Decision model for legacy systems

Legacy systems pose major problems for industry-existing software seems so difficult and expensive to change quickly to keep up with the needs of business. The authors firstly summarise the general problems with modifying existing software-termed software maintenance-and then address the problems of legacy systems. They show that one of the major difficulties is trying to decide rationally among very different options, ranging from discarding the old software completely, through reverse engineering, to freezing it, or outsourcing. A novel two-phase model is presented to assist organisations in making decisions about legacy systems. The first phase, often neglected, is to model business strategy from a top-down perspective, involving many stakeholders. This is then used as input to a technical phase, where solutions are evaluated according to their ability to meet the objectives identified in phase one