Clean Architecture - hands on

Transcript

1. @yot88
   Clean architecture
   

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2. Who am I ?
   Technical Agile coach, Software craftsman
   I’m Yoan THIRION (freelance)
   • design software since more than 15 years
   • fundamental to succeed in that area : agility and technical excellence
   • help teams deliver well crafted software
   • implementation of agile and technical practices (eXtreme programming, Refactoring, DDD, Mob programming, …)
   Let’s connect
   My services
   https://www.yoan-thirion.com/
   Technical agile coaching Communities of practice Cultural change
   devops Brown bags Serious games
   

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3. @yot88
   Learning Objectives
   • Discover the fundamentals of Clean Architecture
   • how to design for maintainability, extensibility and reusability
   • Show you a method to set your project on a path with higher success chances
   

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4. @yot88
   Clean architecture
   Robert C. Martin a.k.a Uncle bob
   2017
   

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5. @yot88
   Alistair Cockburn Jeffrey Palermo
   What characteristics do these architectures have in common?
   Onion architecture
   hexagonal architecture
   

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6. @yot88
   Hexagonal Architecture
   

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7. @yot88
   Source : https://blog.octo.com/architecture-hexagonale-trois-principes-et-un-exemple-dimplementation/
   Hexagonal Architecture
   

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8. @yot88
   Hexagonal Architecture
   Source : https://blog.octo.com/architecture-hexagonale-trois-principes-et-un-exemple-dimplementation/
   Business + rules
   

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9. @yot88
   Hexagonal Architecture
   Completely isolatethe core of your system (your business logic) and test automatically its behavior
   independently of other concerns (Database, Services, …)
   class Program {
   static void Main(string[] args) {
   // 1. Instantiate right-side adapter(s) ("I want to go outside the hexagon")
   IObtainPoems fileAdapter = new PoetryLibraryFileAdapter(@".\Rimbaud.txt");
   // 2. Instantiate the hexagon
   IRequestVerses poetryReader = new PoetryReader(fileAdapter);
   // 3. Instantiate the left-side adapter(s) ("I want ask/to go inside the hexagon")
   var consoleAdapter = new ConsoleAdapter(poetryReader);
   System.Console.WriteLine("Here is some...");
   consoleAdapter.Ask();
   System.Console.WriteLine("Type enter to exit...");
   System.Console.ReadLine();
   }
   }
   

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10. @yot88
    Onion Architecture
    

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11. @yot88
    Onion Architecture
    Source : https://dzone.com/articles/onion-architecture-is-interesting
    Entities and classes closely related to them
    Domain-defined processes
    Application-specific logic / use cases
    Outer layer
    Peripheral concerns
    

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12. @yot88
    Onion Architecture
    Source : https://dzone.com/articles/onion-architecture-is-interesting
    Between the layers of the Onion, there is a strong dependency rule
    outer layers can depend on lower layers, but no code in the lower
    layer can depend directly on any code in the outer layer.
    Dependency Inversion Principle for the
    architecture
    

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13. @yot88
    Onion Architecture
    

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14. @yot88
    Alistair Cockburn Jeffrey Palermo
    What characteristics do these architectures have in common?
    Onion architecture
    hexagonal architecture
    

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15. @yot88
    Independent of frameworks
    Does not depend on the existence of libraries
    Allow us to use frameworks as tools (not a constraint)
    Independent of the front-end
    Can easily change the UI (from web to console)
    Independent of the database
    Business rules not bound to Database logic
    Independent of any external agency
    Business rules don’t know anything about outside world
    What characteristics do these architectures have in common?
    

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16. @yot88
    Business rules can be tested without external components
    Testable
    

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17. @yot88
    Use Cases
    

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18. @yot88
    Use case driven approach
    Ivar Jacobson
    

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19. @yot88
    

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20. @yot88
    Entities (Enterprise business rules)
    • Encapsulate Enterprise wide business rules
    • Can be
    o Object with methods
    o Set of data structures and functions
    • Could be used by many different applications in the enterprise.
    

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21. @yot88
    Use cases (Application business rules)
    • Capture business rules
    • Structure should indicate what the application is, not how it does it
    • Application specific business rules
    

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22. @yot88
    Interface adapters
    • Set of adapters
    o Convert data
    § from the format most convenient for the use cases and entities,
    § to the format most convenient for some external agency such as the Database or the Web
    • In a MVC architecture :
    o Presenters, Views, and Controllers
    

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23. @yot88
    Frameworks & drivers
    • Frameworks and tools such as
    o Database
    o Web Framework
    Glue code that communicates to the next circle inwards.
    • This layer is where all the details go
    o Keep these things on the outside where they can do little harm.
    

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24. @yot88
    The dependency rule
    Source code dependencies can only point inwards.
    

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25. @yot88
    The dependency rule
    

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26. @yot88
    Clean architecture kata
    Objective
    • Learn and practice the concepts behind clean architecture
    The features of the application are basic crud :
    • Create a user
    • Find a user
    • List all users
    • Login a user with their password
    

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27. @yot88
    Clean architecture kata
    How to
    • Clone the repository at : https://github.com/ythirion/clean-architecture-example
    • Discover the code
    • Draw the sequence diagram of the create User
    

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28. @yot88
    Clean architecture kata
    

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29. @yot88
    What benefits do you see?
    Pros and cons ?
    La “Clean architecture” c’est la vie ?
    

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30. @yot88
    Pros and cons
    • Learning curve – I don’t know why, but people tend
    to mess up splitting responsibilities between layers,
    especially harming the domain model
    • Indirection – interfaces everywhere!
    • Potentially heavy
    • Plays well with DDD – architecture that builds everything on top
    of a domain model
    • Directed coupling – the most important code in our application
    depends on nothing, everything depends on it
    • Flexibility – from an inner-layer perspective, you can swap out
    anything in any of the outer layers and things should work just
    fine
    • Testability – since your application core does not depend on
    anything else, it can be easily and quickly tested in isolation
    

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31. @yot88
    Archunit – Unit test your java architecture
    https://sequencediagram.org/
    To enforce your architecture
    https://www.archunit.org/
    

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32. @yot88
    What about Fp ?
    

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33. @yot88
    In oo world
    Scott Wlaschin
    F# guru
    

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34. @yot88
    Functional core, imperative shell
    functional core
    • pure functions : in / out
    • easy to test without any mocks
    imperative shell or reactive
    • service logic
    • integration tests
    

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35. @yot88
    In fp world
    https://increment.com/software-architecture/primer-on-functional-architecture/
    Scott Wlaschin
    F# guru
    

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36. @yot88
    In fp world
    Property-based testing
    Scott Wlaschin
    F# guru
    

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37. @yot88
    Pure domain
    Combined with immutable data structures this means you can be sure
    the same inputs will give the same outputs.
    Pure functions don’t refer to any global state.
    The same inputs will always get the same output.
    let Double i = i * 2
    

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38. @yot88
    dependencies
    

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39. @yot88
    conclusion
    Liked Learned
    Lacked Longed for
    

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40. @yot88
    To go further
    Scott Wlaschin
    F# guru
    https://fsharpforfunandprofit.com/
    

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41. @yot88
    To go further
    https://yoan-thirion.gitbook.io/knowledge-base/
    

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