Explain the 'Onion Architecture'.
Updated Apr 28, 2026
Short answer
An architectural pattern that places the domain model at the center and uses dependency inversion to point dependencies inward.
Deep explanation
Middle-tier architecture often deals with reliability. Using a Circuit Breaker prevents a cascading failure where one slow service bogs down the entire system. Onion architecture ensures the core business logic remains independent of the database or external APIs.
Real-world example
A payment gateway middleware that retries a transaction only if it hasn't been processed yet (Idempotency).
Common mistakes
- Mixing business logic directly into the middleware, making it hard to test the core domain.
Follow-up questions
- How does a 'Sidecar' pattern relate to middleware?