Workflow Management: Models, Methods, and Systems

375 Pages·2002·9.513 MB·English

by  Wil van der Aalst, Kees van Hee

Cooperative Information Systems

Michael Papazoglou, Joachim W. Schmidt, and

John Mylopoulos, editors

Advances in Object-Oriented Data Modeling,
Michael P. Papazoglou, Stefano Spaccapietra, and
Zahir Tari, editors, 2000

Workflow Management: Models, Methods, and
Systems, Wil van der Aalst and Kees Max van Hee,
2002
Workflow Management

Models, Methods, and Systems

Wil van der Aalst and Kees van Hee
The MIT Press Cambridge, Massachusetts London,
England
This translation © 2002 Massachusetts Institute of Technology

Originally published under the title Workflow Management:
Modellen, Metho-den en Systemen, 1997, by Academic Service.

All rights reserved. No part of this book may be reproduced in any
form by any electronic or mechanical means (including
photocopying, recording, or information storage and retrieval)
without permission in writing from the publisher.

This book was set in Sabon on 3B2 by Asco Typesetters, Hong
Kong, and was printed and bound in the United States of America.

Library of Congress Cataloging-in-Publication Data

Aalst, Wil van der.

Workflow management / Wil van der Aalst,
Kees van Hee. p. cm. — (Cooperative
information systems)

Includes bibliographical references and index.

ISBN 0-262-01189-1 (he. : alk. paper)

1. Management information systems. 2. Production
management.
3. Workflow. I. Hee, Kees Max van, 1946- II. Title.
III. Series.
T58.6.A17 2002
658.5'1—dc21 2001042602
Contents

Series Foreword vii
Acknowledgments xi
Introduction xiii

1 Organizing Workflows 1
2 Modeling Workflows 31
3 Management of Workflows 75
4 Analyzing Workflows 99
5 Functions and Architecture of Workflow Systems 145
6 Roadmap for Workflow System Development 211
7 Sagitta 2000 Case Study 243
Appendix A: Workflow Theory 267

Appendix B: Workflow Modeling Using UML 293

Solutions to Exercises 305

Glossary 345

Bibliography 359

Index 365
Series Foreword

The traditional view of information systems as tailor-made, cost-intensive
database applications is changing rapidly. The change is fueled partly by a
maturing software industry, which is making greater use of off-the-shelf
generic components and standard software solutions, and partly by the
onslaught of the information revolution. In turn, this change has resulted in a
new set of demands for information services that are homogeneous in their
presentation and interaction patterns, open in their software architecture,
and global in their scope. The demands have come mostly from application
domains such as e-commerce and banking, manufacturing (including the
software industry itself), training, education, and environmental management,
to mention just a few.

Future information systems will have to support smooth interaction with
a large variety of independent, multi-vendor data sources and legacy
applications running on heterogeneous platforms and distributed infor-
mation networks. Metadata will play a crucial role in describing the contents
of such data sources and in facilitating their integration.

As well, a greater variety of community-oriented interaction patterns will
have to be supported by next-generation information systems. Such
interactions may involve navigation, querying, and retrieval, and will have
to be combined with personalized notification, annotation, and profiling
mechanisms. Such interactions will also have to be intelligently interfaced
with application software, and will need to be dynamically integrated into
customized and highly connected cooperative environments. Morever the
massive investments in information resources, by governments and
businesses alike, call for specific measures that ensure security, privacy, and
accuracy of their contents.
viii Series Foreword

All these are challenges for the next generation of information systems.
We call such systems Cooperative Information Systems, and they are the
focus of this series.

In layman terms, cooperative information systems are servicing a di-
verse mix of demands characterized by content—community—commerce.
These demands are originating in current trends for off-the-shelf soft-
ware solutions such as enterprise resource planning and e-commerce
systems.

A major challenge in building cooperative information systems is to
develop technologies that permit continuous enhancement and evolution
of current massive investments in information resources and systems.
Such technologies must offer an appropriate infrastructure that supports
not only development, but also evolution of software.

Early research results on cooperative information systems are becom-
ing the core technology for community-oriented information portals or
gateways. An information gateway provides a "one-stop shopping" place
for a wide range of information resources and services, thereby creating a
loyal user community.

The research advances that will lead to cooperative information system
will not come from any single research area within the field of infor-
mation technology. Database and knowledge-based systems, distributed
systems, groupware, and graphical user interfaces have all matured as
technologies. While further enhancements for individual technologies are
desirable, the greatest leverage for technological advancement is expected
to come from their evolution into a seamless technology for building and
managing cooperative information systems.

The MIT Press Cooperative Information Systems series will cover this
area through textbooks and research editions intended for the researcher
and the professional who wishes to remain up-to-date on current devel-
opments and future trends.

