Receiving Device Events in a Service

The system broadcasts device change events to all services. These events can be received by a service in a window procedure or in its service control handler. To specify which events your service should receive, use the RegisterDeviceNotification function.

When a service calls RegisterDeviceNotification, the service also specifies either a window handle or a service status handle. If a service specifies a window handle, the window procedure receives the notification events. If a service specifies its service status handle, its service control handler receives the notification events. For more information, see HandlerEx.

Device notification handles returned by RegisterDeviceNotification must be closed by calling the UnregisterDeviceNotification function when they are no longer needed.