Microservices Patterns

Service decomposition, communication, resilience, and orchestration patterns.

Service Decomposition

Pattern	Description	Use When
Domain-Driven	Align services with bounded contexts	Complex business domains
Data-Ownership	Service owns its data store	Data isolation required
Team-Aligned	One service per team	Large organizations

Communication Patterns

Sync: HTTP/gRPC

```yaml

API Gateway routing

routes:

• match: { prefix: /orders } route: { cluster: order-service }
• match: { prefix: /users } route: { cluster: user-service } ```

Async: Message Queue

``` Producer → Exchange → Queue → Consumer (Topic) (DLQ on failure) ```

Use async for: event propagation, eventual consistency, load leveling.

Resilience Patterns

Circuit Breaker

```typescript // Example with opossum const breaker = new CircuitBreaker(fetchUserProfile, { timeout: 3000, errorThresholdPercentage: 50, resetTimeout: 30000, }); ```

Retry with Backoff

```typescript async function retryWithBackoff(fn, maxRetries = 3) { for (let i = 0; i < maxRetries; i++) { try { return await fn(); } catch (e) { await sleep(Math.pow(2, i) * 1000); } } throw new Error('Max retries exceeded'); } ```

Data Patterns

Pattern	Consistency	Complexity	Use When
Saga (orchestration)	Eventual	High	Complex multi-service transactions
Saga (choreography)	Eventual	Medium	Simple event chains
Event sourcing	Eventual	High	Audit trail, time travel
Shared database	Strong	Low	Anti-pattern, avoid

API Gateway

Tools: Kong, AWS API Gateway, Envoy, NGINX.

Responsibilities: routing, auth, rate limiting, request transformation, load balancing.

Observability Stack

• Distributed tracing: Jaeger / Tempo
• Metrics: Prometheus + Grafana
• Logs: ELK / Loki
• Service mesh: Istio / Linkerd (adds mTLS, traffic management)

Related Skills

• backend-architect — single-service architecture
• event-sourcing-architect — event sourcing patterns
• kubernetes-architect — deployment patterns
• deployment-engineer — CI/CD for microservices