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From Valentin Kulichenko <valentin.kuliche...@gmail.com>
Subject Re: Interoperable Ignite.NET Dates
Date Tue, 03 Nov 2020 08:10:02 GMT
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
>

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