drums module

Hello

I'm interested on developing a drums module (I mean something like
http://www.harmony-central.com/Synth/Data/Roland/M-BD1-rev.html ) and
I'd like to know if someone can point me in the right direction.
I'm not sure of the theory behind it. At a first view, it seens simple:
You record sounds of real drums in a memory and, when the eletronic
drum is hitted, it sends a signal to the drums module telling the power
and it will determine the volume and for how long the sound will play
(it may accept a "stop" or "gradatively stop [how long]" signal too).

I heard there's already a DSP specially done thinking about reproducing
sounds for this kind of thing.

Any suggetion or direction will be appreciated.

Thanks

anyone?