AWS Lambda Durable Functions with Callback

This project demonstrates a high-level flow of using AWS Lambda Durable Functions with a callback mechanism to handle human or external system approvals in a serverless workflow.

Flow Overview

1. Durable Lambda Function

   • Executes the initial logic (e.g., preparing a document).
   • Sends a notification (e.g., to a human or system) requesting approval.
   • Pauses execution and emits a Callback ID.

2. External Interaction / Human Action

   • An external system or human receives the approval request.
   • They perform an action (e.g., approve or reject) and trigger an API call to resume the Durable Lambda function.

3. Notify Lambda Function (Callback Handler)

   • Receives the callback with the Callback ID and the decision (approve or reject).
   • Calls send_durable_execution_callback_success to resume the Durable Lambda function.

4. Durable Lambda Resumes

   • Based on the callback response, continues execution:
     • If approved → finalizes the workflow.
     • If rejected → archives or handles rejection logic.