# Tutorials

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This page was generated from content adapted from the [AWS Developer Guide](https://github.com/awsdocs/aws-step-functions-developer-guide.git)
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## Create a Step Functions state machine that uses Lambda

* **Note**\
  In Step Functions, a workflow is called a *state machine*, which is a series of event-driven steps. Each step in a workflow is called a *state*. A `Task` state represents a unit of work that another AWS service, such as AWS Lambda, performs. A `Task` state can call any AWS service or API. For more information, see:\
  [What is AWS Step Functions?](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/welcome.md) [Call other AWS services](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/connect-to-services.md)
* **Important**\
  Ensure that your Lambda function is under the same AWS account and AWS Region as your state machine.
* **Note**\
  You can also pass payloads while invoking Lambda from a state machine. For more information and examples about invoking Lambda by passing payload in the `Parameters` field, see [Invoke Lambda with Step Functions](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/connect-lambda.md).

## Handling Error Conditions Using a State Machine

* **Note**\
  You can also create state machines that `Retry` on timeouts or those that use `Catch` to transition to a specific state when an error or timeout occurs. For examples of these error handling techniques, see [Examples Using Retry and Using Catch](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/concepts-error-handling.md#error-handling-examples).
* **Important**\
  Ensure that your Lambda function is under the same AWS account and AWS Region as your state machine.

## Starting a State Machine Execution in Response to Amazon S3 Events

* **Note**\
  You must configure EventBridge rule in the same AWS Region as the Amazon S3 bucket.

## Creating a Step Functions API Using API Gateway

* **Note**\
  Although Amazon API Gateway can start a Step Functions execution by calling `[StartExecution](https://docs.aws.amazon.com/step-functions/latest/apireference/API_StartExecution.html)`, you must call `[DescribeExecution](https://docs.aws.amazon.com/step-functions/latest/apireference/API_DescribeExecution.html)` to get the result.
* **Note**\
  For more information, see the `StartExecution` [Request Syntax](https://docs.aws.amazon.com/step-functions/latest/apireference/API_StartExecution.html#API_StartExecution_RequestSyntax) in the *AWS Step Functions API Reference*.\
  If you don't want to include the ARN of your state machine in the body of your API Gateway call, you can configure a body-mapping template, as shown in the following example.
* **Note**\
  You can view the execution by choosing your state machine on the [AWS Step Functions console](https://console.aws.amazon.com/states/).

## Creating an Activity State Machine

* **Important**\
  Ensure that your activity task is under the same AWS account as your state machine.
* **Note**\
  For a more complete example of an activity worker, see [Example Activity Worker in Ruby](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/example-ruby-activity-worker.md). This example provides an implementation based on best practices, which you can use as a reference for your activity worker. The code implements a consumer-producer pattern with a configurable number of threads for pollers and activity workers.
* **Note**\
  The `EnvironmentVariableCredentialsProvider` class in this example assumes that the `AWS_ACCESS_KEY_ID` (or `AWS_ACCESS_KEY`) and `AWS_SECRET_KEY` (or `AWS_SECRET_ACCESS_KEY`) environment variables are set. For more information about providing the required credentials to the factory, see [AWSCredentialsProvider](https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/AWSCredentialsProvider.html) in the *AWS SDK for Java API Reference* and [Set Up AWS Credentials and Region for Development](https://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/setup-credentials.html) in the *AWS SDK for Java Developer Guide*.\
  By default the AWS SDK will wait up to 50 seconds to receive data from the server for any operation. The `GetActivityTask` operation is a long-poll operation that will wait up to 60 seconds for the next available task. To prevent receiving a `SocketTimeoutException` error, set SocketTimeout to 70 seconds.

## Iterating a Loop Using Lambda

* **Note**\
  If you set `index` to `9` for this test, the `index` increments to `10`, and `continue` is `false`.

## Continuing Ongoing Work as a New Execution

* **Note**\
  If you have completed the [Iterating a Loop Using Lambda](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/tutorial-create-iterate-pattern-section.md) tutorial, you can skip this step and use that Lambda function.
* **Note**\
  If you set `index` to `9` for this test, the `index` increments to `10`, and `continue` is `false`.
* **Note**\
  Save the Amazon Resource Name (ARN) of this state machine.
* **Note**\
  You can update the `"Resource": "*"` line in the previous example to reference the ARN of your `ContinueAsNew` state machine. This restricts the policy so that it can only start an execution of that specific state machine.

## Using Code Snippets

* **Note**\
  Under the **Task state options** section, you can also configure `Retry`, `Catch`, and `TimeoutSeconds` options. See [Error handling in Step Functions](https://github.com/kevinslin/aws-reference-notes/blob/main/services/aws_step_functions/concepts-error-handling.md).

## Deploying an Example Human Approval Project

* **Note**\
  You will need to provide a valid email address that you have access to when you create the AWS CloudFormation stack.

## View X-Ray traces in Step Functions

* **Important**\
  Ensure that your Lambda function is under the same AWS account and AWS Region as your state machine.