Event Response - modelint/shlaer-mellor-metamodel GitHub Wiki

Each State must provide a response for each Signaling Event defined on a State Model. This correspondence is commonly represented with a state table like the following:

images/state-subsystem/event-response-10.png

An event response must be defined for each cell Event-State intersection in the state table. [LSSYNC] Three standard miUML responses are possible: Transition, Ignore and Can’t Happen. The second two options are grouped together as Non-Transition Responses since they don’t require any special data or relationships.

Note that it is possible to define a Signaling Event which is not associated with any Transition. It may, for example, be ignored in all States. There would be no utility to such a non-transitioning Event in a delivered software product. But during the model editing and diagnostic phases, it might be useful to ‘disable’ an Event by setting all responses to Ignore. Alternatively, an Event marked Can’t happen in all States could be specified for the diagnostic purpose of making it possible to easily crash a State Model. Neither use is necessarily recommended, but it is worthwhile to point out the possibility.