Why we failed at modularizing our app

Modularization is the new trend, almost everybody in the Android ecosystem is refactoring their apps to use a modularized approach. We at Sky are no different, we had a big monolithic codebase supporting 4 apps in different countries that we started modularizing in September 2017. But we failed, big time.

This talk is an honest retrospective of everything that went wrong, the bad decisions that we made, the approach we initially took and how we, against all odds, eventually started re-building a maintainable, sustainable and extensible modularized codebase. In this talk you will learn from our mistakes and struggles, like defining what is a module and its responsibilities, how to integrate Dagger in a multi-module environment, set some rules and best practices and much more but, more importantly, you will learn what not to do when modularizing your codebase.

Transcript

1. Why we failed at modularizing “our app” An honest retrospective Droidcon Berlin 19
2. Marcos Holgado @Orbycius
3. “Common sense is not that common” @Orbycius Voltaire, Dictionnaire Philosophique (1764)
4. @Orbycius
5. @Orbycius
6. @Orbycius
7. @Orbycius
8. @Orbycius
9. @Orbycius
10. @Orbycius
12. How does it work? @Orbycius
13. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius
14. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius App
15. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius App src
16. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius App src main
17. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius App src main germany uk italia international
18. @Orbycius App src main germany uk italia international
19. @Orbycius src main uk germany
20. @Orbycius src main uk germany Feature 1
21. @Orbycius src main uk germany Feature 1
22. @Orbycius src main uk germany Feature 1 Feature 2
23. @Orbycius src main uk germany Feature 1.1 Feature 2
24. @Orbycius src main uk germany Feature 1.1 Feature 2
25. @Orbycius src main uk germany Feature 1.1 Feature 2
26. @Orbycius Author: Marcos Holgado <…@sky.uk> Date: Bug fix for tab colours... again Tue Oct 17 09:36:44 2017 +0100
27. @Orbycius Author: Marcos Holgado <…@sky.uk> Date: Bug fix for tab colours... again Author: Marcos Holgado <…@sky.uk> Date: Fix tab colours again :( Tue Oct 17 09:36:44 2017 +0100 Mon Oct 23 16:10:08 2017 +0100
28. @Orbycius Author: Marcos Holgado <…@sky.uk> Date: Bug fix for tab colours... again Author: Marcos Holgado <…@sky.uk> Date: Fix tab colours again :( Tue Oct 17 09:36:44 2017 +0100 Mon Oct 23 16:10:08 2017 +0100
29. Long build times Change one break many Painful to work with It doesn’t scale … @Orbycius
30. Convincing people is hard @Orbycius
31. Convincing people out of your team is hard @Orbycius
32. “The Vision” @Orbycius
33. Showcase App @Orbycius
34. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
35. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
36. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
37. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
38. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
39. Feature 1 @Orbycius Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
40. What is a module? @Orbycius
41. @Orbycius Feature modules Core
42. @Orbycius Feature modules Core
43. @Orbycius
44. @Orbycius Inputs
45. @Orbycius Inputs Outputs
46. @Orbycius Inputs Outputs listeners()
