Clean Architecture

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

Transcript

1. Clean Architecture
2. What is Architecture?
3. • MVP • Realm • RxJava • Dagger • Retrofit • Gson
4. • MVP • Realm • RxJava • Dagger • Retrofit • Gson NO!
5. Tools • MVP • Realm • RxJava • Dagger • Retrofit • Gson
6. Screaming Architecture
9. Architecture is about intent
10. Architecture is about use cases
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
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
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
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
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
16. POLICIES The Dependency Rule MECHANISMS
17. POLICIES The Dependency Rule MECHANISMS
18. POLICIES The Dependency Rule MECHANISMS
19. POLICIES The Dependency Rule MECHANISMS
20. POLICIES The Dependency Rule MECHANISMS
21. Independent of Frameworks
22. Testable
23. Independent of UI
24. Independent of Database
25. Independent of External Agency
26. Decoupled
27. A Clean App
28. github.com/pardom/CleanNews
29. Entities Use cases Data sources, Presentation models Delivery mechanisms, databases Core App Presentation Data Android Desktop CleanNews ├── android ├── app ├── core ├── data ├── desktop └── presentation
30. Entities Use cases Data sources, Presentation models Delivery mechanisms, databases Core App Presentation Data Android Desktop CleanNews ├── android ├── app ├── core ├── data ├── desktop └── presentation
31. Entities Use cases Data sources, Presentation models Delivery mechanisms, databases App Presentation Data Android Desktop CleanNews ├── android ├── app ├── core ├── data ├── desktop └── presentation
32. Entities Use cases Data sources, Presentation models Delivery mechanisms, databases Presentation Data Android Desktop CleanNews ├── android ├── app ├── core ├── data ├── desktop └── presentation
33. Entities Use cases Data sources, Presentation models Delivery mechanisms, databases Android Desktop CleanNews ├── android ├── app ├── core ├── data ├── desktop └── presentation
34. app/src/main/kotlin/clean/news/app/
 ├── item
 │ ├── GetChildren
 │ ├── GetItemById
 │ ├── GetItemsByListType
 │ └── SaveItem
 └── user
 ├── GetUserById
 └── SaveUser
35. app/src/main/kotlin/clean/news/app/
 ├── item
 │ ├── GetChildren
 │ ├── GetItemById
 │ ├── GetItemsByListType
 │ └── SaveItem
 └── user
 ├── GetUserById
 └── SaveUser
36. Entities
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.”
38. apply plugin: 'java'
 
 dependencies { 
 } Core
39. core/src/main/kotlin/clean/news/core/entity/
 ├── Item.kt
 └── User.kt
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)
 }
 }
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)
 }
 }
42. data class User(
 val id: String,
 val delay: Int,
 val created: Date,
 val karma: Int,
 val about: String,
 val submitted: List<Long>
 )
43. Entities • Contain enterprise wide business rules • Encapsulate high-level rules • Unaffected by external layers
44. Use Cases
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.”
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.
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.
48. apply plugin: 'java'
 
 dependencies {
 compile project(':core')
 } Core App
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
50. Presenter Controller Use Case Input Port Use Case Interactor Use Case Output Port Flow of Control
51. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
52. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
53. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
54. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
55. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
56. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
57. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
58. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
59. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
60. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
61. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
62. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
63. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
64. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
65. Request Model Response Model Use Case Boundary <I> Boundary Presentation Model
66. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
67. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
68. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
69. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
70. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
71. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
72. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
73. interface UseCase<I : Request, O : Response> {
 
 fun execute(request: I): Observable<O>
 
 interface Request
 
 interface Response
 
 }
74. interface UseCase<R> {.
 
 fun execute(): Observable<R>
 
 }.
75. interface UseCase1<A, R> {.
 
 fun execute(arg1: A): Observable<R>
 
 }.
76. interface UseCase2<A, B, R> {.
 
 fun execute(arg1: A, arg2: B): Observable<R>
 
 }.
77. interface UseCase3<A, B, C, R> {.
 
 fun execute(arg1: A, arg2: B, arg3: C): Observable<R>
 
 }.
78. app/src/main/kotlin/clean/news/app/
 └── usecase
 ├── item
 │ ├── GetChildren.kt
 │ ├── GetItemById.kt
 │ ├── GetItemsByListType.kt
 │ └── SaveItem.kt
 └── user
 ├── GetUserById.kt
 └── SaveUser.kt
79. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
80. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
81. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
82. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
83. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
84. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
85. GetChildren.Request GetChildren.Response GetChildren ItemNetworkDataSource ItemRetrofitDataSource ItemDetailsViewModel
86. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
87. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
88. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
89. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
90. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
91. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
92. class GetChildren @Inject constructor(
 private val network: ItemNetworkDataSource) : UseCase<Request, Response> {
 
 override fun execute(request: Request): Observable<Response> {
 return network.getChildren(request.item)
 .map { Response(it) }
 }
 
 class Request(val item: Item) : UseCase.Request
 
 class Response(val items: List<Item>) : UseCase.Response
 }
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
94. interface DataSource<T, ID> {
 fun getAll(): Observable<List<T>>
 
 fun getById(id: ID): Observable<T>
 
 fun save(t: T): Observable<Boolean>
 }
95. interface ItemDataSource : DataSource<Item, Long> {
 fun getItems(listType: ListType): Observable<List<Item>>
 
