Why do we need Clean Architecture

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1. Why do we need Clean Architecture? Igor Wojda @igorwojda
2. About me
3. Why do we need good architecture? 1519 1520 1521 1522 1523 1524
4. MVP View Presenter Model
5. MVP + Repository View Presenter Repository DataSource DataSource
6. “ We should think about our applications as group of use cases that describe the intent of the application and group of plugins that give those uses cases access to outside word. Uncle Bob
7. Why Clean Architecture? ◦ Independent of libraries & frameworks ◦ Independent of UI ◦ Independent of data sources Business Logic UI Frameworks Data sources
8. UI Data source Presenter Repository Use case Dependency rule Entity
9. Dependency rule UI Data source Presenter Repository Use case Entity Dependency rule Data Flow
10. UI Data source Presenter Repository Use case Entity Layers
11. Presentation Layer Domain Layer Data Layer Layers
12. Presentation Layer Data Layer Presenter View Use case Entity Repository Network Data Source Disk Data Source Layers Domain Layer Dependencies
13. Dependency inversion UseCase Repository • Define interface • Class Repository implements this interface • Class Repository is injected into class UseCase UseCase Repository
14. Presentation Layer Domain Layer Data Layer Presenter View Use case Repository Network Data Source Disk Data Source Layers Abstractions Entity
15. Data model data class PatientModel( val id: String, val firstName: String, val lastName: String, val dateOfBirth: String )
16. Data model (GSON) data class PatientModel( @SerializedName("id") val id: String, @SerializedName("first_name") val firstName: String, @SerializedName("last_name") val lastName: String, @SerializedName("date_of_birth") val dateOfBirth: String )
17. Data model (GSON + Room) @Entity(tableName = "patients") data class PatientModel( @SerializedName("id") @PrimaryKey val id: String, @SerializedName("first_name") @ColumnInfo(name = "first_name") val firstName: String, @SerializedName("last_name") @ColumnInfo(name = "last_name") val lastName: String, @SerializedName("date_of_birth") @ColumnInfo(name = "date_of_birth") val dateOfBirth: String )
18. Data model (GSON + Room + Getters) @Entity(tableName = "patients") data class PatientModel( @SerializedName("id") @PrimaryKey val id: String, @SerializedName("first_name") @ColumnInfo(name = "first_name") val firstName: String, @SerializedName("last_name") @ColumnInfo(name = "last_name") val lastName: String, @SerializedName("date_of_birth") @ColumnInfo(name = "date_of_birth") val dateOfBirth: String ) { private val UNDER_AGE_LIMIT = 16 val fullName = "$firstName $lastName" val adult = DateTime.parse(dateOfBirth) .plusYears(UNDER_AGE_LIMIT) .isAfter(DateTime.now()) }
19. Data models Presentation Layer Domain Layer Data Layer PatientPresentation Model Patient PatientNetworkModel PatientRoomModel PatientNetworkMapper PatientRoomMapper PatientViewMapper
20. Separate data model data class PatientNetworkModel( @SerializedName("id") val id: String, @SerializedName("first_name") val firstName: String, @SerializedName("last_name") val lastName: String, @SerializedName("date_of_birth") val dateOfBirth: String ) Data Layer
21. Separate data model Data Layer @Entity(tableName = "patients") data class PatientRoomModel( @PrimaryKey val id: String, @ColumnInfo(name = "first_name") val firstName: String, @ColumnInfo(name = "last_name") val lastName: String, @ColumnInfo(name = "date_of_birth") val dateOfBirth: String )
22. Separate data model Domain Layer data class Patient( val id: String, val firstName: String, val lastName: String, val dateOfBirth: DateTime )
23. Separate data model data class PatientPresentationModel( val fullName: String, val adult: Boolean, val dateOfBirth: String ) Presentation Layer
24. Data representations Presentation Layer Domain Layer Data Layer
25. Data representations Presentation Layer Domain Layer Data Layer "20171026T170000Z" DateTime "26th Oct 2017" 1509037200
26. Mapper interface Mapper<in FROM, out TO> { fun map(from: FROM): TO } class PatientNetworkModelMapper : Mapper<PatientNetworkModel, Patient> { override fun map(patientNetworkModel: PatientNetworkModel) = Patient( id = patientNetworkModel.id, firstName = patientNetworkModel.firstName, lastName = patientNetworkModel.lastName, dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth) ) }
