Projects: Module 03 — Async Patterns¶

See the topic-level PROJECTS.md for Project 5 (Saga Orchestrator Design) which directly applies this module.

Module Project: Choreography Saga for Hotel Booking¶

Difficulty: Intermediate Time estimate: 4–5 hours

Brief: Implement a choreography saga in Python for a hotel booking system with three steps: 1. Reserve room (HotelService) 2. Charge credit card (PaymentService) 3. Send confirmation email (NotificationService)

Each step must: - Be triggered by an event from the previous step - Publish its own success or failure event - Have an explicit compensating transaction

Simulate failures at each step and verify correct rollback behavior.

Acceptance Criteria: - Failure at step 2 triggers compensation of step 1 (room release) - Failure at step 3 triggers compensation of steps 1 and 2 - All compensation is logged with clear output - No shared state between services (each service maintains its own in-memory store)