Learning series · 5 episodes · Senior / Staff / Principal
One order, five failure boundaries
Follow one order through checkout retries, event publication, redelivery, historical replay and regional failover.
Start series →Follow the decisions in order
- Part 1 of 5
Senior
The customer clicked once. Why are there two orders?An HTTP timeout leaves the outcome unknown. Stable operation identity and a database constraint turn retries into one business decision.
- Part 2 of 5
Staff
The order exists. Why has the warehouse never heard about it?Atomic order creation cannot make broker publication atomic. A durable publication obligation, relay recovery, and source ordering solve a new boundary.
- Part 3 of 5
Staff
The warehouse processed the event. Why did it arrive again?Consumer offsets are progress markers, not proof of completed business effects. Atomic receipts and business identities defend separate races.
- Part 4 of 5
Staff
The replay worked. Why did it reserve stock again?Replay is a separate capability with permission boundaries, history completeness, and cutover conditions. It is not just a consumer group reset.
- Part 5 of 5
Principal
The region failed over. Which promises survived?Local transaction atomicity does not imply regional survival. Acknowledgment, promotion authority, and consequential publication must protect the same business decision.