Invalidating weak injected objects

[Doug Warren]

Is it possible for an object to be injected with a weak reference that later through some business logic the reference releases itself and nils all injected instances?  If so is there a way to notify the objects that were injected?  And finally is there a way to rewire up the object if a new instance becomes valid?  An example use case could be a networking object.  As long as the network is connected the object is valid and able to take messages.  When the network disconnects the object is invalid, if later the network reconnects a new object describing the new connection is now valid.