[chord] routing-level information change notification

[Byung-Gon Chun]

Hi,

I'm wondering whether chord has an interface to notify some 
routing-level information (successor or routing table changed) to 
applications (e.g. dhash) using chord.
For example, in Bamboo, an application using bamboo router can register 
for events in which it's interested (e.g., BambooLeafSetChanged or 
BambooRoutingTableChanged) to get notifications.
I'm looking for something similar in chord.
If there isn't, what's a quick way to add interface?

Thanks,
Gon