W. van der Aalst et al. (Eds.): Business Process Management, LNCS 1806, pp 16-29, 2000
 Springer-Verlag Berlin Heidelberg 2000
Modeling Processes and Workflows
by Business Rules
Gerhard Knolmayer
1
, Rainer Endl
1,2
, Marcel Pfahrer
1,3
1
Institute of Information Systems, University of Bern,
Engehaldenstrasse 8, CH 3012 Bern, Switzerland
{knolmayer, endl, pfahrer}@ie.iwi.unibe.ch
2
igim ag, Felsenstrasse 88, CH 9001 St. Gallen, Switzerland
3
Urs Sauter + Marcel Pfahrer AG, Mettlenweg 7,
CH 2504 Biel, Switzerland
Abstract. This contribution describes a rule-based method for modeling
business processes and workflows. Business rules are defined as statements
about guidelines and restrictions with respect to states and processes in an orga-
nization. After introducing an extended Event-Condition-Action (ECA) nota-
tion, an approach for the refinement of business rules is developed in order to
achieve a consistent decomposition of the business processes. Thus, ECA rules
serve as an integration layer between different process modeling and
(workflow) specification languages. Finally, we propose an architecture of a
rule-oriented repository supporting the modeling and refinement process.
1 Introduction
Several methods and tools have been developed to describe business processes and
workflows. These methods and tools differ in their constructs, notation, ease of use,
and other aspects. Often different methods are employed at different stages of the de-
velopment process.
In this contribution we propose a rule-based methodology to provide a uniform
modeling approach at different abstraction levels. This approach suggests to transform
a rule-based description of a business process in one or several refinement steps into a
rule-based workflow specification. The (business) rules that underlie the business
process are first described in natural language. In subsequent steps these rules are
refined in a structured manner. This results in a set of structured rules representing the
business process at different abstraction levels. Comparisons and case studies
[KEPS97] show that this rule-based methodology has advantages compared to
established approaches like Petri-Nets [cf. Ober96] and Event-Driven Process Chains
[cf. Sche92]. Recently, business rules are often considered as a very important
component of modern information systems [cf., e.g., MWBG98; dPLL98]. Several
software and consulting companies focus their activities on business rules.
There are two kinds of relationships between business rules: First, there is a
relationship at the same abstraction level, establishing the control flow between the
components that are defined at this level. Second, we propose a hierarchical
relationship representing the derivation of business rules that are relevant at a lower

Modeling Processes and Workflows by Business Rules 17
abstraction level from higher-level rules. During the overall modeling process the
same basic constructs are used; these may be extended by additional constructs
according to the level of abstraction. The proposed approach should lead to a more
consistent modeling procedure than applying various methods at different abstraction
levels.
In a decentralized organization, a virtual enterprise, or in coordinating processes in
a supply chain often different methods and tools are employed for representing
processes and workflows. To support the development of coordinated process or
workflow models across enterprise boundaries or locations, a layer into which the
different (sub-)process models can be transformed and another layer from which the
specifications for different workflow tools may be derived, are highly desirable. We
suggest to use business rule layers for these descriptions (cf. Fig. 1) [cf. Knol98].
Stepwise Refinement of Business Rules
Universe of Discourse
Process Modeling
Method 1
(e.g. ARIS)
Process Modeling
Method 3
(e.g. Petri Nets)
Process Modeling
Method n
(e.g. ECAA)
Business Transactions
in Application Code
W F Specification
for commercial
available W FMS
(e.g. FlowMark)
Triggers and
Stored Procedures
of active DBMS
W F Specification
for Event Engine EvE

Business Rule Oriented Process Model
W F Specification for
Enterprise
Management Systems
(e.g. SAP R/3)
Process Modeling
Method 2
(e.g. BONAPART)
Business Rule Oriented Workflow Model

Additional
Information
Fig. 1. Business rules as integration layers.
The business rule approach can serve as an integration platform for different
process modeling techniques and different target systems that implement the
workflow or parts of them. For the representation of business rules we use the ECAA-
notation which is based on events, conditions, actions, and the selection construct; the
resulting constructs are enhanced with different constructs for representing static
components of business processes, i.e., organizational units, roles, actors, and entity-
relationship-models.
In order to maintain the dependencies between process and workflow models at
different modeling levels, it is helpful to store the business rules in a rule repository.