Software Engineering Institute Carnegie Mellon

Incremental Modernization for Legacy Systems

Santiago Comella-Dorda
Grace Lewis
Pat Place
Dan Plakosh
Robert Seacord

Technical Note
CMU/SEI-2001-TN-006

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This report shows an objective technique for developing an incremental code-migration strategy for large legacy Common Business-Oriented Language (COBOL) systems. Specifically, it describes a case study that involves the modernization of a large Supply System (SS). The system consists of approximately 2 million lines of COBOL code operating in a mainframe environment.

The SEI developed the System Analysis and Migration (SAM) tool to generate a code migration strategy based upon legacy system analysis data. SAM considers a set of factors that includes minimizing scaffolding code (code that is discarded before the completion of the project), balancing iterations, and grouping related functionality.