Re: [wsbpel] Issue - 64 - Explicit declaration of process instantiation

["Dieter Roller" <ROL@de.ibm.com>]

Ricky,

I'm not sure that I understand how you want to solve the multiple start
activities.

In Method 1 the actual representation of the business process, which says
upon receipt of either message the business process is started, is gone.
What we end up is with a physical representation of two different views of
the same process. Any change to the real process must then be propagated
down to the  two physcial representations of the process. I think this is
hard to comprehend as a mental model.

In Method2 I'm not sure that I understand what causes a process instance to
be created.

Cheers,

dieter




|---------+---------------------------->
|         |           Ricky Ho         |
|         |           <riho@cisco.com> |
|         |                            |
|         |           09/16/2003 01:47 |
|         |           AM               |
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  |       To:       wsbpel@lists.oasis-open.org                                                                                                 |
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  |       Subject:  Re: [wsbpel] Issue - 64 - Explicit declaration of process  instantiation                                                    |
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Ron, thanks for bringing up the multi-start points.

First I consider most business processes have a single, well-defined
starting point.  For this kind, I hope I've convinced that explicitly
declare the initialization is a merit.

Now go back to your scenario (which I hope to be a rare situation), then
there maybe 2 ways to handle that.


Mechanism 1: Define multiple process
=============================
ProcessA:  Receive buyer request first
ProcessB:  Receive shipper request first

In other words, I have multiple processes.  Depends on which is the first
message being received, I'll select the corresponding process to
start.  Therefore, within each process, I have a well-defined single
starting point.


Mechanism 2: Define an empty triggeredBy
================================
In this case, the process instance is started without any variable
initialization, and the variables are initialized at the first moment of
<receive>.  This is the same as current BPEL model.


Best regards,
Ricky

At 08:20 AM 9/15/2003 -0700, you wrote:
>Ricky,
>
>    Doesn't explicitly separating start activities lose the ability to
> have multiple starts, which are used to support non-deterministic start
> conditions? For example, a shipping company may have a process for
> receiving shipment requests from a purchaser and seller; where both must
> send messages before the shipment can be arranged. However, the purchaser

> and seller have no way to co-ordinate to assure that one of them is the
> first to send a message to the shipping company (i.e., parallelism in the

> global process). To handle this type of situation, we must be able to
> model the idea that multiple start points (activities) are possible, and
> that once the process is started (a particular start activity is "fired",
> the other start activities become "normal" non-start activities instead.
> (This all hinges on correlation of course).
>
>    It seems to me that the lack of more explicit start activities is a
> benefit, at least with respect to non-deterministic start. Or are you
> suggesting that the <triggeredBy> element of a process be added to the
> current BPEL vocabulary, to make it more readable?
>
>Cheers,
>-Ron


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