Event Storming

Introduction to Domain Driven Design with Event Storming

Transcript

1. Event Storming Introduction to Domain Driven Design with Event Storming Jakub Pięta
2. –Eric Evans “The critical complexity of most software projects is in understanding the domain itself.”
3. What is Event Storming?
5. It’s powerful
6. It’s engaging
7. It’s efficient
8. It’s easy
9. It’s fun (imo)
10. How does it work?
11. Invite the right people •Large meeting room •6-8 people •People who know what questions to ask •People who know the answers
12. Provide unlimited modeling space
15. What’s an Event? Product added to cart
16. –Martin Fowler “Things happen. Not all of them are interesting, some may be worth recording but don’t provoke a reaction. The most interesting ones cause a reaction. Many systems need to react to interesting events. Often you need to know why a system reacts 
 in the way it did.”
17. Event Flows Order Placed Order Packed Order Shipped
18. What’s a reaction?
19. This happens whenever that happens Whenever a new user account is created
 we will send him an acknowledgement by email
20. What’s a Policy? Send Email Email Sent Email Sent Send Email Send Email
21. What else can cause reactions?
22. Events
23. Events Command External Systems
24. Events Command External Systems Actor
25. Example flow
26. Credit card payment
27. Credit Card Submitted
28. Credit Card Submitted Customer
29. Enter Credit Card Credit Card Submitted Customer
30. Enter Credit Card Credit Card Submitted Customer Process Payment
31. Enter Credit Card Credit Card Submitted Customer Process Payment Payment Gateway
32. Example bonus targets
33. Exploring Subdomains
34. Exploring Bounded Contexts
35. Exploring Bounded Contexts (allows to keep high cohesion)
36. Aggregates
37. Turning the model into code
38. Turning the model into code (DDD practitioners like Event Storming)
39. Benefits
40. •Discovering complexity early on •Finding missing concepts •Understanding the business process •Modelling or solving a specific problem in detail •Learning how to model and think about modelling
42. What is needed? •Suitable room •Writable surface •A lot of sticky notes •Markers •The right people •A facilitator
43. Your outcome is knowledge, not a paper roll with sticky notes
44. –Alberto Brandoliny “Software development is a learning process, working code is a side effect.”
45. Thank you :)