Découvrez en pratique l'architecture hexagonale, indispensable pour vos applications complexes ! Ce style d'architecture permet d'adapter votre code à tout changement de technologie sans souffrir. Si vous aimez changer de frameworks ou de librairies, tester correctement ou appliquer le Domain-Driven Design, alors vous avez besoin d'architecture hexagonale ! Avec des exemples en code Java, et au travers d’un kata d’architecture auquel vous pourrez participer, nous vous montrerons les pièges à éviter et comment mettre en œuvre ce pattern sans trop galérer, et ce dès votre retour au bureau !

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

5. Architecte
Société Générale
Thomas Pierrain

6. 6

7. 7

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

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

10. TDD
BDD
DDD
Legacy

11. Architecte
Technique
Central

12. Architecte
Technique
Central

13. 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

14. Let’s start

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

16. STOP !

17. Alistair Cockburn

18. Uncle Bob Martin

19. Hexagonal

20. 100% Domain Inside

21. Thin layer of Use-cases

22. Ports/Adapters all around

23. Adapter

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

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

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

27. Hexagonal?

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

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

30. 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

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

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

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

34. DIP principle
X

35. DIP principle
Interface
Adapter

36. interface

37. interface
REPOSITORY

38. interface
Start with mocks
MOCK

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

40. We can demo!

41. Quick Win 1
Focus on
what really
matters

42. Implement the repository

43. Implement the repository
On the
cloudz!

44. Implement actual persistence
interface
Amazon
Adaptor

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

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

47. 47
MAX
IGNORANCE

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

49. Ebay as additional retailer?

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

51. Même pas …

52. New shipping provider?

53. interface
FEDEX
Adaptor
New shipping provider?!

54. Again:
Même pas
mal !!!

55. Quick Win 3
Embrace the
changes

56. X
Allowed way for
dependencies
Hexagonal architecture

57. Quick Win 4
Low coupling
High cohesion

58. Before
(legacy architecture)

59. After
(Hexagonal Architecture)

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

61. 61

62. Hexagonal Architecture
Use & Abuse!

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

64. Même pas !
;-)

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

66. 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“)

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

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

70. 70

71. FUZZY

72. FUZZY

73. FUZZY

74. Pattern

75. Port
Vs
Adapter?

77. Port = Existing Techno
Adapter = Your code

78. You disagree?

79. Not that important.

80. Symmetries?
80

81. Not that important.

82. Inside
vs.
Outside

83. Who’s talking about
hexagonal?

84. Alistair Cockburn
84

85. ”Uncle Bob” Martin
85

86. Steeve Freeman & Nat Pryce (GOOS)
86

87. Vaughn Vernon (IDDD)
87

88. Jeffrey Palermo (Onion Architecture)
88

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

90. Many notations!

91. Still, not well-known

92. +--------------+!
| presentation |!
|--------------|!
| domain |!
|--------------|!
| persistence |!
+--------------+
Layers?

93. +-----+-------------+----------+!
| gui | file system | database |!
|-----+-------------+----------+!
| domain |!
|------------------------------+
Infra the other way round!
Layering
http://matteo.vaccari.name/blog/archives/154

94. Inside
vs.
Outside

95. Un Dedans
et
Un Dehors

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

97. For real

98. 98

99. 99
Ted Neward

100. We’re launching a
startup, man.

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

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

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

105. 105

106. How to enforce?

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

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

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

111. 111
Living Diagrams

112. 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

113. Conformist
vs.
Hexagonal

114. Conformist (accidental)

115. Hexagonal Architecture

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

117. Architecture = ?

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

119. Architecture
!
”What everybody should know”

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

121. Architecture
!
”What’s irreversible”

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

123. 50% TECH
50% COMM

124. 50% TECH
50% COMM
(10% MATHS)

125. Communication FTW!

126. AGREE
ON
MAXIMS

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

128. Repository

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

130. 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

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

132. Repository

133. In Legacy

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

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

136. Anti-corruption
layer

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

138. Module ==
library
Accès aux
services
extérieurs

139. Hexagonal Architecture
Scenario test
data
Adapters

140. Bounded Contexts

141. 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.

142. Different
MY activity is not the

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

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

148. 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

149. 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

150. 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
!

153. Apply DDD!
153

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

155. 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