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First Workflow Tutorial

Learn to build a complete workflow with multiple steps, inputs, and outputs.

What We'll Build

A workflow that: 1. Takes a list of numbers as input 2. Calculates statistics (sum, average, min, max) 3. Returns a formatted report

Step 1: Create the Workflow File

Create workflows/number-stats.yaml:

name: number-stats
version: "1.0"
description: Calculate statistics for a list of numbers

inputs:
  numbers:
    type: string
    description: Comma-separated list of numbers
    default: "1,2,3,4,5"

steps:
  - id: parse
    code: |
      raw = "{{ inputs.numbers }}"
      numbers = [float(n.strip()) for n in raw.split(",")]
      result = numbers

  - id: calculate
    depends_on: [parse]
    code: |
      numbers = {{ steps.parse.output }}
      result = {
          "count": len(numbers),
          "sum": sum(numbers),
          "average": sum(numbers) / len(numbers),
          "min": min(numbers),
          "max": max(numbers)
      }

  - id: format
    depends_on: [calculate]
    code: |
      stats = {{ steps.calculate.output }}
      result = f"""
      Number Statistics Report
      ========================
      Count:   {stats['count']}
      Sum:     {stats['sum']}
      Average: {stats['average']:.2f}
      Min:     {stats['min']}
      Max:     {stats['max']}
      """

output: "{{ steps.format.output }}"

Step 2: Understand the Structure

Metadata

name: number-stats      # Unique identifier
version: "1.0"          # Semantic version
description: ...        # Human-readable description

Inputs

inputs:
  numbers:
    type: string        # Input type
    description: ...    # Help text
    default: "1,2,3,4,5"  # Default value

Steps

Each step has: - id: Unique identifier within the workflow - code: Python code to execute - depends_on: List of steps that must complete first

Output

output: "{{ steps.format.output }}"

References the output of the format step using Jinja2 templating.

Step 3: Validate

ael validate workflows/number-stats.yaml

Step 4: Run

With default input:

ael run workflows/number-stats.yaml

With custom input:

ael run workflows/number-stats.yaml -i "numbers=10,20,30,40,50"

Expected output: 

Number Statistics Report
========================
Count:   5
Sum:     150.0
Average: 30.00
Min:     10.0
Max:     50.0

Key Concepts

Step Dependencies

Steps execute in order based on depends_on:

steps:
  - id: step1
    code: ...

  - id: step2
    depends_on: [step1]  # Waits for step1
    code: ...

  - id: step3
    depends_on: [step1, step2]  # Waits for both
    code: ...

Accessing Step Outputs

Use Jinja2 templates to access previous step outputs:

- id: use_previous
  code: |
    data = {{ steps.previous_step.output }}

The result Variable

Each code step must set a result variable. This becomes the step's output:

- id: example
  code: |
    result = {"key": "value"}  # This is the step output

Next Steps