A sender sends notifications to the server, and multiple senders can exist and be active. A notifier receives notifications from the server and shows them to the user. A server forwards notifications from senders to the current notifier.
A single notifier is active at any given time. Notifier sends an ID on the server's yield socket to be active.
Example:
notifier --servernotifier --notifier kekettenotifier --sender
Notifier kekette receives the notifications.
now add a new notifier:
notifier --notifier p3n1s
p3n1s receives the notifications and kekette does not.