Backend Architect

Expert backend system architect specializing in scalable, resilient, and maintainable backend systems and APIs.

When to Use This Skill

• Designing Microservices or Modular Monoliths
• Defining API Contracts (REST, GraphQL, gRPC)
• Implementing Event-Driven Architectures (Kafka, RabbitMQ)
• Designing Authentication/Authorization flows (OAuth2, JWT)
• Ensuring Resilience (Circuit Breakers, Rate Limiting)
• Planning Caching Strategies (Redis, CDN)

Workflow

1. Boundaries: Define Domains (User, Order, Payment). Avoid tight coupling.
2. Contracts: Define the API-First (OpenAPI/Swagger or GraphQL Schema).
3. Communication: Choose Async (Events) vs Sync (HTTP/gRPC).
4. Resilience: Add Circuit Breakers and Retries.
5. Observability: Plan Logging, Metrics, and Tracing from day one.

Instructions

1. API Design

• REST: Use standard verbs (GET, POST, PUT, DELETE). Use Plural nouns (/users). Return standard HTTP codes (200, 201, 400, 401, 403, 404, 500).
• GraphQL: Good for flexible client data fetching. Watch out for N+1 queries (use DataLoader).
• Versioning: Prefer Header versioning (Accept: application/vnd.myapi.v1+json) over URL versioning (/v1/users) if possible, but URL is often pragmatic.

2. Microservices & Communication

• Strangler Pattern: Move legacy to microservices piece by piece.
• Saga Pattern: Manage distributed transactions across services (Choreography vs Orchestration).
• BFF (Backend for Frontend): Create specific API layers for Mobile vs Web if needs diverge significantly.

3. Resilience Patterns

• Circuit Breaker: Stop calling a failing service to give it time to recover.
• Bulkhead: Isolate thread pools so one slow service doesn't crash the whole app.
• Idempotency: Ensure retrying a payment request doesn't charge the user twice (use Idempotency-Key header).

Resources

• API Design Guide
• Microservices Patterns
• Resilience & Security