Support for MAUI runtimes in ASP.NET Core?

[JustArchi]

Hey,

I apologize in advance if this is not the correct place to ask this, but I didn't find any better one. Feel free to move this issue if appropriate.

For testing purposes, in MAUI net6.0-android project I've tried to reference other project of mine targetting net6.0 which is a library. I didn't have any issues doing so, but during compilation I've stumbled upon following error:

Error NETSDK1082 There is no Microsoft.AspNetCore.App runtime package available for the specified RuntimeIdentifier "android-x86"

If I understand this right, I can reference standard net6.0 projects because Microsoft.NETCore.App.Runtime.Mono.android-x86 exists and is usable, at least I successfully did that with example net6.0 library. However, I'd like to reference a library that has actual ASP.NET Core elements (Kestrel web server, API with MVC etc), which according to the error is impossible because it can't find a required android-x86 runtime, which seems to be correct as of today.

Now I apologize if I'm trying to do some extreme stupidity, or I don't understand something, but I wanted to verify whether it'd be possible to "convert" existing CLI project of mine which uses Kestrel and API controllers into an Android MAUI app that could start the "backend" part on the target machine, with some nice frontend utilizing those API endpoints over HTTP. I'm testing this in .NET 6.0 preview 6 if it matters.

Is this possible/planned? Or perhaps I'm doing something horribly wrong?

In any case, thank you in advance for answering, I appreciate it.

[Eilon]

(Transferring back to aspnetcore repo...)

Hi @JustArchi , code that is specific to ASP.NET Core scenarios, such as hosting Kestrel, requires platform support, which as you discovered, it not available on some platforms, such as Android.

I think this might really be a question for the ASP.NET folks as to whether there is a desire to support certain features, such as Kestrel, on "arbitrary" platforms, or whether to specifically add support to particular platforms (e.g. android-x86).

Hosting a local web server in a cross-platform app is something reasonable (though perhaps not super common), so it's worth considering.

For right now I'm not aware of any plan to support this.

[Eilon]

Tagging @danroth27 because I think you mentioned something about this the other day.

[JustArchi]

Thanks for your answer @Eilon, I appreciate it.

Hosting a local web server in a cross-platform app is something reasonable (though perhaps not super common), so it's worth considering.

Yeah I definitely don't see everybody jumping on this idea right away and bundling every Android/iOS/etc app with a local web server, but I also came to conclusion that it's something reasonable enough to at least suggest/evaluate on. I have no idea how much work would be required to bring ASP.NET Core runtime to those new .NET 6.0 platforms, but if it helps in any way then I'd be definitely interested in making use of such functionality, at least for that one use case I have in mind.

It could also be a decent alternative if somebody wanted to build an app that looks more like a typical website to you. To give you some idea, I have a CLI app realizing its functionality with bundled Kestrel web server and MVC APIs, which is not really any different from a typical ASP.NET Core website, but it's more of the CLI app and APIs are just an extra. Anyway, I bundle that app with frontend written in html/css/js (static files that Kestrel serves), which results in user navigating to his localhost app address, where he can control the app through a website interface (that calls appropriate API endpoints).

As an experiment I tried to convert this "idea" into Android app, where the app could create a very simple Webview with that localhost address (where the frontend is already mobile-aware), while launching the backend part the same as on all other OSes I build this for. This in result failed as of today, since there is no ASP.NET Core runtime for Android (which is just an example platform I tried to test it on).

I'm describing that just to give you some insight into what this whole "feature request" could be useful for, while MAUI is great on its own and building new apps is definitely going to be interesting, there might be more of such CLI apps with some kind of web interface that could easily be converted into Android apps without much hassle if just the ASP.NET Core runtime was available to make use of. It's not like my app requires something more than a web server with static files and MVC APIs anyway.

In any case thank you in advance for evaluation of this idea, perhaps it could be something to think of for the future.

[mkArtakMSFT]

@davidfowl feel free to update the label. This seems to be the closest match.

[juwens]

@JustArchi to second your "reasonable scenario" statement.

We are actually started using local GRPC (client and server) in our current Xamarin app as an IPC technology to communicate between two apps.

We have some LOB-concerns which forces us to do a lot (and kinda complex) local IPC between our app and a third party app.

And to use one identical API technology on all Platforms targets (Android, iOS and Windows) we've chosen grpc.

