Question

You are designing a new set of microservices that need to interact with external systems. How do you ensure loose coupling and resilience in this interaction?

Answer

I would implement design patterns to ensure loose coupling and resilience:

Circuit Breaker Pattern

Use a circuit breaker to handle external service failures and prevent cascading failures within the microservices. This ensures that temporary failures do not overwhelm the entire system.

Retry Pattern

Implement retries with exponential backoff for transient failures when calling external services. This prevents immediate failure and allows the external system time to recover.

Bulkhead Pattern

Isolate parts of the system (e.g., external service calls) in different pools or resources to limit the impact of failures in one area of the system on other parts.

API Gateway Pattern

Use an API Gateway to act as a single entry point for external clients. It can handle cross-cutting concerns like security, logging, rate-limiting, and versioning.