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Subject: [ebxml-cppa-negot] RE: BPSS Start element
Hmmm. I go away for a few hours and you guys get way ahead of me :-) I am
going to reply to each posting in sequence rather than attempting to
analyze everything first.
JJ, I would like the BSI to detect and flag an error if my business partner
opens the conversation by erroneously sending the message that is
appropriate for the enbedded collaboration without first traversing the
outer collaboration. The whole point of expressing the choreography as an
XML description is to allow middleware (BSI) to police what is being done.
If middleware weren't going to police the choreography, I might as well
just describe the choreography in text and let the application programmers
figure out whether it is done correctly by the other partner. So, I need
the ability to distinguish between nested business collaborations and
independent ones. I need something that tells the deployment tool that
each conversation must start with the outer collaboration. One way to do
this is to omit the Start element for the embedded collaboration. The
schema actually allows me to do that (minOccurs="0") but there is nothing
that tells a BSI what omitting the Start element means.
Regards,
Marty
*************************************************************************************
Martin W. Sachs
IBM T. J. Watson Research Center
P. O. B. 704
Yorktown Hts, NY 10598
914-784-7287; IBM tie line 863-7287
Notes address: Martin W Sachs/Watson/IBM
Internet address: mwsachs @ us.ibm.com
*************************************************************************************
"Jean-Jacques
Dubray" To: Martin W Sachs/Watson/IBM@IBMUS, "'John Yunker'" <john.
<jjd@eigner.com> yunker@bleuciel.org>
cc: <ebtwg-bps@lists.ebtwg.org>, <ebxml-cppa-negot@lists.oasis-open.org>,
08/09/2002 03:12 "'Jean-Jacques Dubray'" <jjd@eigner.com>
PM Subject: RE: BPSS Start element
To me, the Start-B pseudo state is not necessarily causing any trouble.
Then the BSI reaches the state of collaboration activity (defined by
collaboration B), it enters it, reaches the start-B state which has an
automatic transition to the first BTA of collaboration B. The BSI is
then in the position of enabling the request of this BTA to happen. I
don't see anything illogic about it, hence I don't see any reason not to
use a start-B state. Do you?
Thanks,
Jean-Jacques Dubray____________________
Chief Architect
Eigner Precision Lifecycle Management
200 Fifth Avenue
Waltham, MA 02451
781-472-6317
jjd@eigner.com
www.eigner.com
>>-----Original Message-----
>>From: Martin W Sachs [mailto:mwsachs@us.ibm.com]
>>Sent: Friday, August 09, 2002 3:01 PM
>>To: John Yunker
>>Cc: ebtwg-bps@lists.ebtwg.org; ebxml-cppa-negot@lists.oasis-open.org;
>>Jean-Jacques Dubray
>>Subject: Re: BPSS Start element
>>
>>
>>
>>
>>
>>
>>John,
>>
>>Thanks, I believe you do understand what I am driving at. I believe
that
>>the reply I just posted to JJ is also appropriate to your posting but
let
>>me restate in your terms:
>>
>>I believe that if I want the nested collaboration to be treated as a
state
>>machine encapsulated within the outer collaboration, I should state my
>>intention by omitting a Start element from the nested collaboration.
The
>>transition element in the outer collaboration will take me to the
>>encapsulated nested collaboration at the appropriate place in the
>>choreography without needing a start element in the nested
collaboration.
>>I
>>don't find words in the BPSS spec that tell me to do that,
>>
>>Regards,
>>Marty
>>
>>**********************************************************************
****
>>***********
>>
>>Martin W. Sachs
>>IBM T. J. Watson Research Center
>>P. O. B. 704
>>Yorktown Hts, NY 10598
>>914-784-7287; IBM tie line 863-7287
>>Notes address: Martin W Sachs/Watson/IBM
>>Internet address: mwsachs @ us.ibm.com
>>**********************************************************************
****
>>***********
>>
>>
>>
>> "John Yunker"
>> <john. To: Martin W
>>Sachs/Watson/IBM@IBMUS, "Jean-Jacques Dubray" <jjd@eigner.com>
>> yunker@bleuciel. cc: <ebtwg-
>>bps@lists.ebtwg.org>, <ebxml-cppa-negot@lists.oasis-open.org>
>> org> Subject: Re: BPSS
Start
>>element
>>
>> 08/09/2002 02:35
>> PM
>>
>>
>>
>>
>>
>><MWS> I have a BPSS instance two binary collaborations, one nested
inside
>>the other, and both have Start elements. How does a BSI know which
Start
>>element actually starts the choreography? </MWS>
>>
>>Actually, this question is easily answered. Since the collaborations
>>inherit from UML activity model, which itself is a state model, it is
>>clear
>>that the outer collaboration "Start Element" starts the collaboration.
>>Now,
>>if the nested collaboration is part of the initiating business action,
>>then
>>no messages are exchanged until the nested transaction starts.
>>
>>This is actually a very important feature, since business state may
>>dictate
>>that a collaboration is required. That state can be expressed on the
>>outer
>>start state, and still have conditions critical to the function of the
>>inner
>>transaction normalized to the inner transaction. The fact the
>>collaboration
>>instance has been "started" is of value regardless of whether any
message
>>exchanges have taken place.
>>
>>So, to recap, the nested collaboration must be considered a state
machine
>>encapsulated in an individual state within the encapsulating
transaction,
>>(nested state machines) thus for the encapsulated collaboration to
start,
>>the encapsulating collaboration must have started.
>>
>>I can see incredible value in being able to normalize conditional
elements
>>between the two start elements.
>>
>>Thanks,
>>John
>>
>>(p.s. I cannot post to the CPPA list, Marty, could you do it for me?
>>Thanks!!!)
>>
>>
>>
>>
>>
>>
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