[eestein]

I've got the "same" problem.
I'm trying to add DI to my maui app using the idea James wrote here https://montemagno.com/add-asp-net-cores-dependency-injection-into-xamarin-apps-with-hostbuilder/
And then I get the error:

NETSDK1082 There was no runtime pack for Microsoft.AspNetCore.App available for the specified RuntimeIdentifier 'iossimulator-x64'.
Sample.Mobile.Maui
C:\Program Files\dotnet\sdk\6.0.100-rc.2.21505.57\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.FrameworkReferenceResolution.targets 427

The same goes for maccatalyst-x64, android-x86 and linux-arm.

I created a mauilib with the default structure:

<Project Sdk="Microsoft.NET.Sdk">

	<PropertyGroup>
		<TargetFrameworks>net6.0-ios;net6.0-android;net6.0-maccatalyst</TargetFrameworks>
		<!-- <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows')) and '$(MSBuildRuntimeType)' == 'Full'">$(TargetFrameworks);net6.0-windows10.0.19041</TargetFrameworks> -->
		<TargetPlatformMinVersion Condition="$(TargetFramework.Contains('-windows'))">10.0.17763.0</TargetPlatformMinVersion>
		<UseMaui>true</UseMaui>
		<SingleProject>true</SingleProject>

		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-ios'">14.2</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-maccatalyst'">14.0</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-android'">21.0</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="$(TargetFramework.Contains('-windows'))">10.0.18362.0</SupportedOSPlatformVersion>
	</PropertyGroup>

	<ItemGroup>
	  <Folder Include="Platforms\iOS\" />
	  <Folder Include="Platforms\Windows\" />
	  <Folder Include="Resources\Fonts\" />
	  <Folder Include="Resources\Images\" />
	</ItemGroup>

</Project>

I tried recreating the projects twice from the command line, but it still won't work. dotnet new maui and dotnet new mauilib.

Is there a workaround for this? I'd very much like to be able to use DI, but I'm blocked as is.

Checking up the nuget repository, I found the references, but for .Mono. Is there something I'm doing incorrectly?

[danroth27]

@eestein .NET MAUI already has support for dependency injection built-in. MauiAppBuilder exposes a Services property that you can use to configure your services. You shouldn't need to add any additional dependencies.

[eestein]

@danroth27 thanks, I appreciate you taking the time to evaluate my question.
The thing is, I'm not adding anything extra.

This is the info for my maui lib.

These are my usings:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Maui.Hosting;

These are the only nuget packages I've got installed:

These are the dependencies:

This is my csproj:

<Project Sdk="Microsoft.NET.Sdk">

	<PropertyGroup>
		<TargetFrameworks>net6.0;net6.0-ios;net6.0-android;net6.0-maccatalyst</TargetFrameworks>
		<Nullable>enable</Nullable>
		<UseMaui>true</UseMaui>
		<SingleProject>true</SingleProject>

		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-ios'">14.2</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-maccatalyst'">14.0</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="'$(TargetFramework)' == 'net6.0-android'">21.0</SupportedOSPlatformVersion>
		<SupportedOSPlatformVersion Condition="$(TargetFramework.Contains('-windows'))">10.0.18362.0</SupportedOSPlatformVersion>
	</PropertyGroup>

	<ItemGroup>
		<ProjectReference Include="..\Sample.Data\Sample.Data.csproj" />
	</ItemGroup>

</Project>

And I still get the error:

/usr/local/share/dotnet/sdk/6.0.100-rc.2.21505.57/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(427,5): error NETSDK1082: There was no runtime pack for Microsoft.AspNetCore.App available for the specified RuntimeIdentifier 'iossimulator-x64'. [/Users/eestein/Documents/dev/smp/sample-repo/Sample/Sample.Mobile.Maui/Sample.Mobile.Maui.csproj]

I'm not trying to waste anyone's time here, believe me when I tell you I research a lot before asking. The thing is I'm stuck on this one since yesterday. Before trying many things I found online I recreated the projects twice and they still won't work. I tried recreating from VS2022 and also from the command line on my macOS. I still get the error when I reference my mauilib from the maui app.

[davidfowl]

Why did you include ASP.NET Core if you're only trying to use dependency injection?

[eestein]

@davidfowl I didn't... I just created the maui lib using the provided template. And, I also tried removing that framework, I just couldn't find a way to do so.

I do need to use HttpClient, though