antigravity-skills-reference/web-app/public/skills/dbos-python/references/step-basics.md

title, impact, impactDescription, tags

title	impact	impactDescription	tags
Use Steps for External Operations	HIGH	Steps enable recovery by checkpointing results	step, external, api, checkpoint

Use Steps for External Operations

Any function that performs complex operations, accesses external APIs, or has side effects should be a step. Step results are checkpointed, enabling workflow recovery.

Incorrect (external call in workflow):

import requests

@DBOS.workflow()
def my_workflow():
    # External API call directly in workflow - not checkpointed!
    response = requests.get("https://api.example.com/data")
    return response.json()

Correct (external call in step):

import requests

@DBOS.step()
def fetch_data():
    response = requests.get("https://api.example.com/data")
    return response.json()

@DBOS.workflow()
def my_workflow():
    # Step result is checkpointed for recovery
    data = fetch_data()
    return data

Step requirements:

• Inputs and outputs must be serializable
• Should not modify global state
• Can be retried on failure (configurable)

When to use steps:

• API calls to external services
• File system operations
• Random number generation
• Getting current time
• Any non-deterministic operation

Reference: DBOS Steps