Harnessing Domain Driven Design

1. Harnessing Domain Driven Design Gayathri Thiyagarajan Lead Software Engineer Capgemini Andrew Harmel Law Principal Software Engineer Capgemini

2. @YourTwitterHandle#YourSessionHashtag Harnessing Domain Driven Design for Distributed Systems Gayathri Thiyagarajan & Andrew Harmel-Law, Capgemini UK http://capgemini.github.io @gaythu_rajan / @al94781#harnessing_ddd

3. cc: kennymatic - https://www.flickr.com/photos/99472898@N00 @gaythu_rajan / @al94781#harnessing_ddd Who are we?

4. Who are we? @gaythu_rajan / @al94781#harnessing_ddd

5. “Microservice”? @gaythu_rajan / @al94781#harnessing_ddd

6. “Microservice”? (cont.) @gaythu_rajan / @al94781#harnessing_ddd

11. Microservices ROCK! cc: RaeAllen - https://www.flickr.com/photos/30628871@N00 @gaythu_rajan / @al94781#harnessing_ddd

12. Microservices are HARD @gaythu_rajan / @al94781#harnessing_ddd

13. “Getting service boundaries wrong can result in having to make lots of changes in service-service collaboration. An expensive operation.” from Sam Newman, “Building Microservices” (section: When shouldn’t you use Microservices) Boundaries are HARDEST @gaythu_rajan / @al94781#harnessing_ddd

14. Microservices LOVE DDD cc: {AndreaRenee} - https://www.flickr.com/photos/30282864@N02 “Despite the hype [microservices] probably giv[e] us the best environment we have ever had for doing Domain-Driven Design” (Interview with Eric Evans at 2015 DDD Exchange) @gaythu_rajan / @al94781#harnessing_ddd

15. cc: taberandrew - https://www.flickr.com/photos/88442983@N00 @gaythu_rajan / @al94781#harnessing_ddd Unfortunately...

16. Some steps... @gaythu_rajan / @al94781#harnessing_ddd cc: marsupium photography - https://www.flickr.com/photos/43405950@N07

17. The Core How DDD helps our CODE cc: Laurence Vagner - https://www.flickr.com/photos/86078191@N00 @gaythu_rajan / @al94781#harnessing_ddd

18. Ubiquitous Language cc: mag3737 - https://www.flickr.com/photos/50318388@N00 @gaythu_rajan / @al94781#harnessing_ddd

19. Hands-On Modellers cc: jovike - https://www.flickr.com/photos/49503078599@N01 @gaythu_rajan / @al94781#harnessing_ddd

20. The Misapplied How DDD helps our overall Architecture cc: juhansonin - https://www.flickr.com/photos/38869431@N00 @gaythu_rajan / @al94781#harnessing_ddd

21. The Important Bits • Models • Aggregates • Contexts • Bounded Contexts • Context Maps @gaythu_rajan / @al94781#harnessing_ddd

22. Shared Payment Services Our Case Study: cc: Khánh Hmoong - https://www.flickr.com/photos/7997148@N05 @gaythu_rajan / @al94781#harnessing_ddd

23. Shared Payment Services @gaythu_rajan / @al94781#harnessing_ddd

24. @gaythu_rajan / @al94781#harnessing_ddd Shared Payment Services

27. Models cc: Rob Swatski - https://www.flickr.com/photos/50946274@N02 @gaythu_rajan / @al94781#harnessing_ddd

28. @gaythu_rajan / @al94781#harnessing_ddd

34. Aggregates cc: J-W Brown - https://www.flickr.com/photos/13797487@N00 @gaythu_rajan / @al94781#harnessing_ddd

36. Contexts cc: petitshoo - https://www.flickr.com/photos/29426084@N00 @gaythu_rajan / @al94781#harnessing_ddd

39. Bounded Contexts cc: bryce_edwards - https://www.flickr.com/photos/98185064@N00 @gaythu_rajan / @al94781#harnessing_ddd

42. Context Maps cc: roger4336 - https://www.flickr.com/photos/24736216@N07 @gaythu_rajan / @al94781#harnessing_ddd

44. Why Aggregates? @gaythu_rajan / @al94781#harnessing_ddd

45. @gaythu_rajan / @al94781#harnessing_ddd Aggregate == Microservice

46. @gaythu_rajan / @al94781#harnessing_ddd Aggregate == Microservice

47. But, Aggregate != Microservice (not always) @gaythu_rajan / @al94781#harnessing_ddd

48. @gaythu_rajan / @al94781#harnessing_ddd But, Aggregate != Microservice (not always)

50. 1. Draw a Model and begin to implement it cc: Muffet - https://www.flickr.com/photos/53133240@N00 An Approach @gaythu_rajan / @al94781#harnessing_ddd

51. 1. Draw a Model and begin to implement it 2. As you draw it and code it, listen to the Language and cultivate your Model accordingly cc: Muffet - https://www.flickr.com/photos/53133240@N00 An Approach @gaythu_rajan / @al94781#harnessing_ddd

52. 1. Draw a Model and begin to implement it 2. As you draw it and code it, listen to the Language and cultivate your Model accordingly 3. Identify your Aggregates - these are your starter Microservices cc: Muffet - https://www.flickr.com/photos/53133240@N00 An Approach @gaythu_rajan / @al94781#harnessing_ddd

