State or Events? Which Shall I Keep?
summary
Live-codes an event-sourced credit-card aggregate (behaviors → events) and proves it works end-to-end: commands emit LimitAssigned, CardWithdrawn, CardRepaid events, events buffer in an in-memory stream then publish to Kafka, a Kafka Streams job folds them into a snapshot in a Kafka Streams state store (read via REST), and a scheduler simulates traffic — the demo runs. Uses Java + Spring Kafka/Kafka Streams; warns about event versioning, eventual consistency and exactly-once tradeoffs.
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chapters (18)
- 0:00Introduction
- 1:15Overview
- 2:13Object Selection
- 3:17Environments
- 6:45Implement
- 10:55Events
- 12:35Query
- 17:25Finding Events
- 23:58Event Streams
- 27:58Folding State
- 31:43Creating Handlers
- 34:18Kafka
- 36:58Demo
- 42:38Kafka Streams
- 44:13Kafka Snapshot
- 50:53Credit Card Controller
- 55:18Event Store
- 56:53State vs Events
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