dates are much more important than storing
> time
> > > >    zone info. Why do we store time zones for every date on the server
> > > > anyway?
> > > >    Time zone is client-side info.
> > > >    2. Simpler application code: no more manual configuration to
> trigger
> > > the
> > > >    portable behavior.
> > > >    3. Non-trivial code to make the truly portable UTC<->Local
> > conversion
> > > is
> > > >    implemented once inside Ignite instead of having every Ignite.NET
> > > >    application implementing it.
> > > >
> > > > Thank you!
> > > >
> > > > --
> > > > Best regards,
> > > > Alexey
> > > >
> > >
> >
> >
> > --
> > Best regards,
> > Alexey
> >
>


-- 
Best regards,
Alexey

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