Legacy Modernization

Modernize legacy systems incrementally using strangler fig pattern, facade layers, and strategic refactoring.

Instructions

1. Assessment: Understand current system behavior, pain points
2. Strangler Fig: New services alongside old monolith; gradually redirect traffic
3. Facade Layer: Wrap legacy with modern API without changing internals
4. Refactoring: Extract modules one at a time to modern stack
5. Incremental Value: Each phase delivers business value

Anti-Patterns

• Rewrite Everything: "Let's rebuild it right." Result: 2-3 years, misses market. Guard: Keep old system running while new builds alongside.
• No Business Alignment: Modernize things users don't care about. Guard: Modernize parts causing business pain first.

Further Reading