Clean Architecture

A practical guide to making your code more readable, testable, and maintainable using clean architecture.

Transcript

1. Clean Architecture
   

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2. What is Architecture?
   

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3. • MVP
   • Realm
   • RxJava
   • Dagger
   • Retrofit
   • Gson
   

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4. • MVP
   • Realm
   • RxJava
   • Dagger
   • Retrofit
   • Gson
   NO!
   

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5. Tools
   • MVP
   • Realm
   • RxJava
   • Dagger
   • Retrofit
   • Gson
   

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6. Screaming Architecture
   

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9. Architecture is about intent
   

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10. Architecture is about use cases
    

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11. Entities
    Use Cases
    Controllers
    Gateways
    Presenters
    Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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12. Entities
    Use Cases
    Controllers
    Gateways
    Presenters
    Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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13. Use Cases
    Controllers
    Gateways
    Presenters
    Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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14. Controllers
    Gateways
    Presenters
    Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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15. Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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16. POLICIES
    The Dependency Rule
    MECHANISMS
    

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17. POLICIES
    The Dependency Rule
    MECHANISMS
    

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18. POLICIES
    The Dependency Rule
    MECHANISMS
    

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19. POLICIES
    The Dependency Rule
    MECHANISMS
    

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20. POLICIES
    The Dependency Rule
    MECHANISMS
    

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21. Independent of Frameworks
    

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22. Testable
    

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23. Independent of UI
    

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24. Independent of Database
    

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25. Independent of External Agency
    

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26. Decoupled
    

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27. A Clean App
    

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28. github.com/pardom/CleanNews
    

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29. Entities
    Use cases
    Data sources, Presentation models
    Delivery mechanisms, databases
    Core
    App
    Presentation
    Data
    Android
    Desktop
    CleanNews
    ├── android
    ├── app
    ├── core
    ├── data
    ├── desktop
    └── presentation
    

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30. Entities
    Use cases
    Data sources, Presentation models
    Delivery mechanisms, databases
    Core
    App
    Presentation
    Data
    Android
    Desktop
    CleanNews
    ├── android
    ├── app
    ├── core
    ├── data
    ├── desktop
    └── presentation
    

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31. Entities
    Use cases
    Data sources, Presentation models
    Delivery mechanisms, databases
    App
    Presentation
    Data
    Android
    Desktop
    CleanNews
    ├── android
    ├── app
    ├── core
    ├── data
    ├── desktop
    └── presentation
    

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32. Entities
    Use cases
    Data sources, Presentation models
    Delivery mechanisms, databases
    Presentation
    Data
    Android
    Desktop
    CleanNews
    ├── android
    ├── app
    ├── core
    ├── data
    ├── desktop
    └── presentation
    

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33. Entities
    Use cases
    Data sources, Presentation models
    Delivery mechanisms, databases
    Android
    Desktop
    CleanNews
    ├── android
    ├── app
    ├── core
    ├── data
    ├── desktop
    └── presentation
    

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34. app/src/main/kotlin/clean/news/app/

    ├── item

    │ ├── GetChildren

    │ ├── GetItemById

    │ ├── GetItemsByListType

    │ └── SaveItem

    └── user

    ├── GetUserById

    └── SaveUser
    

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35. app/src/main/kotlin/clean/news/app/

    ├── item

    │ ├── GetChildren

    │ ├── GetItemById

    │ ├── GetItemsByListType

    │ └── SaveItem

    └── user

    ├── GetUserById

    └── SaveUser
    

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36. Entities
    

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37. “An entity is something that exists as itself, as a subject or as an object,
    actually or potentially, concretely or abstractly, physically or not.”
    

