Android Architecture Design With Koin

Koin (https://insert-koin.io) is a pragmatic dependency injection framework for Kotlin/Android developers, well known for its ease of use. In this session, I propose to see together how we can structure our components, for the following topics:
* Classical Components in MVP, MVVM
* Dealing with Scopes
* Jetpack Navigation
* Jetpack Compose
* Integrating with MultiPlatform

And bonus, we will talk about new features.

Transcript

1. Android Architecture Design With Koin Arnaud Giuliani @arnogiu
2. Koin Project Lead Google Dev Expert - Kotlin @arnogiu Arnaud GIULIANI
3. Architecture Recipes With Koin
4. Koin Core Concepts 🛠
5. Just use Koin, what else?
6. class ClassA() class ClassB(val a : ClassA)
7. class ClassA() class ClassB(val a : ClassA) module { }
8. class ClassA() class ClassB(val a : ClassA) module { single { ClassB() } }
9. class ClassA() class ClassB(val a : ClassA) module { single { ClassA() } single { ClassB(???) } }
10. class ClassA() class ClassB(val a : ClassA) module { single { ClassA() } single { ClassB(get()) } } - Constructor injection con fi gured via Koin DSL - Instances are called by Koin Container
11. class MyApp { val classB : ClassB }
12. class MyApp : KoinComponent { val classB : ClassB }
13. class MyApp : KoinComponent { val classB by inject<ClassB>() } - Use the Koin API to retrieve a dependency - Host class is not created by Koin MyApp().classB
14. Classical MVP-MVVM 🎯
15. https:/ /github.com/InsertKoinIO/architecture-samples/tree/dev-koin https:/ /github.com/android/architecture-samples
16. Tasks Repository Tasks DataSource Tasks Local DataSource TasksViewModel TasksActivity Tasks Database
17. Since Koin 3.x! // Android implementation "io.insert-koin:koin-android:$koin_version" implementation "io.insert-koin:koin-androidx-viewmodel:$koin_version" implementation "io.insert-koin:koin-androidx-scope:$koin_version" implementation "io.insert-koin:koin-androidx-fragment:$koin_version"
18. Tasks DataSource class TasksRemoteDataSource : TasksDataSource // Koin DSL single<TasksDataSource> { TasksRemoteDataSource() }
19. Tasks DataSource Tasks Local DataSource class TasksRemoteDataSource : TasksDataSource class TasksLocalDataSource( private val tasksDao: TasksDao, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksDataSource // Koin DSL single<TasksDataSource> { TasksRemoteDataSource() } single<TasksDataSource> { TasksLocalDataSource(get(),get()) }
20. Tasks DataSource Tasks Local DataSource class TasksRemoteDataSource : TasksDataSource class TasksLocalDataSource( private val tasksDao: TasksDao, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksDataSource // Koin DSL single<TasksDataSource>(named("RemoteDS")) { TasksRemoteDataSource() } single<TasksDataSource>(named("LocalDS")) { TasksLocalDataSource(get(),get()) }
21. class DefaultTasksRepository( private val tasksRemoteDataSource: TasksDataSource, private val tasksLocalDataSource: TasksDataSource, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksRepository // Koin DSL single<TasksRepository> { DefaultTasksRepository( get(), get(), get() ) } Tasks Repository
22. class DefaultTasksRepository( private val tasksRemoteDataSource: TasksDataSource, private val tasksLocalDataSource: TasksDataSource, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksRepository // Koin DSL single<TasksRepository> { DefaultTasksRepository( get(named("RemoteDS")), get(named("LocalDS")), get() ) } Tasks Repository
23. // Koin DSL single { Room.databaseBuilder( androidContext().applicationContext, ToDoDatabase::class.java, "Tasks.db" ).build() } single { get<ToDoDatabase>().taskDao() } Tasks Database
24. // Koin DSL single { Room.databaseBuilder( androidContext().applicationContext, ToDoDatabase::class.java, "Tasks.db" ).build() } single { get<ToDoDatabase>().taskDao() } Tasks Database
25. class TasksViewModel( private val tasksRepository: TasksRepository, private val savedStateHandle: SavedStateHandle ) : ViewModel() // Koin DSL viewModel { TasksViewModel(get(),get()) } TasksViewModel
