RE: [wsbpel] Issue 27 - Setting link status in case of transition condition

["Satish Thatte" <satisht@microsoft.com>]

Assaf,

I finally see what you are talking about.  You are talking about the
case

<scope>
  <source linkName="myLink" 
          transitionCondition=             
                 "bpws:getVariableData('amount')>=10000"/>
  <variables>
  ...
  </variables>
  Activity
</scope>

Two questions seem to arise.

A.  Do we allow the variable 'amount' to be declared as a local variable
of the scope even though in this case it is part of an expression that
is supposed to be evaluated after the scope has "successfully
completed"?

B.  What happens if the evaluation of the transition condition faults.
In which scope is the fault deemed to have occurred?

Good catch.  My gut says treat the evaluation of the transition
condition as part of the scope's work because I would expect to be
allowed to use a local variable like 'amount' but this is clearly a
tricky border case.

Satish
 
-----Original Message-----
From: Assaf Arkin [mailto:arkin@intalio.com] 
Sent: Thursday, September 25, 2003 7:24 PM
To: Satish Thatte
Cc: wsbpel@lists.oasis-open.org
Subject: Re: [wsbpel] Issue 27 - Setting link status in case of
transition condition

The text I propose refers to computation within the source activity in 
general.

When the source activity is enclosed within a scope then a fault in the 
transition condition would propagate to the fault handler of that scope.

The specification already provides for this behavior.

The issue seems to emerge when the scope activity is also the source 
activity. Since it did not establish the correct value for the outgoing 
links it is dangerous for other activities to depend on the source link 
status. If the source/scope activity throws a fault then it does not 
install a compensation handler, which makes it impossible to recover for

the work. IMO it needs to be able to catch the fault and deal with it 
using a fault handler defined for the source/scope activity.

What would you propose to do in this case?

arkin

Satish Thatte wrote:

>Assaf,
>
>Did you mean ".. computation within the [source] activity .." as
opposed
>to computation within the scope enclosing the source activity?
>
>Satish
>
>-----Original Message-----
>From: Assaf Arkin [mailto:arkin@intalio.com] 
>Sent: Thursday, September 18, 2003 12:12 PM
>To: wsbpel@lists.oasis-open.org
>Subject: [wsbpel] Issue 27 - Setting link status in case of transition
>condition 
>
>Proposed change to the text based on the F2F discussion:
>
>Page 65 describes how incoming and outgoing links are handled. I would 
>recommend adding the following text to the first bullet item, or as a 
>remark just below the bullet-item list:
>
>"Note that the transition condition is evaluated as part of the 
>computation within the activity. If an error occurs while evaluating
the
>
>transition condition, a fault would be thrown and can be caught locally

>by the activity. The status of all outgoing links will be set to
false."
>
>This would clarify that in the event of a transition condition throwing

>a fault, and that transition condition defined for a <scope> activity, 
>the fault handler is still installed and able to catch the fault, and 
>the activity would complete as if a fault was generated before the 
>transition conditions were evaluated.
>
>arkin
>
>
>
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