How can one controller refresh the view of another controller?

Hello,

I am writing a reporting app, where every report has 2 common
parameters, the starting date and ending date. So I have put them in a
session variable, with the intension that it can be changed separately
from report's other parameters and the reports will get refreshed with
new dates.

I am bit confused about the implementation part. My requirement is
that this should be part of every report page and after clicking the
update button, the corresponding report should be automatically
refreshed.

I can put the date updation form in all views [that's to start, but I
guess there are better ways] to solve the first problem, but I am
stuck at the second problem. The date updation form calls a method in
the same controller and it should refresh what ever view that was
displayed in the screen. This is where I am stuck.

So basically it boils down to, how can one controller refresh the view
of another controller?

raj