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AWS Step Functions
Developer Guide

Document History

This section lists major changes to the AWS Step Functions Developer Guide.

Change Description Date Changed

Update

Added a new topic on handling Lambda service errors. See Handle Lambda Service Exceptions.

June 20, 2018

New feature

AWS Step Functions is now available the Asia Pacific (Mumbai) region. See Supported Regions for a list of supported regions.

June 28, 2018
New feature

AWS Step Functions is now available the AWS GovCloud (US) region. See Supported Regions for a list of supported regions. For information about using Step Functions in the AWS GovCloud (US) Region, see AWS GovCloud (US) Endpoints.

June 28, 2018

Update

Improved documentation on error handling for Parallel states. See Error Handling.

June 20, 2018

Update

Improved documentation about Input and Output processing in Step Functions. Learn how to use InputPath, ResultPath, and OutputPath to control the flow of JSON through your workflows, states, and tasks. See:

June 7, 2018

Update

Improved code examples for parallel states. See Parallel.

June 4, 2018

New feature

You can now monitor API and Service metrics in CloudWatch. See Monitoring Step Functions Using CloudWatch.

May 25, 2018

Update StartExecution, StopExecution, and StateTransition now have increased throttling limits in the following regions:
  • US East (N. Virginia)

  • US West (Oregon)

  • EU (Ireland)

For more information see Limits.
May 16, 2018
New feature

AWS Step Functions is now available the US West (N. California) and Asia Pacific (Seoul) regions. See Supported Regions for a list of supported regions.

May 5, 2018
Update

Updated procedures and images to match changes to the interface.

April 25, 2018
Update

Added a new tutorial that shows how to start a new execution to continue your work. See Continue as a New Execution. This tutorial describes a design pattern that can help avoid some service limitations. See, Avoid Reaching the History Limit.

April 19, 2018
Update

Improved introduction to states documentation by adding conceptual information about state machines. See States.

March 9, 2018
Update In addition to HTML, PDF, and Kindle, the AWS Step Functions Developer Guide is available on GitHub. To leave feedback, choose the GitHub icon in the upper right-hand corner.

March 2, 2018
Update Added a topic describing other resources relating to Step Functions.

See Related Step Functions Resources.

February 20, 2018
New feature
February 19, 2018
Update Added a topic that describes an example activity worker written in Ruby. This implementation can be used to create a Ruby activity worker directly, or as a design pattern for creating an activity worker in another language.

See Example Activity Worker in Ruby.

February 6, 2018
Update Added a new tutorial describing a design pattern that uses a Lambda function to iterate a count.

See Creating a Lambda State Machine.

January 31, 2018
Update Updated content on IAM permissions to include DescribeStateMachineForExecution and UpdateStateMachine APIs.

See Creating Granular IAM Permissions for Non-Admin Users.

January 26, 2018
Update Added newly available regions: Canada (Central), Asia Pacific (Singapore).

See Supported Regions.

January 25, 2018
Update Updated tutorials and procedures to reflect that IAM allows you to select Step Functions as a role. January 24, 2018
Update Added a new Best Practices topic that suggests not passing large payloads between states.

See Use ARNs Instead of Passing Large Payloads.

January 23, 2018
New Feature Corrected procedures to match updated interface for creating a state machine: January 17, 2018
New Feature You can use Sample Projects to quickly provision state machines and all related AWS resources. See Sample Projects,

Available sample projects include:

Note

These sample projects and related documentation replace tutorials that described implementing the same functionality.

January 11, 2018
Update Added a Best Practices section that includes information on avoiding stuck executions. See Best Practices for Step Functions. January 5, 2018
Update Added a note on how retries can affect pricing:

Note

Retries are treated as state transitions. For information on how state transitions affect billing, see Step Functions Pricing.

December 8, 2017
Update Added information related to resource names:

Note

Step Functions allows you to create state machine, execution, and activity names that contain non-ASCII characters. These non-ASCII names don't work with Amazon CloudWatch. To ensure that you can track CloudWatch metrics, choose a name that uses only ASCII characters.

December 6, 2017
Update Improved security overview information and added a topic on granular IAM permissions. See Security and Creating Granular IAM Permissions for Non-Admin Users. November 27, 2017
New Feature

You can update an existing state machine. See Update a State Machine.

