Techniques and methodologies for the migration of legacy systems to object-oriented platforms

Over the past years it has become evident that the benefits of object orientation warrant the design and development of reengineering methods that aim to migrate legacy procedural systems to modern object oriented platforms. However, most of the research in this direction focuses on the extraction of an object model from the legacy procedural code without taking into account quality requirements for the target migrant system.; This thesis presents a reengineering framework that allows for quality requirements of the target system to be modelled as soft-goals, and transformations to be applied selectively towards achieving specific quality requirements for the target system. In this context, the migration process is denoted by a sequence of transformations each one of which alters the state of the system being migrated. A state transition system and the Viterbi algorithm are used to identify the optimal sequence of transformations that can be applied at any given state of the migration process. To deal with large software systems, a system can be decomposed into a collection of work areas. The reengineering framework can be applied incrementally to each of the work areas. Furthermore, a technique that allows for the integration of the migrant systems with other third party applications in a Web enabled environment is presented. A reengineering toolkit to automatically migrate a set of open source procedural systems, such as Apache, Bash and Clips to an object oriented platform has been developed using the theory presented in this thesis. The obtained results demonstrate the effectiveness and usefulness of the proposed incremental quality driven migration technique.