This playbook codifies the migration patterns we have refined across dozens of COBOL/CICS-to-J2EE engagements. It is opinionated, battle-tested, and designed to be adapted to your specific landscape.
The Approach
Phase one is discovery: an automated parse of the entire codebase to build a dependency graph of programs, copybooks, JCL, and data stores. Without this graph, scope estimates are guesses.
"Modernization is less about technology and more about managing risk while sustaining the business."
— Arun Mehta, Modernization Director
What Works in Practice
Phase two is transformation. We favor automated translation for the bulk of business logic, with hand-tuned rewrites reserved for performance-critical or architecturally awkward modules.
Pitfalls to Avoid
Phase three is coexistence. A message-bridge layer keeps the legacy and target systems in sync during the cutover window, allowing function-by-function migration with full rollback capability.
Key takeaways
- Decompose monoliths incrementally rather than attempting a big-bang rewrite.
- Use parallel-run strategies to validate behavior before cutover.
- Pair legacy and modern teams to preserve institutional knowledge.
- Treat governance and observability as first-class deliverables.