Delivery Semantics & Idempotency
Exactly-once is a property of your handler
Free
4h · 5 lessons
Overview
Queues, publish/subscribe, and the log as a primitive. Delivery semantics, idempotency and ordering, then the architectures they make possible — and the debugging they cost you.
This module is 04.4 of the 5 in Messaging & Event Streams. It runs about 4 hours across 5 lessons, and closes with Duplicate — Every message is delivered twice and one is out of order. Charge the card exactly once anyway.
Lessons
1. At-most-once, at-least-once, exactly-once
Concept · 35 minutes
2. Idempotency keys and dedupe windows
Concept · 40 minutes
3. The outbox pattern
Concept · 35 minutes
4. Ordering: global, per-key and none
Concept · 35 minutes
5. Make a payment handler safe to retry
Lab · 50 minutes
Before this
Module information
Duration
4 hours
Lessons
5
Level
Intermediate
Track
Messaging & Event Streams
Drill
Duplicate
Price
Free
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