A practical introduction to DDD, CQRS & Event Sourcing
summary
Shows a concrete mortgage application model: a MortgageApplication aggregate that enforces the invariant “all proofs must be signed” with optimistic concurrency via a version number. Writes become domain events stored in an event store (apply for mortgage, proof added, application approved) and reads are fast materialized views (Mongo/Elasticsearch) built by projectors that rebuild projections. Demonstrates auditability and time travel, blue‑green reprojection for schema changes, tradeoffs: eventual consistency lag, projector complexity, archiving/tombstoning and when CRUD would have been simpler.
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chapters (7)
- 0:00Introduction and motivation
- 7:02Domain-Driven Design basics
- 11:33CQRS and read/write separation
- 17:56Event Sourcing introduction
- 24:40When to use these patterns
- 33:33Handling projections and versions
- 43:17Q&A and closing
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