Re: [ebxml-bp] ebBP 11/21/2005: BPMN Updates and Discussion

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

A reminder that the TC team is to review these questions and the updated 
diagrams, particularly the questions regarding exclusive and 
inclusive/or gateways.  We will discuss 29 November 2005. Please post 
your questions if possible before Tuesday's meeting. Thanks.


> As we discussed in Tuesday's call last week, the team wished to review 
> in more detail the BPMN v1.0 and draft v1.1 specification, and the 
> diagrams as updated. As previously indicated, I had worked with Ugo 
> Corda to determine if and how using BPMN we can show how ebBP can map 
> the Business Transaction Activity to a series of operations 
> (OperationMapping). 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 this 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. There are some other points to consider regarding 
> differentiating signals from business messages, how to accurately show 
> an operation, and what objects/lines to use to show responses vs. faults.
>
> Here is a summary of the discussion and potential items to address:
>
>    * Question 1: How to map complex activities to a series of
>      operations, where these operations may be associated with or
>      related to a BTA? When you choose this particular mapping are you
>      in essence combining different process diagrams in the BPMN
>      vernacular?
>
>          * It is not an embedded subprocess
>
>        "....An Embedded (or nested) Sub-Process object is an activity
>        that contains other activities (a Process). The Process within
>        the Process is dependent on the parent Process for instigation
>        and has visibility to the parent’s global data. No mapping of
>        data is required. The objects within the Embedded Sub-Process,
>        being dependent on their parent, do not have all the features of
>        a full Business Process Diagram, such as Pools and Lanes. Thus,
>        an expanded view of the Embedded Sub-Process would only contain
>        Flow Objects, Connecting Objects, and Artifacts....
>
>          * It is not a group (relatively speaking), although it shares
>            some characteristics of a group.
>
>        "...A box around a group of objects for documentation
>        purposes)....A grouping of activities that does not affect the
>        Sequence Flow. The grouping may be used for documentation or
>        analytic purposes. Groups can also be used to identify
>        activities of a distributed transaction that is shown across 
> Pools."
>
>          * 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).
>
>        "...To satisfy additional modeling concepts that are not part of
>        the basic set of flow elements, BPMN provides the concept of
>        Artifacts that can be linked to the existing Flow Objects
>        through Associations. Thus, Artifacts do not affect the basic
>        Sequence or Message Flow, nor do they affect mappings to
>        execution languages....An Association is used to associate
>        information with Flow Objects. Text and graphical non-Flow
>        Objects can be associated with the Flow Objects...."
>
>    * Question 2: 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).
>          o The BPMN team had questioned why we used an exclusive/or
>            rather than inclusive/or gateway (See Section 3.2 objects)
>            when we could have multiple input or output from a fork or
>            join. This is represented in a gateway in BPMN. The
>            inclusive/or gateway with the message flow is not allowed in
>            BPMN.
>          o The BPMN team had questioned why we needed to have multiple
>            messages as input to or output from a gateway (which is not
>            allowed in BPMN).
>
>        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. See v2.0.1 CD and v2.0.1
>        PR diagram changes to visually represent this discussion. Please
>        also review BPMN Section 4.5 that talks about exclusive/or
>        gateway and how condition expressions are used (XPath based for
>        example) to effect what path(s) is/are taken. 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).
>
>    * Question 3: Differentiating business messages and/or business
>      signals: As allowable extensions, I have differentiated business
>      messages from business signals (blue and green respectively for
>      color, and used a heavier weight line). The BPMN team may consider
>      that this differentiation is important for intentional 
> collaboration.
>    * Question 4 (related to Question 1) : 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 8.
>
> Diagrams I've included:
>
>   1. Diagrams as specified in v2.0.1 Committee Draft (2 diagrams)
>          * 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.
>   2. Diagrams updated given comments from BPMN team for v2.0.1 Public
>      Review draft candidate (2 diagrams)
>          * 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.
>
> Relevant references:
>
>    * Updated ebBP diagrams -
>      
> http://www.oasis-open.org/apps/org/workgroup/ebxml-bp/email/archives/200511/msg00035.html 
>
>      (14 November 2005)
>          o All diagrams uploaded to ebBP site for ease of accessibility:
>                + (TC)
>                  
> http://www.oasis-open.org/apps/org/workgroup/ebxml-bp/document.php?document_id=15368 
>
>                + (public)
>                  
> http://www.oasis-open.org/committees/document.php?document_id=15368&wg_abbrev=ebxml-bp 
>
>
>            Note. The file (.zzz) needs to be renamed to a (.zip) to
>            open and view the four diagrams.
>
>    * BPMN v1.0:
>      http://www.bpmn.org/Documents/BPMN%20V1-0%20May%203%202004.pdf
>    * BPMN v1.1 (draft): http://www.bpmn.org/Documents/BPMN%201-X.pdf
>
> Finally, Stephen and Ugo, I'd like to log these as questions to the 
> BPMN team for future consideration as appropriate. Thanks.