UML23 — Section: 14.3.13 Interaction (from BasicInteraction, Fragments)

Text from the specs states: "Description An interaction is a unit of behavior that focuses on the observable exchange of information between ConnectableElements. ..." "Semantics Interactions are units of behavior of an enclosing Classifier. Interactions focus on the passing of information with Messages between the ConnectableElements of the Classifier." One issue is that in several other places of the specs interactions are described as being "owned" - not "enclosed" - by Classifier, e.g below on p. 492 we read "The classifier owning an Interaction may be specialized, and ..." Another question I have is that semantics of interaction as described now is focusing on passing of information between ConnectableElements of that specific Classifier - but traces of interaction include OccurrenceSpecifications of possibly several participants represented by LifeLines of one to many Classifiers. The case when Classifier interacts only with itself or a single other Classifier should be quite rare. When we have several Classifiers (represented by LifeLines) interacting, that interaction should include ConnectableElements of those several Classifiers involved, unless the "ConnectableElements of the Classifier" are considered to be some transitive closure of all ConnectableElements depicted on the interaction. In other words, I'd clarify both Description and Semantics of Interaction to something like: Interactions are units of behavior of an owning Classifier. Interactions focus on the passing of information with Messages between the ConnectableElements of the owning Classifier and ConnectableElements of other interacting Classifiers. All Classifiers participating in the interaction - including owner Classifier - are represented by LifeLines."

The requested change contradicts the Lifeline Constraint “same_classifier” which states:
“The classifier containing the referened ConnectableElement must be the same classifier, or an ancestor, of the classifier
that contains the intraction enclosing the Lifeline.”
Disposition: Closed - No Change