How to author an out-of-process WinRT exe server with CsWinRT?

[hez2010]

I found this sample: https://github.com/microsoft/DesktopBridgeToUWP-Samples/tree/master/Samples/WinformsOutOfProcessWinRTComponent

I'm trying to replace the C++ WinRT server with C# using CsWinRT:

WinUIApp1.Server:

using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Storage;
using Windows.Storage.Streams;

namespace WinUIApp1.Server;

class Program
{
    static async Task Main()
    {
        while (true)
        {
            await Task.Delay(1000);
        }
    }
}

public sealed class TestClass
{
    public IAsyncOperation<IInputStream> GetFileStreamAsync(string fileName)
    {
        Console.WriteLine("Received IPC Call");
        return AsyncInfo.Run(async _ =>
        {
            var file = await StorageFile.GetFileFromPathAsync(fileName);
            return await file.OpenSequentialReadAsync();
        });
    }
}

and the csproj is:

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0-windows10.0.19041.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <CsWinRTComponent>true</CsWinRTComponent>
    <Platforms>x86;x64;arm64</Platforms>
    <UseWindowsForms>true</UseWindowsForms>
    <SelfContained>true</SelfContained>
    <RuntimeIdentifier>win10-x64</RuntimeIdentifier>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.CsWinRT" Version="1.4.1" />
  </ItemGroup>

</Project>

Then in my client app I referenced the generated WinUIApp.Server.winmd and wrote below code:

var server = new TestClass();

And finally I created a package and registered the WinUIApp.Server.TestClass as out-of-process activatiableClass:

    <Extension Category="windows.activatableClass.outOfProcessServer">
      <OutOfProcessServer ServerName="WinUIApp1.Server" uap5:IdentityType="activateAsPackage" uap5:RunFullTrust="true">
        <Path>WinUIApp1.Server\WinUIApp1.Server.exe</Path>
        <Instancing>singleInstance</Instancing>
        <ActivatableClass ActivatableClassId="WinUIApp1.Server.TestClass"></ActivatableClass>
      </OutOfProcessServer>
    </Extension>

But it doesn't work. While calling the new TestClass(), I can see the server exe being launched successfully, but then the client stuck forever.

A minimal repro:
WinUIApp1.zip

[angelazhangmsft]

@hez2010, we currently don't have a sample for OOP WinRT, but there is a sample on OOP COM: https://github.com/dotnet/samples/tree/main/core/extensions/OutOfProcCOM

For WinRT, you would use the same model as the OutofProcCOM sample but replace CoRegisterClassObject with RoRegisterActivationFactories, and use RoRevokeActivationFactories on shutdown to unregister the activation factories.

[hez2010]

Thank you. I will have a try.

[hez2010]

Is there any sample about usage to RoRegisterActivationFactories in C#?

[angelazhangmsft]

@hez2010 we don't have a sample today, but I've opened #1177 and it's on our backlog to look at.

[hez]

👋 Dunno anything about this, sorry! Let me know if you want some consultation.

[cay7man]

is there any update? Any sample available now?

[hez2010]

I made a sample for this: https://github.com/hez2010/WinRTServer

Note here we need two workarounds:

1. The winmd needs to be removed from _AppxWinmdFilesToHarvest, see the target RemoveOutOfProcWinMD in the wapproj. Otherwise an incorrect inProcessServer entry will be added to the manifest despite there's no inProcessServer at all, which will make the build fail.
2. The server project also needs to include the winmd in the ItemGroup, otherwise the server implementation (WinRTServer.dll) will be removed from the package layout if you publish it to appx package, which can lead to failure while starting the server.

[wherewhere]

Dose it supports UWP?

[hez2010]

Yes.

[wherewhere]

Wow!

[wherewhere]

Dev Home is using oop to create extension by cs/winrt, and winget oop is written in cpp/winrt. I make a Loopback Exemption Manager in UWP by oop. But I don't know how to use wrl to manage server. So I use the destructor to watching disposing...