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

["David RR Webber" <david@drrw.info>]

John and mine comments brought into clear focus.

Compare and contrast a BPSS interaction to
this dialogue from the BPEL world!!!

I need say nothing else here ; -)

DW

----- Original Message ----- 
From: "Yaron Y. Goland" <ygoland@bea.com>
To: "Dieter Koenig1" <dieterkoenig@de.ibm.com>
Cc: "Prasad Yendluri" <pyendluri@webmethods.com>;
<wsbpel@lists.oasis-open.org>
Sent: Thursday, June 17, 2004 2:02 PM
Subject: Re: [wsbpel] Issue - 126 - Event Handlers with local partnerLinks &
Correlation Sets


> If I understand the proposal correctly then it would make the following
> scenario nearly impossible to support.
>
> scope
>     partnerLinks
>        partnerLink name="A"
>     eventHandlers
>        onEvent partnerLink="A"
>           do stuff...
>     ...
>
> In this code partnerLink A is not initialized anywhere. However, if a
> message arrives that matches the onEvent element then it will be
> 'caught' by the onEvent handler and a local copy of partnerLink A will
> be created and partnerRole on the local copy of partnerLink A will be
> initialized to point at who ever sent the message.
>
> Now lets say that the desired semantics are that when the first event
> arrives the partnerLink's partnerRole initialized to point at the sender
> and then future events will ONLY be accepted from that specific sender
> in the future.
>
> That's mostly impossible if a local copy of partnerLink A is created
> because the initialization upon receiving the message will only apply to
> the local copy of A and any other instance of the event handler will not
> see it.
>
> But in the current proposal to resolve 126 a local copy is only created
> if the programmer explicitly asks for it by including a local
> partnerLink declaration as a child of the onEvent element.
>
> In other words, the current proposal gives the programmer a choice. They
> can either use a common partnerLink whose state is visible to all
> instances of the event handler or they can use a local partnerLink whose
> state is only visible to a single instance. Both choices are required in
> order to support the two scenarios defined in
> <http://lists.oasis-open.org/archives/wsbpel/200406/msg00046.html>.
>
> Yaron