Comprehending the Knowledge Stored in Aged Legacy Systems to Improve Their Qualities with a Renewal Process

This study describes the application of a renewal process to a very old legacy system working in the banking environment. The term renewal process refers to a combination of reverse engineering and restoration processes. The latter, similar to restructuring but taking account of the semantics of the components to be restructured, is better explained in the paper. Judged from the maintainer’s point of view, the main result of the case study described is that the renewal process renders the system easier to understand, so that the effort required to improve its quality can then be tailored to the benefits aimed at, even on a very old system. This case study had other spin-off benefits, providing guidelines for analyses to be made during the reverse engineering process in order to reduce the size of the system to be renewed and to extract the knowledge stored so as to understand and improve the existing application. It also made it possible to draw a distinction between the restoration process and those of reverse engineering and reengineering and, finally, pointed out the need to carry out reverse engineering even on systems which will certainly require reengineering.