Functional and Reactive Event Sourced Applications
summary
Argues that Event Sourcing is the real win and CQRS is optional, demonstrates a Scala app built with Fun.CQRS on top of Akka Persistence (Cassandra/Postgres plugins available) that models commands/events, persists them to a journal, replays history and builds projections into an in‑memory read view. Shows a working lottery aggregate that rejects invalid commands (cannot run twice), uses snapshotting (configurable; example 100 events) to avoid replaying long histories (notes typical aggregates have ~10–20 events, pathological cases reach 300k). Emphasizes single ordered event store as single source of truth.
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chapters (7)
- 0:00Introduction and background
- 1:34Understanding CQRS
- 5:54Akka and event sourcing
- 12:48Implementing the right model
- 22:41Demonstration of the system
- 27:40Query side and projections
- 32:49Conclusion and Q&A
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