serverless-orchestration

Serverless Orchestration (Step Functions)

Core Architecture

When building complex serverless applications, orchestrating multiple AWS Lambda functions becomes a challenge. AWS Step Functions solve this by maintaining state across functions using State Machines.

1. State Machines (JSON ASL)

Defined using the Amazon States Language (ASL). You can define logical flows: Task, Choice (If/Else), Parallel, Map (For-loop), and Wait.

• Stateless Lambdas: Lambdas should do one thing and forget. Step Functions hold the state and pass the output of one Lambda as the input to the next.

2. Error Handling & Retries

Step Functions natively support try/catch blocks, exponential backoff retries, and dead-letter queue routing without writing any code inside the Lambda.

Orchestration Map

%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
    subgraph Orchestrator ["AWS Step Functions (State Machine)"]
        A["Start"]
        B["Task: Process Payment (Lambda)"]
        C{"Choice: Payment Success?"}
        D["Task: Fulfill Order (Lambda)"]
        E["Task: Send Fail Email (Lambda)"]
        F["End"]
    end
    
    A --> B
    B --> C
    C -->|"Yes"| D
    C -->|"No"| E
    D --> F
    E --> F