Evolution and Migration of Information Systems

Abstract

Abstract Modernisation of information systems is a fundamental but sometimes neglected aspect of conceptual modelling. Themanagement of evolution, migration and refinement and the ability for information systems to deal with modernisation is an essential component in developing and maintaining truly useful systems that minimise service disruption and down time and maximise availability of data and applications.Many approaches to handling evolution and migration have been pro- posed in various areas of data management. Most of them are rather informal de- scriptions of the project management of either evolution management or migration management. Typical problems that have been considered are modelling and man- agement of evolution and migration; handling of changes and versioning; managing information system upgrades and schema changes; semantics of modernisation in time and space; handling changes in metadata, schema evolution, migration and versioning; change detection, monitoring and mining. This chapter provides a systematic inside look at the first two problems.We show thatmigration and evolution are interwoven aspects. Threemigration strategies (big bang, chicken little, butterfly) can be based on systematic evolution steps. Evolution steps use the theory of model suites. An information system is specified by models such as the database structure model, the view model, the functionality model and the interaction model. Model suites thus support the co-evolution of models during system evolution and migration. We restrict migration and evolution to model as- pects. The theory, technics and methodology can, however, be extended to database or information base evolution and migration by the derivation of corresponding sup- port functions based on mappings among the models.