Runic.Platform.Runtime 0.9.1

Runic.Platform.Runtime

Single instance, requests to open files and URLs, and file transfers for Runic applications, and the contract for native platform providers.

Preview API targeting .NET 10. Native providers are explicitly selected; this package has no Desktop or ASP.NET Core dependency.

The package has two audiences:

• Applications use the single instance (ApplicationInstance.ClaimAsync, ApplicationInstanceOptions), the requests to open files and URLs (ApplicationInstance.CreateOpenRequests) and the managed file transfers (LocalFileTransfers.Create()). They need no window and no Desktop host.
• Hosts and native providers implement the provider contract.

The presentation lifetime, the argument checks the providers share and the settings base class are internal to Runic's own providers and hosts.

Provider contract

A host gives each window an INativeWindowOwner: the window's generation, whether it is still available, and InvokeAsync(Action<nint>), which runs a callback on the window's native thread with its handle (an HWND, an NSWindow* or a GtkWindow*). The handle must not escape the callback. Once the window has closed, InvokeAsync throws OwnerClosedException.

A file-dialog provider is an IPickerBackend. NativePickerBackend turns an INativeFilePicker into one: it passes each dialog's filters, initial folder and multiplicity as a NativeFileDialogRequest to INativeFilePicker.SelectAsync(request, cancellationToken), and the initial folder of a directory dialog to INativeDirectoryPicker.SelectDirectoryAsync(initialDirectory, cancellationToken). A picker that cannot show a dialog throws NativeBackendUnavailableException, which the backend reports as Unavailable(BackendUnavailable). A picker that returns more than one selection also returns true from SupportsMultipleSelection; otherwise OpenFilesAsync reports Unavailable(BackendUnavailable) without showing a dialog. The backend releases the access of every selection it does not hand to a lease, including after a failure or cancellation, and reports the native error of a failed selection or commit in the Diagnostic of the result.

Single instance and replies to later launches

ApplicationInstance.ClaimAsync makes the first launch of an application the running instance and forwards later launches to it over a Unix domain socket in a directory only the user can use (on Linux, macOS and Windows). By default a later launch hands over its arguments and exits, and the running instance raises IApplicationInstance.Launched.

With ApplicationInstanceOptions.ReplyToLaunches, a later launch, such as a command line, also waits for the running instance's reply: messages (output lines or JSON events, as UTF-8 strings of at most 1 MiB) and an exit status. Set it in every process of the application, so whichever process is the running instance answers.

var options = new ApplicationInstanceOptions { ReplyToLaunches = true };
var claim = await ApplicationInstance.ClaimAsync("org.example.Manager", ApplicationLaunch.FromProcess(args), options);

// A later launch: print the running instance's messages and exit with its status.
if (claim is PlatformResult<ApplicationInstanceClaim>.Success { Value: ApplicationInstanceClaim.Forwarded { Reply: { } reply } })
{
    await using (reply)
    {
        // Ctrl+C asks the running instance to cancel; its last messages and exit status still arrive.
        Console.CancelKeyPress += (_, e) => { e.Cancel = true; _ = reply.CancelAsync(); };
        await foreach (var line in reply.ReadMessagesAsync()) Console.WriteLine(line);
        return await reply.WaitForExitAsync() is PlatformResult<int>.Success(var code) ? code : 1;
    }
}

// The running instance: launches that wait carry a reply; complete each one.
instance.Launched += (_, launch) => _ = Task.Run(async () =>
{
    if (launch.Reply is not { } reply) { /* Only handed over: raise the window. */ return; }
    await reply.WriteAsync("working");
    await reply.CompleteAsync(reply.Cancelled.IsCancellationRequested ? 130 : 0);
});

• IApplicationLaunchReply.Cancelled is cancelled when the launching process asks to cancel, disconnects (disposing its reply, or cancelling a read), or when the running instance ends. CancelRequested is cancelled only for the request (IForwardedLaunchReply.CancelAsync, such as on Ctrl+C), and Disconnected only when the reply ends without an exit status; each is cancelled before Cancelled. Pass CancelRequested to work that should outlive the launching process, such as an operation started over an SSH session that drops. Writes after the launching process went away return false.

• A write waits while the launching process does not read, so large output is not buffered in memory. Pass a token to WriteAsync to bound the wait; a write cancelled that way ends the reply.

• When the running instance ends or crashes before the exit status, the messages end and WaitForExitAsync reports Failed(IOError).

• With ApplicationInstanceOptions.ForwardOnly, the process never becomes the running instance: a command line that talks to a running daemon gets ApplicationInstanceClaim.Forwarded, or ApplicationInstanceClaim.NotRunning when no instance runs, and then does the work itself or reports it. It does not listen meanwhile, so a daemon that starts at the same moment does not wait for it. An instance that is starting is waited for, as with a claim.

  var options = new ApplicationInstanceOptions { ReplyToLaunches = true, ForwardOnly = true };
  switch (await ApplicationInstance.ClaimAsync("org.example.Manager", ApplicationLaunch.FromProcess(args), options))
  {
      case PlatformResult<ApplicationInstanceClaim>.Success { Value: ApplicationInstanceClaim.Forwarded { Reply: { } reply } }:
          /* Read the reply as above. */ break;
      case PlatformResult<ApplicationInstanceClaim>.Success { Value: ApplicationInstanceClaim.NotRunning }:
          /* No daemon: run here. */ break;
  }
  

• An instance claimed without ReplyToLaunches, or by an SDK before 0.8.0-preview.3, refuses launches that wait: the claim fails with ResourceBusy and an ApplicationInstance diagnostic, and the launch is not handled. Launches without ReplyToLaunches keep the one-way protocol and reach any instance.

Opening files and URLs

ApplicationInstance.CreateOpenRequests(options, instance, launch) turns this launch (by default none) and each later launch of instance into IDesktopOpenRequests.Opened requests: the arguments that are URLs with a registered scheme and, with IncludeFiles, existing files. Linux desktop entries (Exec=app %U) and Windows registrations ("app.exe" "%1") pass them that way. The instance's own Launched handlers still receive every launch. See the opening files and URLs design.

File transfers

LocalFileTransfers.Create() is the IDesktopFileTransfers engine every platform uses, and what AddRunicPlatformServices() registers on Runic Desktop. It copies in 1 MiB blocks under hidden temporary names, renames into place with an exclusive rename, and moves by renaming within a file system. A CS-WebUI application can register it itself. See Copy and move and the file transfer design.