47. Inputs Outputs listeners() App @Orbycius
48. Inputs Outputs listeners() App @Orbycius implements
49. What is a feature? @Orbycius
50. Inputs Outputs App @Orbycius Article List
51. Inputs Outputs ArticleListActivity App @Orbycius Article List
52. Inputs Outputs ArticleListActivity App @Orbycius Article List ArticleWebViewActivity?
53. Inputs Outputs App @Orbycius Article List onArticleClick() Article Reader Inputs Outputs
54. Inputs Outputs App @Orbycius implements Article List onArticleClick() Article Reader Inputs Outputs
55. Inputs Outputs App @Orbycius implements Article List onArticleClick() Article Reader Inputs Outputs
56. The first module @Orbycius
57. App @Orbycius
58. App @Orbycius Streaming
59. App @Orbycius Streaming
60. App @Orbycius Streaming Live TV
61. App @Orbycius Streaming Live TV
62. App @Orbycius Streaming Live TV
63. Extremely complicated feature @Orbycius
64. Extremely complicated feature Hard deadline @Orbycius
65. Extremely complicated feature Hard deadline Mainly done by one person @Orbycius
66. Extremely complicated feature Hard deadline Mainly done by one person Very bad 1st example @Orbycius
67. Start with the easiest @Orbycius
68. Splash Screen @Orbycius
69. Start with the most valuable @Orbycius
70. Integrate ASAP @Orbycius
71. @Orbycius
72. @Orbycius
73. Don’t compromise your modules @Orbycius
74. Dependency Injection @Orbycius
75. App @Orbycius Streaming Live TV Streaming player
76. App @Orbycius Streaming Live TV Core Streaming player
77. App @Orbycius Streaming Live TV Core Streaming player
78. App @Orbycius Streaming Live TV Core Streaming player
79. App @Orbycius Streaming Live TV Core Streaming player User
80. App @Orbycius Streaming Live TV Core Streaming player User User
81. App @Orbycius Streaming Live TV Core Streaming player User User
82. App @Orbycius Streaming Live TV Core Streaming player User User
83. Dagger to the rescue @Orbycius
84. Dagger to the rescue @Orbycius ?
85. Dagger vs Koin @Orbycius
86. If you don’t want to understand it, don’t use it @Orbycius
87. SODD @Orbycius
88. Stack Overflow Driven Development @Orbycius
89. @Orbycius @Provides public ForegroundManager provideForegroundManager(Context context) { useForegroundManager = new ForegroundManager((Application) context); if (!foregroundManager.compareAndSet(null, useForegroundManager)) { useForegroundManager = foregroundManager.get(); } } return useForegroundManager; } private final AtomicReference<ForegroundManager> foregroundManager; ForegroundManager useForegroundManager = foregroundManager.get(); if (useForegroundManager == null) { } @Singleton
90. @Orbycius @Provides public ForegroundManager provideForegroundManager(Context context) { useForegroundManager = new ForegroundManager((Application) context); if (!foregroundManager.compareAndSet(null, useForegroundManager)) { useForegroundManager = foregroundManager.get(); } } return useForegroundManager; } private final AtomicReference<ForegroundManager> foregroundManager; ForegroundManager useForegroundManager = foregroundManager.get(); if (useForegroundManager == null) { } @Singleton
91. @Orbycius @Provides public ForegroundManager provideForegroundManager(Context context) { useForegroundManager = new ForegroundManager((Application) context); if (!foregroundManager.compareAndSet(null, useForegroundManager)) { useForegroundManager = foregroundManager.get(); } } return useForegroundManager; } private final AtomicReference<ForegroundManager> foregroundManager; ForegroundManager useForegroundManager = foregroundManager.get(); if (useForegroundManager == null) { } @Singleton
92. @Orbycius public class PlayerActivity extends AppCompatActivity { @Inject Utility utility; @Override protected void onCreate(Bundle savedInstanceState) { .getStreamingComponent() .addSubcomponent(new StreamingModule(this)) .inject(this); } [...] } } // Check that a sub-class hasn't just done DI for us! if (utility == null) { StreamingModuleMain.getStreamingModuleHelper()
93. @Orbycius public class PlayerActivity extends AppCompatActivity { @Inject Utility utility; @Override protected void onCreate(Bundle savedInstanceState) { .getStreamingComponent() .addSubcomponent(new StreamingModule(this)) .inject(this); } [...] } } // Check that a sub-class hasn't just done DI for us! if (utility == null) { StreamingModuleMain.getStreamingModuleHelper()
94. @Orbycius public class PlayerActivity extends AppCompatActivity { @Inject Utility utility; @Override protected void onCreate(Bundle savedInstanceState) { .getStreamingComponent() .addSubcomponent(new StreamingModule(this)) .inject(this); } [...] } } // Check that a sub-class hasn't just done DI for us! if (utility == null) { StreamingModuleMain.getStreamingModuleHelper()
