UML22 — simple time model" in CommonBehavior

For the "simple time model" in CommonBehavior, it is unclear when the DurationObservationAction and TimeObservationAction would be executed. For one, it is not stated when these actions are executed. I assume that when the execution of the model reaches the point of the attached model elements, then these actions are executed. Several problems: It is unclear what determines when these actions are executed. If the actions are embedded in a sequence of actions, where control flow indicates when they execute, what is the meaning of the association to a named element? If that named element is reached later in the execution, does the execution wait? If it is reached earlier, does that element have to wait until the action sequence is enabled? (ii) There should be some constraint on the "NamedElements" associated with TimeExpression that limits those to elements that can be enountered during execution, as these elements appear to determine when these actions are evaluated. There is a tension between these actions being embedded in a sequence of actions where their execution is determined by the control and data flow, and the associated "NamedElements" that would determine the observation of time also. Normally, actions are used within a sequence of actions (an activity). These two actions are different in that they seem to make no sense within an activity due to that they have very special invocation points. They seem to only make sense as stand-alone elements. Maybe it should not be an action, but some other model element, that should dictate how time and duration are observed.

Discussion: Fixed as part of the resolution to issue 8894 in UML 2.1 Revised Text: N/A Disposition: Closed, no change