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There are many myths and misunderstandings surrounding the market sector that is know as Business Process Management. One of the major misunderstandings normally comes to light during discussions regarding standards. Whenever I speak to anyone on the subject it soon becomes clear that the standards bodies have simply failed to get the message across.
In 2003 there were more than 10 recognized groups defining standards for BPM related activities, 7 of these bodies were working on modeling definitions so it’s no wonder that the whole picture got very confused. Fortunately there has been a lot of “drop off” and consolidation to a point where there are, currently, only 3 key standards to really take notice:
But just having three to focus on still manages to cause some concern and confusion.
Many believe that these standards are in some way competing with each other but the fact of the matter is very different. It is with this in mind that we need to clarify the picture and set the record straight.
BPMN is the easiest one to clarify since it is very easy to visualize where it sits in the “standards” stack. The Business Process Modeling Notation (BPMN) is a standardized graphical notation for drawing business processes in a workflow. BPMN’s primary goal is to provide a standard notation that is readily understandable by all business stakeholders. Stakeholders in this definition include business analysts, technical developers and business managers. Consequently BPMN is intended to serve as common language to bridge the communication gap that frequently occurs between business process design and subsequent implementation.
The real question comes when talking about BPEL and XPDL. There is a general misconception that these two standards are in some competing with one another but the reality is entirely different – BPEL and XPDL are complimentary standards and easily coexist. So what do they do?
BPEL is an "execution language" the goal of which is to provide a definition of web service orchestration, the underlying sequence of interactions and the flow of data from point to point. Ultimately, BPEL is all about bits and bytes being moved from place to place and manipulated. It does not, however, attempt to represent the drawing that was used to specify the orchestration or process.
Developed by the WfMC, XPDL’s primary goal is to store and exchange the process diagrams, or specifically to allow one tool to model a process diagram, and another to read the diagram and edit, another to "run" the process model on an XPDL-compliant BPM engine, and so on. The XPDL file can provide this design interchange because it offers a one-for-one representation of the original BPMN process diagram. It can be written and re-read to recover the original diagram. BPEL, by contrast, is a non-trivial mapping, which is widely recognized as being one directional: You can take a BPMN diagram and produce BPEL, but it is difficult or impossible to recover the original BPMN diagram from the BPEL. This is not surprising since BPEL was not designed for process design interchange.
For this reason, XPDL is described not an executable programming language like BPEL, but specifically a process design format that literally represents the "drawing" of the process definition. To wit, it has ‘XY' or vector coordinates, including lines and points that define process flows. This allows an XPDL to store a one-to-one representation of a BPMN process diagram. For this reason, XPDL is effectively the file format or "serialization" of BPMN, as well as any non-BPMN design method or process model that use in their underlying definition the XPDL meta-model.
There are many who believe that XPDL is a dead or irrelevant standard that has been overlooked by the major platform vendors. These comments are at best ill-informed and at worst uttered by those that don’t really understand the dynamics at play – so it would be a foolish individual that uttered “XPDL is dead in the water”.
To date there are over 50 major BPM and application vendors that support the XPDL standard these include IBM, Oracle, BEA, Fujitsu, Tibco and Global 360. In fact 8 of the 11 top vendors listed in Gartner's 2006 BPMS Magic Quadrant 11 support XPDL. Furthermore, because XPDL has been stable for such a long time, there has been a large uptake in the open source community. Unlike some standards, XPDL is made freely available without any licensing restrictions."
As Keith Swenson of Fujitsu said in a recent article1 “process interchange is very important to customers who invest significant dollars in best-of-breed tools and a tremendous amount of time in developing their process diagrams, process archiving is also becoming very important." When asked recently which file format should be used by a business that wants to preserve its investment and ensure stored processes would be readable in the future, he responded: "XPDL is the only standard XML diagramming format supported today by dozens of vendors, and likely to be supported by tools in years to come. WfMC’s commitment to upward and downward compatibility is the assurance that XPDL 3, whenever it comes out, will be fully compatible with the current versions."
Available today, XPDL is a proven format for process design interchange, and it is the most practical standard for establishing a Process Design Ecosystem. The standard may not receive the same levels of press and pure hype as others I could mention, but it goes silently and dependably about its work, just as it was designed to do.
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