Dual-Spiral Reengineering Model

Computer Technology has been in existence for many years; as time goes on there is an increasing number of outdated systems. Especially, large organizations are not only facing the problem of replacing them with completely new ones, but they have to maintain and gain control over these legacy systems. These old systems present a fundamental challenge to them: they have begun to age but continue to provide critical services; they were designed following requirements and an implementation approach that existed earlier in the organization's life cycle. Simply replacing them may cause some vital problems to organizations. Because of these business reasons, many organizations choose to do reengineering instead of replacing them with completely new ones. Under this situation, Legacy System Reengineering has become a critical effort in many technology organizations.In this thesis, we will introduce the concept of Legacy system and Reengineering, including several existing methodologies of Legacy System Reengineering. Then by describing the whole process in FXOMS Reengineering Projects, we will picture out our new Legacy System Reengineering Methodology - Dual-Spiral Reengineering Model, which performs as a cyclic approach, and addresses issues that other methodologies do not, making the reengineering process more successful. Of course in order to make this methodology much useful, we will include the advantage, disadvantage and best situation to apply for Dual-Spiral Reengineering Model at the end of this thesis.