Observer pattern in J2EE

I have a question about the Observer patterne.

I have tried to implement it im my application but without result. First my idea was to save all the client Object references in A linked List in a bean on the server. Then each time a certain event ocurs on my server I will call a method fire() which iterate through my linked list and finds all my client references. Then I will make a "call back" to all the clients which are in my linked list. But my teacher tells my that is not the way to do. He belives that there is a much easier way to make sure that all the clients get updates. But he does't know how to do it. So my question is how do I implements Observer Design patterns in the J2ee enviroment ?

[735 byte] By [Thomaz] at [2007-9-26 10:13:47]