26. // by ViewModel() in Activity & Fragment class TasksActivity : AppCompatActivity() { // also inject SavedStateHandle val viewModel : TasksViewModel by viewModel() } TasksActivity
27. Tasks Repository Tasks DataSource Tasks Local DataSource TasksActivity Tasks Database
28. Tasks Repository Tasks DataSource Tasks Local DataSource TasksPresenter TasksActivity Tasks Database
29. class TasksPresenter( private val tasksRepository: TasksRepository, private val view: TasksView ) // Koin DSL - Parameter injection for Presenter factory { TasksPresenter(get(), ??? ) } TasksViewPresenter
30. class TasksPresenter( private val tasksRepository: TasksRepository, private val view: TasksView ) // Koin DSL - Parameter injection for Presenter factory { (view: TasksView) -> TasksPresenter(get(),view) } TasksViewPresenter
31. class TasksActivity : TasksView, AppCompatActivity() { // inject itself as a view val presenter : TasksPresenter by inject { parametersOf(this) } } TasksView
32. val appModule = module { // Presentation Layers viewModel { TasksViewModel(get(),get()) } factory { (view: TasksView) -> TasksPresenter(get(),view) } // Repository single<TasksRepository> { DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get()) } // Data Sources single<TasksDataSource>(named("RemoteDS")) { TasksRemoteDataSource() } single<TasksDataSource>(named("LocalDS")) { TasksLocalDataSource(get(),get()) } // Room single { Room.databaseBuilder(...).build() } single { get<ToDoDatabase>().taskDao() } }
33. - Layers, features … - Granularity & Testability Organising Modules? 🤔
34. val dataModule = module { } val uiModule = module { } val appModule = dataModule + uiModule startKoin { modules(appModule) }
35. Clean Architecture 🏗
37. Tasks Repository Tasks DataSource Tasks Local DataSource TasksViewModel TasksActivity Tasks Database
38. Tasks Repository Tasks DataSource Tasks Local DataSource TasksViewModel TasksActivity Tasks Database GetTaskUseCase
39. class TasksViewModel( private val getTaskUseCase: GetTaskUseCase, private val savedStateHandle: SavedStateHandle ) : ViewModel() // Koin DSL viewModel { TasksViewModel(get(),get()) } TasksViewModel
40. class GetTaskUseCase( private val tasksRepository: TasksRepository ) // Koin DSL // Don’t hold instance - ensure it’s stateless factory { GetTaskUseCase(get()) } GetTaskUseCase
41. val appModule = module { // Presentation Layers viewModel { TasksViewModel(get(),get()) } factory { (view: TasksView) -> TasksPresenter(get(),view) } // Repository single<TasksRepository> { DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get()) } // Data Sources single<TasksDataSource>(named("RemoteDS")) { TasksRemoteDataSource() } single<TasksDataSource>(named("LocalDS")) { TasksLocalDataSource(get(),get()) } // Room single { Room.databaseBuilder(...).build() } single { get<ToDoDatabase>().taskDao() } }
42. val appModule = module { // Presentation Layers viewModel { TasksViewModel(get(),get()) } factory { (view: TasksView) -> TasksPresenter(get(),view) } // Usecase factory { GetTaskUseCase(get()) } // Repository single<TasksRepository> { DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get()) } // Data Sources single<TasksDataSource>(named("RemoteDS")) { TasksRemoteDataSource() } single<TasksDataSource>(named("LocalDS")) { TasksLocalDataSource(get(),get()) } // Room single { Room.databaseBuilder(...).build() } single { get<ToDoDatabase>().taskDao() } }
43. Let’s wrap up 👍
44. Tasks Repository Tasks DataSource Tasks Local DataSource TasksPresenter TasksActivity Tasks Database TasksViewModel Koin API factory or viewModel single single single
45. Koin API factory or viewModel single single single Tasks Repository Tasks DataSource Tasks Local DataSource TasksViewModel TasksActivity Tasks Database GetTaskUseCase TasksPresenter factory
46. Koin API factory or viewModel single single single Repository DataSource Local DataSource ViewModel Android UI Database UseCase / Interactor Presenter factory
