Architectural Journey

At Badoo, we have a long history when it comes to Android development. Since the beginning, the product has experienced huge growth, and our codebase and our team have grown with it. We now have over 420 million registrations, as well as several new apps to support. Over the years we’ve tried MVP, Clean architecture, MVI, and many more approaches, some of them brewed in-house. In this talk we’ll go on an architectural journey and discuss some of the major problems we needed to find solutions for in the last few years, before ending on what is ahead of us.

1. Architectural journey
2. Zsolt Kocsi Android engineer @ Badoo @ZsoltKocsi
3. Badoo products
4. Badoo products ? ? ?
5. Problem #1 State
6. 1. MVP Pros Better than nothing Cons Doesn’t scale well 6
7. 1. MVP
 2. Clean architecture Pros Clear separation of layers Cons ? 7
8. 1. MVP
 2. Clean architecture 8
9. 1. MVP
 2. Clean architecture Our real problems State-related 9
12. View Intent Model 12
13. View Intent Model Model changes Immutable state Reducer Pros Single point of mutation Easier to understand 13
14. 1. MVP
 2. Clean architecture 3. ??? What we need Immutable state How to do it best ??? 14
15. 1. MVP
 2. Clean architecture 3. Proto-MVI Inspired by Redux Frankenstein’s monster of • MVP • Clean architecture • Immutable state stores • RxJava 15
16. 1. MVP
 2. Clean architecture 3. Proto-MVI Pros Easier to reason about what can happen to the state State problems gone! Cons We needed structure 16
17. 1. MVP
 2. Clean architecture 3. Proto-MVI
 4. Experiments ??? 17
18. 1. MVP
 2. Clean architecture 3. Proto-MVI 4. Experiments
 5. MVICore https://github.com/badoo/MVICore 18
19. 19 Feature State machines Reducer only
20. 20 Reducer Feature Wish State State machines Reducer only
21. 21 data class State( val counter: Int = 0 )£ R Fe
22. 22 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• R Fe
23. 23 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { }¢ R Fe
24. 24 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke( }¢ R Fe
25. 25 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State }¢ R Fe
26. 26 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish) }¢ R Fe
27. 27 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = }¢ R Fe
28. 28 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { }™ }¢ R Fe
29. 29 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { IncreaseCounter -> state.copy( counter = state.counter + 1 )§ }™ }¢ R Fe
30. 30 data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { IncreaseCounter -> state.copy( counter = state.counter + 1 )§ is MultiplyBy -> state.copy( counter = state.counter * wish.value )¡ }™ }¢ R Fe
31. 31 R Fe class SimpleFeature : ReducerFeature<Wish, State, Nothing>( initialState = State(), reducer = ReducerImpl() ) { data class State( val counter: Int = 0 )£ sealed class Wish { object IncreaseCounter : Wish() data class MultiplyBy(val value: Int) : Wish() }• class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { IncreaseCounter -> state.copy( counter = state.counter + 1 )§ is MultiplyBy -> state.copy( counter = state.counter * wish.value )¡ }™ }¢ }
33. Problem #2 Side-effects
34. 34 Reducer Feature Wish State State machines Reducer only
35. 35 Reducer Feature State machines Reducer only Side-effects externally Wish State
36. 36 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )• sealed£class£Wish£{ ¢¢¢¢object StartedLoading : Wish() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Wish() §§§§data class Failed(valªthrowable:ªThrowable)ª: Wish() }º R Fe
37. 37 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )• sealed£class£Wish£{ ¢¢¢¢object StartedLoading : Wish() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Wish() §§§§data class Failed(valªthrowable:ªThrowable)ª: Wish() }º class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { StartedLoading -> state.copy( isLoading = true )º R Fe
38. 38 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )• sealed£class£Wish£{ ¢¢¢¢object StartedLoading : Wish() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Wish() §§§§data class Failed(valªthrowable:ªThrowable)ª: Wish() }º class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { StartedLoading -> state.copy( isLoading = true )º is Success -> state.copy( isLoading = false, hasError = false, payload = wish.payload )¡ R Fe
