Redis, pub/sub, rails 3, phusion passenger

I have another application publishing messages to redis server. Within
my
rails application, when a user clicks a button, I want a popup to
display
that shows live updates. I want the controller to publish notifications
to
redis, and I want my javascript to subscribe to those events and respond
when it finds a suitable channel. What I do not know how to do is
actually
keep a control open like that: to continuously publish messages when it
finds them on redis. Is this possible to do in rails 3/phusion
passenger?