47. Working with Scopes 🚑
48. Why do we need a scope? 📦 keep instances ⏱ specific time
49. What about Android scope? We maintain instances for the duration of an Android component lifecycle.
50. Follow the Android Components
51. class MyActivity : AppCompatActivity() { val myPresenter : MyPresenter by inject() } // Koin DSL factory { MyPresenter(...) } 💥
52. Android Scope
53. class MyActivity : ScopeActivity() { // Resolved in MyActivity's scope val myPresenter : MyPresenter by inject() val myAdapter : MyAdapter by inject() } // Koin DSL scope<MyActivity> { scoped { MyPresenter() } scoped { MyAdapter(get()) } } class MyAdapter(val presenter : Mypresenter) 💥 ScopeActivity use Activity’s scope by default
54. ViewModel
55. class MyActivity : Activity() { val myViewModel : MyViewModel by viewModel() } // Koin DSL viewModel { MyViewModel() } ♻ class MyViewModel() : ViewModel()
56. class MyActivity : ScopeActivity() { // Override current scope to Activity's scope by default override val scope : Scope by activityRetainedScope() val myViewModel : MyViewModel by viewModel() val myAdapter : MyAdapter by inject() } All components are backed By ViewModel ✅
57. Navigation Graph ViewModel
58. // Android Nav implementation “io.insert-koin:koin-androidx-navigation:$koin_version"
59. class NavViewModel() : ViewModel() // Koin DSL viewModel { NavViewModel() } NavViewModel
60. class MyFragment : Fragment() { val navViewModel : NavViewModel by koinNavGraphViewModel(R.id.nav_graph) } MyFragment Nav Graph
61. Scopes - Wrap up 👍
62. // Koin DSL scope<MyActivity> { scoped { MyPresenter() } scoped { MyAdapter(get()) } } Define a scope class MyActivity : ScopeActivity() { } interface AndroidScopeComponent { override val scope : Scope by activityScope() } Use a scope with Android API
63. // create scope getKoin().createScope(...) // ... get it elsewhere val scope = getKoin().getScope(...) scope.get<>() Get the Scope API class MyFragment : Fragment() { val navViewModel : NavViewModel by koinNavGraphViewModel(R.id.nav_graph) } ViewModel scoped to Nav Graph
64. Koin API factory or viewModel single single single Repository DataSource Local DataSource ViewModel Android UI Database Presenter
65. Koin API factory, viewModel or Scope single single single Repository DataSource Local DataSource ViewModel Android UI Database Presenter
66. Keep your Koin con fi g simple ✨
67. Less Code = Less Bugs Chet Haase
68. New Architectures! 🦄
69. Jetpack Compose 🦄
70. Injecting in Compose
71. // Android Nav implementation “io.insert-koin:koin-androidx-compose:$koin_version”
72. // Retrieving instance in a composable @Composable fun App() { val myService = get<MyService>() // or by inject<MyService>() } Getting instances in a Composable // Default parameter value @Composable fun App(myService: MyService = get()) { }
73. // Retrieving ViewModel in a composable @Composable fun App() { val myViewModel = getViewModel<MyViewModel>() // or by viewModel<MyViewModel>() } Getting ViewModel in a Composable // Default parameter value @Composable fun App(myViewModel: MyViewModel = getViewModel()) { }
74. https:/ /github.com/InsertKoinIO/compose-samples Jetpack Compose Samples
75. Koin API factory or viewModel single single single Repository DataSource Local DataSource ViewModel Android UI Database Presenter
76. Koin API factory or viewModel single single single Repository DataSource Local DataSource ViewModel Composable Database Presenter
77. Dependency Injection For Kotlin Multiplatform ⭐
79. Repository DataSource Local DataSource Presentation Android UI Database
80. Repository DataSource Local DataSource Native UI (Android, iOS) Database Presentation
81. Shared Kotlin Common Repository DataSource Local DataSource Native UI (Android, iOS) Database Presentation
82. People In Space https:/ /github.com/joreilly/PeopleInSpace
84. Android App Common Code iOS App Backend & web app
85. Common Code
86. Common DI Modules
87. Kermit Logging Json Serialization Ktor Http Client + API Component Data Repository
88. Json Serialization Ktor Http Client + API Component Data Repository Kermit Logging => Data Storage with SQLDelight
90. JVM Impl iOS Impl
91. val appModule = module { viewModel { PeopleInSpaceViewModel(get()) } } ViewModel -> Repository
92. Koin API factory or viewModel single single single Kotlin Multiplatform API 🚀 Repository DataSource Local DataSource Native UI (Android, iOS) Database Presentation
93. New features! 🌈
94. New Feature Proposal ✨
95. Limits of Koin DSL 🤨
96. Kotlin Compiler Plugin! 🛠
97. KSP Powered 🔥 👉 Generate Koin stu ff DSL for you https:/ /github.com/google/ksp
98. Koin Semantic 🤔
99. koin_annotations_version = “1.0.0-beta-2” implementation "io.insert-koin:koin-annotations:$koin_ksp_version" ksp "io.insert-koin:koin-ksp-compiler:$koin_ksp_version"
