Coder sans peur du changement avec la meme pas mal hexagonal architecture

1. @cyriux @tpierrain#MemePasMal Coder sans peur du changement, avec la "même pas mal !" architecture hexagonale Cyrille MARTRAIRE (@cyriux) Arolla ! Thomas PIERRAIN (@tpierrain) Société Générale

2. @cyriux @tpierrain#MemePasMal CODER SANS PEUR DU CHANGEMENT, AVEC LA "MÊME PAS MAL !" ARCHITECTURE HEXAGONALE Cyrille MARTRAIRE (@cyriux) Arolla ! Thomas PIERRAIN (@tpierrain) Société Générale

3. Architecte Société Générale Thomas Pierrain

6. Passionate developer PARIS Since 1999 ! @cyriux Cyrille Martraire

7. Paris Software Craftsmanship Community http://www.meetup.com/paris-software-craftsmanship/

8. TDD BDD DDD Legacy

9. Architecte Technique Central

10. Architecte Technique Central

11. Your own Sweets Box Online! Use-cases 1. Choose your box and the sweets to put inside 2. Get a price 3. Order, & consult past orders

12. Let’s start

13. As usual:  Chose the DB &   Design the DB schema!

14. STOP !

15. Alistair Cockburn

16. Uncle Bob Martin

17. Hexagonal

18. 100% Domain Inside

19. Thin layer of Use-cases

20. Ports/Adapters all around

21. Adapter

22. Dependencies always   towards the inside! X Allowed way for dependencies

23. Dependencies always   towards the inside! Vers l’intérieur, qu’il dit le monsieur !

24. Ports/Adapters? “REST”Port “REST” Adapter “EMS“ Adapter “Tibco EMS” Port

25. Hexagonal?

26. Users Vs. Providers THEY   NEED ME I NEED THEM API (Application Provider Interface) SPI (Service Provider Interface)

27. Tests Vs. Production Deliver value to PROD Verify behavior in TEST Test Robots Fakes, Mocks Clients Stores etc.

28. Scenario-Driven… Given a sweets box of size XL And a selection of 500g of M&Ms And assuming the following prices | item | price | currency | | XL Box | 2.50 | EUR | | M&M (100g)| 5.00 | EUR | ! When I ask for a price Then the price is 27.50 EUR

29. Modeling the domain… Sweets CustomSweetsBox SweetsBoxPricer AllOrders Catalog Order ShippingCostEstimat or Caramels Nougat Fudge

30. Modeling the domain… Sweets CustomSweetsBox SweetsBoxPricer AllOrders Catalog Order ShippingCostEstimat or Caramels Nougat Fudge Beware of Modelism!

31. I need to call external services, but I don’t want to know about them

32. DIP principle X

33. DIP principle Interface Adapter

34. interface

35. interface REPOSITORY

36. interface Start with mocks MOCK

37. Add an html web app… “REST” Adapter

38. We can demo!

39. Quick Win 1  Focus on what really matters

40. Implement the repository

41. Implement the repository On the cloudz!

42. Implement actual persistence interface Amazon Adaptor

43. Même pas mal !  (“that didn't hurt one bit“)

44. Quick Win 2  Choose the technology last (when we know best)

45. 47 MAX IGNORANCE

46. 48 Who’s that architect who can’t decide the technologies early?

47. Ebay as additional retailer?

48. Ebay as additional retailer! “REST” Adapter Ebay Adapter

49. Même pas …

50. New shipping provider?

51. interface FEDEX Adaptor New shipping provider?!

