microservices-patterns

Microservices Architecture Patterns

Core Design Patterns

Designing resilient microservices requires managing distributed state, failures, and complex communication networks.

1. The Saga Pattern (Distributed Transactions)

In a microservices world, you cannot use ACID database transactions across multiple services. Instead, use Sagas.

• Choreography: Services publish events when they complete their local transaction. Other services listen and react.
• Orchestration: A central "Saga Orchestrator" commands services to execute local transactions and coordinates rollbacks (compensating transactions) if any step fails.

2. Circuit Breaker Pattern

If a downstream service is struggling, hitting it repeatedly will cause a cascading failure. A Circuit Breaker detects failures and "trips" (opens) to block requests, returning a fast fallback error until the service recovers.

Saga Orchestration Map

%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
    subgraph Client ["Frontend"]
        A["Checkout Request"]
    end
    
    subgraph Orchestrator ["Order Saga Orchestrator"]
        B["Start Saga"]
        C["Compensating Action (Rollback)"]
    end
    
    subgraph Services ["Microservices"]
        D["Inventory Service (Deduct)"]
        E["Payment Service (Charge)"]
        F["Shipping Service (Schedule)"]
    end
    
    A --> B
    B -->|"1. Command"| D
    D -->|"Success"| B
    B -->|"2. Command"| E
    E -.->|"Failed (Insufficient Funds)"| B
    B -->|"3. Compensating Command"| C
    C -->|"Restore Inventory"| D