Legacy System Wrapping for Department of Defense Information System Modernization

摘要

This document explains the activities, benefits, problems, and issues in usingthe object-oriented technique of software wrapping to support the migration from legacy information systems to modernized systems. DoD legacy systems have obsolete technologies such as closed systems, stovepipe design, and outmoded programming languages or database systems. Software wrapping is used to create an interface around data, individual modules, subsystems, or whole systems, allowing access to the entities in the original system. Examples of wrapping implementation and guidelines, using the Ada programming language (Ada 83), are given for functions or subprograms originally written in the Cobol, C, Fortran, and Assembler. In addition, software wrapping is analyzed in the broader context of alternative migration strategies for a whole system. The unite-and-conquer strategy appears to be better suited to software wrapping, using a unified object model throughout progressive stages of migration, as compared to the other three strategies (divide-and-conquer, divide-and-wrap, one-short-rebuild).