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Why do we need Clean Architecture? 1

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2 Hello! I AM IGOR WOJDA Android Developer Advocate, Vonage @igorwojda

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WHY DO WE NEED GOOD ARCHITECTURE? 3

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“MVX ARCHITECTURE” 4 Controller Model Presenter Intent View ViewModel MVC MVP MVVM MVI X

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MVVM 5 View ViewModel Model

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MVVM + REPOSITORY 6 View ViewModel Repository DataSource DataSource

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“ 7 We should think about our applications as group of use cases that describe the intent of the application group of plugins that give those uses cases access to outside word. Uncle Bob and

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WHY CLEAN ARCHITECTURE? ◦ Independent of libraries & frameworks ◦ Independent of UI ◦ Independent of data sources 8 Business Logic UI Libraries & Frameworks Data sources

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DEPENDENCY RULE 9

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DEPENDENCY RULE 10 UI Data source ViewModel Repository Use case Entity

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UI Data source ViewModel Repository Use case Entity DEPENDENCY RULE 11 Dependency rule Data Flow

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UI Data source ViewModel Repository Use case Entity LAYERS 12

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UI Data source ViewModel Repository Use case Entity Presentation Layer Domain Layer Data Layer LAYERS 13 Data Flow Dependency rule Dependency rule Data Flow

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ViewModel View Use case Entity Repository Network Data Source Disk Data Source 14 LAYERS Presentation Layer Domain Layer Data Layer

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DEPENDENCY INVERSION 15 UseCase Repository • Define interface • Class Repository implements this interface • Class Repository is injected into UseCase class UseCase Repository

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16 LAYERS ViewModel View Use case Entity Repository Network Data Source Disk Data Source Dependencies Presentation Layer Domain Layer Data Layer

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MODEL GOING WRONG 17

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DATA MODEL 18 data class User( val id: String, val firstName: String, val lastName: String, val birthDate: String )

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ADD GSON ANNOTATIONS 19 data class User( @PrimaryKey("id") val id: String, @SerializedName("first_name") val firstName: String, @SerializedName("last_name") val lastName: String, @SerializedName("birth_date") val birthDate: String )

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ADD ROOM ANNOTATIONS 20 @Entity(tableName = "users") data class User( @PrimaryKey("id") @SerializedName("id") val id: String, @ColumnInfo(name = "first_name") @SerializedName("first_name") val firstName: String, @ColumnInfo(name = "last_name") @SerializedName("last_name") val lastName: String, @ColumnInfo(name = "birth_date") @SerializedName("birth_date") val birthDate: String )

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ADD GETTERS 21 @Entity(tableName = "users") data class User( @PrimaryKey("id") @SerializedName("id") val id: String, @ColumnInfo(name = "first_name") @SerializedName("first_name") val firstName: String, @ColumnInfo(name = "last_name") @SerializedName("last_name") val lastName: String, @ColumnInfo(name = "birth_date") @SerializedName("birth_date") val birthDate: String ) { val fullName = "$firstName $lastName” val isAdult = DateTime.parse(dateOfBirth) .plusYears(18) .isAfter(DateTime.now()) }

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THE GOOD MODEL 22 @Entity(tableName = "users") data class User( @PrimaryKey("id") @SerializedName("id") val id: String, @ColumnInfo(name = "first_name") @SerializedName("first_name") val firstName: String, @ColumnInfo(name = "last_name") @SerializedName("last_name") val lastName: String, @ColumnInfo(name = "birth_date") @SerializedName("birth_date") val birthDate: String ) { val fullName = "$firstName $lastName” val isAdult = DateTime.parse(dateOfBirth) .plusYears(18) .isAfter(DateTime.now()) }

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SOLUTION? 23

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DATA MODELS 24 UserPresentationModel UserModel UserNetworkModel UserRoomModel UserNetworkMapper UserRoomMapper UserViewMapper Presentation Layer Domain Layer Data Layer

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USER NETWORK MODEL 25 Data Layer data class UserNetworkModel( @SerializedName("id") val id: String, @SerializedName("first_name") val firstName: String, @SerializedName("last_name") val lastName: String, @SerializedName("birth_date") val birthDate: String )

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USER ROOM MODEL 26 Data Layer @Entity(tableName = "users") data class UserRoomModel( @PrimaryKey("id") val id: String, @ColumnInfo(name = "first_name") val firstName: String, @ColumnInfo(name = "last_name") val lastName: String, @SerializedName("birth_date") val birthDate: String )