52. Again:  Même pas mal !!!

53. Quick Win 3  Embrace the changes

54. X Allowed way for dependencies Hexagonal architecture

55. Quick Win 4  Low coupling  High cohesion

56. Before   (legacy architecture)

57. After  (Hexagonal Architecture)

58. Quick Win 5  Our business code is not victim of IT fads anymore!

59. 61

60. Hexagonal Architecture Use & Abuse!

61. Need other areas of behaviors? • Business intelligence? • Supply Chain management • CRM? • …

62. Même pas !   ;-)

63. Hexagonal all the things New Bounded Contexts? New Micro-services?

64. Main benefits ! 1.Focus on what really matters  (business value first!) ➔ have you ever tried DDD? ! 2.Choose the technology last   (when we know best our concrete needs) ! 3.Embrace the changes   (“Même pas mal !” / “that didn't hurt one bit“)

65. Thanks! Cyrille MARTRAIRE @cyriux Thomas PIERRAIN @tpierrain

66. @cyriux @tpierrain#MemePasMal CODER SANS PEUR DU CHANGEMENT, AVEC LA "MÊME PAS MAL !" ARCHITECTURE HEXAGONALE Cyrille MARTRAIRE (@cyriux) Arolla ! Thomas PIERRAIN (@tpierrain) Société Générale

67. 70

68. FUZZY

69. FUZZY

70. FUZZY

71. Pattern

72. Port Vs Adapter?

73. Port = Existing Techno Adapter = Your code

74. You disagree?

75. Not that important.

76. Symmetries? 80

77. Not that important.

78. Inside vs. Outside

79. Who’s talking about hexagonal?

80. Alistair Cockburn 84

81. ”Uncle Bob” Martin 85

82. Steeve Freeman & Nat Pryce (GOOS) 86

83. Vaughn Vernon (IDDD) 87

84. Jeffrey Palermo (Onion Architecture) 88

85. h;p://pragprog.com/magazines/2009-‐12/going-‐naked Depends on nothing Pragmatic Programmers

86. Many notations!

87. Still, not well-known

88. +--------------+! | presentation |! |--------------|! | domain |! |--------------|! | persistence |! +--------------+ Layers?

89. +-----+-------------+----------+! | gui | file system | database |! |-----+-------------+----------+! | domain |! |------------------------------+ Infra the other way round! Layering http://matteo.vaccari.name/blog/archives/154

90. Inside vs. Outside

91. Un Dedans et Un Dehors

92. Un Dedans et Un Dehors #des reperes pour nos enfants

93. For real

94. 98

95. 99 Ted Neward

96. We’re launching a startup, man.

97. Sentiment Analysis ! Automatically extract the sentiment of English sentences submitted on the web, using a given lexicon. Keep track of the submitted sentences.

98. Your Turn ! 5mn Small groups Any technology / approach Propose an architecture on paper ! Then we’ll debrief a selection of them

99. Sentiment Analysis ! Automatically extract the sentiment of English sentences submitted on the web, using a given lexicon. Keep track of the submitted sentences.

100. 105

101. How to enforce?

102. 108 http://books.sonatype.com/mvnref-book/reference/flex-dev-sect-creating-with-archetype.html Maven multi- module

103. 109 http://clarkware.com/software/JDepend.html JDepend

104. 110https://leanpub.com/livingdocumentation/

105. 111 Living Diagrams

106. 4 novel coupling metrics 1. Undesirable Dependency Count 2. Undesirable Distinct Dependency Count 3. Undesirable Dependency Max Repetition 4. Undesirable Distinct Assembly Count ! Bad Good ● Provoke conversations

107. Conformist vs. Hexagonal

108. Conformist (accidental)

109. Hexagonal Architecture

110. Hexadecimal Architecture: Need at least 16 layers in the code

111. Architecture = ?

112. Architecture ! ”The key technology choices” BOF…

113. Architecture ! ”What everybody should know”

114. Architecture ! ”What’s hard to change”

115. Architecture ! ”What’s irreversible”

116. Reversible decisions FTW! Defer technology decisions Change your mind easily

117. 50% TECH 50% COMM

118. 50% TECH 50% COMM (10% MATHS)

119. Communication FTW!

120. AGREE ON MAXIMS

121. ”Le principe du nombril : on regarde vers l’intérieur”

122. Repository

123. Persistence Ignorance ! ! •You can defer decisions about persistence (and UI) for a long ^me •Your domain must NOT care!