95. @Orbycius public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } ModuleHelper getModuleHelper();
96. @Orbycius public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } ModuleHelper getModuleHelper();
97. @Orbycius public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } public interface ModuleHelper { void setCoreComponent(CoreComponent coreComponent); CoreComponent getCoreComponent(); } ModuleHelper getModuleHelper();
98. Subcomponents @Orbycius
99. App @Orbycius Streaming @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } @Subcomponent(modules = [StreamingModule::class]) interface StreamingSubcomponent { fun inject(activity: PlayerActivity) } streamingComponent: StreamingSubcomponent
100. App @Orbycius Streaming @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } @Subcomponent(modules = [StreamingModule::class]) interface StreamingSubcomponent { fun inject(activity: PlayerActivity) } streamingComponent: StreamingSubcomponent
101. App @Orbycius Streaming @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } @Subcomponent(modules = [StreamingModule::class]) interface StreamingSubcomponent { fun inject(activity: PlayerActivity) } streamingComponent: StreamingSubcomponent
102. App @Orbycius Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent
103. App @Orbycius Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent
104. App @Orbycius Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent
105. Subcomponents @Orbycius
106. Subcomponents @Orbycius
107. @Orbycius @Component( modules = StreamingModule.class, dependencies = CoreComponent.class ) public interface StreamingComponent { }
108. App @Orbycius Streaming Core interface CoreComponentProvider { CoreComponent provideCoreComponent(); } interface AppComponentProvider { AppComponent provideAppComponent(); } interface StreamingComponentProvider { StreamingComponent provideStComponent(); }
109. App @Orbycius Streaming Core interface CoreComponentProvider { CoreComponent provideCoreComponent(); } interface AppComponentProvider { AppComponent provideAppComponent(); } interface StreamingComponentProvider { StreamingComponent provideStComponent(); } class SkySportsApplication extends Application implements CoreComponentProvider, AppComponentProvider { }
110. @Orbycius interface AppComponentProvider { AppComponent provideAppComponent(); } class SkySportsApplication extends Application implements CoreComponentProvider, AppComponentProvider { private CoreComponent coreComponent; private AppComponent appComponent; @Override public CoreComponent provideCoreComponent() { if (coreComponent == null) { coreComponent = DaggerCoreComponent.builder() .commonModule(new CommonModule(this)) .build(); } return commonComponent; } }
111. @Orbycius public class UKSportsApplication extends implements { private StreamingComponent streamingComponent; } SkySportsApplication StreamingComponentProvider .coreComponent(provideCoreComponent()) @Override public StreamingComponent provideStreamingComponent() { if (streamingComponent == null) { streamingComponent = DaggerStreamingComponent.builder() .streamingModule(new StreamingModule( .build(); } return streamingComponent; } provideAppComponent().getUser()
112. @Orbycius public class UKSportsApplication extends implements { private StreamingComponent streamingComponent; } SkySportsApplication StreamingComponentProvider .coreComponent(provideCoreComponent()) @Override public StreamingComponent provideStreamingComponent() { if (streamingComponent == null) { streamingComponent = DaggerStreamingComponent.builder() .streamingModule(new StreamingModule( .build(); } return streamingComponent; } provideAppComponent().getUser()
113. @Orbycius public class UKSportsApplication extends implements { private StreamingComponent streamingComponent; } SkySportsApplication StreamingComponentProvider .coreComponent(provideCoreComponent()) @Override public StreamingComponent provideStreamingComponent() { if (streamingComponent == null) { streamingComponent = DaggerStreamingComponent.builder() .streamingModule(new StreamingModule( .build(); } return streamingComponent; } provideAppComponent().getUser()
114. @Orbycius public class UKSportsApplication extends implements { private StreamingComponent streamingComponent; } SkySportsApplication StreamingComponentProvider .coreComponent(provideCoreComponent()) @Override public StreamingComponent provideStreamingComponent() { if (streamingComponent == null) { streamingComponent = DaggerStreamingComponent.builder() .streamingModule(new StreamingModule( .build(); } return streamingComponent; } provideAppComponent().getUser()
