Chapter 3, BPMN for Business Process Modeling, explains the concepts of business process modeling with BPMN. Most likely, the first version of a BPMN model concentrates on the logical flow of activities. Aspects such as exception handling, data mapping, or the decision between synchronous and asynchronous system calls, are very often not part of the abstract model that the developer gets from the business analyst. In order to make the model executable, we need to concretize it step by step.
An executable business process needs to deal with all the variances that can happen in real life. Abstract business process models focus on communication with business departments. It is thus feasible to omit some of the more obscure variances. The art of concretizing the business process model that we get from the business department and refining it towards being concrete is difficult since it's important to find the...