Previous UML Classes Table of Contents UML Packages Next

14.3.10 ExecutionSpecification




    InteractionFragment (from BasicInteractions , Fragments ) on page 505


   An ExecutionSpecification is a specification of the execution of a unit of behavior or action within the Lifeline . The duration of an ExecutionSpecification is represented by two ExecutionOccurrenceSpecification s, the start ExecutionOccurrenceSpecification and the finish ExecutionOccurrenceSpecification .



   [1] The startEvent and the finishEvent must be on the same Lifeline .

   start.lifeline = finish.lifeline


   The trace semantics of Interactions merely see an Execution as the trace <start, finish>. There may be occurrences between these. Typically the start occurrence and the finish occurrence will represent OccurrenceSpecifications such as a receive OccurrenceSpecification (of a Message) and the send OccurrenceSpecification (of a reply Message).


   ExecutionOccurences are represented as thin rectangles (grey or white) on the lifeline (see Lifeline (from BasicInteractions , Fragments ) on page 511).

   We may also represent an ExecutionSpecification by a wider labeled rectangle, where the label usually identifies the action that was executed. An example of this can be seen in Figure 14.13 on page 495.

Issue 8329 - reword paragraph

   For ExecutionSpecifications that refer to atomic actions such as reading attributes of a Signal (conveyed by the Message), the Action symbol may be associated with the reception OccurrenceSpecification with a line in order to emphasize that the whole Action is associated with only one OccurrenceSpecification (and start and finish associations refer to the very same OccurrenceSpecification).

   Overlapping execution occurrences on the same lifeline are represented by overlapping rectangles as shown in Figure

    14.15 .

Figure 14.15 - Overlapping execution occurrences