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  1. OMG Issue

FUML_ — UML input pins do not accept more tokens than their actions can immediately consume

  • Key: FUML_-2
  • Legacy Issue Number: 14992
  • Status: closed  
  • Source: NIST ( Mr. Conrad Bock)
  • Summary:

    UML input pins do not accept more tokens than their actions can
    immediately consume. The execution engine should reflect this.

    The Activities, Action, Semantics, item 1, says "The object flow
    prerequisite is satisfied when all of the input pins are offered all
    necessary tokens and accept them all at once, precluding them from being
    consumed by any other actions. This ensures that multiple action
    executions competing for tokens do not accept only some of the tokens
    they need to begin, causing deadlock as each execution waits for tokens
    that are already taken by others."

    The "necessary tokens" in the first sentence above are the ones needed
    to execute the actions (meeting the minimum multiplicity), but should
    include any additional ones offered up the maximum multiplicity. Only
    these are accepted by the input pins, then immediately consumed by the
    action. The second sentence gives the motivation, which is to avoid
    having tokens in input pins that are not immediately consumed. This
    would prevent those tokens from being used to execute other actions,
    potentially creating deadlock or starvation. Deadlock is discussed more
    in issue 7221 of the UML 2.0 FTF report

    This is also clarified in the revised text for UML RTF issue 13914.

  • Reported: FUML 1.0b2 — Sun, 10 Jan 2010 05:00 GMT
  • Disposition: Resolved — FUML 1.0
  • Disposition Summary:

    The resolution to Issue 14550, in response to UML Issue 13914, changes the fUML semantics so that the fUML semantics reflect the constraint discussed in the issue.
    Revised Text:
    Disposition: Duplicate/Merged

  • Updated: Sat, 7 Mar 2015 08:56 GMT