rider-state-management.asl.json

{
  "Comment": "A description of my state machine",
  "StartAt": "Is rider id and next state valid?",
  "States": {
    "Is rider id and next state valid?": {
      "Type": "Choice",
      "Choices": [
        {
          "And": [
            {
              "Variable": "$.input.rider_id",
              "IsPresent": true
            },
            {
              "Variable": "$.input.next_state",
              "IsPresent": true
            },
            {
              "Or": [
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Not Working"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Available"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Starting"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Working"
                }
              ]
            }
          ],
          "Next": "Get current rider state"
        }
      ],
      "Default": "Send event to DLQ for manual handling"
    },
    "Send event to DLQ for manual handling": {
      "Type": "Task",
      "Resource": "arn:aws:states:::sqs:sendMessage",
      "Parameters": {
        "MessageBody.$": "$",
        "QueueUrl": "${QUEUE_URL}"
      },
      "Next": "Fail"
    },
    "Get current rider state": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:getItem",
      "Parameters": {
        "TableName": "${TABLE_NAME}",
        "Key": {
          "Area#Entity": {
            "S.$": "$.input.rider_id"
          }
        }
      },
      "Next": "Is next state a valid transition?",
      "ResultSelector": {
        "rider_id.$": "$.Item.Area#Entity.S",
        "timestamp.$": "$.Item.Timestamp.N",
        "state.$": "$.Item.State.S",
        "lat.$": "$.Item.Lat.N",
        "long.$": "$.Item.Long.N"
      },
      "ResultPath": "$.rider"
    },
    "Is next state a valid transition?": {
      "Type": "Choice",
      "Choices": [
        {
          "Or": [
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Not Working"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Available"
                }
              ]
            },
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Not Working"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Starting"
                }
              ]
            },
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Available"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Not Working"
                }
              ]
            },
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Available"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Starting"
                }
              ]
            },
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Starting"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Not Working"
                }
              ]
            },
            {
              "And": [
                {
                  "Variable": "$.rider.state",
                  "StringEquals": "Working"
                },
                {
                  "Variable": "$.input.next_state",
                  "StringEquals": "Not Working"
                }
              ]
            }
          ],
          "Next": "Transition rider to next state"
        },
        {
          "And": [
            {
              "Variable": "$.rider.state",
              "StringEquals": "Starting"
            },
            {
              "Variable": "$.input.next_state",
              "StringEquals": "Working"
            }
          ],
          "Next": "Validate start point and device token"
        }
      ],
      "Default": "Send event to DLQ for manual handling"
    },
    "Transition rider to next state": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:updateItem",
      "Parameters": {
        "TableName": "${TABLE_NAME}",
        "Key": {
          "Area#Entity": {
            "S.$": "$.input.rider_id"
          }
        },
        "UpdateExpression": "SET #state = :nextState",
        "ExpressionAttributeNames": {
          "#state": "State"
        },
        "ExpressionAttributeValues": {
          ":nextState": {
            "S.$": "$.input.next_state"
          }
        }
      },
      "Next": "Emit rider state change event",
      "ResultSelector": {
        "status_code.$": "$.SdkHttpMetadata.HttpStatusCode"
      },
      "ResultPath": "$.ddb",
      "Retry": [
        {
          "ErrorEquals": [
            "States.ALL"
          ],
          "BackoffRate": 1.5,
          "IntervalSeconds": 1,
          "MaxAttempts": 5,
          "Comment": "Retry all errors"
        }
      ]
    },
    "Emit rider state change event": {
      "Type": "Task",
      "Resource": "arn:aws:states:::sns:publish",
      "Parameters": {
        "Message.$": "$",
        "TopicArn": "${TOPIC_ARN}"
      },
      "End": true,
      "ResultSelector": {
        "status_code.$": "$.SdkHttpMetadata.HttpStatusCode"
      },
      "ResultPath": "$.sns",
      "Retry": [
        {
          "ErrorEquals": [
            "States.ALL"
          ],
          "BackoffRate": 2,
          "IntervalSeconds": 1,
          "MaxAttempts": 5
        }
      ]
    },
    "Fail": {
      "Type": "Fail"
    },
    "Validate start point and device token": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "Parameters": {
        "Payload.$": "$",
        "FunctionName": "${FUNCTION_ARN}"
      },
      "Retry": [
        {
          "ErrorEquals": [
            "Lambda.ServiceException",
            "Lambda.AWSLambdaException",
            "Lambda.SdkClientException"
          ],
          "IntervalSeconds": 2,
          "MaxAttempts": 6,
          "BackoffRate": 2
        }
      ],
      "Next": "Transition rider to next state",
      "Catch": [
        {
          "ErrorEquals": [
            "States.ALL"
          ],
          "Next": "Send event to DLQ for manual handling"
        }
      ],
      "ResultPath": "$.validator",
      "ResultSelector": {
        "statusCode.$": "$.Payload.statusCode",
        "valid.$": "$.Payload.valid"
      }
    }
  }
}