Strangler.md

Strangler

• Motivation
• Solution
  • Concepts
  • Implementation
• Pros & Cons
  • Pros
  • Cons
• Consideration
• When To Use
• References

Motivation

• the big-bang (cut-over) rewrite of the legacy application is extremely risky and will likely end in failure.

Solution

Concepts

• Incrementally refactor the legacy application to the new application and services.

Implementation

• General advices
  • Migrate the high-value areas of the legacy application to the new application first.
  • Avoid making widespread changes to the legacy applicaton when migrating to the new application.
  • Design the new application in such a way as to make it easier for it to be strangled (refactored) in the future.

Pros & Cons

Pros

• Reduce the risk of the big-bang (cut-over) rewrite of the legacy application.
• Demonstrate the value of refactoring the legacy application early and often.

Cons

Consideration

Topic	Consideration	Possible Solution Options
Collaboration	How to collaborate between the legacy application and the new application during the migration.	Implementing an Anti-Corruption Layer (ACL) between the legacy application and the new application. Create a strangler façade that route requests either to the legacy application or the new application.

When To Use

References

• Book: Chris R.(2018). Chapter 13 Refactoring to microservices, Microservices Patterns (pp. 428-471). Manning Publications
• Web Article: Pattern: Strangler application | https://microservices.io/patterns/refactoring/strangler-application.html
• Web Article: StranglerFigApplication | https://martinfowler.com/bliki/StranglerFigApplication.html
• Web Article: Legacy Application Strangulation : Case Studies | https://paulhammant.com/2013/07/14/legacy-application-strangulation-case-studies/
• Web Article: Strangler pattern | https://docs.microsoft.com/en-us/azure/architecture/patterns/strangler