Re: [wsbpel] Do we need the createInstance attribute?

[Danny van der Rijn <dannyv@tibco.com>]

this is dealt with in 11.4:

In addition, receive activities play a role in the lifecycle of a business
process. The only way

to instantiate a business process in BPEL4WS is to annotate a receive
activity with the

createInstance attribute set to "yes" (see Pick for a variant). The default
value of this

attribute is "no". A receive activity annotated in this way MUST be an
initial activity in the

process, that is, the only other basic activities may potentially be
performed prior to or

simultaneously with such a receive activity MUST be similarly annotated
receive activities.



could probably be made more clear, but at least its there.  something else
that is there, but could be made much more clear is the following definition
of instance creators (also there above) from 6.4



To be instantiated, each business process must contain at least one such
"start activity."

This must be an initial activity in the sense that there is no basic
activity that logically

precedes it in the behavior of the process.



my objection is that what is a "basic" activity and what is a "structured"
activity is defined solely (i think) by what section of the doc they appear
in.  that seems pretty weak to me, and hard to read unless you understand
that.

----- Original Message ----- 
From: "Satish Thatte" <satisht@microsoft.com>
To: "Ron Ten-Hove" <Ronald.Ten-Hove@Sun.COM>; <ygoland@bea.com>
Cc: "Wsbpel@Lists. Oasis-Open. Org (E-mail)" <wsbpel@lists.oasis-open.org>
Sent: Thursday, October 23, 2003 10:02 AM
Subject: RE: [wsbpel] Do we need the createInstance attribute?


Good point.  We need clarity on whether all initial activities must (A)
be receives or picks and assuming that (B) must have createInstance set
to "yes".

I expect there are various opinions on this ..

Satish


-----Original Message-----
From: Ron Ten-Hove [mailto:Ronald.Ten-Hove@Sun.COM]
Sent: Thursday, October 23, 2003 8:54 AM
To: ygoland@bea.com
Cc: Satish Thatte; 'Wsbpel@Lists. Oasis-Open. Org (E-mail)'
Subject: Re: [wsbpel] Do we need the createInstance attribute?

Yaron Goland wrote:

>I think an editorial change that describes 'createInstance' as a marker
of a
>start activity, explains that it is redundant and then describes why it
is
>there anyway should do nicely. Can we add that to the list you are
>maintaining of things for the editors to do?
>
Does this really answer the original question you posed? Is the sample
process fragment you supplied considered illegal?

I can easily imagine someone trying to exploit such a "feature" if it
was not explicitly banned. Borrowing from your example:

<process>
   ...
   <flow>
      <receive partnerLink="A" createInstance="yes".../>
      <receive partnerLink="B" createInstance="no".../>
   </flow>
</process>

This could be used by partner B as a kind of polling mechanism to see if

partner A has done his thing yet. Kind of an event handler for process
instances that don't exist. Useful for non-deterministic (parallel)
sections of a choreography.

Do we wish to support this usage, or ban it? I think we need some
explicit wording one way or the other.

-Ron





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