Developing Microservices with Aggregates

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" summary

Argues that Domain-Driven Design aggregates let a tangled domain model split into services by using one transaction per aggregate and referencing other aggregates by ID only, avoiding object links across services. Replaces distributed two‑phase commits with sagas with compensating transactions driven by events (example: order created -> customer reserves credit -> order approved/rejected). Recommends event sourcing as atomic persist-and-publish and shows a microservice design built on Spring Cloud and an event store that yields eventual consistency and an audit-ready event log.

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" chapters (32)

1. 0:00Developing Microservices with Aggregates
2. 0:53About Chris
3. 4:31Microservice architecture
4. 5:58Domain model = tangled web of classes
5. 7:07Reliance on ACID transactions to enforce invariants
6. 9:46and requires 2PC
7. 10:112PC is not an option
8. 11:58Domain Driven Design - building blocks
9. 14:36About Aggregates
10. 16:18Aggregate: rule #1
11. 17:30Domain model = collection of loosely connected aggregates
12. 17:46Easily partition into microservices
13. 18:17Aggregate rule #2
14. 19:01Transaction scope = service
15. 21:29How to maintain data consistency between aggregates?
16. 22:20Using event-driven Sagas instead of 2PC
17. 23:49Saga-based, eventually consistent order processing
18. 26:53Complexity of compensating transactions
19. 29:11How atomically update database and publish an event
20. 29:33Failure = inconsistent system
21. 31:29Event sourcing = event-centric persistence
22. 33:25Persists events NOT current state
23. 36:00Replay events to recreate state
24. 36:32The Customer aggregate
25. 37:29Customer command processing
26. 38:09Customer applying events
27. 38:57Request handling in an event sourced application
28. 39:45Event Store publishes events consumed by other services
29. 40:32Event store = database + message broker
30. 41:10Benefits of event sourcing
31. 46:08Drawbacks of event
32. 48:50Summary

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