DDDamn good!
summary
A real subscription-management service for a real-estate product is implemented using DDD with functional Scala, MongoDB and Kafka; aggregates are modeled as immutable state plus a aggregate as reducer function that returns a new state and a list of integration events, letting tests assert both state and emitted events. A critical invariant—delete-email deactivates subscriptions—is enforced inside the aggregate. Cross-service delivery uses an Outbox pattern/CDC to persist state and reliably publish Kafka events; this design ships to production and reduces ambiguity between product and engineering.
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chapters (10)
- 0:00Introduction
- 2:15What is DDD and why
- 4:47Use cases and ubiquitous language
- 14:15Event storming for team sync
- 25:09Modeling aggregates in code
- 29:43Aggregates and transactional consistency
- 37:29Bounded context and responsibility
- 47:58Distributed system integration
- 57:11Outbox pattern and data changes
- 1:01:02Recommendations and conclusion
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