115. @Orbycius public class UKSportsApplication extends implements { private StreamingComponent streamingComponent; } SkySportsApplication StreamingComponentProvider .coreComponent(provideCoreComponent()) @Override public StreamingComponent provideStreamingComponent() { if (streamingComponent == null) { streamingComponent = DaggerStreamingComponent.builder() .streamingModule(new StreamingModule( .build(); } return streamingComponent; } provideAppComponent().getUser()
116. @Orbycius public class PlayerActivity extends AppCompatActivity { @Inject Utility utility; @Inject User user; @Override protected void onCreate(Bundle savedInstanceState) { StreamingInjectHelper.provideStreamingComponent( getApplicationContext() ).inject(this); } }
117. @Orbycius public class StreamingInjectHelper { public static StreamingComponent provideStreamingComponent(final Context context){ if (context instanceof StreamingComponentProvider) { return ((StreamingComponentProvider)context).provideStreamingComponent(); } else { throw new IllegalStateException("The context you have passed does not implement StreamingComponentProvider"); } } }
118. Understand what you do Share knowledge @Orbycius
119. @Orbycius KI S S
120. @Orbycius K I S S Keep It Simple Stupid
121. @Orbycius Too smart to fail?
122. @Orbycius If the team can’t understand it, you already failed
123. @Orbycius @Provides @IntoMap @IntKey(TableRow.CRICKET_ROW) SportsListViewHolderFactory provideCricketViewHolder() { return new CricketStandingViewHolderFactory(); } @Provides @IntoMap @IntKey(TableRow.RUGBY_ROW) SportsListViewHolderFactory provideRugbyViewHolder() { return new RugbyStandingViewHolderFactory(); } @Provides @IntoMap @IntKey(TableRow.F1_ROW) SportsListViewHolderFactory provideF1DriverViewHolder() { return new F1DriverStandingViewHolderFactory(); }
124. @Orbycius @Provides Map<Integer, SportsListViewHolderFactory> provideSportsListViewHolderFactoryMap() { Map<Integer, SportsListViewHolderFactory> map = new HashMap<>(); map.put(TableRow.F1_ROW, new F1DriverStandingViewHolderFactory()); map.put(TableRow.CRICKET_ROW, new CricketStandingViewHolderFactory()); map.put(TableRow.RUGBY_ROW, new RugbyStandingViewHolderFactory()); return map; }
125. @Orbycius public class Config implements Parcelable { /** * Config Sections */ private final Map<String, ConfigSection> sections; }
126. @Orbycius public class Config implements Parcelable { /** * Config Sections */ private final Map<String, ConfigSection> sections; } public interface ConfigSection extends Parcelable { /** * Name of the section to use as a key * * @return Name of the section to use for lookups */ String getSectionName(); }
127. @Orbycius public class ConfigDeserialiser implements JsonDeserializer<Config> { /** * Deserialiser for individual sections, keyed on the sections they support * * Note that this means each deserialiser may appear more than once! */ private final Map<String, ConfigSectionDeserialiser> sectionDeserialisers; }
128. @Orbycius public class ConfigDeserialiser implements JsonDeserializer<Config> { /** * Deserialiser for individual sections, keyed on the sections they support * * Note that this means each deserialiser may appear more than once! */ private final Map<String, ConfigSectionDeserialiser> sectionDeserialisers; } public interface ConfigSectionDeserialiser<T extends ConfigSection> { Collection<String> supportedParentKeys(); String sectionKey(); @NonNull T deserialiseSection(String key, JsonElement sectionSource, @Nullable T existingSection); T getDefaultSection(); }
129. @Orbycius public class ForcedUpgradeDeserialiser implements ConfigSectionDeserialiser<ForcedUpgrade> { public static final String LATEST_VERSION = "lver"; public static final String MESSAGE_TITLE = "title"; public static final String MESSAGE_BODY = "message"; public static final String FORCE_UPGRADE = "shouldForce"; }
130. @Orbycius public class ForcedUpgradeDeserialiser implements ConfigSectionDeserialiser<ForcedUpgrade> { public static final String LATEST_VERSION = "lver"; public static final String MESSAGE_TITLE = "title"; public static final String MESSAGE_BODY = "message"; public static final String FORCE_UPGRADE = "shouldForce"; } public class ForcedUpgrade implements ConfigSection { public static final String FORCED_UPGRADE = "shouldForce"; /** * Latest version code */ private int latestVersion; }
131. @Orbycius “Deleted a lot of classes around config because let's be honest, is just a json so why over complicating it?”
