AWS Step Functions: Orchestrating Serverless Workflows

Step Functions orchestrate serverless workflows. After building production workflows, here’s how to use them effectively.

Step Functions Basics

State Machine Definition

{
  "Comment": "Order processing workflow",
  "StartAt": "ValidateOrder",
  "States": {
    "ValidateOrder": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789:function:validate-order",
      "Next": "ProcessPayment"
    },
    "ProcessPayment": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789:function:process-payment",
      "Next": "CreateShipment"
    },
    "CreateShipment": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789:function:create-shipment",
      "End": true
    }
  }
}

Parallel Execution

{
  "ProcessInParallel": {
    "Type": "Parallel",
    "Branches": [
      {
        "StartAt": "SendEmail",
        "States": {
          "SendEmail": {
            "Type": "Task",
            "Resource": "arn:aws:lambda:...:send-email",
            "End": true
          }
        }
      },
      {
        "StartAt": "UpdateInventory",
        "States": {
          "UpdateInventory": {
            "Type": "Task",
            "Resource": "arn:aws:lambda:...:update-inventory",
            "End": true
          }
        }
      }
    ],
    "End": true
  }
}

Error Handling

Retry and Catch

{
  "ProcessPayment": {
    "Type": "Task",
    "Resource": "arn:aws:lambda:...:process-payment",
    "Retry": [
      {
        "ErrorEquals": ["States.TaskFailed"],
        "IntervalSeconds": 2,
        "MaxAttempts": 3,
        "BackoffRate": 2.0
      }
    ],
    "Catch": [
      {
        "ErrorEquals": ["PaymentFailed"],
        "Next": "HandlePaymentFailure"
      }
    ],
    "Next": "CreateShipment"
  }
}

Best Practices

1. Keep states simple - Single responsibility
2. Handle errors - Retry and catch
3. Use parallel - When possible
4. Monitor - CloudWatch metrics
5. Test - State machine testing
6. Document - Clear workflows
7. Version - State machine versions
8. Optimize - Reduce execution time

Conclusion

Step Functions enable:

• Workflow orchestration
• Error handling
• Parallel execution
• Visual workflows

Start with simple workflows, then add complexity. The patterns shown here orchestrate production serverless workflows.

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AWS Step Functions from August 2023, covering workflow orchestration.