39. 39 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )• sealed£class£Wish£{ ¢¢¢¢object StartedLoading : Wish() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Wish() §§§§data class Failed(valªthrowable:ªThrowable)ª: Wish() }º class ReducerImpl : Reducer<State, Wish> { override fun invoke(state: State, wish: Wish): State = when (wish) { StartedLoading -> state.copy( isLoading = true )º is Success -> state.copy( isLoading = false, hasError = false, payload = wish.payload )¡ is Failed -> state.copy( isLoading = false, hasError = true )™ R Fe
40. 40 Reducer Feature Wish State State machines Reducer only Side-effects externally
41. 41 State machines Reducer only Side-effects as loop
 Reducer Feature Command Wish State
42. 42 class Reducer( private val initialState: State = State(), private val ex: Executor ) : StateReducer<State, Message, Effect> { override fun invoke(state: State, msg: Message): Pair<State, Command<Effect>?> = when (msg) { is Reset -> initialState to null is Get -> state to { ex.getSettings(state) }.takeIf { !state.loaded } is Retry -> state.retry() to { ex.getSettings(state)“}.takeIf { state.status == FAILURE } is Updated -> state.change(msg.setting) to { executor.saveSettings()≥}.takeIf { msg.saveImmediately }˜ is Done -> state to { ex.saveSettings(state.getValues(), state.mode) }∫ is Logout -> state to { ex.logout() }å is DeleteAccount -> state to { ex.deleteAccount() }~ is PublicProfile -> state.profile() to { ex.saveAndGet(state.profile()) ±}.takeIf { msg.mode == state.mode }^ is Get -> state.onGet(msg) to null is Save -> state.onSave(msg) to null is Logout -> state to null }@ }£ R Fe
43. 43 State machines Reducer only Side-effects as loop
 Reducer Feature Command Wish State
44. 44 Reducer Feature Actor State machines Reducer only Side-effects with Actor Wish State Effect
45. 45 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å≈ R Fe Ac
46. 46 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å≈ sealed•class•Wish•{ ••••object•LoadSomething•:•Wish() }Ω R Fe Ac
47. 47 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å≈ sealed•class•Wish•{ ••••object•LoadSomething•:•Wish() }Ω sealed£class£Effect£{ ¢¢¢¢object StartedLoading : Effect() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Effect() §§§§data class Failed(valªthrowable:ªThrowable)ª:ªEffect() }º R Fe Ac
48. 48 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å≈ sealed£class£Effect£{ ¢¢¢¢object StartedLoading : Effect() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Effect() §§§§data class Failed(valªthrowable:ªThrowable)ª:ªEffect() }º R Fe Ac
49. 49 data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å sealed£class£Effect£{ ¢¢¢¢object StartedLoading : Effect() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Effect() §§§§data class Failed(valªthrowable:ªThrowable)ª:ªEffect() }™ class ReducerImpl : Reducer<State, Effect> { override fun invoke(state: State, effect: Effect): State = when (effect) { StartedLoading -> state.copy( isLoading = true ) is Success -> state.copy( isLoading = false, hasError = false, payload = wish.payload ) is Failed -> state.copy( isLoading = false, hasError = true ) R Fe Ac
50. 50 sealed£class£Effect™{ ¢¢¢¢object StartedLoading : Effect() ∞∞∞∞data class Success(val¶payload:¶Any)¶:¶Effect() §§§§data class Failed(valªthrowable:ªThrowable)ª:ªEffect() }™ R Fe Ac
51. 51 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect™{ object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ R Fe Ac
52. 52 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { }º R Fe Ac
53. 53 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() }º R Fe Ac
54. 54 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): }º R Fe Ac
55. 55 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = }º R Fe Ac
56. 56 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = when (wish) { is LoadSomething -> }£ }º R Fe Ac
57. 57 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = when (wish) { is LoadSomething -> service.invoke() .toObservable() }£ }º R Fe Ac