November 15, 2017
Update

Added a note to clarify Lambda.Unknown errors and linked to the Lambda documentation in the following sections:

Note

Unhandled errors in Lambda are reported as Lambda.Unknown in the error output. These include out-of-memory errors, function timeouts, and hitting the concurrent Lambda invoke limit. You can match on Lambda.Unknown, States.ALL, or States.TaskFailed to handle these errors. For more information about Lambda Handled and Unhandled errors, see FunctionError in the AWS Lambda Developer Guide.

October 17, 2017
Update

Corrected and clarified IAM instructions and updated the screenshots in all tutorials.

October 11, 2017
Update
October 6, 2017
Update

Rewrote the IAM instructions in the following sections to reflect changes in the IAM console:

October 5, 2017
Update

Rewrote the State Machine Data section.

September 28, 2017
New feature

The limits related to API action throttling are increased for all regions where Step Functions is available.

September 18, 2017

Update
  • Corrected and clarified information about starting new executions in all tutorials.

  • Corrected and clarified information in the Limits Related to Accounts section.

September 14, 2017

Update

Corrected and clarified information in the Templates section.

September 1, 2017

Update

Rewrote the following tutorials to reflect changes in the Lambda console:

August 28, 2017

New feature

Step Functions is available in EU (London).

August 23, 2017

New feature

The visual workflows of state machines let you zoom in, zoom out, and center the graph.

August 21, 2017

New feature

Important

An execution can't use the name of another execution for 90 days.

When you make multiple StartExecution calls with the same name, the new execution doesn't run and the following rules apply.

August 18, 2017
Input Type Execution State
Open Closed
Identical Success ExecutionAlreadyExists
Different ExecutionAlreadyExists ExecutionAlreadyExists

For more information, see the name request parameter of the StartExecution API action in the AWS Step Functions API Reference.

Update

Added information about an alternative way of passing the state machine ARN to the Creating a Step Functions API Using API Gateway tutorial.

August 17, 2017

Update Added the new Creating a Job Status Poller tutorial.

August 10, 2017

New feature

August 3, 2017

Update

Updated the instructions in the To create a role for API Gateway section.

July 18, 2017

Update

Corrected and clarified information in the Choice section.

June 23, 2017

Update

Added information about using resources under other AWS accounts to the following tutorials:

June 22, 2017

Update

Corrected and clarified information in the following sections:

June 21, 2017

Update

Rewrote all tutorials to match the Step Functions console refresh.

June 12, 2017

New feature

Step Functions is available in Asia Pacific (Sydney).

June 8, 2017

Update

Restructured the Amazon States Language section.

June 7, 2017

Update

Corrected and clarified information in the Creating an Activity State Machine section.

June 6, 2017

Update

Corrected the code examples in the Examples Using Retry and Using Catch section.

June 5, 2017

Update

Restructured this guide using AWS documentation standards.

May 31, 2017

Update

Corrected and clarified information in the Parallel section.

May 25, 2017

Update

Merged the Paths and Filters sections into the Input and Output Processing section.

May 24, 2017

Update

Corrected and clarified information in the Templates section.

May 16, 2017

Update

Corrected and clarified information in the Monitoring Step Functions Using CloudWatch section.

May 15, 2017

Update

Updated the GreeterActivities.java worker code in the Creating an Activity State Machine tutorial.

May 9, 2017

Update

Added an introductory video to the What Is AWS Step Functions? section.

April 19, 2017

Update

Corrected and clarified information in the following tutorials:

April 19, 2017

Update

Added information about Lambda templates to the Creating a Lambda State Machine and Handling Error Conditions Using a State Machine tutorials.

April 6, 2017

Update

Changed the "Maximum input or result data size" limit to "Maximum input or result data size for a task, state, or execution" (32,768 characters). For more information, see Limits Related to Task Executions.

March 31, 2017

New feature

March 21, 2017

New feature

March 16, 2017

New feature

Step Functions is available in EU (Frankfurt).

March 7, 2017

Update

Reorganized the topics in the table of contents and updated the following tutorials:

February 23, 2017

New feature

  • The State Machines page of the Step Functions console includes the Copy to New and Delete buttons.

  • Updated the screenshots to match the console changes.

February 23, 2017

New feature

February 14, 2017

New feature

February 10, 2017

Update

Clarified the current behavior of the ResultPath and OutputPath fields in relation to Parallel states.

February 6, 2017

Update

  • Clarified state machine naming restrictions in tutorials.

  • Corrected some code examples.

January 5, 2017

Update

Updated Lambda function examples to use the latest programming model.

December 9, 2016

New feature

The initial release of Step Functions.

December 1, 2016