I would suggest Observer pattern.
Basically there is an Observable
objects which maintains a set of Observers
which are registered to that object to listen on some action. When Observable
object make such an action, Observers
are notified that an action was made and can react on it.
So in your case the Trigger
would be an Observable
object and Target
objects would be Observers
. Target
objects can be registered on Trigger
object and can react (make feedback) on Trigger
action.