YAWL: yet another workflow language

  • Authors:

  • W. M. P. van der Aalst;A. H. M. ter Hofstede

  • Affiliations:

  • Department of Technology Management, Faculty of Technology and Management, Eindhoven University of Technology, Eindhoven, The Netherlands and Centre for Information Technology Innovation, Queensla ...;Centre for Information Technology Innovation, Queensland University of Technology, Brisbane, Australia

  • Venue:
  • Information Systems
  • Year:
  • 2005

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Abstract

Based on a rigorous analysis of existing workflow management systems and workflow languages, a new workflow language is proposed: yet another workflow language (YAWL). To identify the differences between the various languages, we have collected a fairly complete set of workflow patterns. Based on these patterns we have evaluated several workflow products and detected considerable differences in their ability to capture control flows for non-trivial workflow processes. Languages based on Petri nets perform better when it comes to state-based workflow patterns. However, some patterns (e.g. involving multiple instances, complex synchronisations or non-local withdrawals) are not easy to map onto (high-level) Petri nets. This inspired us to develop a new language by taking Petri nets as a starting point and adding mechanisms to allow for a more direct and intuitive support of the workflow patterns identified. This paper motivates the need for such a language, specifies the semantics of the language, and shows that soundness can be verified in a compositional way. Although YAWL is intended as a complete workflow language, the focus of this paper is limited to the control-flow perspective.