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USER MODEL 27 data class UserModel( val id: String, val firstName: String, val lastName: String, val birthDate: DateTime ) Domain Layer

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USER PRESENTATION MODEL 28 Presentation Layer data class UserPresentationModel( val fullName: String, val birthDate: String )

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FIRST NAME REPRESENTATION 29 UserPresentationModel UserModel UserNetworkModel UserRoomModel UserNetworkMapper UserRoomMapper UserPresentationMapper Presentation Layer Domain Layer Data Layer “Igor" “Igor" “Igor" “Igor"

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DATE & TIME REPRESENTATION 30 UserPresentationModel UserModel UserNetworkModel UserRoomModel UserNetworkMapper UserRoomMapper UserPresentationMapper Presentation Layer Domain Layer Data Layer "20201107T170000Z" 1604407243 "11th Nov 2020” DateTime

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MAPPERS 31

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MAPPERS 32 UserPresentationModel UserModel UserNetworkModel UserRoomModel UserNetworkMapper UserRoomMapper UserPresentationMapper Presentation Layer Domain Layer Data Layer

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MAPPER 33 DataType1 Mapper DataType2 UserNetworkModel Mapper UserModel

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IMPLEMENTATION 34

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MAPPER AS INFERFACE 35 interface Mapper { fun map(from: FROM): TO } class UserNetworkModelMapper : Mapper { override fun map(UserNetworkModel: UserNetworkModel) = UserModel( id = UserNetworkModel.id, firstName = UserNetworkModel.firstName, lastName = UserNetworkModel.lastName, birthDate = DateTime.parse(UserNetworkModel.birthDate) ) }

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MAPPER AS INFERFACE 36 interface Mapper { fun map(from: FROM): TO } class UserNetworkModelMapper : Mapper { override fun map(UserNetworkModel: UserNetworkModel) = UserModel( id = UserNetworkModel.id, firstName = UserNetworkModel.firstName, lastName = UserNetworkModel.lastName, birthDate = DateTime.parse(UserNetworkModel.birthDate) ) }

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MAPPER AS INFERFACE 37 interface Mapper { fun map(from: FROM): TO } class UserNetworkModelMapper : Mapper { override fun map(UserNetworkModel: UserNetworkModel) = UserModel( id = UserNetworkModel.id, firstName = UserNetworkModel.firstName, lastName = UserNetworkModel.lastName, birthDate = DateTime.parse(UserNetworkModel.birthDate) ) }

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MAPPER AS EXTENSION 38 val usedModel = userNetworkModel.toDomainModel() fun UserNetworkModel.toDomainModel() = UserModel( id = this.id, firstName = this.firstName, lastName = this.lastName, birthDate = DateTime.parse(UserNetworkModel.birthDate) )

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ViewModel View Use case Entity Repository Network Data Source Disk Data Source 39 VIEW MODEL IMPLEMENTATION Presentation Layer Domain Layer Data Layer Abstractions

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ViewModel View Use case Entity Repository Network Data Source Disk Data Source 40 VIEW MODEL IMPLEMENTATION Presentation Layer Domain Layer Data Layer Abstractions

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VIEW MODEL IMPLEMENTATION 41 class UsersViewModel(val getUsersUseCase: GetUsersUseCase) : ViewModel {
 
 }

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VIEW MODEL IMPLEMENTATION 42 class UsersViewModel(val getUsersUseCase: GetUsersUseCase) : ViewModel {
 
 fun getUsers() { 
 }
 }

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VIEW MODEL IMPLEMENTATION 43 class UsersViewModel(val getUsersUseCase: GetUsersUseCase) : ViewModel {
 
 fun getUsers() { viewModelScope.launch {
 getUsersUseCase.execute().also { }
 }
 }

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VIEW MODEL IMPLEMENTATION 44 class UsersViewModel(val getUsersUseCase: GetUsersUseCase) : ViewModel {
 
 fun getUsers() { viewModelScope.launch {
 getUsersUseCase.execute().also { result -> when (result) { is Success -> { // do something } is Error -> { // do something } } }
 }
 }

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VIEW MODEL IMPLEMENTATION 45 class UsersViewModel(val getUsersUseCase: GetUsersUseCase) : ViewModel {
 
 fun getUsers() { viewModelScope.launch {
 getUsersUseCase.execute().also { result -> when (result) { is Success -> { // do something } is Error -> { // do something } } }
 }
 }

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Presentation Layer Domain Layer Data Layer ViewModel View Use case Entity Repository Network Data Source Disk Data Source 46 USE CASE IMPLEMENTATION Abstractions

