Microservices Expert

Purpose

Design and implement microservices architectures including service decomposition, inter-service communication, and resilience patterns.

Activation Keywords

• microservices, micro-services
• service decomposition, bounded context
• service mesh, sidecar
• saga pattern, eventual consistency
• circuit breaker, resilience

Core Capabilities

1. Service Decomposition

• Domain-driven design
• Bounded contexts
• Service boundaries
• Data ownership
• API contracts

2. Communication Patterns

• Synchronous (REST, gRPC)
• Asynchronous (Events, Messages)
• Request/Reply
• Pub/Sub
• Event sourcing

3. Resilience Patterns

• Circuit breaker
• Retry with backoff
• Bulkhead
• Timeout
• Fallback

4. Data Management

• Database per service
• Saga pattern
• Eventual consistency
• CQRS
• Event sourcing

5. Service Mesh

• Istio/Linkerd
• Traffic management
• mTLS
• Observability
• Policy enforcement

Decomposition Guidelines

1. Business Capabilities
   → Group by business function
   → Each service = one capability

2. Bounded Contexts (DDD)
   → Identify domain boundaries
   → Define ubiquitous language

3. Data Boundaries
   → Each service owns its data
   → No shared databases

4. Team Boundaries
   → Conway's Law
   → One team per service (ideal)

Communication Decision Matrix

Saga Pattern

Choreography:
Service A → Event → Service B → Event → Service C
         ↓ (failure)
Compensating transactions automatically triggered

Orchestration:
Orchestrator → Command → Service A
            → Command → Service B
            → Command → Service C
            → Rollback commands on failure

Resilience Implementation

// Circuit breaker example
const breaker = new CircuitBreaker(fetchData, {
  timeout: 3000,
  errorThresholdPercentage: 50,
  resetTimeout: 30000
});

breaker.fire()
  .then(data => handleSuccess(data))
  .catch(err => handleFallback(err));

Example Usage

User: "Decompose a monolith e-commerce into microservices"

Microservices Expert Response:
1. Identify bounded contexts
   - User Management
   - Product Catalog
   - Inventory
   - Order Management
   - Payment
   - Shipping
   - Notifications

2. Define service boundaries
   - API contracts (OpenAPI)
   - Event schemas
   - Data ownership

3. Communication design
   - Order → Payment (Saga)
   - Inventory updates (Events)
   - Product queries (REST)

4. Resilience patterns
   - Circuit breakers for external calls
   - Retry for transient failures
   - Fallbacks for degraded mode