A large banking institution operates a mission-critical, high-transaction, mainframe-based core banking system on-premises. They aim to modernize this system by gradually migrating components to AWS while maintaining full transactional consistency and immediate rollback capability for any migrated component. The migration must ensure that both on-premises and cloud components can process transactions concurrently during the transition phase. Which migration pattern supports this requirement for gradual modernization with stringent consistency and rollback needs?
- ADatabase Migration Service (DMS) for a one-time migration of the mainframe database to Amazon RDS.
- BLift and Shift (Re-hosting) the entire mainframe application to EC2 instances.
- CBig Bang Migration, moving all components to AWS simultaneously during a single maintenance window.
- DStrangler Fig Pattern, by incrementally replacing functionalities with new AWS services.
Show answer & explanationAnswer & explanation
Correct answer: D. Strangler Fig Pattern, by incrementally replacing functionalities with new AWS services.
The Strangler Fig Pattern allows for gradual modernization by incrementally replacing functionalities of a monolithic application with new services. A facade routes requests to either the old or new system, enabling concurrent operation, consistency, and easy rollback, which is ideal for a mission-critical mainframe with strict requirements.
Why the other options are wrong
- A. DMS is for database migration, not for gradually modernizing a complex application with transactional consistency across hybrid components.
- B. Lift and Shift a mainframe is often not feasible or desirable due to its unique architecture and would not address the gradual modernization or concurrent processing needs.
- C. Big Bang Migration involves significant risk and downtime, directly contradicting the requirement for gradual modernization and immediate rollback capability.
Strangler Fig Pattern
The Strangler Fig Pattern is a software development pattern where a new system is built around an old system, and the new system gradually takes over the functionality of the old system until the old system can be retired. It's used for safely refactoring large, complex monolithic applications.
- Gradual replacement of functionality
- Reduces risk of big-bang rewrites
- Enables concurrent operation of old and new systems
- Often uses a facade or proxy to route traffic
Memory trick: Strangler Fig: Slowly choke the old, nurture the new.