1. Business logic preservation requires expertise in both old and new paradigms.
The most dangerous migrations are those where the team understands the destination technology but not the origin.
2. Testing must be exhaustive, not representative. When migrating critical business logic, testing a few scenarios isn't enough—you need to validate every possible path through the code.
3. Performance can't be an afterthought.
The architecture of modern distributed systems fundamentally differs from legacy mainframes, requiring careful consideration of how logic flows through the system.
4. Documentation is your future-proofing strategy.
We created comprehensive documentation mapping the old logic to new implementations, ensuring the client wouldn't face the same archaeology expedition during their next migration.