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Subject: Issue - R25 - wording for conflictingReceive and ambiguousReceive

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Issue - R25 - wording for conflictingReceive and ambiguousReceive

Status: received
Date added: 18 Oct 2006
Origin: Public comment - Marlon Dumas, 18 Oct 2006
Date submitted: 18 October 2006
Description: The following statement may need to be clarified in the spec: "If during the execution of a business process instance, two or more receive activities for the same partnerLink, operation and correlationSet(s) are simultaneously enabled, then the standard fault bpel:conflictingReceive MUST be thrown."

In this constraint, "two or more receive activities" should not be interpreted as meaning "two or more instances of the same receive activity", but instead: "two or more instances of different receive activities". Indeed, it is possible that the same "receive activity" within a scope nested in an event handler or parallel foreach, is "enabled" multiple times simultaneously, possibly once for each instance of the scope. In such cases, I am assuming that "conflictingReceive" should not be thrown (otherwise, most "receive activities" appearing in a parallel foreach or event handler would unavoidably lead to faults). Consider the following example:

<foreach ... parallel="yes" ...>
       <partnerLink name="PL1" ... />
       <correlationSet name="S1" ... />+
    <invoke name="RA1" partnerLink="PL1" ... operation="OP1" inputVariable="...">
      <correlation set="S1" initiate="yes"/>
    <receive name="RA" partnerLink="PL1" ... operation="OP1" ...>
      <correlation set="S1" initiate="no"/>
In this example, it is likely that multiple instances of the IMA "RA" may be enabled simultaneously. But no "conflictingReceive" would be thrown.

On the other hand, the following example may lead to a "conflictingReceive", as one instance of activity "RA1" may be enabled at the same time as one instance of "RA2".

   <receive name="RA1" partnerLink="PL1" portType="PT1" operation="OP1" ...>
     <correlation set="S1" .../>
   <receive name="RA2" partnerLink="PL1" portType="PT1" operation="OP1">
     <correlation set="S1" .../>

The first example discussed above also illustrates that the wording in the definition of "ambiguousReceive" in Appendix A warrants some clarification. The current definition says: "Thrown when a business process instance simultaneously enables two or more IMAs for the same partnerLink, portType, operation but different correlationSets, and the correlations of multiple of these activities match an incoming request message." The above is an example where two enabled instances of the same IMA may match the same incoming message.
Changes: 18 Oct 2006 - new issue

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