{
  "Comment": "Order Processing Workflow",
  "StartAt": "ValidateOrder",
  "States": {
    "ValidateOrder": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:eu-west-1:account:function:validate-order",
      "Next": "CheckInventory",
      "Retry": [
        {
          "ErrorEquals": ["Lambda.ServiceException", "Lambda.TooManyRequestsException"],
          "IntervalSeconds": 2,
          "MaxAttempts": 3,
          "BackoffRate": 2
        }
      ],
      "Catch": [
        {
          "ErrorEquals": ["ValidationError"],
          "Next": "OrderFailed",
          "ResultPath": "$.error"
        }
      ]
    },
    "CheckInventory": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:getItem",
      "Parameters": {
        "TableName": "Inventory",
        "Key": {
          "productId": {"S.$": "$.productId"}
        }
      },
      "Next": "IsAvailable"
    },
    "IsAvailable": {
      "Type": "Choice",
      "Choices": [
        {
          "Variable": "$.Item.quantity.N",
          "NumericGreaterThan": 0,
          "Next": "ProcessPayment"
        }
      ],
      "Default": "OrderOutOfStock"
    },
    "ProcessPayment": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:eu-west-1:account:function:process-payment",
      "Next": "ParallelFulfillment"
    },
    "ParallelFulfillment": {
      "Type": "Parallel",
      "Branches": [
        {
          "StartAt": "SendConfirmationEmail",
          "States": {
            "SendConfirmationEmail": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:eu-west-1:account:function:send-email",
              "End": true
            }
          }
        },
        {
          "StartAt": "UpdateInventory",
          "States": {
            "UpdateInventory": {
              "Type": "Task",
              "Resource": "arn:aws:states:::dynamodb:updateItem",
              "Parameters": {
                "TableName": "Inventory",
                "Key": {"productId": {"S.$": "$.productId"}},
                "UpdateExpression": "SET quantity = quantity - :qty",
                "ExpressionAttributeValues": {":qty": {"N": "1"}}
              },
              "End": true
            }
          }
        }
      ],
      "Next": "OrderComplete"
    },
    "OrderComplete": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:putItem",
      "Parameters": {
        "TableName": "Orders",
        "Item": {
          "orderId": {"S.$": "$.orderId"},
          "status": {"S": "completed"}
        }
      },
      "End": true
    },
    "OrderFailed": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:eu-west-1:account:function:notify-failure",
      "End": true
    },
    "OrderOutOfStock": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:eu-west-1:account:function:notify-out-of-stock",
      "End": true
    }
  }
}
Serverless Architecture — Lambda, API Gateway, Step Functions

Serverless Architecture — Lambda, API Gateway, Step Functions

Serverless Architecture — Lambda, API Gateway, Step Functions
