ebBP/BPMN 2/2/2005: BPMN-ebBP Call 7 February 2006 (Call and Details)

[Monica J Martin <Monica.Martin@Sun.COM>]

ebBP and BPMN teams,
Here is the email sent to the BPMN team in late December 2005 re: our 
ebBP questions.  Today, I attended the BPMN call and that team has 
agreed to meet with us on Tuesday, 7 February at 9 a.m. PST at our 
regular TC call.  This will be our main agenda item.  In addition, if 
needed, we can meet with the BPMN team at 8 a.m. PST, Thursday, 9 
February 2006. The conference details for that optional short Thursday 
call, if required, will be distributed on Tuesday. The conference 
details for the Tuesday call are provided below. ebBP members are 
strongly encouraged to attend. Thanks!

866 882 3998 
international 865 525 0769 
passcode 9081038#

Call in details: http://www.oasis-open.org/apps/org/workgroup/ebxml-bp/event.php?event_id=9088&day=1139310000
(public: http://www.oasis-open.org/committees/event.php?event_id=9088)

Email reference: http://www.oasis-open.org/apps/org/workgroup/ebxml-bp/email/archives/200601/msg00044.html
(public: http://lists.oasis-open.org/archives/ebxml-bp/200601/msg00044.html)
Note, this email contains the .zip file with the diagrams.

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Email 27 December 2005: [start]
BPMN team.
In ebBP, we've had several discussions about BPMN semantics and notation. We're hoping we can effectively represent what we wish to
in BPMN for a ebBP collaboration.

We have open questions about what was requested and whether this is properly representing the intent of the collaboration
and business transaction activities as well as using BPMN in an appropriate way. To explain:

1. In the last BPMN meeting I attended earlier this fall, I presented the diagrams that were in the v2.0.1 ebBP technical specification
Committee Draft. Antoine suggested we use an inclusive OR gateway and intermediate messages for representing that a response could be 
several different types of responses (cancel, change, accept for example).  The current BPMN semantics preclude use
of message flows into / out of a gateway. In addition, we couldn't determine how to indicate that multiple types of 
business messages (specifically) may occur. We originally used exclusive rather than an inclusive OR gateway notation object
(BPMN suggestion in September).  With inclusive OR, parallelism could result. For example, in a decision, it is modeled that one path is 
taken. In order to represent the sequence flow into a gateway, and several possible paths out (termed intermediate messages in BPMN), I opted to use the inclusive OR gateway at the 
suggested by your team.

In ebBP, forks can be non-deterministic intentionally. Forks can resemble a non-deterministic OR or parallel ANDs or exclusive OR (like a 
Decision). We need feedback on the options and their appropriateness to represent this. We could also choose to annotate the diagram for more clarity
but this may be an unnecessary extension.

What gateway control type is appropriate when you actually could have -n- potential paths on a fork or join, and either only one is actually performed or many could be performed,
and business messages are sent? This is actually a conceptual difference in current BPMN v1.0 and collaboration whereby not all paths may be rendered executable or be used in execution
(monitorable in ebBP context).

Instead of using an exclusive/or gateway with multiple message flows into or out of an exclusive/or gateway, I updated the
diagrams to show an inclusive/or with sequence flows to intermediate messages to show that one actual Response on the Responding Business Activity results. 
It appears that an exclusive/or gateway could be used but the assumptions are different (shows sequence rather than the potential flow of business messages which may suit our needs).

Issue: Can't have gateways with messages flowing into or out of them. How to represent -n- potential paths on a fork or join.

2. How can ebBP show the relationship/map between the Business Transaction Activities or ComplexBTA which are business messages that may occur (alternate paths supported) and that 
can relate to a series of abstract operations (via OperationMapping constructs in ebBP) in BPMN. What is important here and perhaps 
should be considered by BPMN team is there is effectively no mechanism to specify a relationship between activity objects unless they are 
considered a subprocess or a transaction or within a pool/lane. Neither of these truly represent our use case. There are (at least) 
two levels of specification where we should be able to associate or relate the BTA to those operations, each effectively activities in 
their own right. 

a. It is not an embedded process.
b. It is not a group of objects for documentation purposes.
c. It is not an association (dotted line) although we can relate or associate the abstract WSDL operations to BTA
(Note that the operation is not an artifact, it is in essence another flow object).

Issue: Can't describe how to map business messages in Business Transaction Activity to a series of operations (that may be mapped but don't have
to be) where the abstract operations are NOT a subprocess. When you choose this particular mapping are you in essence combining 
different process diagrams in BPMN?

3. There is no mechanism to differentiate business signals from business messages, which have different
substantive impact on the expectations of the parties and any activity fulfilled. We can use an allowed extension
to color code business messages and business signals (which I have done in the examples), but this is not adequate where pictures may be printed or
displayed in a black-white way.

Issue: No way to differentiate business signals and messages other than by extension.

4. How do we accurately show an operation, and what objects/lines to use to show responses vs. faults. When you have a complex
activity that may be mapped multiple operations, how do you represent the fact that an abstract WSDL operation could have the
Response or a fault(s)? See our updated Figure.

Issue: How to show an operation could be a response (of several types) or a fault?

Diagrams we have provided (old and new)
* Requesting and Responding Business Activity on a typical Commercial Transaction pattern.
* Requesting and Responding Business Activity on a typical Commercial Transaction pattern using Operation Mapping

(map to abstract operations).
[end]

Other References:
1. BPMN v1.0: http://www.bpmn.org/Documents/BPMN%20V1-0%20May%203%202004.pdf
Note: An updated v1.0 adopted draft specification is available to OMG members at: 
http://www.omg.org/cgi-bin/doc?dtc/2006-01-01
2. BPMN v1.1 (draft): http://www.bpmn.org/Documents/BPMN%201-X.pdf