Moving forward with new packaging for UI framework features

[idg10]

We are moving forward with our plans to modify how UI-framework-specific features are packaged in Rx.NET. This is the last chance to offer feedback on #2086

Back in November 2023, we announced that we intended to fix some long-standing problems by making changes to Rx.NET packaging.

In February 2024, we created PR #2086 which enumerated the various options under consideration (and described all the suggestions we'd had from the community since the initial announcement).

Also in February we created PR #2084 as a prototype showing how this change might look, with some changes in March in response to community feedback.

.NET 9.0 is due to ship very soon. We intend to produce a new Rx.NET release not long after that happens.

This new version seems like the right time to move forward with the packaging plan. The first phase is to make new UI-framework-specific Rx packages available. We will not remove anything from System.Reactive at this time, but will mark all UI-framework-specific types and methods as [Obsolete], beginning the process

(Note: Rx 6.0 will work on .NET 9.0—anyone using Rx 6.0 today won't need to upgrade just to be able to move to .NET 9.0. The motivation for a new Rx.NET release is mainly that .NET 6.0 will be going out of support. And a secondary motivation is that a lot of people don't really understand how TFMs work, and mistakenly think that the absence of a net8.0 target indicates a lack of support for .NET 8.0. In fact we've supported Rx 6.0 on .NET 8.0 since .NET 8.0 shipped. But we want to make it clear that .NET 6.0 will not be officially supported by Rx.NET once it is no longer supported by Microsoft. So Rx 7.0 will not offer net6.0 TFMs. We plan to offer netstandard2.0, net472, net8.0, net8.0-windows10.0.19041 and uap10.0.18632.)

[Sergio0694]

This sounds awesome! I have a couple questions:

• Would this first phase also include the new "base" package mentioned in Future Rx.NET Packaging #2038 (comment)?
• This sounds like the perfect occasion to also add .NET 9 support for the UWP flavor of System.Reactive (see the announcement). Would this be something you'd accept as a contribution? Without this, there would be no way for UWP apps to continue using System.Reactive when moving to .NET 9 (eg. that applies to us too in the Microsoft Store app) . I'd love to help with this🙂

[idg10]

Would this first phase also include the new "base" package

This one encountered significant push back from the community, and so we have instead decided to go down the slower, but less disruptive path of keeping System.Reactive as the main package. Since we found a workaround for the package bloat problems that were being caused by having the UI frameworks integrated into System.Reactive, it was no longer an absolute requirement to separate them out at the earliest opportunity.

.NET 9 support for [...] UWP

I was briefly excited when I saw that announcement, but as I mentioned in the UAP ADR (currently on the .NET 9.0 SDK branch), unfortunately it seems to impose a minimum target version of Windows 11 22H2 (26100). Windows 10 will remain in support for a few years yet, so we can't require that.

[kmgallahan]

Ehhh, resolved the IAsyncOperation issues, but now I have the same errors as before when disabling transitive refs:

error CS7069: Reference to type 'Dispatcher' claims it is defined in 'WindowsBase', but it could not be found
error CS7069: Reference to type 'DispatcherObject' claims it is defined in 'WindowsBase', but it could not be found
error CS0012: The type 'Control' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Windows.Forms, Version=6.0.2.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

Seems the code for these things is in the platform files, which have references to the old framework namespaces.

https://github.com/dotnet/reactive/tree/main/Rx.NET/Source/src/System.Reactive/Platforms

https://github.com/dotnet/reactive/blob/main/Rx.NET/Source/src/System.Reactive/Platforms/Desktop/Linq/ControlObservable.cs

[Sergio0694]

Yeah, that's why I specifically added a reference to the net6.0 .dll, not to the net6.0-windows10.0.19041 one 🙂

[kmgallahan]

Still have a pile of framework files ¯\_(ツ)_/¯

[Sergio0694]

Not sure how that's possible assuming you're also using PackageDownload. You'd need to get a binlog to figure out where they're coming from. I've tested in our repo and publishing with Native AOT did result in no WPF references left with this setup.

[kmgallahan]

I forgot to respond here. If I remember correctly, the process of elimination indicated that the FlaUI package was responsible for the unwanted files due to its dependencies.