tomevault-io Microservices Patterns
Master microservices architecture patterns including service boundaries, inter-service communication, data management, and resilience patterns for building distributed systems.
When to Use This Skill
- Decomposing monoliths into microservices
- Designing service boundaries and contracts
- Implementing inter-service communication
- Managing distributed data and transactions
- Building resilient distributed systems
- Implementing service discovery and load balancing
- Designing event-driven architectures
Core Concepts
1. Service Decomposition Strategies
By Business Capability
- Organize services around business functions
- Each service owns its domain
- Example: OrderService, PaymentService, InventoryService
By Subdomain (DDD)
- Core domain, supporting subdomains
- Bounded contexts map to services
- Clear ownership and responsibility
Strangler Fig Pattern
- Gradually extract from monolith
- New functionality as microservices
- Proxy routes to old/new systems
See detailed guide: Service Decomposition
2. Communication Patterns
Synchronous (Request/Response)
- REST APIs
- gRPC
- GraphQL
Asynchronous (Events/Messages)
- Event streaming (Kafka)
- Message queues (RabbitMQ, SQS)
- Pub/Sub patterns
See detailed patterns: Communication Patterns
3. Data Management
Database Per Service
- Each service owns its data
- No shared databases
- Loose coupling
Saga Pattern
- Distributed transactions
- Compensating actions
- Eventual consistency
See detailed patterns: Data Management
4. Resilience Patterns
Circuit Breaker
- Fail fast on repeated errors
- Prevent cascade failures
Retry with Backoff
- Transient fault handling
- Exponential backoff
Bulkhead
- Isolate resources
- Limit impact of failures
See detailed implementations: Resilience Patterns
Quick Start
Basic Service Structure
from fastapi import FastAPI
app = FastAPI()
class OrderService:
"""Handles order lifecycle."""
async def create_order(self, order_data: dict) -> Order:
order = Order.create(order_data)
# Publish event for other services
await self.event_bus.publish(
OrderCreatedEvent(
order_id=order.id,
customer_id=order.customer_id,
items=order.items,
total=order.total
)
)
return order
@app.post("/orders")
async def create_order(order_data: dict):
service = OrderService()
return await service.create_order(order_data)
API Gateway Pattern
class APIGateway:
"""Central entry point for all client requests."""
async def call_order_service(self, path: str, method: str = "GET", **kwargs):
response = await self.http_client.request(
method,
f"{self.order_service_url}{path}",
**kwargs
)
return response.json()
async def create_order_aggregate(self, order_id: str) -> dict:
"""Aggregate data from multiple services."""
order, payment, inventory = await asyncio.gather(
self.call_order_service(f"/orders/{order_id}"),
self.call_payment_service(f"/payments/order/{order_id}"),
self.call_inventory_service(f"/reservations/order/{order_id}"),
return_exceptions=True
)
return {"order": order, "payment": payment, "inventory": inventory}
See detailed patterns: API Gateway
Service Decomposition Patterns
Break monoliths into microservices using business capabilities and DDD principles.
See detailed guide: Service Decomposition
Communication Patterns
Synchronous Communication
REST APIs with retry logic and timeouts.
from tenacity import retry, stop_after_attempt, wait_exponential
class ServiceClient:
@retry(
stop=stop_after_attempt(3),
wait=wait_exponential(multiplier=1, min=2, max=10)
)
async def get(self, path: str, **kwargs):
response = await self.client.get(f"{self.base_url}{path}", **kwargs)
response.raise_for_status()
return response.json()
See detailed patterns: Communication Patterns
Asynchronous Event-Driven
Event bus with Kafka for decoupled communication.
async def publish_event(event: DomainEvent):
await event_bus.publish(event)
async def subscribe_to_events(topic: str, handler: callable):
await event_bus.subscribe(topic, handler)
See detailed implementation: Event-Driven Architecture
Data Management Patterns
Saga Pattern
Manage distributed transactions with compensating actions.
class OrderFulfillmentSaga:
"""Orchestrated saga for order fulfillment."""
async def execute(self, order_data: dict) -> SagaResult:
try:
for step in self.steps:
result = await step.action(context)
if not result.success:
await self.compensate(completed_steps, context)
return SagaResult(status=SagaStatus.FAILED)
completed_steps.append(step)
return SagaResult(status=SagaStatus.COMPLETED)
except Exception:
await self.compensate(completed_steps, context)
See detailed implementation: Saga Pattern
Resilience Patterns
Circuit Breaker
Prevent cascade failures by failing fast.
class CircuitBreaker:
async def call(self, func: Callable, *args, **kwargs) -> Any:
if self.state == CircuitState.OPEN:
raise CircuitBreakerOpenError("Circuit breaker is open")
try:
result = await func(*args, **kwargs)
self._on_success()
return result
except Exception:
self._on_failure()
raise
See detailed implementations: Resilience Patterns
Best Practices
- Service Boundaries: Align with business capabilities
- Database Per Service: No shared databases
- API Contracts: Versioned, backward compatible
- Async When Possible: Events over direct calls
- Circuit Breakers: Fail fast on service failures
- Distributed Tracing: Track requests across services
- Service Registry: Dynamic service discovery
- Health Checks: Liveness and readiness probes
See detailed guide: Best Practices
Common Pitfalls
- Distributed Monolith: Tightly coupled services
- Chatty Services: Too many inter-service calls
- Shared Databases: Tight coupling through data
- No Circuit Breakers: Cascade failures
- Synchronous Everything: Tight coupling, poor resilience
- Premature Microservices: Starting with microservices
- Ignoring Network Failures: Assuming reliable network
- No Compensation Logic: Can't undo failed transactions
See detailed solutions: Common Pitfalls
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