UMLR — 17 Semantics of interactions

17 Semantics of interactions (missing constraints for resolving Operations, Signals and Actions in MessageOccurrenceSpecifications & ExecutionOccurrenceSpecifications in the scope of the Interaction itself)
Consider Figure 17.2 (in the UML2.5 Revised August draft):

Clearly we expect that:

"oper1()" is a Message whose Message::signature refers to A::oper1()

"callback()" is a Message whose Message::signature refers to C::callback()

However, there is nothing in the spec that constrains the ownership of a Message::signature : NamedElement relative to the Interaction context of that Message.

In fact, other possible interpretations because UML does not prescribe a particular resolution process for determining the Behavior for a given BehavioralFeature or Reception (see section 13.2.3)

The spec does not currently specify any kind of bound on this resolution process — that is, Behaviors could be found potentially anywhere in the model.

This is obviously absurd: it is unreasonable to expect that Figure 17.2 corresponds to a model where neither A nor C define "oper1()" or "callback()" but rather that these 2 operations are defined in an completely unrelated class not involved in the interaction at all – e.g., B.