III. LITERATURE OVERVIEW Many researchers have studied the transformation between BPMN and BPEL. Most research conducted in this area is analytical in nature. There is little information on the practical use of BPMN. These include the work of Ouyang et al. [10, 11] and [12], which propose that the BPMN to BPEL transformation is accomplished by matching multiple phases of pattern and graph transformation. An algorithm for generating readable BPEL code from the BPMN model is presented in [10] which generates BPEL code from the BPMN model by discovering structural patterns in the BPMN models which in turn are mapped into structured BPEL activities. The original BPD is decomposed into well-structured components having an entry point and an exit point. The automated BPDs are then gradually transformed into BPEL blocks. For example, a component having a purely sequential structure is mapped into a BPEL sequence construct, while a component containing a parallel structure is mapped into a flow construct. The BPEL generation algorithm also transforms an unstructured subset of the BPMN model by exploiting BPEL's event handler construct. As a result, any BPMN model consisting of tasks, events, parallel gateways, and XOR gateways (data-driven and event-driven) connected in arbitrary topologies can be mapped to BPEL. In contrast, a model with unstructured topologies or having constructs such as OR join and complex gateway cannot be mapped to BPEL. Additionally, the BPEL generation algorithm only translates a smaller set of captured models into the main subset of the BPMN model by applying certain restrictions - such as each loop must have a single entry and exit point - on the original model. A well-formed central BPD may contain the components that are not well structured, e.g. loops with...... middle of paper ......Rosemann et al., “How good is the real BPMN? Insights from Theory and Practice,” 2009.[17] M. Rosemann, P. Green, M. Indulska et al., “Using an ontology for representational analysis of process modeling techniques,” International Journal of Business Process Integration and Management, vol. 4, no. 2, 2009.[18] T. Wahl and G. Sindre, “An Analytical Evaluation of BPMN Using a Semiotic Quality Framework,” Advanced Topics in Database Research: Volume 5, pp. 94, 2006.[19] G. Decker and J. Mendling, “Instantiation semantics for process models”, Proceedings of the 6th BPM, Milan Italy, pp. 164-179, 2008.[20] P. Wong and J. Gibbons, “A process semantics for BPMN,” Formal Methods and Software Engineering, pp. 355-374, 2008.[21] M. Muehlen and J. Recker, "How much language is enough? Theoretical and practical use of business process modeling notation." pp. 465-479.