COBOL to Java and Newspapers Still Get Delivered

TL;DR

This paper reports on migrating a legacy COBOL-based newspaper delivery system to Java on Linux, highlighting the process, challenges, and lessons learned from ensuring functional equivalence and maintaining the modernized application.

Contribution

It presents a detailed experience report on automated code translation, data migration, and testing strategies for modernizing a critical enterprise application.

Findings

Achieved functional equivalence between legacy and modernized systems

Identified key testing challenges in migration projects

Gained insights on operational maintenance and knowledge transfer

Abstract

This paper is an experience report on migrating an American newspaper company's business-critical IBM mainframe application to Linux servers by automatically translating the application's source code from COBOL to Java and converting the mainframe data store from VSAM KSDS files to an Oracle relational database. The mainframe application had supported daily home delivery of the newspaper since 1979. It was in need of modernization in order to increase interoperability and enable future convergence with newer enterprise systems as well as to reduce operating costs. Testing the modernized application proved to be the most vexing area of work. This paper explains the process that was employed to test functional equivalence between the legacy and modernized applications, the main testing challenges, and lessons learned after having operated and maintained the modernized application in production over the last eight months. The goal of delivering a functionally equivalent system was achieved, but problems remained to be solved related to new feature development, business domain knowledge transfer, and recruiting new software engineers to work on the modernized application.