Why do we need Clean Architecture

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Transcript

1. Why do we need
   Clean Architecture?
   Igor Wojda
   @igorwojda
   

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2. About me
   

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3. Why do we need good architecture?
   1519
   1520
   1521
   1522
   1523
   1524
   

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4. MVP
   View Presenter Model
   

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5. MVP + Repository
   View Presenter Repository
   DataSource
   DataSource
   

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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
   

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7. Why Clean Architecture?
   ◦ Independent of libraries & frameworks
   ◦ Independent of UI
   ◦ Independent of data sources
   Business
   Logic
   UI
   Frameworks
   Data sources
   

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8. UI
   Data source
   Presenter
   Repository
   Use case
   Dependency rule
   Entity
   

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9. Dependency rule
   UI
   Data source
   Presenter
   Repository
   Use case
   Entity Dependency
   rule
   Data Flow
   

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10. UI
    Data source
    Presenter
    Repository
    Use case
    Entity
    Layers
    

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11. Presentation Layer Domain Layer Data Layer
    Layers
    

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12. Presentation Layer Data Layer
    Presenter
    View
    Use case
    Entity
    Repository
    Network
    Data Source
    Disk
    Data Source
    Layers
    Domain Layer
    Dependencies
    

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13. Dependency inversion
    UseCase Repository
    • Define interface
    • Class Repository implements this interface
    • Class Repository is injected into class UseCase
    UseCase Repository
    

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14. Presentation Layer Domain Layer Data Layer
    Presenter
    View
    Use case
    Repository
    Network
    Data Source
    Disk
    Data Source
    Layers
    Abstractions
    Entity
    

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15. Data model
    data class PatientModel(
    val id: String,
    val firstName: String,
    val lastName: String,
    val dateOfBirth: String
    )
    

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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
    )
    

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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
    )
    

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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())
    }
    

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19. Data models
    Presentation Layer Domain Layer Data Layer
    PatientPresentation
    Model
    Patient
    PatientNetworkModel
    PatientRoomModel
    PatientNetworkMapper
    PatientRoomMapper
    PatientViewMapper
    

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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
    

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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
    )
    

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22. Separate data model
    Domain Layer
    data class Patient(
    val id: String,
    val firstName: String,
    val lastName: String,
    val dateOfBirth: DateTime
    )
    

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23. Separate data model
    data class PatientPresentationModel(
    val fullName: String,
    val adult: Boolean,
    val dateOfBirth: String
    )
    Presentation Layer
    

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24. Data representations
    Presentation Layer Domain Layer Data Layer
    

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25. Data representations
    Presentation Layer Domain Layer Data Layer
    "20171026T170000Z"
    DateTime
    "26th Oct 2017"
    1509037200
    

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26. Mapper
    interface Mapper {
    fun map(from: FROM): TO
    }
    class PatientNetworkModelMapper : Mapper {
    override fun map(patientNetworkModel: PatientNetworkModel) = Patient(
    id = patientNetworkModel.id,
    firstName = patientNetworkModel.firstName,
    lastName = patientNetworkModel.lastName,
    dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth)
    )
    }
    

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27. Mapper
    interface Mapper {
    fun map(from: FROM): TO
    }
    class PatientNetworkModelMapper : Mapper {
    override fun map(patientNetworkModel: PatientNetworkModel) = Patient(
    id = patientNetworkModel.id,
    firstName = patientNetworkModel.firstName,
    lastName = patientNetworkModel.lastName,
    dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth)
    )
    }
    

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28. Mapper
    interface Mapper {
    fun map(from: FROM): TO
    }
    class PatientNetworkModelMapper : Mapper {
    override fun map(patientNetworkModel: PatientNetworkModel) = Patient(
    id = patientNetworkModel.id,
    firstName = patientNetworkModel.firstName,
    lastName = patientNetworkModel.lastName,
    dateOfBirth = DateTime.parse(patientNetworkModel.dateOfBirth)
    )
    }
    