100. Tasks Repository Tasks DataSource Tasks Local DataSource TasksViewModel TasksActivity Tasks Database
101. De fi nitions
102. Tasks DataSource class TasksRemoteDataSource : TasksDatasource
103. Tasks DataSource @Single class TasksRemoteDataSource : TasksDatasource
104. Tasks DataSource Tasks Local DataSource class TasksRemoteDataSource : TasksDatasource class TasksLocalDataSource( private val tasksDao: TasksDao, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksDatasource
105. Tasks DataSource Tasks Local DataSource @Single class TasksRemoteDataSource : TasksDatasource @Single class TasksLocalDataSource( private val tasksDao: TasksDao, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksDatasource
106. Tasks DataSource Tasks Local DataSource @Single @Named("RemoteDS") class TasksRemoteDataSource : TasksDatasource @Single @Named("LocalDS") class TasksLocalDataSource( private val tasksDao: TasksDao, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksDatasource
107. class DefaultTasksRepository( private val tasksRemoteDataSource: TasksDataSource, private val tasksLocalDataSource: TasksDataSource, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksRepository Tasks Repository
108. @Single class DefaultTasksRepository( private val tasksRemoteDataSource: TasksDataSource, private val tasksLocalDataSource: TasksDataSource, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksRepository Tasks Repository
109. @Single class DefaultTasksRepository( @Named("RemoteDS") private val tasksRemoteDataSource: TasksDataSource, @Named("LocalDS") private val tasksLocalDataSource: TasksDataSource, private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO ) : TasksRepository Tasks Repository
110. class TasksViewModel( private val tasksRepository: TasksRepository, private val savedStateHandle: SavedStateHandle ) : ViewModel() TasksViewModel
111. @KoinViewModel class TasksViewModel( private val tasksRepository: TasksRepository, private val savedStateHandle: SavedStateHandle ) : ViewModel() TasksViewModel
112. // by ViewModel() in Activity & Fragment class TasksActivity : AppCompatActivity() { // also inject SavedStateHandle val viewModel : TasksViewModel by viewModel() } TasksActivity
113. class TasksPresenter( private val tasksRepository: TasksRepository, private val view: TasksView ) TasksViewPresenter
114. @Factory class TasksPresenter( private val tasksRepository: TasksRepository, private val view: TasksView ) TasksViewPresenter
115. @Factory class TasksPresenter( private val tasksRepository: TasksRepository, @InjectedParam private val view: TasksView ) TasksViewPresenter
116. class TasksActivity : TasksView, AppCompatActivity() { // inject itself as a view val presenter : TasksPresenter by inject { parametersOf(this) } } TasksView
117. Tasks Repository Tasks DataSource Tasks Local DataSource TasksPresenter TasksActivity Tasks Database TasksViewModel Koin API @Factory or @koinViewModel @Single @Single @Single
118. Modules
119. Gathering definitions into Modules @Module class AppModule
120. Gathering definitions into Modules @Module @ComponentScan("com.my.app") class AppModule
121. import org.koin.ksp.generated.* startKoin { modules( // Class Module AppModule().module ) } Starting with Modules
122. import org.koin.ksp.generated.* startKoin { modules( // DSL Module otherDSLModule, // Class Module AppModule().module ) } Mix Classes & DSL Modules
123. @Module class DatabaseModule { @Single fun taskDao(db : ToDoDatabase) : TaskDao = db.taskDao() } Tasks Database
124. @Module class DatabaseModule { @Single fun taskDao(db : ToDoDatabase) : TaskDao = db.taskDao() } Tasks Database
125. Kotlin Compiler Plugin ☢ Code Generation
126. Fast Compilation Time 🏎 ~2 sec - 1000 components
127. Easy to Debug 🚒 Generated Koin DSL modules
128. DSL and Annotations Choose what is best for you 👍
129. 👉 https:/ /github.com/InsertKoinIO/ koin-annotations
130. What’s Next? 🚀
131. Koin Downloads Volume 📦 📦 5M Downloads in 2020 9M Downloads in 2021 🚀✨🌈 2022: Trends of 5M / Month
132. 🗓 Roadmap 2022 Structured Release Cycle (~6months) - Fix Version (bug fi xes, fi x updates) - Minor Version (deprecations, minor features…) - Major Version (hard breaking …)
133. 🗓 Roadmap 2022 Q4 Releases: Koin 3.3, Koin for Compose End of Track: Koin 3.1 Q2 Releases: Koin 3.2, Koin Annotations 1.0 👉 New DSL, Module includes …
134. ⚠ End of support for Koin 2.X insert-koin.io/docs/migration/migrate
135. // Latest version! koin_version = "3.1.6" // Current beta koin_version = "3.2.0-beta-1"
136. Koin — open source and community driven! 👍
137. @insertkoin_io insert-koin.io
138. But need of real company support
139. Long Term Support Releases & Professional Services
140. 🌐 kotzilla.io @kotzilla_io 🌐 blog.kotzilla.io
141. #goodies 🙌
142. Arnaud Giuliani @arnogiu Thank you! 🙂