A Brief History of AWS Step Functions

Once upon a time (2016, to be precise), AWS noticed that people were duct-taping their Lambda functions together using SNS, SQS, and sheer willpower.

So they said, “What if we made a thing that handles all this orchestration for you?” And thus, AWS Step Functions was born!

It officially launched at AWS re:Invent 2016, instantly becoming a favorite among developers who were tired of manually handling retries, error handling, and managing workflow states.

What Are AWS Step Functions?

Think of Step Functions as your cloud-based workflow orchestrator. It lets you coordinate multiple AWS services into serverless workflows using a visual state machine.

Imagine you’re making a pizza 🍕. The process looks something like this:

1. Take an order
2. Make the dough
3. Add toppings
4. Bake it
5. Deliver it

Each of these steps depends on the previous one and requires different actions. AWS Step Functions lets you define these processes programmatically, making sure things happen in the right order, retry on failures, and even run in parallel if needed.

Key Features

• Visual Workflow: You can actually see how your functions connect.
• Built-in Retry Mechanism: Because failures are a fact of life.
• Error Handling: Define how errors should be handled without crying.
• Parallel Execution: Run multiple tasks at once.
• Human Approval Steps: If your process needs someone to say “Yep, looks good!”

AWS Step Functions in Action: A Code Example

Enough talk—let’s see some code! Below is a simple AWS Step Functions definition written in Amazon States Language (ASL). This state machine executes two tasks sequentially:

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{
  "Comment": "A simple Step Function example",
  "StartAt": "FirstTask",
  "States": {
    "FirstTask": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789012:function:FirstFunction",
      "Next": "SecondTask"
    },
    "SecondTask": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789012:function:SecondFunction",
      "End": true
    }
  }
}

This workflow does the following:

1. Calls FirstFunction (a Lambda function).
2. Once FirstFunction completes, it triggers SecondFunction.
3. Done! 🎉

Advanced Step Function Features

1. Parallel Execution

Need to run multiple things at once? No problem.

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{
  "StartAt": "ParallelState",
  "States": {
    "ParallelState": {
      "Type": "Parallel",
      "Branches": [
        {
          "StartAt": "TaskA",
          "States": {
            "TaskA": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-east-1:123456789012:function:TaskA",
              "End": true
            }
          }
        },
        {
          "StartAt": "TaskB",
          "States": {
            "TaskB": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-east-1:123456789012:function:TaskB",
              "End": true
            }
          }
        }
      ],
      "End": true
    }
  }
}

This executes TaskA and TaskB at the same time.

2. Error Handling & Retries

AWS Step Functions let you handle errors gracefully.

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{
  "StartAt": "FailingTask",
  "States": {
    "FailingTask": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-east-1:123456789012:function:UnreliableFunction",
      "Retry": [
        {
          "ErrorEquals": ["States.TaskFailed"],
          "IntervalSeconds": 5,
          "MaxAttempts": 3,
          "BackoffRate": 2
        }
      ],
      "Catch": [
        {
          "ErrorEquals": ["States.ALL"],
          "Next": "ErrorHandler"
        }
      ]
    },
    "ErrorHandler": {
      "Type": "Fail"
    }
  }
}

This state machine retries a failing task up to three times, waiting 5 seconds between each try. If it still fails, it moves to an ErrorHandler state.

Key Ideas

References

1. AWS Step Functions Documentation
2. AWS re:Invent 2016 Step Functions Launch
3. Amazon States Language