27. Mapper interface Mapper<in FROM, out TO> { fun map(from: FROM): TO } class PatientNetworkModelMapper : Mapper<PatientNetworkModel, Patient> { override fun map(patientNetworkModel: PatientNetworkModel) = Patient( id = patientNetworkModel.id, firstName = patientNetworkModel.firstName, lastName = patientNetworkModel.lastName, dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth) ) }
28. Mapper interface Mapper<in FROM, out TO> { fun map(from: FROM): TO } class PatientNetworkModelMapper : Mapper<PatientNetworkModel, Patient> { override fun map(patientNetworkModel: PatientNetworkModel) = Patient( id = patientNetworkModel.id, firstName = patientNetworkModel.firstName, lastName = patientNetworkModel.lastName, dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth) ) }
29. Presentation Layer Domain Layer Data Layer Presenter View Use case Entity Repository Network Data Source Disk Data Source Implementations Abstractions
30. Presenter class PatientsPresenter @Inject constructor( val getPatientsUseCase: PatientsUseCase, val mapper: PatientPresentationMapper) : BasePresenter<PatientsContract.View>, PatientsContract.Presenter { override fun onAttachView() { getPatientsUseCase.execute(PatientSubscriber()) } inner class PatientSubscriber : DisposableSingleObserver<List<Patient>>() { override fun onSuccess(patients: List<Patient>) { when { patients.isEmpty -> view?.showEmptyState() else -> view?.showPatients(Patients.map { patientMapper::map }) } } override fun onError(exception: Throwable) { view?.showErrorState() } //… } }
31. Presenter class PatientsPresenter @Inject constructor( val getPatientsUseCase: PatientsUseCase, val mapper: PatientPresentationMapper) : BasePresenter<PatientsContract.View>, PatientsContract.Presenter { override fun onAttachView() { getPatientsUseCase.execute(PatientSubscriber()) } inner class PatientSubscriber : DisposableSingleObserver<List<Patient>>() { override fun onSuccess(patients: List<Patient>) { when { patients.isEmpty -> view?.showEmptyState() else -> view?.showPatients(mapper.map { patientMapper::map }) } } override fun onError(exception: Throwable) { view?.showErrorState() } //… } }
32. Presenter class PatientsPresenter @Inject constructor( val getPatientsUseCase: PatientsUseCase, val mapper: PatientPresentationMapper) : BasePresenter<PatientsContract.View>, PatientsContract.Presenter { override fun onAttachView() { getPatientsUseCase.execute(PatientSubscriber()) } inner class PatientSubscriber : DisposableSingleObserver<List<Patient>>() { override fun onSuccess(patients: List<Patient>) { when { patients.isEmpty -> view?.showEmptyState() else -> view?.showPatients(mapper.map { patientMapper::map }) } } override fun onError(exception: Throwable) { view?.showErrorState() } //… } }
33. Presenter class PatientsPresenter @Inject constructor( val getPatientsUseCase: PatientsUseCase, val mapper: PatientPresentationMapper) : BasePresenter<PatientsContract.View>, PatientsContract.Presenter { override fun onAttachView() { getPatientsUseCase.execute(PatientSubscriber()) } inner class PatientSubscriber : DisposableSingleObserver<List<Patient>>() { override fun onSuccess(patients: List<Patient>) { when { patients.isEmpty -> view?.showEmptyState() else -> view?.showPatients(mapper.map { patientMapper::map }) } } override fun onError(exception: Throwable) { view?.showErrorState() } //… } }
34. Presenter class PatientsPresenter @Inject constructor( val getPatientsUseCase: PatientsUseCase, val mapper: PatientPresentationMapper) : BasePresenter<PatientsContract.View>, PatientsContract.Presenter { override fun onAttachView() { getPatientsUseCase.execute(PatientSubscriber()) } inner class PatientSubscriber : DisposableSingleObserver<List<Patient>>() { override fun onSuccess(patients: List<Patient>) { when { patients.isEmpty -> view?.showEmptyState() else -> view?.showPatients(mapper.map { patientMapper::map }) } } override fun onError(exception: Throwable) { view?.showErrorState() } //… } }
35. Presentation Layer Domain Layer Data Layer Presenter View Use case Entity Repository Network Data Source Disk Data Source Layers Abstractions