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29. Presentation Layer Domain Layer Data Layer
    Presenter
    View
    Use case
    Entity
    Repository
    Network
    Data Source
    Disk
    Data Source
    Implementations
    Abstractions
    

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30. Presenter
    class PatientsPresenter @Inject constructor(
    val getPatientsUseCase: PatientsUseCase,
    val mapper: PatientPresentationMapper)
    : BasePresenter, PatientsContract.Presenter {
    override fun onAttachView() {
    getPatientsUseCase.execute(PatientSubscriber())
    }
    inner class PatientSubscriber : DisposableSingleObserver>() {
    override fun onSuccess(patients: List) {
    when {
    patients.isEmpty -> view?.showEmptyState()
    else -> view?.showPatients(Patients.map { patientMapper::map })
    }
    }
    override fun onError(exception: Throwable) {
    view?.showErrorState()
    }
    //…
    }
    }
    

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31. Presenter
    class PatientsPresenter @Inject constructor(
    val getPatientsUseCase: PatientsUseCase,
    val mapper: PatientPresentationMapper)
    : BasePresenter, PatientsContract.Presenter {
    override fun onAttachView() {
    getPatientsUseCase.execute(PatientSubscriber())
    }
    inner class PatientSubscriber : DisposableSingleObserver>() {
    override fun onSuccess(patients: List) {
    when {
    patients.isEmpty -> view?.showEmptyState()
    else -> view?.showPatients(mapper.map { patientMapper::map })
    }
    }
    override fun onError(exception: Throwable) {
    view?.showErrorState()
    }
    //…
    }
    }
    

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32. Presenter
    class PatientsPresenter @Inject constructor(
    val getPatientsUseCase: PatientsUseCase,
    val mapper: PatientPresentationMapper)
    : BasePresenter, PatientsContract.Presenter {
    override fun onAttachView() {
    getPatientsUseCase.execute(PatientSubscriber())
    }
    inner class PatientSubscriber : DisposableSingleObserver>() {
    override fun onSuccess(patients: List) {
    when {
    patients.isEmpty -> view?.showEmptyState()
    else -> view?.showPatients(mapper.map { patientMapper::map })
    }
    }
    override fun onError(exception: Throwable) {
    view?.showErrorState()
    }
    //…
    }
    }
    

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33. Presenter
    class PatientsPresenter @Inject constructor(
    val getPatientsUseCase: PatientsUseCase,
    val mapper: PatientPresentationMapper)
    : BasePresenter, PatientsContract.Presenter {
    override fun onAttachView() {
    getPatientsUseCase.execute(PatientSubscriber())
    }
    inner class PatientSubscriber : DisposableSingleObserver>() {
    override fun onSuccess(patients: List) {
    when {
    patients.isEmpty -> view?.showEmptyState()
    else -> view?.showPatients(mapper.map { patientMapper::map })
    }
    }
    override fun onError(exception: Throwable) {
    view?.showErrorState()
    }
    //…
    }
    }
    

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34. Presenter
    class PatientsPresenter @Inject constructor(
    val getPatientsUseCase: PatientsUseCase,
    val mapper: PatientPresentationMapper)
    : BasePresenter, PatientsContract.Presenter {
    override fun onAttachView() {
    getPatientsUseCase.execute(PatientSubscriber())
    }
    inner class PatientSubscriber : DisposableSingleObserver>() {
    override fun onSuccess(patients: List) {
    when {
    patients.isEmpty -> view?.showEmptyState()
    else -> view?.showPatients(mapper.map { patientMapper::map })
    }
    }
    override fun onError(exception: Throwable) {
    view?.showErrorState()
    }
    //…
    }
    }
    

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35. Presentation Layer Domain Layer Data Layer
    Presenter
    View
    Use case
    Entity
    Repository
    Network
    Data Source
    Disk
    Data Source
    Layers
    Abstractions
    

