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You attended talk: An introduction to event sourcing (short)

You attended talk: An introduction to event sourcing (short)

Imagine for a moment you work for a large online retailer specialising in household goods. One morning, the head of marketing comes to you and says "I've had this great idea we're going to send discount vouchers to anyone who's changed their address in the past 3 months; people who've recently moved are more likely to be buying new furniture. Could you retrieve a list of all these customers?" You explain to him your systems only store a customers current address and doesn't record when it was last changed, a new feature is added to the backlog and the head of marketing leaves a little disappointed.

What if you could build a system which was able to answer this kind of question without knowing it up front? A possible solution is to use event sourcing, being able to go back to any previous state of your data is just one advantage of using event sourcing in your application. Event sourcing is a total paradigm shift from the more traditional model of storing an application's current state and can appear to be a very unnatural way to think about and build a system. In this talk I'm going to show you examples of why event sourcing can be a superior model and how to go about building an event sourced system in PHP.

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carnage

May 13, 2016
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Transcript

  1. You Attended Talk: An Introduction To Event Sourcing Christopher Riley

    PHP Day, May 2016 1
  2. Introduction

  3. A familiar model 2

  4. Deleting data LineItem table id order id product code quantity

    1 1 PK00001 3 2 1 PK00002 1 3 2 PK00002 1 4 3 PK00007 4 5 4 PK00003 2 6 4 PK00005 6 3
  5. Deleting data LineItem table id order id product code quantity

    1 1 PK00001 3 3 2 PK00002 1 4 3 PK00007 4 5 4 PK00003 2 6 4 PK00005 6 4
  6. Deleting data LineItem table id order id product code quantity

    deleted 1 1 PK00001 3 0 2 1 PK00002 1 0 3 2 PK00002 1 0 4 3 PK00007 4 0 5 4 PK00003 2 0 6 4 PK00005 6 0 5
  7. Deleting data LineItem table id order id product code quantity

    deleted 1 1 PK00001 3 0 2 1 PK00002 1 1 3 2 PK00002 1 0 4 3 PK00007 4 0 5 4 PK00003 2 0 6 4 PK00005 6 0 6
  8. Editing data LineItem table id order id product code quantity

    deleted 1 1 PK00001 3 0 2 1 PK00002 1 1 3 2 PK00002 1 0 4 3 PK00007 4 0 5 4 PK00003 2 0 6 4 PK00005 6 0 7
  9. Editing data LineItem table id order id product code quantity

    deleted 1 1 PK00001 2 0 2 1 PK00002 1 1 3 2 PK00002 1 0 4 3 PK00007 4 0 5 4 PK00003 2 0 6 4 PK00005 6 0 8
  10. Editing data LineItem table id order id product code quantity

    deleted version 1 1 PK00001 3 0 1 2 1 PK00002 1 1 1 3 2 PK00002 1 0 1 4 3 PK00007 4 0 1 5 4 PK00003 2 0 1 6 4 PK00005 6 0 1 9
  11. Editing data LineItem table id order id product code quantity

    deleted version 1 1 PK00001 3 0 1 2 1 PK00002 1 1 1 3 2 PK00002 1 0 1 4 3 PK00007 4 0 1 5 4 PK00003 2 0 1 6 4 PK00005 6 0 1 1 1 PK00001 2 0 2 10
  12. A familiar model (again) 11

  13. Event sourcing

  14. Event sourcing example 12

  15. Advantages

  16. Technical advantages • Debugging 13

  17. Technical advantages • Debugging • Scalabilty 14

  18. Technical advantages • Debugging • Scalabilty • Auditing 15

  19. Technical advantages • Debugging • Scalabilty • Auditing • Testing

    16
  20. Example test 17

  21. Summary

  22. Retrieving data

  23. Performance Problems?

  24. CQRS

  25. MVC Application 18

  26. CQRS Application 19

  27. Technical advantages • Scalabilty 20

  28. Technical advantages • Scalabilty • Performance 21

  29. Technical advantages • Scalabilty • Performance • Multiple read models

    22
  30. CQRS + Event sourcing Application 23

  31. Should I use Event sourcing? • Complex to implement 24

  32. Should I use Event sourcing? • Complex to implement •

    Development overhead 25
  33. Should I use Event sourcing? • Complex to implement •

    Development overhead • Less understanding 26
  34. Should I use Event sourcing? • Complex to implement •

    Development overhead • Less understanding • Hard to retofit 27
  35. Conclusions

  36. Further reading • Greg Young • https://github.com/qandidate-labs/broadway • https://github.com/carnage/broadway-bowling 28

  37. Thanks • @giveupalready • https://github.com/carnage • http://joind.in/talk/1d28c 29