The document discusses an archetype architecture for modern Android app development. It introduces key concepts like view models, use cases, repositories, actions, and middleware to solve common architectural problems like navigation, dialogs, network requests, state management, and more. The architecture aims to provide better code organization, testability, and flexibility through abstraction layers and dependency injection. It is presented as an alternative to Google's Architecture Components that uses smaller abstractions to break problems into solvable pieces.

1. Archetype - modern
Android app
architecture
Stepan Goncharov @ AppsConf 2017

2. Video produc+on pla/orm
Over 16k Videos Created with 2300 Brands

3. What is mobile app
Architecture?

4. Unified set of rules that allow teams
to effectively solve problems and
implement business requirements
Architecture

5. Source code problems
• Code organisation rules
• Better code understanding
• Flexibility
• Extendability
• Testability

6. Problems every architecture need to solve
• Navigation
• Dialogs
• Network requests
• Restore state
• Services
• Lifecycle
• Activity result
• and more

7. Tools
• Android Studio
• Kotlin
• rxJava 2
• Dagger 2
• DataBindings
• Navi (arch.lifecycle)
• Custom BaseViewModel (arch.ViewModel)

8. Mobius 2017 story

9. Hype driven development?
Not anymore ;)

10. 17 May 2017
Google I/O

11. Google endorses
• Kotlin - supported in Android Studio
• Dagger 2 - recommended DI tool for Android apps
• rxJava 2 - supported by Room ORM
• Arch components announced
• MVVM recommended

12. Archetype vs Architecture components
UI controller
(Activity/Fragment)
ViewModel
Repository
Data Source
XML Layout
View

13. More abstractions!

14. Archetype vs Architecture components
UI Container
(Activity/Fragment)
View Model
Repository
Middleware
(Context)
Binding
Use case
(Interactor)
Action
XML Layout
View

15. Building blocks
• View’s - DataBinding’s layout
• View-Property Binding’s
• ViewModel’s
• UseCase’s aka Interactor
• Repositories
• Action’s
MVVM

16. View
• Android XML layout
<layout …>
<data>
<variable name="user" type="com.example.User"/>
</data>
<LinearLayout …>
<TextView …
android:text="@{user.firstName}"/>
<TextView …
android:text="@{user.lastName}"/>
</LinearLayout>
</layout>

17. Binding
• Generated from XML
//SomeFragment.kt
override fun onCreateView(
inflater: LayoutInflater?,
container: ViewGroup?,
state: Bundle?): View {
super.onCreateView(inflater, container, savedInstanceState)
binding = DataBindingUtil.inflate(inflater, layoutId, container, false)
…
}

18. ViewModel
• Transform data for View
• Fragment* set ViewModel in Binding
class LoginViewModel @Inject constructor(
viewModel: ViewModel,
loginState: LoginState,
resourceProvider: ResourceProvider,
loginUseCase: LoginUseCase
) :
ViewModel by viewModel,
LoginState by loginState,
ResourcesProvider by resourceProvider,
LoginComponent by loginUseCase {
…
}

19. UseCase
• Encapsulate Business logic
interface EnvironmentUseCase {
fun observeEnvironment(): Observable<EnvironmentModel>
}
class EnvironmentUseCaseImpl @Inject constructor(
val repo: EnvironmentRepo
) : EnvironmentUseCase {
override fun observeEnvironment()
= repo.observe().filterNonEmpty()
}

20. Repo
• Encapsulate Access to data
class FirebaseAuthModelRepo(
db: FirebaseDatabase
) : AuthModelRepo,
SingleValueRepo<AuthModel> by FirebaseSingleValueRepo(db, AUTH_MODEL)
interface AuthModelRepo
: SingleValueRepo<AuthModel> {
fun push(value: UserLoginModel) = LoginAction(value).asSingle()
}

21. Action
• Interact with Middleware
• Serializable - ID + Args
• Non-serialisable

22. Middleware
• DB
• Network
• Android SDK
• Libraries
• Sensors
• etc.

23. Data flow
BindingView

24. Data flow
BindingView
Middleware
(Context)
Action

25. Data flow
View ModelBindingView
Middleware
(Context)
Action

26. Data flow
View ModelBindingView
Middleware
(Context)
Action
Middleware
(Context)
Action

27. Data flow
View ModelBinding
Use case
(Interactor)
View
Middleware
(Context)
Action
Middleware
(Context)
Action

28. Data flow
View ModelBinding
Use case
(Interactor)
View
Middleware
(Context)
Action
Middleware
(Context)
Action
Middleware
(Context)
Action

29. Data flow
View Model Repository
Middleware
(Context)
Binding
Use case
(Interactor)
Action
View
Middleware
(Context)
Action
Middleware
(Context)
Action
Middleware
(Context)
Action

30. Data flow
View Model Repository
Middleware
(Context)
Binding
Use case
(Interactor)
Action
View
Middleware
(Context)
Action
Middleware
(Context)
Action
Middleware
(Context)
Action

31. Composition
Repository
Use case
(Interactor)

32. Composition
Repository
Use case
(Interactor)
Repository

33. Composition
Repository
Use case
(Interactor)
Use case
(Interactor)
Repository
View Model
Use case
(Interactor)
Use case
(Interactor)

35. How does it help?
• Better code organisation - fixed amount of abstractions
• Smaller abstractions
• Easier testing
• Flexible 2-5 layers
• Extendable through Middleware

36. Back to our problems

37. Navigation
• Middleware - android.content.Context
class ShowEpisodeAction : IntentAction,
IntentMaker by Injector().intentMaker() {
override fun invoke(context: Context, args: Args): Completable
= startIntent<PlayerActivity>(context, args)
}

38. Dialogs
• Middleware - android.content.Context
class ShowEpisodeDialog(dialogMaker: DialogMaker) :
DialogMaker by dialogMaker {
override fun invoke(context: Context, args: Args): Completable
= showDialog<EpisodeDialog>(context, args)
}

39. State/data sharing
Service

40. State/data sharing
RepositoryService

41. Network
• Middleware - Retrofit
class GetEpisodesAction : ApiAction {
val episodesRepo by lazyInject { episodesRepo() }
override fun invoke(context: Api, args: Args): Completable = context.feed()
.map { it.channel.item.map(::transformResponse) }
.flatMap { episodesRepo.save(it.associateBy({ it.id }) { it }) }
.subscribeOn(io())
.toCompletable()
}

42. Call action from repo
interface EpisodesModelRepo : KeyValueRepo<Long, EpisodesModel> {
val action: ActionGetEpisodes
fun pull(): Completable = action.invoke()
}

43. Lifecycle events
class EpisodesViewModel(
naviComponent: NaviComponent
) :
ViewModel by ViewModelImpl(naviComponent = naviComponent) {
init {
observe(Event.RESUME)
.doOnNext { refresh() }
.bindSubscribe()
}
fun refresh() = …
}

44. Activity result
class EpisodesViewModel(
naviComponent: NaviComponent
) :
ViewModel by ViewModelImpl(naviComponent = naviComponent) {
init {
observe(Event.ACTIVITY_RESULT)
.doOnNext { handleActivityResutl(it) }
.bindSubscribe()
}
fun handleActivityResult() = …
}

45. Thanks!

46. Whats next
• Ask your question right now
• Get example https://github.com/stepango/Archetype
• Watch Mobius 2017 talk

47. Social links
• @stepango
• @nekdenis
• http://androiddev.apptractor.ru
• https://t.me/archetype_android

48. Q&A
What challenges you have in your project?
P.S. We are hiring!