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38. apply plugin: 'java'

    

    dependencies {
    

    }
    Core
    

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39. core/src/main/kotlin/clean/news/core/entity/

    ├── Item.kt

    └── User.kt
    

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40. data class Item(

    val id: Long,

    val type: Type,

    val by: String?,

    val time: Date,

    val text: String?,

    val url: String?,

    val title: String?) {

    

    enum class Type(val canComment: Boolean) {

    JOB(false), STORY(true), COMMENT(true), POLL(true), POLLOPT(true), NONE(false)

    }

    }
    

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41. data class Item(

    val id: Long,

    val type: Type,

    val by: String?,

    val time: Date,

    val text: String?,

    val url: String?,

    val title: String?) {

    

    enum class Type(val canComment: Boolean) {

    JOB(false), STORY(true), COMMENT(true), POLL(true), POLLOPT(true), NONE(false)

    }

    }
    

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42. data class User(

    val id: String,

    val delay: Int,

    val created: Date,

    val karma: Int,

    val about: String,

    val submitted: List

    )
    

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43. Entities
    • Contain enterprise wide business rules
    • Encapsulate high-level rules
    • Unaffected by external layers
    

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44. Use Cases
    

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45. “A use case is a list of actions or event steps, typically defining the
    interactions between a role and a system, to achieve a goal.”
    

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46. Title (goal)
    Primary Actor: …

    Scope: …

    Level: …
    (Story): the body of the use case is simply a paragraph or two of text,
    informally describing what happens.
    

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47. Retrieve story details
    Primary Actor: Reader

    Scope: A Hacker News client

    Level: User goal
    The reader invokes the client to retrieve the details for a story. This includes
    the children of a story, namely the comments.
    

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48. apply plugin: 'java'

    

    dependencies {

    compile project(':core')

    }
    Core
    App
    

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49. Entities
    Use Cases
    Controllers
    Gateways
    Presenters
    Devices
    Web
    DB UI
    External
    Interfaces
    Enterprise Business Rules
    Application Business Rules
    Interface Adapters
    Frameworks & Drivers
    Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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50. Presenter
    Controller
    Use Case
    Input Port
    Use Case
    Interactor
    Use Case
    Output Port
    Flow of Control
    

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51. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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52. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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53. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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54. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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55. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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56. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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57. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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58. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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59. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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60. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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61. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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62. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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63. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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64. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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65. Request Model
    Response Model
    Use Case Boundary
    Boundary
    Presentation Model
    

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66. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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67. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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68. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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69. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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70. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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71. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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72. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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73. interface UseCase {

    

    fun execute(request: I): Observable

    

    interface Request

    

    interface Response

    

    }
    

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74. interface UseCase {.

    

    fun execute(): Observable

    

    }.
    

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75. interface UseCase1 {.

    

    fun execute(arg1: A): Observable

    

    }.
    

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76. interface UseCase2 {.

    

    fun execute(arg1: A, arg2: B): Observable

    

    }.
    

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77. interface UseCase3 {.

    

    fun execute(arg1: A, arg2: B, arg3: C): Observable

    

    }.
    

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78. app/src/main/kotlin/clean/news/app/

    └── usecase

    ├── item

    │ ├── GetChildren.kt

    │ ├── GetItemById.kt

    │ ├── GetItemsByListType.kt

    │ └── SaveItem.kt

    └── user

    ├── GetUserById.kt

    └── SaveUser.kt
    

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79. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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80. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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81. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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82. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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83. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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84. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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85. GetChildren.Request
    GetChildren.Response
    GetChildren ItemNetworkDataSource
    ItemRetrofitDataSource
    ItemDetailsViewModel
    

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86. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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87. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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88. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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89. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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90. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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91. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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92. class GetChildren @Inject constructor(

    private val network: ItemNetworkDataSource) : UseCase {

    

    override fun execute(request: Request): Observable {

    return network.getChildren(request.item)

    .map { Response(it) }

    }

    

    class Request(val item: Item) : UseCase.Request

    

    class Response(val items: List) : UseCase.Response

    }
    

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93. app/src/main/kotlin/clean/news/app/

