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Subject: Re: [wsbpel] Issue - 126 - Event Handlers with local partnerLinks& Correlation Sets


There are two different scenarios for event handlers. I believe we need 
to support both of them.

1) The event handler uses a new partnerLink for each message (thus 
allowing it to accept any message that matches both operation and 
correlation set)

2) The event handler always uses the same partnerLink

My proposed change to BPEL would support both of these scenarios.

	Yaron

Prasad Yendluri wrote:

> 
> 
> Ugo Corda wrote:
> 
>>I think the difficulty I am having with your Part A example is that the
>>BPEL spec is not very clear about the rules for endpoint initialization
>>of partnerLinks.
>>
>>In the specific case of Event Handlers, one interpretation could be
>>that, like in our resolution for issue 36, each Event Handler instance
>>gets a separate copy of the partnerLink with an uninitialized endpoint
>>value. So at Time 2 a new instance of the handler is created with a copy
>>of partnerLink having an uninitialized endpoint value, which is then set
>>to point to monitor B.
>>
> I like this approach better than having to declaring partnerLinks in a 
> scope local to the EventHandler, explicitly.
> Only thing is, the partnerLink end-point (corresponding the partnerRole) 
> would be set to the correct value, based on
> where the message that triggered the event originated from, rather than 
> being initialized and then set (by who?).
> 
> Now the reply will get routed to the correct end-point.
> 
> I guess this would amount to an implicit local partnerLink declaration 
> with the same name,
> at the same time keeping the current syntax where it is obvious on which 
> parterLink the event is expected etc.
> 
> Regards, Prasad
> 
>>Ugo
>>
>>  
>>
>>>-----Original Message-----
>>>From: Yaron Y. Goland [mailto:ygoland@bea.com] 
>>>Sent: Monday, June 14, 2004 2:41 PM
>>>To: Ugo Corda
>>>Cc: wsbpel@lists.oasis-open.org <mailto:wsbpel@lists.oasis-open.org>
>>>Subject: Re: [wsbpel] Issue - 126 - Event Handlers with local 
>>>partnerLinks & Correlation Sets
>>>
>>>
>>>In the example the partnerLink monitor is uninitialized. Monitor A then 
>>>sends a message to the BPEL process. Monitor A's message is caught by 
>>>the BPEL process's event handler. As a consequence the Monitor 
>>>partnerLink partnerRole value (being used for the first time in the BPEL 
>>>process) is initialized to point at Monitor A.
>>>
>>>This then leads to time 2 where monitor B, a separate web service, also 
>>>sends a message to the BPEL process. This message will match on 
>>>portType, operation and probably even correlation set but it can't be 
>>>caught by the event handler because the event handler receives messages 
>>>using the partnerLink monitor and that is already initialized to point 
>>>to monitor A so, by definition, it cannot be used to receive a message 
>>>from monitor B.
>>>
>>>In BPEL today there is no way to write an event handler which can accept 
>>>messages from multiple different partners so that simple scenarios like 
>>>receiving asynchronous updates from multiple sources are almost 
>>>impossible to implement.
>>>
>>>	Yaron
>>>
>>>Ugo Corda wrote:
>>>    
>>>
>>>>Yaron,
>>>>As I am reading your Part A, I don't fully understand what you mean,
>>>>under Time 1, by "partnerLink monitor is initialized to point at Monitor 
>>>>      
>>>>
>>>>A" (and, as a consequence, I don't understand your point about Time 2 
>>>>      
>>>>
>>>>either). Could you please clarify?
>>>> 
>>>>Thank you,
>>>>Ugo
>>>>      
>>>>
>>  
>>


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