58. 58 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = when (wish) { is LoadSomething -> service.invoke() .toObservable() .map { Success(it) as Effect } }£ }º R Fe Ac
59. 59 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = when (wish) { is LoadSomething -> service.invoke() .toObservable() .map { Success(it) as Effect } .startWith(Observable.just(StartedLoading)) }£ }º R Fe Ac
60. 60 sealed class Wish { object LoadSomething : Wish() }¡ sealed class Effect { object StartedLoading : Effect() data class Success(val payload: Any) : Effect() data class Failed(val throwable: Throwable) : Effect() }™ class ActorImpl : Actor<State, Wish, Effect> { private val service: () -> Single<Any> = TODO() override fun invoke(state: State, wish: Wish): Observable<out Effect> = when (wish) { is LoadSomething -> service.invoke() .toObservable() .map { Success(it) as Effect } .startWith(Observable.just(StartedLoading)) .onErrorReturn { Failed(it) } }£ }º R Fe Ac
61. 61 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, Nothing>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() ) R Fe Ac
62. 62 Reducer Feature Actor State machines Reducer only Side-effects with Actor Wish State Effect
63. Problem #3 Events
64. 64 R Fe Ac data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å class ReducerImpl : Reducer<State, Effect> { override fun invoke(state: State, effect: Effect): State = when (effect) { is Failed -> state.copy( isLoading = false, hasError = true ) valªhasError:ªBoolean )å is Failed -> state.copy( hasError = true )
65. 65 R Fe Ac data class State( val isLoading: Boolean = false, valªhasError:ªBoolean = false, val payload: Any? = null )å class ReducerImpl : Reducer<State, Effect> { override fun invoke(state: State, effect: Effect): State = when (effect) { is Failed -> state.copy( isLoading = false, hasError = true ) valªhasError:ªBoolean )å is Failed -> state.copy( hasError = true )
66. 66 if (state.hasError) { }º R Fe Ac
67. 67 if (state.hasError) { showToast() }º R Fe Ac
68. State machines Reducer only Side-effects with Actor Events
69. State machines Reducer only Side-effects with Actor Events
70. State machines Reducer only Side-effects with Actor Events
71. 71 Reducer Feature Actor Wish State Effect State machines Reducer only Side-effects with Actor Events
72. 72 News Publ. Reducer Feature Actor Wish State Effect News State machines Reducer only Side-effects with Actor Events
73. 73 News Publ. Reducer Feature Actor Wish State Effect News State machines Reducer only Side-effects with Actor Events
74. 74 Reducer Feature Actor News Publ. Wish State Effect News State machines Reducer only Side-effects with Actor Events
75. 75 Feature News Publ. Reducer Actor Wish State Effect News State machines Reducer only Side-effects with Actor Events
76. 76 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, Nothing>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π F N R A W S E N
77. 77 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, >( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π F N R A W S E N
78. 78 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π F N R A W S E N
79. 79 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ }º F N R A W S E N
80. 80 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, }¡ }º F N R A W S E N
81. 81 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, effect: Effect, }¡ }º F N R A W S E N
82. 82 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, effect: Effect, state: State): }¡ }º F N R A W S E N
83. 83 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, effect: Effect, state: State): News? = }¡ }º F N R A W S E N
84. 84 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, effect: Effect, state: State): News? = when (effect) { is Failed -> News.NetworkRequestFailed( effect.throwable ) else -> null }™ }¡ }º F N R A W S E N
85. 85 class AsyncFeature : ActorReducerFeature<Wish, Effect, State, News>( initialState = State(), actor = ActorImpl(), reducer = ReducerImpl(), newsPublisher = NewsPublisherImpl() )π{ sealed class News { data class NetworkRequestFailed(val throwable: Throwable) : News() }£ class NewsPublisherImpl : NewsPublisher<Wish, Effect, State, News> { override fun invoke(wish: Wish, effect: Effect, state: State): News? = when (effect) { is Failed -> News.NetworkRequestFailed( effect.throwable ) else -> null }™ }¡ }º F N R A W S E N
