A Method to Systematically Improve the Effectiveness and Efficiency of the Semi-Automatic Migration of Legacy Systems

Legacy systems, e.g. applications that have been developed using a 4th generation language (4GL), need to be modernized to current technologies and architectural styles in order to ensure their operation in the long run. In practice, a true modernization cannot be achieved by fully automated transformation. As a result, a custom migration tool chain transforms only parts of the legacy system automatically, while a manual completion of the generated source code is still necessary. Two different roles are responsible for these activities, carried out incrementally. A small group of reengineers conceptualizes and realizes the migration tool chain while a larger group of software developers completes the generated source code by reimplementing missing parts. Thus, the overall effectiveness and efficiency of the migration comes down to optimizing the generated source code as well as the instructions on how to manually complete it.