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AWS Step Functions
API Reference (API Version 2016-11-23)

StartExecution

Starts a state machine execution.

Request Syntax

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{ "input": "string", "name": "string", "stateMachineArn": "string" }

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

The request accepts the following data in JSON format.

input

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

"input": "{\"first_name\" : \"test\"}"

Note

If you don't include any JSON input data, you still must include the two braces, for example: "input": "{}"

Type: String

Length Constraints: Maximum length of 32768.

Required: No

name

The name of the execution. This name must be unique for your AWS account and region for 90 days. For more information, see Limits Related to State Machine Executions in the AWS Step Functions Developer Guide.

Important

When you make multiple StartExecution calls with the same name, the following rules apply:

  • When the original execution is open and the execution input from the new call is different, the ExecutionAlreadyExists error is returned.

  • When the original execution is open and the execution input from the new call is identical, the Success error is returned.

  • When the original execution is closed, the ExecutionAlreadyExists error is returned regardless of input.

A name must not contain:

  • whitespace

  • brackets < > { } [ ]

  • wildcard characters ? *

  • special characters " # % \ ^ | ~ ` $ & , ; : /

  • control characters (U+0000-001F, U+007F-009F)

Type: String

Length Constraints: Minimum length of 1. Maximum length of 80.

Required: No

stateMachineArn

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

Type: String

Length Constraints: Minimum length of 1. Maximum length of 256.

Required: Yes

Response Syntax

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{ "executionArn": "string", "startDate": number }

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

executionArn

The Amazon Resource Name (ARN) that identifies the execution.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 256.

startDate

The date the execution was started.

Type: Timestamp

Errors

For information about the errors that are common to all actions, see Common Errors.

ExecutionAlreadyExists

The execution has the same name as another execution (but a different input).

Note

Executions with the same name and input are considered idempotent.

HTTP Status Code: 400

ExecutionLimitExceeded

The maximum number of running executions has been reached. Running executions must end or be stopped before a new execution can be started.

HTTP Status Code: 400

InvalidArn

The provided Amazon Resource Name (ARN) is invalid.

HTTP Status Code: 400

InvalidExecutionInput

The provided JSON input data is invalid.

HTTP Status Code: 400

InvalidName

The provided name is invalid.

HTTP Status Code: 400

StateMachineDeleting

The specified state machine is being deleted.

HTTP Status Code: 400

StateMachineDoesNotExist

The specified state machine does not exist.

HTTP Status Code: 400

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: