Rapid system understanding: Two COBOL case studies

Rapid system understanding is required in the planning, feasibility assessment and cost estimating phases of a system renovation project. In this paper; we apply a number of analyses on two large legacy COBOL systems from the banking field. We describe the analyses performed, and discuss possible interpretations of these analyses. Lessons learned include: (1) The open architecture adopted is satisfactory, and can take advantage of a wide range of understanding tools available; and (2) To handle inter-system variability effectively the flexibility of lexical analysis is required.