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36. Use case (Interactor)
    class PatientsUseCase
    @Inject constructor(val patientRepository: PatientRepository,
    val schedulers: Schedulers) {
    fun execute(): Single>
    = patientRepository.getPatients()
    .observeOn(schedulers.main)
    .subscribeOn(schedulers.io)
    .filter { it.adult }
    }
    

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37. Use case (Interactor)
    class PatientsUseCase
    @Inject constructor(val patientRepository: PatientRepository,
    val schedulers: Schedulers) {
    fun execute(): Single>
    = patientRepository.getPatients()
    .observeOn(schedulers.main)
    .subscribeOn(schedulers.io)
    .filter { it.adult }
    }
    

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38. Use case (Interactor)
    class PatientsUseCase
    @Inject constructor(val patientRepository: PatientRepository,
    val schedulers: Schedulers) {
    fun execute(): Single>
    = patientRepository.getPatients()
    .observeOn(schedulers.main)
    .subscribeOn(schedulers.io)
    .filter { it.adult }
    }
    

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39. Presentation Layer Domain Layer Data Layer
    Presenter
    View
    Use case
    Entity
    Repository
    Network
    Data Source
    Disk
    Data Source
    Layers
    Abstractions
    

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40. class PatientDataRepository
    @Inject constructor(val diskDataStore: PatientDiskDataStore,
    val networkDataStore: PatientNetworkDataStore)
    : PatientRepository {
    val networkDataStoreWithSave
    = networkDataStore.doOnSuccess { saveToDisk(it) }
    fun getPatients(): Single>
    = Single.concat(diskDataStore, networkDataStoreWithSave)
    .takeFirst()
    fun saveToDisk() { /* … */ }
    }
    Repository
    

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41. class PatientDataRepository
    @Inject constructor(val diskDataStore: PatientDiskDataStore,
    val networkDataStore: PatientNetworkDataStore)
    : PatientRepository {
    val networkDataStoreWithSave
    = networkDataStore.doOnSuccess { saveToDisk(it) }
    fun getPatients(): Single>
    = Single.concat(diskDataStore, networkDataStoreWithSave)
    .takeFirst()
    fun saveToDisk() { /* … */ }
    }
    Repository
    PatientRepository PatientDataRepository:
    PatientRepository
    

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42. class PatientDataRepository
    @Inject constructor(val diskDataStore: PatientDiskDataStore,
    val networkDataStore: PatientNetworkDataStore)
    : PatientRepository {
    val networkDataStoreWithSave
    = networkDataStore.doOnSuccess { saveToDisk(it) }
    fun getPatients(): Single>
    = Single.concat(diskDataStore, networkDataStoreWithSave)
    .takeFirst()
    fun saveToDisk() { /* … */ }
    }
    Repository
    

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43. class PatientDataRepository
    @Inject constructor(val diskDataStore: PatientDiskDataStore,
    val networkDataStore: PatientNetworkDataStore)
    : PatientRepository {
    val networkDataStoreWithSave
    = networkDataStore.doOnSuccess { saveToDisk(it) }
    fun getPatients(): Single>
    = Single.concat(diskDataStore, networkDataStoreWithSave)
    .takeFirst()
    fun saveToDisk() { /* … */ }
    }
    Repository
    

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44. Data flow
    View Presenter Use case Repository
    Network
    Data Source
    SQLite
    Data Source
    Entity
    

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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
    

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46. Testing
    Presentation Layer Domain Layer Data Layer
    Presenter Use case
    View Repository
    Network
    Data Source
    Entity
    Room
    Data Source
    

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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
    

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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
    

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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
    

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50. Thanks!
    ANY QUESTIONS?
    @igorwojda
    igor.wojda@gmail.com
    

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51. Special thanks to SlidesCarnival who made
    and released these awesome presentation
    template for free.
    Credits
    

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