Would it be fair to say that the transition condition is always
evaluated by the enclosing construct?
In other words, if activity X is a source activity and has a transition
condition, and is encapsulated by activity Y, then activity Y is in fact
responsible to evaluate the transation condition using the variables
accessible in its scope and throw a fault if the transition condition
fails? An enclosing construct may also refuse to evaluate any transition
conditions (e.g. a while activity or an event handler).
Another point that I don't think was answered so far is what happens
when there are two transition conditions and a fault occurs when
evaluating one of them? Are both of them set to false, or only the one
that generated a fault? I believe for consistency both of the links
should have their status set to false.
arkin
Satish Thatte wrote:
> You are right, my sentence is misleading. The link status is false
> because of the fault not because the transition condition is not yet
> evaluated. Thanks for the correction. Incidentally, the link status
> matters only if the link target is outside the scope that faulted.
>
>
>
> ------------------------------------------------------------------------
>
> *From:* Ron Ten-Hove [mailto:]
> *Sent:* Friday, October 17, 2003 1:22 PM
> *To:* Satish Thatte
> *Cc:*
> *Subject:* Re: [wsbpel] Issue 27 - Proposal to vote - Setting link
> status in case of transitioncondition
>
>
>
> Satish Thatte wrote:
>
> The link status issue is really more general than this as Goran
> pointed out during the call. A scope can always fault in an unrelated
> place while one or more transition conditions within it are being
> evaluated, in this case, transition conditions on other links sourced
> at the same source scope. It is impossible to specify the exact
> behavior in such races in the presence of true (multi-processor)
> concurrency. If the evaluation of the conditions is not complete
> (i.e., the link has not actually set its status) then the link status
> is False. In the case of the fault occurring in the evaluation of the
> transition condition itself the evaluation of the condition is not
> complete and therefore the link status is False.
>
> My understanding is that links are tri-state: empty, true, or false.
> Until the transition condition is evaluated, the link remains marked
> as empty, not false as you suggested. Faulting the scope should case
> the link given in this case to marked as false, as part of dead-path
> elimination.
>
> -Ron
>
>
>
>
>
> ------------------------------------------------------------------------
>
> *From:* Prasad Yendluri [mailto:]
> *Sent:* Thursday, October 16, 2003 3:48 PM
> *To:* Ashwini Surpur; Assaf Arkin
> *Cc:* <mailto:>
> *Subject:* Re: [wsbpel] Issue 27 - Proposal to vote - Setting link
> status in case of transitioncondition
>
>
>
> True. This aspect was clarified in the discussions related to this
> issue but did not make into the
> proposed resolution (we voted on!).
>
> I also see the need to address what the status of the link ends up
> being in this scenario. The
> obvious answer seems to that "a transition condition evaluation error
> would be same as the
> transition condition having evaluated to 'not ture'/false'." But, I
> somehow feel some will not
> see it this way. In any case we need to make a definitive statement
> here and not leave a
> loose end dangling.
>
> Regards, Prasad
>
> -------- Original Message --------
>
> *Subject: *
>
>
>
> Re: [wsbpel] Issue 27 - Proposal to vote - Setting link status in case
> of transitioncondition
>
> *Date: *
>
>
>
> Thu, 16 Oct 2003 13:18:25 -0700
>
> *From: *
>
>
>
> Ashwini Surpur <>
> <mailto:>
>
> *Organization: *
>
>
>
> Oracle Corporation
>
> *To: *
>
>
>
> Assaf Arkin <> <mailto:>
>
> *CC: *
>
>
>
> <mailto:>
>
>
>
>Also from the discussion on issue 27 I get that the local variables of the scope
>
>cannot be used to evaluate the transition condition of the links and only the
>
>variables of the parent scope should be used. This needs to be documented
>
>explicitly as well.
>
>
>
>-Ashwini
>
>
>
>Assaf Arkin wrote:
>
>
>
>> Proposal to resolve issue 27 by adding the following paragraph to the
>
>> specification in the description of how links are handled (pages 64/65):
>
>>
>
>> Note that the transition condition is evaluated after the activity has
>
>> completed. If an error occurs while evaluating the transition condition,
>
>> that error does not affect the completion status of the activity and is
>
>> handled by the activity's enclosing scope. In the case of
>
>> scopes, completion does not necessarily imply successful completion. A
>
>> scope may suffer an internal fault and yet complete (unsuccessfully) if
>
>> there is a corresponding fault handler associated with the scope and
>
>> that fault handler completes without throwing a fault.
>
>>
>
>> arkin
>
>>
>
>> (This is the same proposal sent on Sep 30, resent for your convenience)
>
>
>
>
>
>
>
>------------------------------------------------------------------------
>
>
>
>
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