Jussi Vanhatallo



In his dissertation, Jussi Vanhatalo presents a decomposition technique for business process models. This research has already received both academic and industrial recognition.

A workflow graph is a model for the control flow of a business process. In his thesis, Jussi Vanhatalo studies the problem of workflow graph parsing, that is, finding the structure of a workflow graph. More precisely, parsing decomposes a workflow graph into a hierarchy of sub-workflows that are subgraphs with a single entry and a single exit of control. Such a decomposition is the crucial step, for example, to translate a process modeled in a graph-based language such as Business Process Modeling Notation (BPMN) into a process modeled in a more structured language such as Web Services Business Process Execution Language (WS-BPEL). For this and other applications, it is desirable that the decomposition be unique, modular and as fine-grained as possible, where modular means that a local change of the workflow graph can only cause a local change of the decomposition. This thesis presents a decomposition that is unique, modular and more fine-grained than in previous work. The decomposition is called the refined process structure tree. It is based on and extends similar work for sequential programs by Tarjan and Valdes [ACM POPL ’80, 1980, pp. 95-105]. The refined process structure tree was introduced in a research paper [14] that received the best paper award of the 6th International Conference on Business Process Management.

The refined process structure tree is already adopted in commercial software products. The decomposition technique is implemented in the IBM WebSphere software products, where it is used, for instance, to speed up control-flow analysis of a process model. The decomposition is also useful in many other applications, such as, refactoring a process model, comparing and merging process models, and pattern-based editing of process models.

Jussi Vanhatalo successfully defended his thesis at University of Stuttgart in July 2009.