Priorities

Priorities resolve some, but not all, transition conflicts. IBM® Rational® Rhapsody® uses state hierarchies to define priorities among conflicting transitions. However, lower-level (nested) states can override behaviors, thus implying higher priority.

The priority for a transition is based on its source state. Priorities are assigned to join transitions based on their lower source state.

For example, if transition t1 has a source state of s1 and transition t2 has a source state of s2,:

Rational Rhapsody does not define a priority with regard to events and transitions other than arrival order. If two transitions within the same orthogonal component are both active (ready to fire), as can happen with non-orthogonal guards, only one of them will actually fire, but statecharts do not specify which one it will be.


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