124. Un service, la facade coté mé^er d’un stockage ! Sans jamais parler de base de données. Repository h;p://www.andeka.co.cc/2011/07/postbox-‐251.html

125. Repository h;p://www.andeka.co.cc/2011/07/postbox-‐251.html Interface DAO

126. Repository

127. In Legacy

128. Bubble Context • Create a little bubble of innovation ! • Brand new model ! • As clean as we like • Highly tested • High hygiene standards

129. Bubble Context • ACL to protect from the legacy code ! • Translates legacy objects & services into new, cleaner ones

130. Anti-corruption layer

131. Module (lib) <<ValueObject<<ValueObject <<ValueObject>> <<ValueObject <<ValueObject>> <<Service>> <<SPI>> <<Service>> <<API>> <<En7ty>> <<Aggregate>> Module == library Accès aux services extérieurs

132. Module == library Accès aux services extérieurs

133. Hexagonal Architecture Scenario test data Adapters

134. Bounded Contexts

135. Bounded Contexts Il n’est pas possible de convenir du sens précis des mots u7lisés par un grand nombre de personnes. ! Il faut accepter ce fait, et donc déﬁnir dans quel contexte un langage est clairement déﬁni sans ambiguité.

136. Different MY activity is not the

137. Merci ! hFp://cathy313.centerblog.net/539-‐bisounours

138. Wrap-up • Concepts & Messages – Subir -> Délibéré – Intérieur Vs Extérieur – Gérer ses dépendances – Langage interne / externe – DIP • Exemples • Kata

139. Content • When not to go Hexagonal? – Conformist – Facebook game – Too small (connector…) ! • Advanced aspects – The adapter pattern – Tech ports diversity – 1 Adapter – many interfaces – 1 interface – many adapters – Data push – Session management – Adapter as a module indeed

140. Content 2 Domain model as a Pure Functions (100% no Entity inside) vs as Aggregates ! -- The Repository pattern Reuse slides Hexagonal for a Bubble Context within a legacy ! Ports = surrounding legacy Adapters = repository / adapter ! Cloakroom / clandestine passenger patterns

141. Content 3 How to enforce? ! Discipline Maven multi modules, .Net projects Static analysis: JDepend rules, NDepend, Sonar plugins — Bounded Context Reuse slides ! Conformist vs ACL isolation Same language or not? ! Autonomous Components / Polyglot persistence ! Influence of sync vs async / push vs pull on the inside of the hexagon ! Examples? Living Documentation Convention (YES)? Annotation on packages? ! The Bounded Contexts / the Domain models vs the rest (ici un seul Bounded Context) ! Domain model -> inside Everything else - that implements something from the domain model -> at the right - everything else that only calls - > at the left !

142. Apply DDD! 153

143. http://www.lexicalscope.com/blog/category/patterns/

144. http://matteo.vaccari.name/blog/archives/154 Problem: write a program that 1. Loads a set of employee records from a flat file 2. Sends a greetings email to all employees whose birthday is today ! The flat file is a sequence of records, separated by newlines; this are the first few lines: last_name, first_name, date_of_birth, email ! Doe, John, 1982/10/08, john.doe@foobar.com ! Ann, Mary, 1975/09/11, mary.ann@foobar.com ! The greetings email contains the following text: Subject: Happy birthday! Happy birthday, dear John! with the first name of the employee substituted for “John” ! 3. REST service to query past greetings ! HINT: today is a tech port! ! ! +-----+-------------+----------+! | gui | file system | database |! |-----+-------------+----------+! | domain |! |------------------------------+ +--------------+! | presentation |! |--------------|! | domain |! |--------------|! | persistence |! +--------------+ Exercise Postgres Sql + Gui (+ myBatis ?) Audit et log dans le domain + Metrics