132. @Orbycius “Deleted a lot of classes around config because let's be honest, is just a json so why over complicating it?”
133. Core @Orbycius
134. Core @Orbycius do you need it?
135. App @Orbycius Streaming Core User User
136. App @Orbycius Streaming Core User User
137. App @Orbycius Streaming Core User About
138. App @Orbycius Streaming Core User About other_libraries
139. App @Orbycius Streaming Core About other_libraries User User
140. App @Orbycius Streaming Core User User
141. App @Orbycius Streaming Core User User Streaming
142. Treat each module* as a library @Orbycius *feature module
143. Treat each module* as a library… maybe @Orbycius
144. Testing @Orbycius
145. Showcase App @Orbycius
146. @Orbycius Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8
147. Showcase App @Orbycius
148. Showcase App @Orbycius
149. Sample Apps @Orbycius
150. @Orbycius Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 Feature 9
151. @Orbycius Resource conflicts
152. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming')
153. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming') My test
154. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming') <string name="test">Core test</string>
155. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming') Core test <string name="test">Core test</string>
156. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> <string name="test">Core test</string> implementation project(path: ':streaming') implementation project(path: ':core')
157. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> My test <string name="test">Core test</string> implementation project(path: ':streaming') implementation project(path: ':core')
158. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> <string name="test">Core test</string> implementation project(path: ':streaming') implementation project(path: ':core') <string name="test">App test</string>
159. App @Orbycius Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> App test <string name="test">Core test</string> implementation project(path: ':streaming') implementation project(path: ':core') <string name="test">App test</string>
160. @Orbycius android { compileSdkVersion androidCompileSdkVersion defaultConfig { minSdkVersion androidMinSdkVersion targetSdkVersion androidTargetSdkVersion versionCode 1 versionName "1.0" } }
161. @Orbycius android { compileSdkVersion androidCompileSdkVersion defaultConfig { minSdkVersion androidMinSdkVersion targetSdkVersion androidTargetSdkVersion versionCode 1 versionName "1.0" } resourcePrefix 'my_prefix' }
162. @Orbycius <resources> <string name="test">My other test</string> </resources> Resource named '`test`' does not start with the project's resource prefix '`my_prefix`'; rename to '`my_prefixTest`' ? !
163. @Orbycius <resources> <string name="test">My other test</string> </resources> Resource named '`test`' does not start with the project's resource prefix '`my_prefix`'; rename to '`my_prefixTest`' ? !
164. @Orbycius Android Studio Scopes
165. @Orbycius
166. @Orbycius
167. @Orbycius
168. @Orbycius Recap
169. @Orbycius App is the glue that holds all together
170. @Orbycius Treat your feature modules as libraries
171. @Orbycius “Everything should be as simple as possible, but not simpler” Albert Einstein
172. @Orbycius THANKS https://github.com/marcosholgado/dagger-playground (blog) http://bit.ly/android-module