The series will present three types of books:

• Textbooks or resource books intended for upper level undergraduate
or graduate level courses;
• Research monographs, which collect and summarize research results
and development experiences over a number of years; and
• Edited volumes, including collections of papers on a particular topic.
Series Foreword ix

Authors are invited to submit to the series editors book proposals
that include a table of contents and sample book chapters. All submis-
sions will be reviewed formally and authors will receive feedback on their
proposal.

John Mylopoulos jm@cs. tor
Michael Papazoglou

onto. edu Dept. of Computer
[email protected]

Science University of
Tilburg University

Toronto Toronto, Ontario
INFOLAB

Canada
P.O. Box 90153

5000 LE Tilburg

Joachim W. Schmidt
The Netherlands

[email protected]
Software Systems Institute
Technische Universitat TUHH
Hamburg, Germany
Acknowledgments

This book was prepared in close cooperation with the workflow
groups at Deloitte & Touche Bakkenist, the Faculty of Mathematics
and Computing Science, and the Faculty of Technology Management at
Eindhoven University of Technology. The authors would like to thank
all (former) members and students of these groups, in particular Twan
Hasten, Silvia de Cast, Ernst Kleiberg, Selma Limam, Michel van Osch,
Jaap Rigter, Eric Verbeek, Marc Voorhoeve, Laurens Vrijnsen, Gerd
Wagner, and Jaap van der Woude. We would also like to thank Michiel
Bos and Niels van Kiel for helping us preparing the English version of
our book and Monique Jansen for proofreading the final version.

Special thanks are also due to our co-authors, Andre Blommers and
Peter van der Toorn, each of whom contributed a chapter. Last but not
least, we would like to thank the Dutch Tax Authority for permission to
use the Sagitta 2000 project as a case study for this book.

December 2000
Wil van der Aalst
Kees van Hee
Introduction

This book is about the management of business processes. This is cer-
tainly not a new topic. Since the beginning of the Industrial Revolution, it
has been written about from every possible point of view—economic,
sociological, psychological, accountancy, mechanical engineering and
business administration. In this book, we examine the management of
business processes from the perspective of computing, or—to put it more
broadly—of information technology. The reason is that information
technology has made huge leaps forward in recent years, resulting in
the creation of completely new ways of organizing business processes.
The development of generic software packages for managing business
processes—so-called workflow management systems (WFMS)—is par-
ticularly important in this respect.

Until recently, the golden rule was: "First organize, then computerize."
This implied that processes were developed with the implicit assumption
that the business process would primarily be managed by people. Then
an organizational structure would be developed under which groups of
people, or departments, were allocated particular tasks. Only then did
people consider whether computers—or rather, information systems—
could partially support, or even take over, the work. This approach does
not sufficiently examine the opportunities offered by information sys-
tems. We have now reached a turning point: we first design business
processes in a more abstract way, without considering implementation,
and then we design the information systems and the organization hand in
hand. In fact, we decide whether each task in a process should be per-
formed by an information system or a person.

There are still some problems with this depiction. First, the notion that
we can organize business processes differently using information systems
xiv Introduction

is not new. People have long done this with business processes whose
primary task is the processing of information. During the 1970s, serious
efforts were made to completely computerize the management of business
processes using information systems. This proved impossible with the
technology then available. Even today, and for the foreseeable future,
there are and will remain many tasks in the business process which can
only be performed by people. In reaction to the reckless attempts of the
1970s, the role played by information technology has been somewhat
restricted.

Information systems are used to reduce people's workload, particularly
in offices. By analyzing thoroughly what people in offices do—by asking
why they do it—the following information processing functions have
been identified: text writing, drawing, calculating, filing, and communi-
cating information. These analyses have led to the development of the
following products: word processors, drawing systems, spreadsheet sys-
tems, database systems and electronic-mail systems. All these systems are
generic in nature: they are not limited to a specific business application—
as, say, accounting systems are—and so are widely used. Thanks to
widespread distribution, this software is of high quality and relatively
cheap. (In fact, accounting systems are widely usable, but not as exten-
sively as word processors.)

Partly because of this development, the impact made by information
technology has increased enormously, which in turn has led to many
more people studying the possibilities presented by it. And this has
resulted in the "BPR wave." BPR stands for business process redesign (or
business process re-engineering) and is a method, for improving the
effectiveness and efficiency of business processes. BPR is based upon the
notion that, if full use is made of information technology, business pro-
cesses could be entirely different than at present. It therefore is wise to
redesign the current processes completely, in the way described above.
How business processes are organized is thus no longer the sole prerog-
ative of the organizational or business expert: the information technolo-
gist now also has a major role to play. This is a good thing, because the
information technologist is a developer of processes par excellence. After
all, every algorithm defines a process. Until recently, however, the role of
the information technologist was limited to the processing of information