The anti-polling pattern for Step Functions

Polling long-running processes in Step Functions is inefficient and costly due to state transition charges. An event-driven alternative uses Lambda with task tokens, DynamoDB for state storage, and EventBridge to listen for completion events, eliminating the Wait-Poll-Choice loop. This pattern works with services that emit events or support callback URLs. The new Lambda Durable Functions feature simplifies both approaches with waitForCondition for polling and waitForCallback for event-driven implementations, reducing state transitions and costs while treating waiting as a first-class operation.