Configuring Loopholes: Interactive Consistency Maintenance of Business Rules

Business rules are the core of information systems. They define under which conditions certain actions may, must not, or need to be taken. Business rules are often collected as such during analysis, but are frequently buried during implementation in different form of application code (within procedures, as pre- or postconditions, or as database triggers). Part of the conceptual design process is to make business rules explicit and associate them with activities of object types. Object-oriented design methods, such as UML, organise object types in pecialisation hierarchies. In the past, various consistency notions have been eveloped for specialising methods (co- and contra-variance), for specialising objectlife cycles (observation- and invocation-consistency), and for specialising active rules (database triggers) in object-type hierarchies. This paper complements these past research results by introducing an application-oriented perspective for the specialisation of business rules. Using the notion of "decision consistency", we introduce a specialization model for business rules that is aligned with commonly used principles in organizational contexts to guarantee consistency between decisions at a higher legislative level (e.g., European Union) and at a lower level (e.g., a member state).