Whoops! Where did my architecture go?

Slides of the talk on maintaining software architecture in Java applications I gave at GeeCON Prague 2014. @springcentral

Transcript

1. Whoops!
   Where did my
   architecture go?
   Architecture management for Java applications
   !
   Oliver Gierke
   

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6. Background
   5 years of consulting
   Lots of code reviews
   Eoin Woods‘ talk on InfoQ
   Lot of input from fellows
   

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7. "If you think
   architecture is
   expensive, try no
   architecture.
   

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8. "Architecture is like
   weather: you can’t
   have none.
   

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9. Macro VS. Micro
   Architecture
   

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10. Orders
    Inventory
    Billing
    Macro-Architecture
    Micro-Architecture
    JMS
    REST
    AMQP
    

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11. JRuby
    Java
    Scala
    Macro-Architecture
    Micro-Architecture
    AMQP
    JMS
    REST
    

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12. Neo4j
    RDBMS
    MongoDB
    Macro-Architecture
    Micro-Architecture
    JMS
    REST
    AMQP
    

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13. Neo4j
    RDBMS
    MongoDB
    Macro-Architecture
    Micro-Architecture
    from Stefan Tilkov -

    Breaking the Monolith
    JMS
    REST
    AMQP
    

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14. Roadmap
    Divide and conquer
    Of layers and slices
    A plain Java based approach
    

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15. Architecture 101
    

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16. Know your
    dependencies
    

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17. Explicit / Visible
    dependencies
    

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18. Granularity
    Modules
    Layers
    Vertical slices
    Subsystems
    

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19. Granularity
    Java ARchive
    Package
    Class
    

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20. Divide and
    conquer
    

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21. Component
    Single unit to understand
    

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22. Component
    Single unit to change
    

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23. Component
    Scope of risk of change
    

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24. B
    Smaller unit to understand
    A
    

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25. B
    Reduced risk of change
    A
    

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26. B
    Cost of separation
    A
    

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27. B
    Definition and maintenance
    of dependencies
    A
    

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28. "Meanwhile, in my
    friend’s project…
    

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29. How do I add a feature?
    

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30. How do I add a feature?
    New

    Feature
    © Eberhard Wolff
    

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31. Of layers
    and slices…
    

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32. Presentation
    Service
    Data Access
    Account Customer Core
    

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33. Layers
    Well understood
    Known to developers
    Less important to business
    

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34. Slices
    Hardly understood
    New to developers
    Key for business requirements
    

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35. Presentation
    Service
    Data Access
    Account Customer Core
    

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36. "How to implement
    an architecture
    inside a codebase?
    

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37. Architecture
    VS.
    Codebase
    

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38. "How to implement
    an architecture
    inside a codebase?
    

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39. "How to maintain
    an architecture
    inside a codebase?
    

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40. Code analysis
    JDepend
    Sonarcube
    

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41. Sonargraph
    Formerly known as SonarJ
    

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42. Demo
    

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43. A plain Java
    based approach
    

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44. "How far can we get
    with plain Java
    means only?
    

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45. Presentation
    Service
    Data Access
    Account Customer Core
    

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46. Packages
    

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47. ….layer.slice
    ….slice.layer
    ….slice
    

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48. ….web.core
    ….service.core
    ….repository.core
    

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49. ….core.web
    ….core.service
    ….core.repository
    

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50. ….core
    ….customer
    ….account
    

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51. "Why the f#$k
    should I even care?
    

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52. "Does it make
    a difference?
    

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53. Dependency
    management
    

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54. "You only need to
    manage, what you
    can refer to…
    

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55. Layers first
    Leaks slice internals
    Lower layers visible to everyone
    

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56. Slices first/only
    Start with package per slice
    Expose interfaces and domain types
    Keep implementations private
    

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57. Slices first/only
    Encapsulates business module
    Internals understood anyway
    

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58. "Start with less
    packages and the
    least visibility
    possible…
    

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59. Presentation
    Service
    Data Access
    Account Customer Core
    

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60. Presentation
    Service
    Data Access
    Account Customer Core
    

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61. Demo
    

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62. Take-aways
    Know your dependencies
    On every granularity
    Start as strict as possible
    Get lenient where necessary
    

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63. Resources
    Spring Data JPA @ GitHub
    Sonargraph
    jQAssistant
    Blogpost
    

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64. Sample Code
    http://github.com/olivergierke/

    whoops-architecture
    

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65. Oliver Gierke
    Spring Data Project Lead
    !
    ogierke@pivotal.io
    olivergierke
    www.olivergierke.de
    

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66. Thanks & Credits
    Eoin Woods - Talk @ InfoQ
    Stefan Tilkov - Talk @ InfoQ
    Eberhard Wolff - Slides @ Slideshare
    

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