Observable or Invocable Behaviour - You Have to Choose

Several object-oriented modeling approaches propose to describe the dynamic behaviour of objects by state transition diagrams. None of them provide precise rules or conditions for the interrelation between the behaviour description of classes and those of their sub-classes. In this paper, we discuss this interrelation in detail. It turns out that one has to distinguish between the observable and the invoca-ble behaviour of objects and that diierent compatibility requirements between the diagrams exist depending on the type of behaviour.