Untangling Unstructured Cyclic Flows – A Solution Based on Continuations
We present a novel transformation method that allows us to map unstructured cyclic business process models to functionally equivalent workflow specifications that support structured cycles only. Our solution is based on a continuation semantics, which we developed for the graphical representation of a process model. By using a rule-based transformation method originally developed in compiler theory, we can untangle the unstructured flow while solving a set of abstract continuation equations. The generated workflow code can be optimized by controlling the order in which the transformation rules are applied.
We then present an implementation of the transformation method that directly manipulates an object-oriented model of the Business Process Execution Language for Web Services BPEL4WS. The implementation maps abstract continuation equations to the BPEL4WS control-flow graph. The transformation rules manipulate the links in the graph such that all cycles are removed and replaced by equivalent structured activities. A byproduct of this work is that, if a continuation semantics is adopted for BPEL4WS, its restriction to acyclic links can be dropped.
Unable to display preview. Download preview PDF.
- 1.Andrews, T., et al.: Business process execution language for web services (2002), www-106.ibm.com/developerworks/webservices/library/ws-bpel/
- 2.Rumbaugh, J., Jacobson, I., Booch, G.: The Unified Modeling Language Reference Manual. Addison Wesley, Reading (1898)Google Scholar
- 3.van der Aalst, W., van Hee, K.: Workflow Management Models, Methods, and Systems. MIT Press, Cambridge (2004)Google Scholar
- 4.van der Aalst, W., Desel, J., Kindler, E.: On the semantics of EPCs: A vicious circle. In: Proceedings of theWorkshop on EPK, pp. 7–18 (2003)Google Scholar
- 12.Hauser, R., Koehler, J.: Compiling process graphs into executable code. In: Third International Conference on Generative Programming and Component Engineering. LNCS, Springer, Heidelberg (2004) (forthcoming)Google Scholar
- 13.Aho, A., Sethi, R., Ullman, J.: Compilers–Principles, Techniques, and Tools. Addison-Wesley, Reading (1986)Google Scholar
- 14.Amsden, J., Gardner, T., Griffin, C., Iyengar, S., Knapman, J.: UML profile for automated business processes with a mapping to BPEL 1.0. IBM Alphaworks, http://dwdemos.alphaworks.ibm.com/wstk/common/wstkdocservices/demos/uml2bpel/docs/ UMLProfileForBusinessProcesses1.0.pdf (2003)
- 15.Warmer, J., Kleppe, A.: The Object Constraint Language – Precise Modeling with UML. Addison-Wesley, Reading (1999)Google Scholar