Oakrey.Applications.UsbNotifying 7.0.0

Oakrey.Applications.UsbNotifying

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

Features

• Wraps DeviceNotificationListener from Nefarius.Utilities.DeviceManagement.
• Exposes USB events through IUsbNotifyingService.
• Uses a synchronized ReplaySubject<UsbEventArgs>(1); late subscribers receive the latest event and concurrent callbacks are serialized.
• Logs device status, VID, and PID with placeholder-based Oakrey.Log messages without exposing a unique serial number.
• Contains callback exceptions so they cannot escape into the native listener.
• Provides idempotent IDisposable cleanup and completes observers during shutdown.

Architecture

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

Public API

public interface IUsbNotifyingService : IObservable<UsbEventArgs> { }

public sealed class UsbNotifyingService : IUsbNotifyingService, IDisposable
{
    public UsbNotifyingService();
    public IDisposable Subscribe(IObserver<UsbEventArgs> observer);
    public void Dispose();
}

UsbEventArgs is provided by Oakrey.Usb and contains:

• DeviceInfo.VID: vendor identifier
• DeviceInfo.PID: product identifier
• DeviceInfo.DeviceId: symbolic link or serial number
• UsbDeviceChangeStatus: Inserted or Removed

Requirements

• .NET 10 for Windows
• Nefarius.Utilities.DeviceManagement 5.2.x
• Oakrey.Log.Abstractions 3.0.x
• Oakrey.Usb 3.2.x
• System.Reactive 6.1.x

Installation

dotnet add package Oakrey.Applications.UsbNotifying

Install-Package Oakrey.Applications.UsbNotifying

Usage

Manual instantiation

using Oakrey.Applications.UsbNotifying;

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

// Keep the application alive while notifications are required.

Dependency injection

services.AddSingleton<IUsbNotifyingService, UsbNotifyingService>();

public sealed class MyHandler : IDisposable
{
    private readonly IDisposable subscription;

    public MyHandler(IUsbNotifyingService usbService)
    {
        subscription = usbService.Subscribe(usbEvent =>
        {
            if (usbEvent.UsbDeviceChangeStatus == UsbDeviceChangeStatus.Inserted)
            {
                // Handle device arrival.
            }
        });
    }

    public void Dispose()
    {
        subscription.Dispose();
    }
}

Development notes

• The service must run on Windows because DeviceNotificationListener uses Windows PnP APIs.
• ReplaySubject(1) replays the most recent event to a new subscriber.
• Subject access is synchronized to protect state when PnP callbacks arrive concurrently.
• Parsing and observer failures are logged and contained at the listener callback boundary.
• Always dispose the service, or its DI container, before application exit.

License

MIT. Copyright (c) Oakrey 2016-present.