Preserving Semantics During Refinement of Business Processes

Different levels of abstraction are needed to define and communicate the business processes an enterprise consists of. Thus, in a business process modeling and implementation process, models are refined towards an executable specification step by step. Unfortunately, until now there is no formal guarantee that during these refinements semantics will not be lost or changed, in particular between different specification levels and viewpoints. Within this project, we intend to solve this problem using Abstract State Machines. Firstly, a uniform model for high-level business process specifications shall be provided, which is capable of integrating interfaces as well as persistency mechanisms. When speaking about interfaces, we particularly are thinking of dialogs and regarding persistence aspects, we mainly want to address databases. Secondly, we want to provide a methodology to express horizontal refinements based on formal semantics. Horizontal refinement for us means to extend models toward interfaces and databases. Thirdly, we want to provide a methodology to express vertical refinements using the same formal basis. This shall support all the steps toward a final, executable specification. Succeeding in this intent at the end of this project, we will be able to deliver a business process specification and implementation methodology that formally guarantees the conservation of semantics during all refinement steps. A lot of today`s error sources in business process implementation projects would be resolved.

The projects most significant results of the conducted research comprise the following activities: (i) development of a formal business process model on the basis of abstract state machines (ASMs) as well as validating the resulting ASM ground model against the (informal) requirements of the BPMN 2.0 specification and (ii) horizontal and (iii) vertical refinements of the ASM ground model by preserving the operational semantics during all refinement steps. Starting from textual descriptions in the BPMN 2.0 specification, in close cooperation with the long-term research project Vertical Model Integration (VMI) at the SCCH, each BPMN element was mapped to a corresponding ASM transition rule. Thereby, several ambiguities in the specification regarding the semantics of dynamic models, such as messaging, inclusive merge (OR), or the instantiation concept, were revised due to the mathematical exactness of ASMs as the formal basis. The horizontal refinement of the ASM ground model implies the extension of the BPMN specification to user interaction, dialogs, and data. Therefore, primarily the activities, control flows in diagrams, and communication aspects were observed. The actual extension is based on a typed, technology-independent approach for integrating workflow definitions and application programming called workflow charts. The semantics of workflow charts was formalized and validated by applying ASMs. The concept of ASM refinement also serves as the formal basis for vertical refinement of the ground model towards an executable specification. That is, the ASM refinement method guarantees transformations of higher-level specifications into more concrete specifications without changing the semantics at the higher level of abstraction. The vertical refinement of the ASM ground model implies adding implementation oriented specifics needed for the execution. The primary focus was put on the control and the event flow, the main two parts of the BPMN specification needed to execute a minimal BPMN workflow. Additional concepts, which concretize the execution of the semantics defined on higher levels, were added targeting filling gaps between the high level model and an implementation. Implications of the conducted research can be expected in particular for the technological area. The comprehensive and sound business process specification methodology will contribute to resolve a lot of todays error sources in business process implementation projects. Techniques and tools can be adjusted accordingly with the effect that semantics of business processes cannot be lost or changed during refinement steps by working within this tools and techniques. This definitively constitutes a big step towards semantically correct business process implementations.