 fun getChildren(item: Item): Observable<List<Item>>
 }
96. interface ItemDiskDataSource : ItemDataSource interface ItemMemoryDataSource : ItemDataSource interface ItemNetworkDataSource : ItemDataSource
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
98. Interface Adapters
99. “a design pattern that allows the interface of an existing class to be used as another interface.”
100. apply plugin: 'java'
 
 dependencies {
 compile project(':app')
 } Core App Presentation Data
101. ItemNetworkDataSource GetChildren ItemRetrofitDataSource ItemDetailViewModel
102. ItemNetworkDataSource GetChildren ItemRetrofitDataSource ItemDetailViewModel
103. ItemNetworkDataSource GetChildren ItemRetrofitDataSource ItemDetailViewModel
104. ItemNetworkDataSource GetChildren ItemRetrofitDataSource ItemDetailViewModel
105. ItemNetworkDataSource GetChildren ItemRetrofitDataSource ItemDetailViewModel
106. presentation/src/main/kotlin/clean/news/presentation/model/
 ├── Model.kt
 ├── item
 │ ├── ItemDetailViewModel.kt
 │ ├── ItemListViewModel.kt
 │ └── ItemUrlViewModel.kt
 └── main
 └── MainViewModel.kt
107. class ItemDetailViewModel @Inject constructor(
 private val getChildren: GetChildren,
 private val item: Item) : Model<Sources, Sinks> {
 
 private val children = getChildren.execute(Request(item))
 .map { it.items }
 .replay(1)
 .autoConnect()
 }
108. class ItemDetailViewModel @Inject constructor(
 private val getChildren: GetChildren,
 private val item: Item) : Model<Sources, Sinks> {
 
 private val children = getChildren.execute(Request(item))
 .map { it.items }
 .replay(1)
 .autoConnect()
 }
109. class ItemDetailViewModel @Inject constructor(
 private val getChildren: GetChildren,
 private val item: Item) : Model<Sources, Sinks> {
 
 private val children = getChildren.execute(Request(item))
 .map { it.items }
 .replay(1)
 .autoConnect()
 }
110. data/src/main/kotlin/clean/news/data/
 ├── lru
 │ ├── ItemLruDataSource.kt
 │ └── UserLruDataSource.kt
 ├── retrofit
 │ ├── ItemRetrofitDataSource.kt
 │ └── UserRetrofitDataSource.kt
 └── sqlite
 ├── ItemSqliteDataSource.kt
 └── UserSqliteDataSource.kt
111. class ItemRetrofitDataSource @Inject constructor(
 private val itemService: ItemService) : ItemNetworkDataSource {
 
 override fun getById(id: Long): Observable<Item> {
 return itemService.getById(id)
 }
 }
112. class ItemRetrofitDataSource @Inject constructor(
 private val itemService: ItemService) : ItemNetworkDataSource {
 
 override fun getById(id: Long): Observable<Item> {
 return itemService.getById(id)
 }
 }
113. class ItemRetrofitDataSource @Inject constructor(
 private val itemService: ItemService) : ItemNetworkDataSource {
 
 override fun getById(id: Long): Observable<Item> {
 return itemService.getById(id)
 }
 }
114. interface ItemService { 
 @GET("item/{item_id}.json")
 fun getById(@Path("item_id") id: Long): Observable<Item> 
 }
115. class ItemRetrofitDataSource @Inject constructor(
 private val itemService: ItemService) : ItemNetworkDataSource {
 
 override fun getById(id: Long): Observable<Item> {
 return itemService.getById(id)
 }
 }
116. Interface Adapters • Convert data between uses cases and external agencies • MVC, MVP, MVVM, RPM implementation • Database adapter • Network adapter
117. Frameworks and Drivers
118. “a universal, reusable software environment that provides particular functionality as part of a larger software platform to facilitate development”
119. apply plugin: 'com.android.application'
 
 dependencies {
 compile project(':presentation')
 compile project(':data')
 } Core App Presentation Data Android Desktop
120. class ItemDetailView : RelativeLayout { 
 @Inject
 lateinit var model: ItemDetailViewModel
 
 @JvmOverloads
 constructor(...) : super(context, attrs, defStyle) {
 ComponentService.getService<ItemDetailComponent>(context)?.inject(this)
 } }
121. class ItemDetailView : RelativeLayout {
 @Inject
 lateinit var model: ItemDetailViewModel
 
 @JvmOverloads
 constructor(...) : super(context, attrs, defStyle) {
 ComponentService.getService<ItemDetailComponent>(context)?.inject(this)
 } }
122. class ItemDetailView : RelativeLayout { 
 @Inject
 lateinit var model: ItemDetailViewModel
 
 @JvmOverloads
 constructor(...) : super(context, attrs, defStyle) {
 ComponentService.getService<ItemDetailComponent>(context)?.inject(this)
 } }
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)
 }
 
 }
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)
 }
 
 }
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)
 }
 
 }
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 }
 ))
 }
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 }
 ))
 }
128. Frameworks and Drivers • Glue code to communicate inwards • Delivery mechanism • Dependency providers
129. POLICIES MECHANISMS
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
131. Questions? @pardom michaelpardo.com