Very Large Information System Challenge

Abstract

This chapter introduces the notion and the properties of a very large information system. Complexity is one key property of such systems. The source and the consequences of complexity are elaborated. The complexity trap is introduced which leads a very large information system over the years to become unmanageable, i.e. delivering less and less business value per investment and becoming less and less modifiable. The complexity trap is shown to be an unavoidable consequence of opportunistic evolution of very large information systems. Alternative evolution strategies of system replacement and of greenfield approach are demonstrated to be applicable only in very specific situations, such as mergers. The only successful and sustainable evolution strategy for very large information systems is managed evolution. Managed evolution is introduced and its context, motivation, paradigms and elements are described as a tour d'horizon. The individual topics are refined in the following chapters of the book.