Introduction to Event Sourcing,CQRS and Axon
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This document introduces event sourcing, CQRS, and the Axon framework. It discusses how event sourcing works by storing all state changes as a sequence of events. It contrasts this with traditional databases that store only the current state. The document also describes how CQRS uses separate models for reading and writing data. Projections rebuild read models by processing streams of events from the event store. The Axon framework provides tools for implementing event sourcing and CQRS in Java applications.
Introduction to Event Sourcing,CQRS and Axon
- 1. Introduction to Event Sourcing,CQRS and Axon
- 2. About me
- 3. CROZ
- 4. How do we develop software?
- 10. Current State
- 12. What are Events?
- 14. How do they look like?
- 16. Order Created Item Added Payment Method Selected Shipping Address Provided Order Placed Timeline
- 17. Item Added Order Created Payment Method Selected Shipping Address Provided Order Placed Event Store
- 18. Just another way of storing information. Data is append only Data is immutable Is there more to it?
- 20. „Apps age like fish, data ages like wine”
- 25. COMMANDS
- 26. Events (past tense) • • • • • Commands (imperative) • • • • •
- 27. AGGREGATES
- 30. Best practice
- 32. Conclusion
- 33. Is there a framework?
- 34. AXON FRAMEWORK
- 35. WRITEREAD
- 36. def depositMoney(DepositMoneyCommand cmd) { commandGateway.send(cmd) } @CommandHandler void handle(DepositMoneyCommand cmd){ //validate command apply(new MoneyDepositedEvent()) } @EventSourcingHandler void on(MoneyDepositedEvent event) { //reload aggregate state } @EventHandler void on(MoneyDepositedEvent event) { // update generate projection }
- 38. 1.Step – Define API
- 39. 2.Step – Implement a test
- 40. 3.Step – Implement write side
- 41. 4.Step – Implement read side
- 43. Questions?