startExecution method

Future<StartExecutionOutput> startExecution({ required String stateMachineArn, String? input, String? name, String? traceHeader, })

Starts a state machine execution.

A qualified state machine ARN can either refer to a Distributed Map state defined within a state machine, a version ARN, or an alias ARN.

The following are some examples of qualified and unqualified state machine ARNs:

• The following qualified state machine ARN refers to a Distributed Map state with a label mapStateLabel in a state machine named myStateMachine.

  arn:partition:states:region:account-id:stateMachine:myStateMachine/mapStateLabel

• The following qualified state machine ARN refers to an alias named PROD.

  arn:

• The following unqualified state machine ARN refers to a state machine named myStateMachine.

  arn:

If you start an execution with an unqualified state machine ARN, Step Functions uses the latest revision of the state machine for the execution.

To start executions of a state machine version, call StartExecution and provide the version ARN or the ARN of an alias that points to the version.

StartExecution isn't idempotent for EXPRESS workflows.

May throw ExecutionAlreadyExists. May throw ExecutionLimitExceeded. May throw InvalidArn. May throw InvalidExecutionInput. May throw InvalidName. May throw KmsAccessDeniedException. May throw KmsInvalidStateException. May throw KmsThrottlingException. May throw StateMachineDeleting. May throw StateMachineDoesNotExist. May throw ValidationException.

Parameter stateMachineArn : The Amazon Resource Name (ARN) of the state machine to execute.

The stateMachineArn parameter accepts one of the following inputs:

• An unqualified state machine ARN – Refers to a state machine ARN that isn't qualified with a version or alias ARN. The following is an example of an unqualified state machine ARN.

  arn:

  Step Functions doesn't associate state machine executions that you start with an unqualified ARN with a version. This is true even if that version uses the same revision that the execution used.

• A state machine version ARN – Refers to a version ARN, which is a combination of state machine ARN and the version number separated by a colon (:). The following is an example of the ARN for version 10.

  arn:

  Step Functions doesn't associate executions that you start with a version ARN with any aliases that point to that version.

• A state machine alias ARN – Refers to an alias ARN, which is a combination of state machine ARN and the alias name separated by a colon (:). The following is an example of the ARN for an alias named PROD.

  arn:

  Step Functions associates executions that you start with an alias ARN with that alias and the state machine version used for that execution.

Parameter input : The string that contains the JSON input data for the execution, for example:

"{"first_name" : "Alejandro"}" Length constraints apply to the payload size, and are expressed as bytes in UTF-8 encoding.

Parameter name : Optional name of the execution. This name must be unique for your Amazon Web Services account, Region, and state machine for 90 days. For more information, see Limits Related to State Machine Executions in the Step Functions Developer Guide.

If you don't provide a name for the execution, Step Functions automatically generates a universally unique identifier (UUID) as the execution name.

A name must not contain:

• white space
• brackets < > { } \[ \]
• wildcard characters ? *
• special characters " # % \ ^ | ~ ` $ & , ; : /
• control characters (U+0000-001F, U+007F-009F, U+FFFE-FFFF)
• surrogates (U+D800-DFFF)
• invalid characters ( U+10FFFF)

To enable logging with CloudWatch Logs, the name should only contain 0-9, A-Z, a-z, - and _.

Parameter traceHeader : Passes the X-Ray trace header. The trace header can also be passed in the request payload.

Implementation

Future<StartExecutionOutput> startExecution({
  required String stateMachineArn,
  String? input,
  String? name,
  String? traceHeader,
}) async {
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.0',
    'X-Amz-Target': 'AWSStepFunctions.StartExecution'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'stateMachineArn': stateMachineArn,
      if (input != null) 'input': input,
      if (name != null) 'name': name,
      if (traceHeader != null) 'traceHeader': traceHeader,
    },
  );

  return StartExecutionOutput.fromJson(jsonResponse.body);
}