Towards a WPSL : a critical analysis of the 20 classical workflow control-flow patterns

In 2000, after a comprehensive survey of tools and techniques for workflow management, 20 control-flow patterns were identified [5] and made these available through www.workflowpatterns.com. Since then, many commercial and academic workflow management systems have been evaluated using these patterns. Moreover, standards such as BPEL and XPDL have been evaluated and these evaluations have triggered improvements in them. Although the 20 workflow patterns have proven to be useful, the selection of these patterns was done in an ad-hoc manner and the description of the patterns in natural language has been rather ambiguous. Therefore, we propose a more analytical approach using a new Workflow Pattern Specification Language (WPSL). WPSL is independent of any implementation language utilized by contemporary workflow management systems. In this paper, we analyze the 20 original workflow patterns using WPSL, discuss the different variants of the patterns, and use WPSL to capture the detailed semantics of existing workflow management systems