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18 W. van der Aalst et al.
Exercises

Exercise 1. Why is it important that a workflow specification language has a formal
syntax and semantics? Provide at least three reasons.

Exercise 2. Explain the difference between the notions of expressive power and
suitability in the context of a workflow specification language.

Exercise 3. Explain the value proposition of patterns.

Chapter Notes

The original founders of the Workflow Patterns Initiative were Wil van der Aalst,
Alistair Barros, Arthur ter Hofstede, and Bartek Kiepuszewski. The first paper
appeared in the CoopIS conference in Eilat in 2000 [7] and the main reference
appeared in the Distributed and Parallel Databases journal in 2003 [16]. Since
then there have been many additional contributors. Since 2005 Nick Russell has
been the main driver in developing workflow patterns for the data [225] and
the resource perspectives [222] as well as for exception handling [221]. He also
led the revision effort of the original control-flow patterns [224]. Marlon Dumas
and Petia Wohed have been involved in many patterns-based evaluations (see,
e.g., [84, 223, 262–265]). Nataliya Mulyar devoted her PhD work [178] to iden-
tifying additional patterns. The main reference site for the Workflow Patterns is
www.workflowpatterns.com. A book on the Workflow Patterns is expected to be
published by MIT Press in the near future.
An early influential book in the area of workflow management was the book by
Stefan Jablonski and Christoph Bussler [124]. Among others, a number of perspec-
tives were described for workflow management, some of which are referred to in
this chapter, though under different names. The book by Wil van der Aalst and Kees
van Hee [11] is a more recent book on workflow management and, among other
topics, discusses in depth the application of Petri nets in this area. Mathias Weske’s
book [260] discusses the original control-flow patterns, but also workflow nets and
YAWL, and, more generally, provides a treatment to the field of business process
management from a computer science perspective. Although it is impossible to pro-
vide an overview of workflow literature here, we would also like to mention the
workflow books by Leymann and Roller [150], Marinescu [157], zur Muehlen [174],
and Lawrence [146]. A recent overview of important topics can be found in the book
on process-aware information systems [82].
Patterns development became popular in computer science due to the work of
Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides [100] in the area of
software design patterns. Other examples of well-known patterns collections in soft-
ware analysis and design were developed by Gregor Hohpe and Bobby Woolf [120]
and by Martin Fowler [98].