R54 - modelint/shlaer-mellor-metamodel GitHub Wiki
R54 / 1:1
Ingress Operation executes one or many Ingress Activity
Ingress Activity is defined on exactly one Ingress Operation
When an Ingress Operation is invoked, it must cause some effect in the local Domain. It can only do that by executing an Activity.
Not all externally triggered internal effects are necessarily mediated by an Ingress Operation. Implicit bridging could result in a direct internal effect, such as a class method invocation or a create action. But, when an Ingress Operation is involved, it must do something.
Formalization
Ingress Operation.(Activity, Domain) -> Ingress Activity.(ID, Domain)