The Unicast mechanism works great to push events to a single
subscriber to a subject. It would be useful for the servlet to cache
a certain number of events that have happened, and when a user
subscribes to that subject, unicast them up to that user. This is
useful when the user resubscribes (resizes window, for example)
and you don't want to lose events.
The cache could be a simple Map of 50 events per subject, say, or
a time expired cache (eg 10 minutes). Maybe set up some kind of
cache policy function or something and allow a system to register
that function on startup? Thinking out loud....
I have an example of a 50 event cache if you would like it.