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  1. OMG Issue

UMLR — Contradiction between the abstract syntax and semantics of an Interval

  • Key: UMLR-449
  • Legacy Issue Number: 18683
  • Status: open  
  • Source: NASA ( Nicolas Rouquette)
  • Summary:

    In UML 2.5 Beta1, section 8.5.3, the semantics of an Interval specifies that:

    An Interval is evaluated by first evaluating each of its constituent ValueSpecifications, which must each evaluate to a single value.
    The value of the Interval is then the range from the min value to the max value—that is, the set of all values greater than or equal to the min value and less than or equal to the max value (which may be the empty set).

    The semantics suggests that an Interval would own its constituent min/max ValueSpecifications; however, the abstract syntax shown in Fig 8.4 shows otherwise: min/max do not have composite aggregation.
    This means that:
    An Interval does not own its constituent min/max ValueSpecifications
    The same ValueSpecification can be used as the min or max of more than one Interval (I.e., multiple Interval can share the same min/max ValueSpecification)
    Intervals are the only ValueSpecifications that do not compositionally own their constituent parts:
    LiteralSpecifications compositionally own their values
    Expressions compositionally own their operands and sub-expressions
    Durations and TimeExpressions own their expressions.
    Some ValueSpecifications have non-compositional properties but these do not have the semantics of "constituent parts" like min/max do for Interval:
    TimeObservations and DurationObservations refer to events non-compositionally
    TImeExpressions and Durations refer to optional observations
    OpaqueExpressions optionally refer to behavior and behavior result parameters non-compositionally.
    Suggest changing all min/max association end properties defined in Interval, TimeInterval and DurationInterval to have composite aggregation.

  • Reported: UML 2.5b1 — Sat, 20 Apr 2013 04:00 GMT
  • Updated: Mon, 25 Jan 2016 20:10 GMT
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