ANSWER

The origins of BPMN began in the area of executable models.  That is, it was created to be precisely interpreted by workflow engines or business process management systems in order to automatically orchestrate how information, documents, or other workflow items are directed through a system. The benefit of an executable model is that it can be changed and immediately re-executed to establish a new workflow.  At least, that’s the idea.

Of course, wouldn’t it be beneficial if the notation that analysts used for these executable models could also be used to document processes for human consumption?  This would mean that the business analyst doesn’t need to learn multiple notations.  In addition, using a notation such as BPMN which is detailed and precise enough for executable models means that the business analyst should have no problem communicating even the most complex business models.  While this is largely true, business models and executable models have differing priorities.

The priority of an executable model is to be accurate and precise so that a workflow engine can interpret it without fail.  BPMN becomes the graphical programming language while the workflow engine is the compiler.  In contrast, the priority of a business model is human comprehension.  The goal is to clearly communicate the modeled process to human stakeholders.  Because of this, the detailed nature of BPMN can present a challenge.  It’s for this reason that often a much smaller subset of BPMN is used for business models.  

It’s up to the business analyst and team to decide what subset of the notation is appropriate to use.  When a situation must be modeled that cannot be defined by pared down notation, textual descriptions can be used to annotate the process.  Again, the paramount priority of the business model is stakeholder comprehension.  In addition, the business analyst may choose not to model every possible exception or alternative process path within a business model.  Instead, judgement must be used to document only those alternative paths and exceptions paths that add significant value or happen most often.  The remaining paths can simply be noted textually.

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Chris Adams
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