Track progress of running process by use of Observer pattern

Hi all,

I know this question has been asked before but this was a long time ago (2008) and the solution back then was to make use of some sort of logging mechanism which I don't completely understand.

I'm rather looking for a listener mechanism to track operator progress. I like to display a progress bar in my web application that approximately indicate total running time. I tried to add an observer to an Operator using the following

public void addObserver(Observer<A> observer, boolean onEDT)

method.  Unfortunately, I don't get back any updates.

Any other ideas?

Wouter