Backend Engineering — Introduction¶
Overview¶
Backend engineering turns business rules into reliable services: APIs that clients call, data that outlives requests, and operational properties like security, scalability, and observability.
Why This Exists¶
Products depend on servers that compose databases, caches, queues, and third parties. This section aligns language-agnostic concepts you will see in every mature stack.
How It Works¶
Topics include REST API design, Authentication, Microservices, Caching, Background jobs, and API scalability.
Architecture¶
flowchart LR
Client --> API[API layer]
API --> Auth[AuthZ/AuthN]
API --> DB[(Database)]
API --> Cache[(Cache)]
API --> Q[Queue]
Key Concepts¶
Operational mindset
Features ship; incidents teach. Design for logs, metrics, traces, safe deploys, and rollbacks from day one—not as an afterthought.
Code Examples¶
Authenticate -> Authorize -> Validate input -> Execute use case -> Persist -> Emit events -> Respond
Interview Questions¶
What is the difference between authentication and authorization?
Authentication establishes identity; authorization decides whether that identity may perform an action on a resource.
Name three ways to scale a read-heavy API.
Caching, read replicas, and materialized views or denormalized read models—each with consistency trade-offs.
Practice Problems¶
- Sketch OpenAPI for a resource with pagination and filtering
- Identify failure modes in a synchronous chain of three internal HTTP calls