La simplicité comme moyen d'être performant, résilient et de réduire le Time To Market.

Il y a 1 an et demi, la Société Générale a décidé de construire un nouveau service de vente électronique de nos produits financiers. Les contraintes étaient claires : "le système sera performant, auditable, résilient et développé de manière à avoir un Time To Market court". Une seule solution s'imposait à nous : faire simple, très simple !
Ainsi à travers cette présentation, nous vous raconterons notre quête de simplicité. Vous verrez ainsi que notre stack technique ne contient quasiment aucun framework, juste quelques bibliothèques utiles ou indispensables. Notre code se structure autour de quelques principes : l'Event Sourcing, un peu de Domain Driven Design et une discipline de fer en matière de qualité et de tests automatisés (BDD for the win!).

Transcript

1. Construire le SI de demain
   REX Société Générale
   La simplicité comme moyen d'être
   performant, résilient
   et de réduire le Time To Market
   

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2. Marie-Laure
   Thuret
   @mlthuret
   Développeur
   chez
   Clément
   Héliou
   @c_heliou
   Développeur
   chez
   Thierry
   Abaléa
   @ThierryAbalea
   Tech Lead
   à la
   Société Générale
   

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3. View Slide

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7. Palladium
   

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9. Commodity
   Trading Company
   

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10. Today
    Hedging
    Commodity
    Trading Company
    

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11. Commodity
    Trading Company
    Few Months Later
    Hedging
    Physical Delivery
    

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13. Sales Person
    Customer Trader
    Booking
    Exchanges
    

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14. Automatize
    the
    processus
    

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15. Orchestrator
    Customer Exchanges
    Pricer
    Booking
    Hedger
    Trading Limit
    Margin
    

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17. The Constraints
    Reliability / Resilience Performance
    Productivity / Time To Market
    

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18. Our Solution
    Simplicity
    

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19. Simple ≠ Easy
    

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20. Choices are
    business-oriented
    

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21. Functional
    and Code
    Reduce the impedance between
    Our Goal
    

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22. Orchestration
    Let’s take an example with
    our main component
    

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26. Event Sourcing
    

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27. « Capture all changes to an
    application state as a
    sequence of events »
    Martin Fowler
    

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28. Date Money Out Money In
    2015/05/14 100 €
    2015/05/14 -20 €
    2015/05/16 -30 €
    2015/05/24 380 €
    2015/06/01 -70 €
    Total -120 € 480 €
    Balance 360 €
    

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29. WithdrawalPerformed
    accountId: 9387
    amount: 30€
    BankAccount
    id: 9387
    balance: 0€
    WithdrawalPerformed
    accountId: 9387
    amount: 20€
    DepositPerformed
    accountId: 9387
    amount: 100€
    BankAccount
    id: 9387
    balance: 50€
    BankAccount
    id: 9387
    balance: 100€
    BankAccount
    id: 9387
    balance: 80€
    Inspired by B. Reitzammer & J. Seitz - http://ookami86.github.io/event-sourcing-in-practice
    Apply to
    Apply to
    Apply to
    Produces
    Produces
    Produces
    

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30. J. Chassaing - http://thinkbeforecoding.com/post/2014/01/04/Event-Sourcing.-Draw-it
    

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31. BankAccount
    id: 9387
    balance: 0€
    WithdrawalPerformed
    accountId: 9387
    amount: 20€
    DepositPerformed
    accountId: 9387
    amount: 100€
    BankAccount
    id: 9387
    balance: 100€
    Bug
    Inspired by B. Reitzammer & J. Seitz - http://ookami86.github.io/event-sourcing-in-practice
    Apply to
    Apply to
    Produces
    Produces
    

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32. WithdrawalPerformed
    accountId: 9387
    amount: 30€
    BankAccount
    id: 9387
    balance: 0€
    WithdrawalPerformed
    accountId: 9387
    amount: 20€
    DepositPerformed
    accountId: 9387
    amount: 100€
    BankAccount
    id: 9387
    balance: 100€
    BankAccount
    id: 9387
    balance: 70€
    Inspired by B. Reitzammer & J. Seitz - http://ookami86.github.io/event-sourcing-in-practice
    Apply to
    Apply to
    Produces
    Produces
    

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33. Domain Driven Design
    

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34. «
    DDD is about designing
    software based on models
    of the underlying
    (business) domain »
    Martin Fowler
    

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35. Ubiquitous
    Language
    Repository
    Aggregate Root
    Entity
    Value Object
    

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36. Durable
    business model
    Extensibility
    Clean Architecture
    Solid Responsibility Segregation
    

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37. Using Event Sourcing
    and DDD concepts in
    Multiplus
    

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38. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    QuoteReceived
    {event}
    QuoteForwarded
    {event}
    Customer
    Event Bus
    QuoteForwardedHandler
    {handler}
    Quote
    Requesting Quoting
    QuoteReceived
    {event}
    QuoteReceived
    {event}
    ForwardQuote
    {action}
    

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39. Transaction
    {aggregate root}
    Pricing
    {entity}
    Execution
    {entity}
    Orchestration
    {entity}
    ReceiveQuote
    {command/value object}
    quoteRequestId: 4563
    price: 100€
    QuoteReceived
    {event/value object}
    accountId: 4563
    price: 110€
    - Multiplus Business Logic -
    

