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Subject: [ebxml-cppa-negot] RE: BPSS Start element
JJ,
OK, now how does this work? (The following use case is for the CPA
negotiation BPSS instance.)
Using your notation, I have a collaboration A with start element "start-A".
Nested inside it, I have a collaboration B with start element "start-B".
It is my intention that Collaboration B start only as a result of a
transition from Collaboration A. So, the choreography normally begins with
the other party sending me document Da. Suppose that some business partner
has a software error and attempts to start collaboration A but sends
document Db. That is an error and the BSI should signal an error. How
will it know that starting with document Db is an error?
I believe that there has to be something about the BPSS instance document
that tells the BSI that each new instantiation is required to begin with
document Da but I can't find anything. I hypothesize that I should omit
start element start-B if I want each new instatiation to always start with
document Da but I can't find any words that allow me to do omit start-B in
order to force the BSI to flag an error if an instantiation starts with
document Db.
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
<jjd@eigner.com> cc:
Subject: RE: BPSS Start element
08/09/2002 02:31
PM
Sorry, I did not understand the question like this. I don't see any
ambiguity unless both collaboration would start from the exact same
(logical) document. The BSI has a global view of all collaboration
definitions so it is not really important if they are nested or part of
the same definition. If collaboration B is nested in collaboration A and
Da (Db) is the document that starts the collaboration A (B) then when Da
arrives as part of the first request, only Collaboration A can be
instantiated. Nothing prevents us to send Db in this case collaboration
B would be instantiated. When a collaboration has started we then have a
correlation for all subsequent message so we know how to distinguish
between a Db that starts a collaboration (no correlation) and a Db that
starts the nested collaboration within collaboration A.
Hope that helps,
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 10:12 AM
>>To: Jean-Jacques Dubray
>>Cc: ebtwg-bps@lists.ebtwg.org; ebxml-cppa-negot@lists.oasis-open.org
>>Subject: RE: BPSS Start element
>>
>>
>>
>>
>>
>>
>>JJ,
>>
>>Thanks for the reply. However, I would like to restate my question.
>>
>>One of the essential services a BSI can provide is to ensure that
everyone
>>is obeying the choreography described in the BPSS instance. That is
>>especially important in a world in which two trading partners may have
>>obtained their application software from different vendors. In order
to
>>perform this service, the BSI must know what is the start of the
>>choreography.
>>
>>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?
>>
>>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, <ebtwg-bps@lists.ebtwg.org>, <ebxml-cppa-
>> <jjd@eigner.com> negot@lists.oasis-
>>open.org>
>> cc:
>> 08/09/2002 09:31 Subject: RE: BPSS
Start
>>element
>> AM
>>
>>
>>
>>
>>
>>Marty:
>>>>
>>>>1. How does a BSI know the starting point of a choreography defined
in
>>a
>>>>BPSS instance document? Is that the function of the Start element?
>>If
>>>>not, what is the indicator? (It can't be preCondition since in BPS
>>1.05,
>>>>that attribute is for documentation only.)
>>>>
>>[JJ] The start element is used to "point to" the first business
>>transaction activity of the binary collaboration (actually nothing
>>prevents you to point to a fork element therefore enabling several BTA
>>at the same time). The request of the BTA pointed to by the start
>>element is the message that will initiate the binary collaboration
>>
>>
>>>>2. If a BPSS instance contains more than one binary collaboration
(not
>>>>nested), are they treated as separate choreographies? Should each
>>have a
>>>>Start element?
>>[JJ] Yes they are completely independent and all should have a start
>>element.
>>>>
>>>>3. If a BPSS instance contains one "top-level" binary collaboration
>>and
>>>>another binary collaboration nested inside it, should both binary
>>>>collaborations have start elements? If so, how does a deployment
tool
>>or
>>>>BSI know where the starting point is? It seems to me that it would
>>have
>>>>to
>>>>analyze the flow in detail to figure out where the choreography
>>begins.
>>>>
>>[JJ] I don't see a probleme there, the start element is a
pseudo-state,
>>so in the case they are nested (as a Collaboration Activity in the
>>parent binary collaboration definition), the BSI will simply expect
the
>>next BTA will be the one pointed to by the start element of the child
>>collaboration. In other words the BSI does not "stop" at this start
>>element, it automatically transitions to the BTA pointed to by this
>>element. You always need a start element to point to where you start.
>>Otherwise, you would have to analyze all the transitions and detect
the
>>BTA that does not have a transition to it.
>>
>>
>>>>I have a suspicion that the answers are:
>>>>
>>>>1. The Start element is supposed to tell the BSI where the
>>choreography
>>>>starts.
>>>>
>>>>2. Non-nested binary collaborations are separate choreographies and
>>each
>>>>needs a Start element.
>>>>
>>>>3. The nested binary collaboration should not have a Start element
>>since
>>>>the choregraphy starts with the top-level binary collaboration and a
>>>>Transition element defines the starting point of the nested binary
>>>>collaboration.
>>>>
>>>>Am I right?
>>>>
>>>>Incidentally, BPSS 1.05 states that for the Start element,
>>>>maxOccurs="unbounded" although the text in 8.1.24 strongly implies
>>that
>>>>maxOccurs should be "1".
>>>>
>>[JJ] That could be a bug, I'll look into it. Conceivably, it is not
>>impossible to think of multiple start element, the question is simply,
>>once such a collaboration has started to we disable the other start
>>element or do we leave them enabled? Note that this behavior can be
>>achieved with a single start followed by a fork (XOR or All) which
will
>>be followed by the corresponding BTAs.
>>
>>Cheers,
>>
>>JJ-
>>
>>
>>>>Regards,
>>>>Marry
>>>>
>>>>********************************************************************
**
>>****
>>>>***********
>>>>
>>>>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
>>>>********************************************************************
**
>>****
>>>>***********
>>>>
>>>>
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>>
>>
>>
>>
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