19th Australasian Conference on Information Systems Integrated Modeling of Business Processes and Rules 3-5 Dec 2008, Christchurch zur Muehlen, Indulska & Kittel Towards Integrated Modeling of Business Processes and Business Rules
Michael zur Muehlen Stevens Institute of Technology Hoboken, NJ, USA Email: Michael.zurMuehlen@stevens.edu
Marta Indulska University of Queensland Brisbane, Australia Email: m.indulska@business.uq.edu.au Kai Kittel University Freiburg Freiburg i.Br., Germany Email: kittel@iig.uni-freiburg.de Abstract While business process models describe business operations in a procedural form, business rules are typically expressed in a declarative fashion. Previous studies have demonstrated that both approaches are complementary as they address distinct aspects of organizational practices. However, both approaches share areas of overlap that allow for the linkage of rule bases and process models. Current technology offerings allow for the pragmatic invocation of rule engines from business process management systems, but an integrated procedure model is lacking that guides modelers when to model organizational aspects as rules or processes and in which order to develop the separate artifacts. The research presented here aims to address this gap by presenting a decision framework for process and rule modeling, and an initial procedure model for integrated modeling with the two approaches. Keywords Business process modeling, business rule modeling, business process management, procedure model INTRODUCTION Managing and improving processes has been named the number one priority of CIOs for five years in a row (Gartner Group, 2005; 2006; 2007; 2008). The renewed focus on organizational processes is motivated by two objectives. On the one hand, economic conditions force organizations to continually search for ways to increase the efficiency of their operations, which is achieved through the reengineering and streamlining of processes with a focus on performance. On the other hand, the increased complexity of the extended enterprise, through new technologies and cross-enterprise information systems, forces organizations to maintain standardized operations and realize economies of scale. To this end, many organizations turn to industry best practices and reference models in areas that do not constitute a competitive advantage. In a similar fashion, the documentation and enforcement of business rules has gained interest in recent years for two reasons. On the one hand, increasing regulatory oversight in the wake of corporate scandals and compliance and privacy breaches has led organizations to define clear constraints under which they can operate. This area of concern is called Governance, Risk and Compliance (GRC). To document and enforce these constraints, many organizations are using Business Rules Engines. On the other hand, organizations are interested in enabling flexibility in their information systems infrastructure through the automated evaluation of its business context (e.g., market conditions or environmental data) and the subsequent initiation of actions that are appropriate in the detected context. This increased interest leads to the development of automated sense-and-respond operations and helps in the streamlining of decision-making. Software that provides support for decision trees and automated reasoning is applied in these circumstances. Both Business Process Management and Business Rule Management are thus approaches that focus on the improvement of organizational efficiency and effectiveness, but as technologies they have evolved separately. There are few examples of integrated systems. For example, Pegasystems’ Pega Rules Process Commander product natively combines a sophisticated business rules development environment with a business process modeling context (Pegasystem Inc., 2008). Other Business Process Management System vendors have partnered with or acquired Business Rules technology vendors to complement their process management capabilities with

19th Australasian Conference on Information Systems Integrated Modeling of Business Processes and Rules 3-5 Dec 2008, Christchurch zur Muehlen, Indulska & Kittel
the ability to document rules. In the other direction, however, Business Rules Engines vendors have made little attempts at adding process support to their products, which supports the view that processes may serve as the primary integration vehicle in this context. At the conceptual level, the Business Process Modeling Notation represents an emerging standard for the graphical documentation of processes (OMG, 2008). It contains several symbols that represent integration points between a graphical process and a rule base: A complex gateway can be employed to reflect the use of business rules to determine branching conditions in a process. A rules event can be used to reflect the reaction to a particular condition, akin to Event-Condition-Action (ECA) rules. However, the BPMN specification does not provide any guidance as to how these rules could be identified or captured. The lack of guidance is confirmed in practice, with a recent empirical study finding that organizations have difficulties in adequately modeling business rules with BPMN (Recker et al., 2006). In summary, while rules and processes address related organizational concerns, their documentation and enforcement are treated as largely separate subjects. What is missing is an integrated procedure model that allows business analysts to simultaneously address rules and processes, separate them where necessary and re-integrate them where appropriate. The work presented in this paper addresses this area in that it presents a decision framework for the modeling of various aspects as either business rules or business process elements, and an initial procedure model for the integrated modeling of rules and processes. The remainder of this paper is structured as follows: In the next section we compare and contrast business process-oriented and business rule-oriented approaches to organizational modeling, and present related work on the integration of the two approaches. The following section presents a decision framework that can be used to guide the choice of modeling an organizational aspect as either a business rule or a business process component. Given that a modeling scenario is likely to incorporate both business rules and business process components, next, we present consolidated guidelines for process and rule modeling, followed by the procedure model for integrated business process and business rule modeling in the subsequent section. We conclude the paper with a summary, a discussion of limitations and an outlook on future work. RELATED WORK While, to our knowledge, no procedural guidelines for the integration of rule- and process-based modeling approaches have been published, our research in this area is informed by a number of related fields. Accordingly, in the following subsections we present a discussion of business rules, business processes, and existing attempts at their integration, as well as published guidelines for the two modeling approaches.
Business Rules A business rule is a statement that aims to influence or guide behavior and information in an organization (Steinke and Nikolette, 2003). The Semantics of Business, Vocabulary and Rules standard of the Object Management Group distinguishes between structural and operational business rules (OMG, 2006). While structural rules are used to express relationships and constraints among data elements, operational rules are used to guide and constrain the behavior of individuals. Two examples for structural rules are integrity and derivation rules (Wagner, 2005). Integrity rules express constraints and define the acceptable relationship between data elements. For example: each order must contain at least one line item. Derivation rules define the validity of facts and can be used to infer new facts based on known facts. For example: A customer with an annual order volume of more than $250,000 is a frequent buyer. John Doe has ordered products worth $300,000. As a conclusion, John Doe is a frequent buyer. Examples of operational rules are reaction rules, production rules, and transformation rules (Wagner, 2005). Reaction rules (aka ECA rules) specify a trigger that activates the evaluation of the rule, a condition that is evaluated, and a subsequent activity that will be carried out if the specified condition is met; For example: On receipt of an invoice the amount of the invoice is evaluated. If the invoice amount is more than $5,000 a manager has to review it. Production rules (also known as condition, action rules) are similar to reaction rules, but do not specify a particular circumstance in which the evaluation takes place; For example: if there are no defects in the last 10 widgets, the entire batch is quality approved. Transformation rules restrict the state changes of objects; For example, an employee’s age can change from 30 to 31, but not from 31 to 30. Business rule modeling languages are typically based on formal logic and have strong and precise expressive power (McBrien and Seltveit, 1995). In general, they belong to the declarative modeling category in that they focus on specifying what is required to take place, rather than how something is accomplished.