Integration between systems has always been difficult; there is little systematic reuse of assets between systems; and new software quickly becomes a liability. To provide for greater reuse, a number of organizations have recently begun implementing software product lines that permit economies of scale and the capability to manage software as an enterprise investment.
The emerging focus on software architectures and product lines has led to an emphasis on the evolvability of software systems. Systems with a well-conceived architecture allow the software to interact across well-defined interfaces without regard for internal implementation details. However, most product lines start with legacy systems that need to be updated to enable them to interact as well-defined components. Although it is possible to update legacy systems through reverse engineering, these techniques are costly. They also usually focus at the code level, and as a result do not usually provide leverage for updating to modern architectures. However, recent architectural extraction techniques [Reconstructing Software Architecture from Available Evidence] provide a basis for extracting the as-built architecture from the existing code, and using this information as a foundation for further evolution.
In conjunction with the architectural extraction work, conceptual "horseshoe" model have been developed by Steven Woods [HorseShoe Model] that distinguishes different levels of reengineering analysis and provides a foundation for transformations at each level, especially for transformations to the architectural level. This model describes the rich set of technical choices that reengineers make. However, because of its technical focus, it has not been accessible to decision makers in a form that can assist them in deciding on complex options regarding the future of their legacy systems.
In this articles, and in a few succeeding ones, the horseshoe model has been taken as a starting point and a structured and accessible vehicle is proposed for making informed choices in a variety of real world situations. This method, "Options Analysis for Reengineering" (OAR) is a reengineering decision aid, grounded in the technical underpinnings of the horseshoe model. It provides a structured and coherent method for making technical, organizational, mission, and programmatic choices in practical reengineering decision making.
References
"Options Analysis for Reengineering (OAR): Issues and Conceptual Approach", by John Bergey, Dennis Smith, Nelson Weiderman and Steven Woods.
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