Validation in an eventually consistent world

on YouTube ↗26m

" summary

Event-sourced microservice architecture uses an event stream as authoritative state, read-model projections, and aggregators that write those projections; validation choices are concrete tradeoffs. For unique emails: accept eventual-consistency checks if collisions in a 100 milliseconds window are unlikely, enforce a unique constraint on read model and let the aggregator fail/flag duplicates, or keep service-local state (Redis) to reject on write. For orders, fulfillment is multi‑phase against the warehouse system of record; payments move to background services, not inline.

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" chapters (6)

1. 0:00Context of microservices
2. 2:50Defining services and state
3. 5:39System components and flow
4. 8:50Registration validation
5. 17:46Order fulfillment logic
6. 21:32Payment and final thoughts

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