An Incremental Approach to the Analysis and Transformation of Workflows Using Region Trees

Abstract

The analysis of workflows in terms of structural correctness is important for ensuring the quality of workflow models. Typically, this analysis is only one step in a larger development process, followed by further transformation steps that lead from highlevel models to more refined models until the workflow can finally be deployed on the underlying workflow engine of the production system. For practical and scalable applications, both analysis and transformation of workflows must be integrated to allow incremental changes of larger workflows. In this paper, we introduce the concept of a region tree (RT) for workflow models that can be used as the central data structure for both workflow analysis and workflow transformation. An RT is similar to a program structure tree and imposes a hierarchy of regions as an overlay structure onto the workflow model. It allows an incremental approach to the analysis and transformation of workflows, and thereby, significantly reduces the overhead because individual regions can be dealt with separately. The RT is built using a set of region-growing rules. The set of rules presented here is shown to be correct and complete in the sense that a workflow is region-reducible as defined through these rules if and only if it is semantically sound.

Understanding Business Process Models: The Costs and Benefits of Structuredness

“…Later, Liu and Kumar [15] presented an alternative taxonomy of unstructured process models and sketched a method to transform some types of unstructured models into structured versions. Different transformation strategies were also illustrated in [18] and an alternative classification of (unstructured) process models was proposed in [9]. A method specifically tailored to untangling unstructured cyclic models and transforming them into structured BPEL models is presented in [10,12].…”

Analysis and Transformation of Behavioral Models Containing Overlapped Patterns.

“…All structurally sound separable process models are semantically sound [9]. The proof is fairly easy.…”

“…We assume models to be in the pinset normal form. This allows us to avoid the distinction between an activity and a region as it was needed for the approach in [9]. Figure 1.…”

“…In [9], we proposed an algorithm that performs analysis and transformation of graphical process models incrementally and fully automatically, and also claimed that it is complete. A workflow is first decomposed into a tree of single-entry-single-exit regions using the approach described in [10] that is linear in time.…”

“…The rules used in [9] fall in three categories. One set of rules handles the sequential single-entry-single-exit regions, i.e., those regions with only or-logic.…”