Thinking about it, you are right. What I was trying to get to is that the BO has to have a mecanism for the UI to know how much work is done. The method I described work for me, but I agree that it is not the best design and the one I would have if I had a multithreaded langage.

Another method would be to have a set of properties and/or methods the UI could query to get the state of the current work. The BO could be started with an internal timer like the method I described before, but instead of having the BO call a callback method in the UI, the UI can have it's own timer to query the state of the BO. It will require more work to implement correcly however.

>PMFJI. It is the responsibility of the UI to ask the BO.