Oakrey.Applications.UsbNotifying 2.0.6

Oakrey.Applications.UsbNotifying

A Windows-only .NET library that monitors USB device arrival and removal events using the Windows PnP notification API and exposes them as a reactive IObservable<UsbEventArgs> stream.

Features

• Wraps DeviceNotificationListener from Nefarius.Utilities.DeviceManagement � no raw Win32 interop required.
• Exposes USB events as IObservable<UsbEventArgs> via IUsbNotifyingService.
• Backed by a ReplaySubject<UsbEventArgs>(1) � late subscribers receive the most recent event immediately.
• Logs device VID, PID, and serial number on every connect/disconnect via Oakrey.Log.
• Implements IDisposable � properly unregisters listeners and disposes subjects.

Architecture

classDiagram
    IObservable~UsbEventArgs~ <|-- IUsbNotifyingService
    IUsbNotifyingService <|.. UsbNotifyingService
    IDisposable <|.. UsbNotifyingService
    UsbNotifyingService --> DeviceNotificationListener : wraps
    UsbNotifyingService --> ReplaySubject~UsbEventArgs~ : broadcasts via

Public API

// Service interface � subscribe to receive USB events
public interface IUsbNotifyingService : IObservable<UsbEventArgs> { }

// Concrete service � register with DI or instantiate directly
public sealed class UsbNotifyingService : IUsbNotifyingService, IDisposable
{
    public UsbNotifyingService();
    public IDisposable Subscribe(IObserver<UsbEventArgs> observer);
    public void Dispose();
}

UsbEventArgs is provided by Oakrey.Usb and carries:

• DeviceInfo.VID � vendor identifier
• DeviceInfo.PID � product identifier
• DeviceInfo.DeviceId � symbolic link / serial number
• UsbDeviceChangeStatus � INSERTED or REMOVED

Requirements

• .NET 10 (Windows)
• Nefarius.Utilities.DeviceManagement 5.2.x
• Oakrey.Usb 3.0.x
• Oakrey.Log 2.0.x
• System.Reactive 6.1.x

Installation

.NET CLI

dotnet add package Oakrey.Applications.UsbNotifying

Package Manager Console

Install-Package Oakrey.Applications.UsbNotifying

NuGet Package Manager UI

Search for Oakrey.Applications.UsbNotifying in Visual Studio under Tools > NuGet Package Manager > Manage NuGet Packages for Solution.

Usage

Manual instantiation

using Oakrey.Applications.UsbNotifying;

await using UsbNotifyingService service = new();

IDisposable subscription = service.Subscribe(e =>
{
    Console.WriteLine($"{e.UsbDeviceChangeStatus}: VID={e.DeviceInfo.VID} PID={e.DeviceInfo.PID}");
});

// Keep the application alive; dispose subscription when done.
subscription.Dispose();

Dependency injection

services.AddSingleton<IUsbNotifyingService, UsbNotifyingService>();

public sealed class MyHandler
{
    private readonly IDisposable subscription;

    public MyHandler(IUsbNotifyingService usbService)
    {
        subscription = usbService.Subscribe(e =>
        {
            if (e.UsbDeviceChangeStatus == UsbDeviceChangeStatus.INSERTED)
            {
                // handle device arrival
            }
        });
    }
}

Development notes

• The service must run on Windows � DeviceNotificationListener calls Win32 PnP APIs. The target framework net10.0-windows enforces this at build time.
• ReplaySubject(1) means any subscriber that registers after the last event still receives it immediately. Use a fresh Subject<T> instead if that behaviour is undesirable.
• DeviceNotificationListener.StartListen is called for DeviceInterfaceIds.UsbDevice. To monitor a different device class, derive from or wrap UsbNotifyingService and pass a different Guid to StartListen.
• Always dispose the service (or the DI container) before application exit to unregister the PnP listener cleanly.

License

MIT. Copyright (c) Oakrey 2016-present.