53. cc: Muffet - https://www.flickr.com/photos/53133240@N00 An Approach @gaythu_rajan / @al94781#harnessing_ddd 1. Draw a Model and begin to implement it 2. As you draw it and code it, listen to the Language and cultivate your Model accordingly 3. Identify your Aggregates - these are your starter Microservices 4. When you hit pain points (indicated by the Language) split into different Bounded Contexts to resolve

54. 1. Draw a Model and begin to implement it 2. As you draw it and code it, listen to the Language and cultivate your Model accordingly 3. Identify your Aggregates - these are your starter Microservices 4. When you hit pain points (indicated by the Language) split into different Bounded Contexts to resolve 5. Revisit your Bounded Contexts now you know more about how each Aggregate - you may end up splitting them cc: Muffet - https://www.flickr.com/photos/53133240@N00 An Approach @gaythu_rajan / @al94781#harnessing_ddd

55. Done? cc: WarzauWynn - https://www.flickr.com/photos/94246031@N00 @gaythu_rajan / @al94781#harnessing_ddd

56. The Ignored How DDD helps our Teams Organise cc: aha42 | tehaha - https://www.flickr.com/photos/31549162@N05 @gaythu_rajan / @al94781#harnessing_ddd

57. @gaythu_rajan / @al94781#harnessing_ddd Customer-Supplier Partnership Anti-Corruption Layer Upstream Downstream

58. Shared Kernel Separate Ways Anti- Corruption Layer Partner- ship Conform- ist Open Host Service Customer / Supplier ControlOverAssociatedTeams Communications Commitment / Capability of Teams @gaythu_rajan / @al94781#harnessing_ddd

61. Upstream/Downstream cc: archer10 (Dennis) (73M Views) - https://www.flickr.com/photos/22490717@N02 @gaythu_rajan / @al94781#harnessing_ddd

62. Partnership cc: practicalowl - https://www.flickr.com/photos/55046645@N00 @gaythu_rajan / @al94781#harnessing_ddd

63. @gaythu_rajan / @al94781#harnessing_ddd Partnership

65. Customer-Supplier cc: TheeErin - https://www.flickr.com/photos/27073477@N00 @gaythu_rajan / @al94781#harnessing_ddd

66. @gaythu_rajan / @al94781#harnessing_ddd Customer-Supplier

67. @gaythu_rajan / @al94781#harnessing_ddd @gaythu_rajan / @al94781#harnessing_ddd

68. Anti-Corruption Layer @gaythu_rajan / @al94781#harnessing_ddd

69. @gaythu_rajan / @al94781#harnessing_ddd Anti-Corruption Layer Upstream Downstream

71. Done Done cc: jayneandd - https://www.flickr.com/photos/8180853@N07 @gaythu_rajan / @al94781#harnessing_ddd

72. Take Home Messages cc: Manoj Kengudelu - https://www.flickr.com/photos/11767573@N02 • Find the right Microservices - or you’ll pine for the Monolith @gaythu_rajan / @al94781#harnessing_ddd

73. Take Home Messages cc: Manoj Kengudelu - https://www.flickr.com/photos/11767573@N02 • Find the right Microservices - or you’ll pine for the Monolith • Don’t get confused about BCs - they will fall out if you listen to the Language @gaythu_rajan / @al94781#harnessing_ddd

74. Take Home Messages • Find the right Microservices - or you’ll pine for the Monolith • Don’t get confused about BCs - they will fall out if you listen to the Language • Organise around your services better - apply the Strategic Patterns cc: Manoj Kengudelu - https://www.flickr.com/photos/11767573@N02 @gaythu_rajan / @al94781#harnessing_ddd

75. Take Home Messages • Find the right Microservices - or you’ll pine for the Monolith • Don’t get confused about BCs - they will fall out if you listen to the Language • Organise around your services better - apply the Strategic Patterns • Be inspired to do more Domain Driven Design cc: Manoj Kengudelu - https://www.flickr.com/photos/11767573@N02 @gaythu_rajan / @al94781#harnessing_ddd

76. And Finally... cc: oatsy40 - https://www.flickr.com/photos/68089229@N06 @gaythu_rajan / @al94781#harnessing_ddd

77. Questions Please cc: Derek Bridges - https://www.flickr.com/photos/84949728@N00 @gaythu_rajan / @al94781#harnessing_ddd

78. Oh, and we (Capgemini ) are hiring! (visit bit.ly/cg-jvm-jobs-ddd) cc: ptrlx - https://www.flickr.com/photos/58615912@N05 @gaythu_rajan / @al94781#harnessing_ddd

79. Read More... • https://capgemini.github.io/architecture/ microservices-reality-check/ • https://capgemini.github.io/architecture/ why-microservices-are-right-for-us-pt1/ • https://capgemini.github.io/architecture/ microservices-like-change/ • https://capgemini.github.io/architecture/ microservices-gotchas/ cc: Manoj Kengudelu - https://www.flickr.com/photos/11767573@N02 @gaythu_rajan / @al94781#harnessing_ddd