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40. What we’ve
    learned
    

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41. Be
    aware of
    Command
    Sourcing
    

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42. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    quoteRequestId: 4563
    price: 100€
    QuoteForwarded
    {event}
    accountId: 4563
    price: 101€
    Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    quoteRequestId: 4563
    price: 100€
    QuoteForwarded
    {event}
    accountId: 4563
    price: 102€
    2015/06/01 Margin: 1%
    2015/11/01 Margin: 2%
    

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44. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    QuoteForwarded
    {event}
    Customer
    Event Bus
    QuoteForwardedHandler
    {handler}
    {Quote n° 65746}
    {Quote n° 65746} ??
    QuoteReceived
    {event}
    ForwardQuote
    {action}
    

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45. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    QuoteForwarded
    {event}
    Customer
    Event Bus
    QuoteForwardedHandler
    {handler}
    Customer
    gateway
    {Quote n° 65746}
    {Quote n° 65746}
    QuoteReceived
    {event}
    ForwardQuote
    {action}
    

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46. Store the events
    produced by the
    Decide function
    

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47. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    quoteRequestId: 4563
    price: 100€
    QuoteForwarded
    {event}
    accountId: 4563
    price: 101€
    Multiplus
    Business
    Logic
    2015/06/01 Margin: 1%
    2015/11/01 Margin: 2%
    QuoteForwarded
    {event}
    accountId: 4563
    price: 101€
    

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48. Multiplus
    Business
    Logic
    ReceiveQuote
    {command}
    QuoteForwarded
    {event}
    Customer
    Event Bus
    QuoteForwardedHandler
    {handler}
    QuoteReceived
    {event}
    ForwardQuote
    {action}
    

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49. It’s all in the past !
    

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50. Date Money Out Money In
    2015/05/14 100 €
    2015/05/14 -20 €
    2015/05/16 -30 €
    2015/05/24 30 €
    2015/06/01 -70 €
    Total -120 € 130 €
    Balance 10 €
    

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51. Behavior Driven
    Development
    Conversation
    Collaboration
    Specifications By Examples
    Three Amigos
    Automation
    Ubiquitous Language
    

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52. deliver
    the
    right
    software
    

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53. Your
    documentation
    will become
    alive
    

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54. you
    will
    new comers
    thank
    

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55. you
    will
    new comers
    thank
    … but you’ll enjoy it too !
    

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56. warning
    

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57. doing BDD right
    easy
    is not
    

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58. BDD
    Common Issues
    Business and developper
    faces collaboration difficulties
    Mess with the
    scenario writing
    Automation Nightmare
    

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59. BDD
    Common Issues
    Business and developper
    faces collaboration difficulties
    Mess with the
    scenario writing
    Automation Nightmare
    

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60. our
    complex
    application
    are
    often
    

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61. we tend to let
    everywhere
    business rules
    being dispatch
    

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62. … making them
    hard to test
    

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63. Hexagonal
    Architecture
    the onion architecture
    the clean architecture
    ports and adapters
    

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64. domain
    adapters
    Port
    (
    inbound)
    Port
    (
    outbound)
    Web
    Message Queue
    Database
    

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65. Advantages
    Testability Flexibility
    Business Centric
    

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66. domain driven
    app structure
    

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67. that’s not
    enough !
    

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68. use different
    granularity
    business scenarios
    when expressing your
    levels
    

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69. Given a quantity value of 1000 in G
    When the quantity is converted in OZ
    Then the converted quantity is 32.1507 OZ
    Given a quote request with a way BUY
    And the credit check request has been sent
    When the credit check response is in error
    Then the pricer does not receive a quote request
    And the platform quote status is REJECTED
    Given an authorized product type
    When the customer sends the rfs
    Then the pricer receives the rfs
    When the pricer sends a quote
    Then the customer receives the quote
    Workflow
    Feature
    Unit
    

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70. « l’enfer c’est les
    autres »
    Jean-Paul Sartre
    

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71. at
    any time
    business validation
    

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73. steroids
    integration testing
    on
    

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74. care about
    the contract
    between your app and another
    

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75. avoid
    accidental
    complexity
    

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76. there’s always
    implicit
    a schema
    even if it’s
    

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77. Hexagonal
    Architecture
    DDD
    Event Sourcing
    BDD
    State Machine
    

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78. Hexagonal
    Architecture
    Java
    DDD
    Event Sourcing
    BDD
    State Machine
    

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79. Hexagonal
    Architecture
    Dagger
    Java
    DDD
    Event Sourcing
    BDD
    State Machine
    

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80. Hexagonal
    Architecture
    Dagger
    Java
    Guava
    DDD
    Event Sourcing
    BDD
    State Machine
    

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81. Our architecture
    is easy to deploy !
    

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82. Simple
    

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83. Simple
    No More Technologies Than Required
    

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84. Simple
    No More Technologies Than Required
    Business Centric
    

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85. Simple
    No More Technologies Than Required
    Business Centric
    Code Understanding is Key
    

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86. Simple
    No More Technologies Than Required
    Business Centric
    Courage
    Code Understanding is Key
    

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87. Any Questions ?
    

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