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Experiences in Migrations of Legacy Systems

November 2015 Presentation
William G. Wood, Michael J. Gagliardi, Philip Bianco

This presentation describes a rational way for modernizing a legacy system using system architectural concepts to develop architectural options, create a scorecard, apply the scorecard, and present the results with recommendations to decision makers.

Publisher:

Software Engineering Institute

Abstract

Many legacy systems were built decades ago using the technologies available at the time and have been operating successfully for many years. But they suffer from being built from components that are becoming obsolete, high licensing costs for COTS components, awkward user interfaces, and business processes that evolved based on expediency rather than optimality. In addition, new software engineers familiar with current technology are unfamiliar with the domain; documentation is scarce and outdated; the business rules are likely to be embedded in the code, which is written in an obsolete language using obsolete data structures; and the cadre of aging domain experts maintaining it is unfamiliar with newer technologies.

There are a number of optional large-grained approaches to modernizing a legacy system. We propose a rational way of using system architectural concepts to develop architectural options, create a scorecard, apply the scorecard, and present the results with recommendations to decision makers.