    └── data

    ├── DataSource.kt

    ├── item

    │ ├── ItemDataSource.kt

    │ ├── ItemDiskDataSource.kt

    │ ├── ItemMemoryDataSource.kt

    │ └── ItemNetworkDataSource.kt

    └── user

    ├── UserDataSource.kt

    ├── UserDiskDataSource.kt

    ├── UserMemoryDataSource.kt

    └── UserNetworkDataSource.kt
    

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94. interface DataSource {

    fun getAll(): Observable>

    

    fun getById(id: ID): Observable

    

    fun save(t: T): Observable

    }
    

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95. interface ItemDataSource : DataSource {

    fun getItems(listType: ListType): Observable>

    

    fun getChildren(item: Item): Observable>

    }
    

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96. interface ItemDiskDataSource : ItemDataSource
    interface ItemMemoryDataSource : ItemDataSource
    interface ItemNetworkDataSource : ItemDataSource
    

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97. Use Cases
    • Contain application specific business rules
    • Orchestrate the flow of data to and from entities
    • Unaffected by external systems like database or UI
    

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98. Interface Adapters
    

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99. “a design pattern that allows the interface of an existing
    class to be used as another interface.”
    

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100. apply plugin: 'java'

     

     dependencies {

     compile project(':app')

     }
     Core
     App
     Presentation
     Data
     

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101. ItemNetworkDataSource
     GetChildren
     ItemRetrofitDataSource
     ItemDetailViewModel
     

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102. ItemNetworkDataSource
     GetChildren
     ItemRetrofitDataSource
     ItemDetailViewModel
     

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103. ItemNetworkDataSource
     GetChildren
     ItemRetrofitDataSource
     ItemDetailViewModel
     

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104. ItemNetworkDataSource
     GetChildren
     ItemRetrofitDataSource
     ItemDetailViewModel
     

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105. ItemNetworkDataSource
     GetChildren
     ItemRetrofitDataSource
     ItemDetailViewModel
     

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106. presentation/src/main/kotlin/clean/news/presentation/model/

     ├── Model.kt

     ├── item

     │ ├── ItemDetailViewModel.kt

     │ ├── ItemListViewModel.kt

     │ └── ItemUrlViewModel.kt

     └── main

     └── MainViewModel.kt
     

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107. class ItemDetailViewModel @Inject constructor(

     private val getChildren: GetChildren,

     private val item: Item) : Model {

     

     private val children = getChildren.execute(Request(item))

     .map { it.items }

     .replay(1)

     .autoConnect()

     }
     

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108. class ItemDetailViewModel @Inject constructor(

     private val getChildren: GetChildren,

     private val item: Item) : Model {

     

     private val children = getChildren.execute(Request(item))

     .map { it.items }

     .replay(1)

     .autoConnect()

     }
     

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109. class ItemDetailViewModel @Inject constructor(

     private val getChildren: GetChildren,

     private val item: Item) : Model {

     

     private val children = getChildren.execute(Request(item))

     .map { it.items }

     .replay(1)

     .autoConnect()

     }
     

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110. data/src/main/kotlin/clean/news/data/

     ├── lru

     │ ├── ItemLruDataSource.kt

     │ └── UserLruDataSource.kt

     ├── retrofit

     │ ├── ItemRetrofitDataSource.kt

     │ └── UserRetrofitDataSource.kt

     └── sqlite

     ├── ItemSqliteDataSource.kt

     └── UserSqliteDataSource.kt
     

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111. class ItemRetrofitDataSource @Inject constructor(

     private val itemService: ItemService) : ItemNetworkDataSource {

     

     override fun getById(id: Long): Observable {

     return itemService.getById(id)

     }

     }
     

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112. class ItemRetrofitDataSource @Inject constructor(

     private val itemService: ItemService) : ItemNetworkDataSource {

     

     override fun getById(id: Long): Observable {

     return itemService.getById(id)

     }

     }
     

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113. class ItemRetrofitDataSource @Inject constructor(

     private val itemService: ItemService) : ItemNetworkDataSource {

     

     override fun getById(id: Long): Observable {

     return itemService.getById(id)

     }

     }
     

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114. interface ItemService {
     

