The software use a MVP architecture associated with an EventBus.
Model-view-presenter (MVP) is a user interface design pattern engineered to facilitate
automated unit testing and improve the separation of concerns in presentation logic.
The EventBus help handling changes in the UI.
First, presenters have to subscribe the a specified type of event (for example
"New Topic", "Updated Queue" or Deleted Message).
When retrieved on the client-side cache, data are processed and event are created
on the EventBus according to the type of data (New, Updated or Deleted data).
The EventBus then automatically informs presenters which have subscribed to the specified
type of event that the data have changed.
The presenter then handle change update data on the UI (View).
Using this pattern help updating multiple presenter with on single event without
caring of how many presenters have to be updated. Once the event have been created on the
EventBus the subscription system send update information to all presenter that need this update.
See GWT HandlerManager for more details.