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USE CASE IMPLEMENTATION 47 class GetAdultUsersUseCase(val UsersRepository: UsersRepository) { }

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USE CASE IMPLEMENTATION 48 class GetAdultUsersUseCase(val UsersRepository: UsersRepository) { suspend fun execute(): List = UserRepository.getUsers() }

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USE CASE IMPLEMENTATION 49 class GetAdultUsersUseCase(val UsersRepository: UsersRepository) { suspend fun execute(): List = UserRepository.getUsers() .filter { it.adult } }

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USE CASE IMPLEMENTATION 50 class GetAdultUsersUseCase(val UsersRepository: UsersRepository) { suspend fun execute(): List = UserRepository.getUsers() .filter { it.adult } }

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Presentation Layer Domain Layer Data Layer ViewModel View Use case Entity Repository Network Data Source Disk Data Source 51 USE CASE IMPLEMENTATION Abstractions

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ENTITY IMPLEMENTATION 52 data class UserModel( val id: String, val firstName: String, val lastName: String, val birthDate: DateTime )

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Presentation Layer Domain Layer Data Layer ViewModel View Use case Entity Repository Network Data Source Disk Data Source 53 USE CASE IMPLEMENTATION Abstractions

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ABSTRACIONS IMPLEMENTATION 54 interface UsersRepository() { fun getUsers(): List }

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Presentation Layer Domain Layer Data Layer ViewModel View Use case Entity Repository Network Data Source Disk Data Source 55 REPOSITORY IMPLEMENTATION Abstractions

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class UsersRepositoryImpl( private val usersRetrofitService: UsersRetrofitService ) : UsersRepository { } REPOSITORY IMPLEMENTATION 56 UserRepository UserRepositoryImpl

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class UsersRepositoryImpl( private val usersRetrofitService: UsersRetrofitService ) : UsersRepository { override suspend fun getUsers() = usersRetrofitService.getUsersAsync() } REPOSITORY IMPLEMENTATION 57

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class UsersRepositoryImpl( private val usersRetrofitService: UsersRetrofitService ) : UsersRepository { override suspend fun getUsers() = usersRetrofitService.getUsersAsync() .map { it.toDomainModel() } } REPOSITORY IMPLEMENTATION 58

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class UsersRepositoryImpl( private val usersRetrofitService: UsersRetrofitService ) : UsersRepository { override suspend fun getUsers() = usersRetrofitService.getUsersAsync() .map { it.toDomainModel() } } REPOSITORY IMPLEMENTATION 59

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LAYERS IMPLEMENTATION 60 Layers in a single module Layers inside the feature modules Layer per module

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61 DATA FLOW View ViewModel Use case Repository Network Data Source SQLite Data Source Mapper

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62 MODULARITY Presentation Layer Domain Layer Data Layer ViewModel Business Logic View GridView Recycler View TabLayout BottomBar User Repository Tracking Repository SQLite Volley Firebase Retrofit MixPanel Room

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63 TESTING Presentation Layer Domain Layer Data Layer Use Case Repository Entity ViewModel View

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64 TESTING Presentation Layer Domain Layer Data Layer ViewModel Use Case View Repository Entity Mapper Mock Room Data Source Mock Network Data Source Mock Repository Mock ViewModel Mock Mapper Mock Mapper Mock Mapper Mock Entity Entity Entity Use Case Mock Mapper Mock

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65 PROS AND CONS • Great for long living projects • Great for big teams • Maintainability • Scalability • Parallel teams • Maintainable • Testable Cons Pros • Boilerplate code • Not suitable for all projects • Multiple ways to implement

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66 REFERENCES Articles • The Clean Architecture https://8thlight.com/blog/uncle-bob/2012/08/13/the-clean- architecture.html • Multiple ways of defining Clean Architecture layers https://proandroiddev.com/ multiple-ways-of-defining-clean-architecture-layers-bbb70afa5d4a Android projects • https://github.com/igorwojda/android-showcase • https://github.com/android10/Android-CleanArchitecture-Kotlin • https://github.com/bufferapp/android-clean-architecture-boilerplate • https://github.com/bufferapp/clean-architecture-components-boilerplate Talks • https://youtu.be/Nsjsiz2A9mg • https://youtu.be/3Mq5newPdck • https://youtu.be/-sEmrJOk1uI • https://youtu.be/su34EYeQ90E

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67 ANY QUESTIONS? Find me on twitter @IgorWojda Thanks!

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68 Special thanks to SlidesCarnival who made and released these awesome presentation template for free. CREDITS