Strangler Pattern

What is the Strangler Pattern?

The Strangler Pattern is a software development technique used to incrementally modernize or replace a legacy system with a more modern architecture, like composable or headless.

The Strangler Pattern is employed when an organization wants to migrate from an existing system to a new system without disrupting the entire business or taking on a high-risk rip-and-replace approach. It is particularly useful when dealing with large, monolithic applications that are difficult to replace all at once.

‍What does the Strangler Pattern Involve?

The Strangler Pattern generally involves the following steps:

1. Identify the boundaries: Identify the individual components or modules within the legacy system that can be extracted or replaced independently, and then build a hierarchy of priority to decide which components need to be replaced first to deliver the highest impact. 

2. Create a façade: Build a new system or module that acts as a wrapper around the existing system. This wrapper intercepts incoming requests and decides whether to handle them internally or delegate them to the legacy system.

3. Incremental replacement: Over time, start developing new modules or services that gradually take over the responsibilities of the legacy system. These new components are integrated with the wrapper and communicate with the legacy system as needed.

4. Retire the legacy system: As more and more functionality is migrated to the new system, the legacy system becomes less critical. Eventually, the legacy system is phased out entirely, and the new system takes its place.

The Strangler Pattern allows for a gradual and controlled transition from an old system to a new one. It reduces the risks associated with a complete system rewrite, such as downtime, data migration challenges, and user adoption issues. Additionally, it enables organizations to leverage modern technologies while minimizing disruption to the business operations.