86. 86 feature.news .subscribe { when (it) { is News.NetworkRequestFailed -> { showToast() } }} F N R A W S E N
87. Problem #4 Connecting Components of Business Logic
88. Data-flow Coupling Scoping Connecting Components of Business Logic
89. Data-flow
90. 90 Connecting components Data-flow F V Pros Easy
91. 91 F V Y X Pros Easy Cons No single-source of truth Connecting components Data-flow
92. 92 F V Connecting components Data-flow
93. 93 F V Connecting components Data-flow
94. 94 F V Connecting components Data-flow
95. 95 Pros Single source of truth! Better control over flow F V Y X Connecting components Data-flow
96. 96 Pros Single source of truth! Better control over flow F V Connecting components Data-flow
97. 97 fun connect() { val source = Observable.just(1, 2, 3) val consumer = Consumer<Int> { Log.d("New number!", it.toString()) }¢ val disposable = source.subscribe(consumer) }ƒ
98. 98 package io.reactivex; /** * Represents a basic, non-backpressured {@link Observab * consumable via an {@link Observer}. * * @param <T> the element type * @since 2.0 */ public interface ObservableSource<T> { /** * Subscribes the given Observer to this ObservableS * @param observer the Observer, not null * @throws NullPointerException if {@code observer} */ void subscribe(@NonNull Observer<? super T> observer); }
99. 99 package io.reactivex.functions; /** * A functional interface (callback) that accepts a singl * @param <T> the value type */ public interface Consumer<T> { /** * Consume the given value. * @param t the value * @throws Exception on error */ void accept(T t) throws Exception; }
100. 100 interface Feature { sealed class Wish data class State }£
101. 101 interface Feature : Consumer<Wish>, ObservableSource<State> { sealed class Wish data class State }£
102. 102 interface Feature : Consumer<Wish>, ObservableSource<State> { sealed class Wish data class State }£ interface View : Consumer<State>, ObservableSource<Wish> { }¡
103. Data-flow Coupling Scoping Connecting Components of Business Logic
104. Coupling
105. 105 interface Feature : Consumer<Wish>, ObservableSource<State> { sealed class Wish data class State } interface View : Consumer<State>, ObservableSource<Wish> { }
106. 106 interface Feature : Consumer<Wish>, ObservableSource<State> { sealed class Wish data class State } interface View : Consumer<ViewModel>, ObservableSource<View.Event> { data class ViewModel sealed class Event }
107. 107 F V Pros No coupling :) Cons ? Connecting components Data-flow Coupling
108. 108 /** * Gluing layer between UI and Feature */ interface Boundary<in UiEvent : Any, ViewModel : Any> : Disposable { fun onUiEvent(uiEvent: UiEvent) val viewModels: Observable<ViewModel> } Connecting components Data-flow Coupling
109. 109 Pros No coupling :) Cons Not flexible :( F V F ??? Connecting components Data-flow Coupling
110. 110 F F ??? Pros No coupling :) Cons Not flexible :( Connecting components Data-flow Coupling
111. 111 F V X Y ??? Pros No coupling :) Cons Not flexible :( Connecting components Data-flow Coupling
112. Data-flow Coupling Scoping Connecting Components of Business Logic
113. Scoping
114. 114 Connecting components Data-flow Coupling Scoping
115. 115 F V V X Y F V Connecting components Data-flow Coupling Scoping
116. 116 F V V X Y F V Connecting components Data-flow Coupling Scoping
117. 117 F V V X Y F V Connecting components Data-flow Coupling Scoping
118. 118 F V V X Y F V Connecting components Data-flow Coupling Scoping
119. 119 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )£ val input: Consumer<String> = Consumer { System.out.println(it) }£ val disposable = Observable .wrap(output) .subscribe(input)
120. 120 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )£ val input: Consumer<String> = Consumer { System.out.println(it) }£ val binder = Binder() binder.bind(output to input)
121. 121 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )£ val input: Consumer<> = Consumer { System.out.println(it) }£ val binder = Binder() binder.bind(output to input)
