Issue 126 - Proposal For Vote

["Yaron Y. Goland" <ygoland@bea.com>]

Issue 126 - Event Handlers with local partnerLinks & Correlation Sets

Disclaimer: This proposal is contingent on my propose for 139 passing

Proposal: Add the ability to declare correlation sets inside of an 
onEvent handler for use within a specific onEvent instance.

Rationale: Issue 126 brought up two questions. The first question was 
based on my assumption that partnerRoles are used to filter incoming 
messages on receives/picks/onEvent handlers. My proposal for issue 139 
would make that assumption invalid and so remove my first question.
	My second question had to do with correlation set initialization on 
event handlers. In some cases, such as the example I gave in the issue 
list, we want to be able to have a correlation set whose value is local 
to a single event handler instance.

Section 13.5.1

From: The usage and interpretation of correlation is exactly the same as 
for receive activities.

To: The usage and interpretation of correlation is exactly the same as 
for receive activities with the addition that it is possible to declare 
correlation sets locally to an onEvent handler instance.  Those locally 
declared correlation sets can then be used as part of onEvent’s receive. 
For example:

…
    <eventHandlers>
       <onEvent partnerLink=”travelAgency”
          portType=”ns:agent”
          operation=”travelUpdate”
          messageType=”ns:travelStatsUpdate”
          variable=”travelUpdate”>
           <correlationSets>
              <correlationSet name=”updateCode” properties=”ns:updateCode”/>
          </correlationSets>
          <correlations>
             <correlation set=”travelCode” initialize=”no”/>
             <correlation set=”updateCode” initialize=”yes”/>
          </correlations>
          …
    </eventHandlers>
…

In this example a process is managing travel reservations for a customer 
and needs to handle reservation updates from the travel booking system. 
The onEvent handler is used to receive the update messages which are 
correlated using the travelCode property, which is defined and 
initialized elsewhere in the process. However sometimes the event 
handler needs to contact the travel booking system to follow up on an 
update message. To do that the outgoing message needs both the value in 
the travelCode property but also the value in an update code included in 
the travel update message. This is where the updateCode correlation set, 
declared locally to the onEvent handler comes in. When the update 
message is received the updateCode correlation set is initialized and 
its value made available only to the onEvent handler instance.

The BNF for eventHandlers needs to be updated in sections 6.2 and 13.5 
to the following:
<eventHandlers>?
<!-- Note: There must be at least one onEvent or onAlarm handler. -->
       <onEvent partnerLink="ncname" portType="qname"?
	operation="ncname" messageType="qname" variable="ncname"
         messageExchange="ncname"? >*
*                 <correlationSets>?
*                       <correlationSet name="ncname" 
properties="qname-list"/>+
*                 </correlationSets>
	      <correlations>?
		<correlation set="ncname"
			initiate="yes|rendezvous|no"?/>+
	      </correlations>
		activity
	</onEvent>
	<onAlarm>*
	  ( <for expressionLanguage="anyURI"?>duration-expr</for> |
	    <until expressionLanguage="anyURI"?>deadline-expr</until> )?
	    <repeatEvery 
expressionLanguage="anyURI"?>duration-expr</repeatEvery>?	    activity
	</onAlarm>
</eventHandlers>