13.3.27 TimeEvent

*Generalizations

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    Event (from Communications ) on page 459

   Description

   A time event specifies a point in time by an expression. The expression might be absolute or might be relative to some other point in time.

   Attributes

Issue 9191 - add default value

   • isRelative: Boolean Specifies whether it is relative or absolute time. Default value is false.

   Associations

   • when: TimeExpression [1] Specifies the corresponding time deadline.

   Constraints

   No additional constraints

   Semantics

   A time event specifies an instant in time by an expression. The expression might be absolute or it might be relative to some other point in time. Relative time events must always be used in the context of a trigger and the starting point is the time at which the trigger becomes active.

   Semantic Variation Points

   There may be a variable delay between the time of reception and the time of dispatching of the TimeEvent (e.g., due to queueing delays).

   Notation

   A relative time trigger is specified with the keyword ‘after’ followed by an expression that evaluates to a time value, such as after (5 seconds). An absolute time trigger is specified with the keyword ‘at’ followed by an expression that evaluates to a time value, such as Jan. 1, 2000, Noon.

   <time-event> ::= <relative-time-event> | <absolute-time-event><relative-time-event> ::= ‘after’ <expression><absolute-time-event> ::= ‘at’ <expression>

   Changes from previous UML

   The attribute isRelative has been added for clarity.