DoD Legacy System Migration Guidelines
1 IntroductionDoD systems, like those of other large complex organizations, contain a substantial amount of software. It is important to acquire and evolve software so that it can be managed as an investment that grows in value rather than as a liability whose value depreciates over time.
Legacy systems have been developed over many years at a substantial cost. These legacy systems often represent a patchwork of mainframe, minicomputer, and desktop applications, both centralized and distributed, under dispersed control. They can be fragmented by geography, database incompatibilities, and corporate mergers. As a result, it is difficult to satisfy the need for these systems to represent enterprise assets rather than liabilities. Despite this difficulty, it is important to ensure the vitality of legacy system assets by protecting, managing, evolving, and modernizing them. Thus, the DoD has interests in the processes, methods, and tools available for migrating legacy systems to more desirable target systems, especially to modern architectures and product lines.
A previous report [Bergey 99] described a set of reasons why reengineering projects have failed. Two other works [Bergey 97], [Bergey 98] describe a structure and context for exploring disciplined approaches to systems evolution. This technical note develops a set of DoD legacy system migration guidelines based, in part, on the insights of these other works.
As discussed in the next section, some of the current guidelines are more relevant to development/system migration organizations, while others apply equally to acquisition organizations.
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