36. Use case (Interactor) class PatientsUseCase @Inject constructor(val patientRepository: PatientRepository, val schedulers: Schedulers) { fun execute(): Single<List<Patient>> = patientRepository.getPatients() .observeOn(schedulers.main) .subscribeOn(schedulers.io) .filter { it.adult } }
37. Use case (Interactor) class PatientsUseCase @Inject constructor(val patientRepository: PatientRepository, val schedulers: Schedulers) { fun execute(): Single<List<Patient>> = patientRepository.getPatients() .observeOn(schedulers.main) .subscribeOn(schedulers.io) .filter { it.adult } }
38. Use case (Interactor) class PatientsUseCase @Inject constructor(val patientRepository: PatientRepository, val schedulers: Schedulers) { fun execute(): Single<List<Patient>> = patientRepository.getPatients() .observeOn(schedulers.main) .subscribeOn(schedulers.io) .filter { it.adult } }
39. Presentation Layer Domain Layer Data Layer Presenter View Use case Entity Repository Network Data Source Disk Data Source Layers Abstractions
40. class PatientDataRepository @Inject constructor(val diskDataStore: PatientDiskDataStore, val networkDataStore: PatientNetworkDataStore) : PatientRepository { val networkDataStoreWithSave = networkDataStore.doOnSuccess { saveToDisk(it) } fun getPatients(): Single<List<Patient>> = Single.concat(diskDataStore, networkDataStoreWithSave) .takeFirst() fun saveToDisk() { /* … */ } } Repository
41. class PatientDataRepository @Inject constructor(val diskDataStore: PatientDiskDataStore, val networkDataStore: PatientNetworkDataStore) : PatientRepository { val networkDataStoreWithSave = networkDataStore.doOnSuccess { saveToDisk(it) } fun getPatients(): Single<List<Patient>> = Single.concat(diskDataStore, networkDataStoreWithSave) .takeFirst() fun saveToDisk() { /* … */ } } Repository PatientRepository PatientDataRepository: PatientRepository
42. class PatientDataRepository @Inject constructor(val diskDataStore: PatientDiskDataStore, val networkDataStore: PatientNetworkDataStore) : PatientRepository { val networkDataStoreWithSave = networkDataStore.doOnSuccess { saveToDisk(it) } fun getPatients(): Single<List<Patient>> = Single.concat(diskDataStore, networkDataStoreWithSave) .takeFirst() fun saveToDisk() { /* … */ } } Repository
43. class PatientDataRepository @Inject constructor(val diskDataStore: PatientDiskDataStore, val networkDataStore: PatientNetworkDataStore) : PatientRepository { val networkDataStoreWithSave = networkDataStore.doOnSuccess { saveToDisk(it) } fun getPatients(): Single<List<Patient>> = Single.concat(diskDataStore, networkDataStoreWithSave) .takeFirst() fun saveToDisk() { /* … */ } } Repository
44. Data flow View Presenter Use case Repository Network Data Source SQLite Data Source Entity
45. Modularity Presentation Layer Domain Layer Data Layer Presenter Business Logic View GridView Recycler View TabLayout BottomBar Patient Repository Tracking Repository SQLite Volley Firebase Firebase Room Retrofit MixPanel
46. Testing Presentation Layer Domain Layer Data Layer Presenter Use case View Repository Network Data Source Entity Room Data Source
47. Testing Presentation Layer Domain Layer Data Layer Mapper Mock RetrofitService Mock Mapper Mock Mock SQLite Data Source Mock Data Source Mock Repository Mock Presenter Mock Mapper Mock Mapper Mock Mapper Mock Entity Entity Entity View Mock Use Case Mock Mapper Mock
48. Pros and cons Boilerplate code Not suitable for all projects Multiple ways to implement Independent of Frameworks and tools Well structured Maintainable Modular Testable Great for big teams Issues Benefits
49. References Articles https://8thlight.com/blog/uncle-bob/2012/08/13/the-clean-architecture.html Talks https://youtu.be/Nsjsiz2A9mg https://youtu.be/3Mq5newPdck https://youtu.be/-sEmrJOk1uI https://youtu.be/su34EYeQ90E Android projects https://github.com/bufferapp/android-clean-architecture-boilerplate https://github.com/bufferapp/clean-architecture-components-boilerplate https://github.com/android10/Android-CleanArchitecture-Kotlin
50. Thanks! ANY QUESTIONS? @igorwojda igor.wojda@gmail.com
51. Special thanks to SlidesCarnival who made and released these awesome presentation template for free. Credits