The IUIBus is responsible for brokerage between applications that
need to reach human users (in order to present information to them and / or
ask them for intervention) and the so-called UIHandlers that can
handle the interaction with human users through UI channels under their
A profile of the UIHandler that describes its capabilites so that
they can be matched with UIRequest ( more specifically User
preferences and abilities added by the IDialogManager) and possibly
some additional parameters.