122. 122 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )£ val input: Consumer<Int> = Consumer { System.out.println(it) }£ val binder = Binder() binder.bind(output to input)
123. 123 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )££ val input: Consumer<Int> = Consumer { System.out.println(it) }£ val transformer : (String) -> Int = { it.length }£ val binder = Binder() binder.bind(output to input)
124. 124 val output: ObservableSource<String> = Observable.just( "item1", "item2", "item3" )£ val input: Consumer<Int> = Consumer { System.out.println(it) }£ val transformer : (String) -> Int = { it.length }£ val binder = Binder() binder.bind(output to input using transformer)
125. 125 binder.bind(view to feature using EventToWish)£ binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
126. 126 binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY) binder.bind(view to analyticsTracker)
127. 127 binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
128. 128 val binder = Binder() binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
129. 129 val lifecycle: Lifecycle = TODO() val binder = Binder()£ binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
130. 130 val lifecycle: Lifecycle = TODO() val binder = Binder(lifecycle)£ binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
131. 131 C S Begin End Begin End Connecting components Data-flow Coupling Scoping
132. 132 C S Lifecycle sources Android / Create-Destroy Android / Start-Stop Android / Resume-Pause From Observable Manual Connecting components Data-flow Coupling Scoping
133. 133 F V V X Y F V Connecting components Data-flow Coupling Scoping
134. 134 X F F Connecting components Data-flow Coupling Scoping
135. 135 F V V X Y F V Connecting components Data-flow Coupling Scoping
136. 136 F X F V A Connecting components Data-flow Coupling Scoping
137. 137 F X F V A Connecting components Data-flow Coupling Scoping
138. 138 binder.bind(view to analyticsTracker) binder.bind(view to feature using EventToWish) binder.bind(feature to view using StateToViewModel) binder.bind(feature to greenX using StateToGX) binder.bind(feature to greenY using StateToGY)
139. Problem #5 Cross-cutting concerns
140. Cross-cutting concerns 140
141. Cross-cutting concerns 141
142. Cross-cutting concerns 142
143. 143 package io.reactivex.functions; /** * A functional interface (callback) that accepts a singl * @param <T> the value type */ public interface Consumer<T> { /** * Consume the given value. * @param t the value * @throws Exception on error */ void accept(T t) throws Exception; }
144. 144 abstract class Middleware<T>¡{ }º
145. 145 abstract class Middleware<T> : Consumer<T>¡{ }º
146. 146 abstract class Middleware<T> : Consumer<T>¡{ override fun accept(t: T) { }& }º
147. 147 abstract class Middleware<T>( private val wrapped: Consumer<T> ) : Consumer<T>¡{ override fun accept(t: T) { }& }º
148. 148 abstract class Middleware<T>( private val wrapped: Consumer<T> ) : Consumer<T>¡{ override fun accept(t: T) { wrapped.accept(t) }& }º
149. 149 abstract class Middleware<T>( private val wrapped: Consumer<T> ) : Consumer<T>¡{ override fun accept(t: T) { // do whatever here wrapped.accept(t) // do whatever here }& }º
150. 150 abstract class Middleware<T>( private val wrapped: Consumer<T> ) : Consumer<T>¡{ override fun accept(t: T) { // Log it! wrapped.accept(t) }& }º
151. 151 abstract class Middleware<T>( private val wrapped: Consumer<T> ) : Consumer<T>¡{ override fun accept(t: T) { // Save it somewhere for later! wrapped.accept(t) }& }º
152. Cross-cutting concerns 152
153. Cross-cutting concerns 153
154. MVICore summary
155. 1. Simple state reducing Feature
156. 1. Simple state reducing 2. Side-effects Feature
157. 1. Simple state reducing 2. Side-effects 3. Events Feature
158. 1. Simple state reducing 2. Side-effects 3. Events
159. 1. Simple state reducing 2. Side-effects 3. Events
160. 1. Simple state reducing 2. Side-effects 3. Events 4. Coupling 5. Scoping
161. 1. Simple state reducing 2. Side-effects 3. Events 4. Coupling 5. Scoping
162. 1. Simple state reducing 2. Side-effects 3. Events 4. Coupling 5. Scoping
163. 1. Simple state reducing 2. Side-effects 3. Events 4. Coupling 5. Scoping 6. Middlewares
