Any DCE device can be made to trigger an event.
So, take for example:
Creating a Security sensor called an audio sensor, in the same category as Generic Sensor. This would, as per the device template emit a Sensor Tripped event.
You would use DCEGen to generate a C++ project skeleton for it...
This code would spawn an audio catching thread, listening for audio over a certain threshold (I won't get into the specifics of that.. it's a well known problem and is easy to put together a solution.) ... and upon a threshold met (set by device data for example!), it would emit an EVENT_Sensor_Tripped(1)
Which you would _THEN_ be able to catch in the web admin.
It's really not hard, for those with a little bit of drive to dig in a bit. I wish you guys would STOP trying to duct tape things around and actually learn the system a bit.