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https://issues.apache.org/jira/browse/IGNITE-12824?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17254491#comment-17254491
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Pavel Tupitsyn commented on IGNITE-12824:
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[~nizhikov] PR looks good to me, thanks!
> .NET: Interoperable DateTime
> ----------------------------
>
> Key: IGNITE-12824
> URL: https://issues.apache.org/jira/browse/IGNITE-12824
> Project: Ignite
> Issue Type: Improvement
> Components: platforms
> Affects Versions: 2.8
> Reporter: Alexey Kukushkin
> Assignee: Nikolay Izhikov
> Priority: Major
> Labels: .NET, iep-54, ignite-3, sbcf
> Fix For: 3.0
>
> Attachments: IGNITE-12824-from-2.9.0.patch
>
> Time Spent: 2h 20m
> Remaining Estimate: 0h
>
> *+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 Solution+*
> # Always write .NET dates as portable Ignite dates: get rid of the
> {{BinaryReflectiveSerializer.ForceTimestamp}} flag that currently triggers
> this behavior.
> Keep the {{ForceTimestamp}} flag if saving .NET dates as transparent objects
> seems a useful case.
> # Automatically convert Local dates to UTC and back *inside* Ignite.NET.
> Add a {{BinaryReflectiveSerializer.UtcDate flag}} to disable this
> conversion. This prevents loosing the {{DateTime.Kind}} property of UTC
> dates. {{UtcDate}} set to true implies the existing behavior: Ignite gets
> UTC dates and throws a "Date must be in UTC" exception on an attempt to write
> a Local date. The {{UtcDate}} flag is false by default.
> # Use [NodaTime|https://nodatime.org/] for UTC<->Local conversions. Noda
> time uses Java calendars making the conversion truly portable.
>
> *+The Benefits+*
> # Portable dates is a more frequent use-case than storing time zone info for
> every date in Ignite. This becomes default behavior and the developers do not
> need to always explicitly configure it.
> # 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.
> +*References*+
> * [Dev-List
> Discussion|http://apache-ignite-developers.2346864.n4.nabble.com/Interoperable-Ignite-NET-Dates-td49946.html]
> * IEP-TBD
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