The last of the four roundtables that I attended was on BPDM, led by Fred Cummins. I started with my (by now) usual question about the distinctions and overlap between XPDL and BPDM: his response was that XPDL is an XML specification, and BPDM is a metamodel that can be exported to XML via XMI. He seemed to imply that they could coexist, but given that BPDM will include a serialization specification for BPMN (in addition to other models that can be represented in BPDM), I’m not sure I see the need for both in the standards world. He later stated that there is an expectation that people will model in BPDM (as visualized by BPMN or other visualizations as appropriate) and transform to an execution language such as BPEL, rather than BPDM being an interchange format; this seems to leave no room in the landscape for XPDL if you adopt BPDM, unless you need it as a legacy interchange format.
Moving on to other points about BPDM, it will include both orchestration and choreography (process flow, messages and collaboration), and will include more concepts than can be represented in BPMN, hence will support other views, e.g., process dependency diagrams, roles/organization view, choreography. A draft submission of the standard is due on June 5th, with a rough plan to finalize the underpinnings to provide BPMN support within 3-4 months, although there is no plan to issue a version with just the serialization as a preliminary release. In order to complete the release, they will likely do BPEL export from BPDM and a UML mapping to BPDM in order to demonstrate usability of the standard on a broad enough basis to initiate its acceptance.
When Cummins provided a summary of all of his roundtables at the end of the conference, he pointed out a couple of questions that had arisen during the discussions:
- Is there a potential for executable BPDM? [I say that if there can be abstract BPEL then why not executable BPDM?]
- Is there a way to achieve compatibility between XPDL and BPDM? [I think that there better be]