CQRS & Event Sourcing in OLX

Transcript

1. CQRS Event Sourcing in OLX
2. CQRS
3. you can use a different model to update information than the model you use to read information http://martinfowler.com/bliki/CQRS.html „
4. Command Query Responsibility Segregation
5. Command Query Responsibility Segregation
6. new AddCredits($userId, $amount); Command
7. Command new AddCredits($userId, $amount); Query new GetCredits($userId);
8. Event Sourcing
9. http://www.martinfowler.com/eaaDev/EventSourcing.html „ ensures that all changes to application state are stored as a sequence of events
10. Not just can we query these events, we can also use the event log to reconstruct past states http://www.martinfowler.com/eaaDev/EventSourcing.html „
11. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query
12. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query Critical section - use transaction
13. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query Critical section - use transaction Treat like temporary cache
14. That’s all
15. E-Wallet Credits; Invoices; Refunds
16. Wallet Credits Bonus Credits Refund Credits EXPIRE: X DAYS EXPIRE: X DAYS EXPIRE: X DAYS INVOICE: YES/NO INVOICE: YES/NO INVOICE: YES/NO
17. Wallet Credits Bonus Credits Refund Credits EXPIRE: NEVER EXPIRE: 90 DAYS EXPIRE: 90 DAYS INVOICE: YES INVOICE: NO INVOICE: YES
18. Opis walleta w Polsce specyfikacja komenty enventy Commands
19. Add Wallet Credits Add Bonus Credits Add Refund Credits
20. Sub Wallet Credits Sub Bonus Credits Sub Refund Credits SubCredits
21. Opis walleta w Polsce specyfikacja komenty enventy Events
22. Wallet CreditsWasAdded Bonus CreditsWasAdded Refund CreditsWasAdded
23. Wallet CreditsWasSubtracted Bonus CreditsWasSubtracted Refund CreditsWasSubtracted
24. specyfikacja komenty enventy 7 commands 6 events
25. specyfikacja komenty enventy What about other stuff?
26. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query ?
27. Broadway komponenty Broadway https://github.com/qandidate-labs/broadway
28. Auditing log whether commands were successful or not
29. CommandHandling Provides the interface and a CommandHandler base class for handling events
30. Domain domain abstractions of the Broadway framework including the aggregate root, domain messages and domain events.
31. EventDispatcher The component provides an event dispatcher interface and a simple implementation
32. EventHandling provides interfaces for an event bus and event listeners, but also an implementation of a simple event bus and an event bus that will record published events
33. EventSourcing Provides base classes for event sourced aggregate roots and entities, an event sourced repository implementation and testing helpers.
34. EventStore implementation based on doctrine/dbal to store events in a relational database and an in-memory implementation that is useful for using in tests
35. ReadModel provides storage for your read models, a projector implementation to create read models from event streams and testing helpers.
36. Repository Component providing an abstraction of the storage of aggregates.
37. Serializers provides a simple serializer interface and a serializer implementation based on "handwritten" serializers
38. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query Broadway
39. Adding Wallet Credits
42. Credits Query
45. Lessons Learned
46. Small Steps Don’t try to CQRS/EventSource everything
47. Keep It Simple Avoid names like BonusCreditsWasSubtractedBecauseAdminHitSubtractBonusCr editsInAdminPanelEvent
48. Event Storming is not that easy as it sounds
49. It’s not RDBM Remember about analysts
50. Code changes Events handle changes to data, what about changes to code?
51. Synchronize Remember about synchronizing read layer - especially after fail
52. Commad Event Model Event Storage Event Bus Command Handler Listeners Read Storage Read Model Query Critical section - use transaction
53. Performance is not an issue - for this case
54. Timezone Agnostic Implement your own EventStore if you want timezone aware records
55. Our Team
56. Paid Features
57. Next challenge Open source Paid Features libraries with Hexagonal Architecture in mind
58. Team Lead PHP Dev Junior PHP Dev You ?
59. Łukasz Szymański Development Team Lead at @szymanskilukasz http://szymanskilukasz.github.io/ https://www.linkedin.com/in/szymanskilukasz https://twitter.com/szymanskilukasz