WinCE 6.0 : Communication between device driver and application

I was doing a stream interface device driver development on Windows CE 6.0 when I came across a requirement that the typical stream interface device driver is unable to provide. What I am missing is a way for the device driver to notify the application of events within the device driver. After some searching in the internet and MSDN, I came across an API, DuplicateHandle, which is able to help me achieve what I needed.

Application
-----------
1. Create an event in the application.

HANDLE g_hALPS_Event;
g_hALPS_Event = CreateEvent(NULL, FALSE, FALSE, NULL);

2. Send the event handle down to the driver using DeviceIoControl call.

DWORD BytesReturned;
DeviceIoControl(g_hBthDll, IOCTL_BTH_REG_ALPS_EVENT, g_hALPS_Event, sizeof(g_hALPS_Event), NULL,
0, &BytesReturned, NULL);

3. Wait for the event object to be signaled.

while(TRUE)
{
WaitForSingleObject(g_hALPS_Event, INFINITE);
}

Device Driver
-------------
1. Declare a device driver side handle.

HANDLE g_hBTH_Event;

2. Define the IOCTL codes.

#define FILE_DEVICE_BTH 12341234
#define REG_ALPS_EVENT 0x000
#define IOCTL_BTH_REG_ALPS_EVENT CTL_CODE(FILE_DEVICE_BTH, REG_ALPS_EVENT, METHOD_BUFFERED,
FILE_ANY_ACCESS)

3. Within the device driver IOControl routine, use DuplicateHandle on the application handle that was passed down.

HANDLE hCallerProc = 0;
HANDLE hCurrentProc = 0;
hCallerProc = GetCallerProcess();
hCurrentProc = GetCurrentProcess();

switch (dwIoControlCode)
{
case IOCTL_BTH_REG_ALPS_EVENT:
g_hBTH_Event = (HANDLE)pBufIn;
DuplicateHandle(hCallerProc, (HANDLE)pBufIn, hCurrentProc, &g_hBTH_Event,
0, FALSE, DUPLICATE_SAME_ACCESS);
break;
}

4. Whenever the driver needs to notify the application, we would use the SetEvent API.

SetEvent(g_hBTH_Event);