This allows you to add a listener on two sets of MBeans (with two addNotificationListenerExtended calls) and remove it from only one set.

Publication points are used not only for applications to add and remove messages on topics, but also to propagate messages from one messaging engine to the others in the bus.

In order to make it concurrent, I tried to remove join from each thread, but then it doesn't download chunks in order and also download only from one server, not from both.