UML22 — transtion

Issue 2: In the same spirit, we would like also to specifiy that a transtion is fired

only if an event is not available at a given instant. We need the concepts of instant

and event absence. Note that the absence combined with "and" and "or" can express kinds of

priorities (e.g., "a and not b").

Triggering a transition with the absence of an event seems to make sense only under a synchronous semantics which defines slices of time where that event might occur or not. It require a major modification or enhancement to the current, asynchronous Run-To-Completion semantics, where events are handled one by one in a timeless sequence. This therefore needs to be postponed to a more major revision, when we will have time to investigate this proposal and see if and how it can be accommodated.

Revised Text:
N/A

Disposition: Closed, out of scope