164. 1. Simple state reducing 2. Side-effects 3. Events 5. Coupling 6. Scoping 7. Middlewares https://github.com/badoo/MVICore
165. The road so far
166. 1. MVP 2. Clean architecture 3. MVICore - separate UI & business logic (somewhat) - separate layers (not the right direction) - solve state-related problems - decouple UI & business logic - standardise business logic 166
167. Problem #6 UI is not shared
169. Problem #7 Complexity
170. 170 class ComponentImpl( private val params: ScreenParams, news: NewsRelay, onDisposeAction: () -> Unit, globalFeature: GlobalFeature, conversationControlFeature: ConversationControlFeature, messageSyncFeature: MessageSyncFeature, conversationInfoFeature: ConversationInfoFeature, conversationPromoFeature: ConversationPromoFeature, messagesFeature: MessagesFeature, messageActionFeature: MessageActionFeature, initialScreenFeature: InitialScreenFeature, initialScreenExplanationFeature: InitialScreenExplanationFeature?, errorFeature: ErrorFeature, conversationInputFeature: ConversationInputFeature, sendRegularFeature: SendRegularFeature, sendContactForCreditsFeature: SendContactForCreditsFeature, screenEventTrackingFeature: ScreenEventTrackingFeature, messageReadFeature: MessageReadFeature?, messageTimeFeature: MessageTimeFeature?, photoGalleryFeature: PhotoGalleryFeature?, onlineStatusFeature: OnlineStatusFeature?, favouritesFeature: FavouritesFeature?, isTypingFeature: IsTypingFeature?, giftStoreFeature: GiftStoreFeature?, messageSelectionFeature: MessageSelectionFeature?, reportingFeature: ReportingFeature?, takePhotoFeature: TakePhotoFeature?, giphyFeature: GiphyFeature, goodOpenersFeature: GoodOpenersFeature?, matchExpirationFeature: MatchExpirationFeature, private val pushIntegration: PushIntegration ) : AbstractMviComponent<UiEvent, States>(
171. This is fine 171 with(binder) { val uiEvents = combinedUiEvents(view) val photoUploadHandler = MultiplePhotoUploadHandler( contextWrapper.context as Activity, contextWrapper.lifecycleEventsRx2() ) bind(encounterEvents to encounterAnalyticsTracker) bind(uiEvents to encounterScreenAnalyticsTracker) bind(combinedViewModels to view) bind(voteInitiations to voteController named "SparkDebug.VoteController") bind(voteController to voteTutorialDialogHandler using EncountersEventToShowTu bind(voteTutorialDialogHandler to view using EncountersEventToAnimation) bind(voteTutorialDialogHandler to voteController) bind(voteControllerVotesResolved to voteProcessor using voteEventToVoteAction) bind(voteProcessor to encountersFeature using VoteResultToEncountersWish) bind(encounterEvents to encountersFeature using EncountersEventToEncountersWis bind(uiEvents to modeTabFeature using EncountersScreenEventToModeTabWish) bind(modeTabFeature.news to encountersFeature using ModeTabsNewsToSwitchEncoun bind(encounterEvents to encounterServerStats) bind(blockEvents to BlockOrReportHandler(view, contextWrapper)) bind(matches to matchScreenFeature) bind(uiEvents to photoUploadHandler using EncountersScreenEventToPhotoUploadEv bind(photoUploadHandler to photoStatusFeature using { PhotoStatusFeature.Wish.NotifyPhotoUpload }) bind(locationUpdates to encountersFeature) if (BuildVariant.INFO) { bind(debugCommands to encountersFeature) } }
172. 172 Stop thinking in screens!
174. 174 Uber RIBs
175. 175 Uber RIBs Badoo RIBs
176. 176 RIBs MVICore
177. 177 Source: https://www.hwsw.hu/hirek/58055/uber-orosz-gergely-mobil-alkalmazas-architektura-ribs-open-source.html
178. 178 Benefits • Helps to break down complexity • Encapsulation of BL + UI • Local navigation • Local DI scope • RIBs + MVICore =
179. Preview available: https://github.com/badoo/RIBs
180. Additional resources GitHub projects https://github.com/badoo/MVICore https://github.com/badoo/RIBs Article about Features https://badootech.badoo.com/a-modern-kotlin-based-mvi- architecture-9924e08efab1 Article about Binder https://badootech.badoo.com/building-a-system-of-reactive- components-with-kotlin-ff56981e92cf Time Travel Debugger Demo https://badootech.badoo.com/time-travel-debug-everything- droidconuk-2018-lightning-talk-445217258401
181. github.com/zsoltk @ZsoltKocsi medium.com/@zsolt.kocsi linkedin.com/in/zsolt-kocsi #MVICore #BadooRIBs Thank you!