     @GET("item/{item_id}.json")

     fun getById(@Path("item_id") id: Long): Observable
     

     }
     

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115. class ItemRetrofitDataSource @Inject constructor(

     private val itemService: ItemService) : ItemNetworkDataSource {

     

     override fun getById(id: Long): Observable {

     return itemService.getById(id)

     }

     }
     

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116. Interface Adapters
     • Convert data between uses cases and external agencies
     • MVC, MVP, MVVM, RPM implementation
     • Database adapter
     • Network adapter
     

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117. Frameworks and Drivers
     

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118. “a universal, reusable software environment that provides
     particular functionality as part of a larger software
     platform to facilitate development”
     

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119. apply plugin: 'com.android.application'

     

     dependencies {

     compile project(':presentation')

     compile project(':data')

     }
     Core
     App
     Presentation
     Data
     Android
     Desktop
     

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120. class ItemDetailView : RelativeLayout {
     

     @Inject

     lateinit var model: ItemDetailViewModel

     

     @JvmOverloads

     constructor(...) : super(context, attrs, defStyle) {

     ComponentService.getService(context)?.inject(this)

     }
     }
     

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121. class ItemDetailView : RelativeLayout {

     @Inject

     lateinit var model: ItemDetailViewModel

     

     @JvmOverloads

     constructor(...) : super(context, attrs, defStyle) {

     ComponentService.getService(context)?.inject(this)

     }
     }
     

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122. class ItemDetailView : RelativeLayout {
     

     @Inject

     lateinit var model: ItemDetailViewModel

     

     @JvmOverloads

     constructor(...) : super(context, attrs, defStyle) {

     ComponentService.getService(context)?.inject(this)

     }
     }
     

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123. @Module

     class DataModule {
     

     @Provides

     @ApplicationScope

     fun itemService(retrofit: Retrofit): ItemService {

     return retrofit.create(ItemService::class.java)

     }

     

     @Provides

     @ApplicationScope

     fun itemNetworkDataSource(itemService: ItemService): ItemNetworkDataSource {

     return ItemRetrofitDataSource(itemService)

     }

     

     }
     

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124. @Module

     class DataModule {
     

     @Provides

     @ApplicationScope

     fun itemService(retrofit: Retrofit): ItemService {

     return retrofit.create(ItemService::class.java)

     }

     

     @Provides

     @ApplicationScope

     fun itemNetworkDataSource(itemService: ItemService): ItemNetworkDataSource {

     return ItemRetrofitDataSource(itemService)

     }

     

     }
     

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125. @Module

     class DataModule {
     

     @Provides

     @ApplicationScope

     fun itemService(retrofit: Retrofit): ItemService {

     return retrofit.create(ItemService::class.java)

     }

     

     @Provides

     @ApplicationScope

     fun itemNetworkDataSource(itemService: ItemService): ItemNetworkDataSource {

     return ItemRetrofitDataSource(itemService)

     }

     

     }
     

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126. override fun onAttachedToWindow() {

     super.onAttachedToWindow()

     val sinks = model.setUp(Sources(

     toolbar.navigationClicks(),

     Observable.empty(),

     toolbar.itemClicks()

     .filter {it.itemId == R.id.item_share }

     .map { Unit }

     ))

     }
     

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127. override fun onAttachedToWindow() {

     super.onAttachedToWindow()

     val sinks = model.setUp(Sources(

     toolbar.navigationClicks(),

     Observable.empty(),

     toolbar.itemClicks()

     .filter {it.itemId == R.id.item_share }

     .map { Unit }

     ))

     }
     

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128. Frameworks and Drivers
     • Glue code to communicate inwards
     • Delivery mechanism
     • Dependency providers
     

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129. POLICIES
     MECHANISMS
     

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130. Resources
     • https://github.com/pardom/CleanNews
     • https://blog.8thlight.com/uncle-bob/2012/08/13/the-clean-architecture.html
     • https://cleancoders.com/episode/clean-code-episode-7/show
     

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131. Questions?
     @pardom
     michaelpardo.com
     

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