Why We Failed At Modularizing Our App. An Honest Retrospective.

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 DIRECTED BY Marcos Holgado @Orbycius
2. Why we failed at modularizing SkySports An honest retrospective DIRECTED BY Marcos Holgado @Orbycius
3. THE FOLLOWING TALK HAS BEEN APPROVED FOR APPROPIATE AUDIENCES BY THE DEVELOPERS ASSOCIATION OF AMERICA THE TALK ADVERTISED HAS BEEN RATED PG-25 DEVELOPERS STRONGLY CAUTIONED SOME MATERIAL MAY BE INAPPROPRIATE FOR DEVELOPERS UNDER 25 SOME AWFUL CODE AND BAD PRACTISES
4. Marcos Holgado
5. Marcos Holgado @Orbycius
6. Marcos Holgado @Orbycius DuckDuckGo
7. “Common sense is not that common” Voltaire, Dictionnaire Philosophique (1764) @Orbycius
8. @Orbycius
9. @Orbycius
10. @Orbycius
11. @Orbycius
12. @Orbycius
13. @Orbycius
14. @Orbycius
15. @Orbycius
16. How does it work? @Orbycius
17. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } @Orbycius
18. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } App @Orbycius
19. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } App src @Orbycius
20. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } App src main @Orbycius
21. productFlavors { uk { ... apply from: 'uk.gradle' } international { ... apply from: 'international.gradle' } germany { ... apply from: 'germany.gradle' } italia { ... apply from: 'italy.gradle' } } App src main germany uk italia international @Orbycius
22. App src main germany uk italia international @Orbycius
23. src main uk germany @Orbycius
24. src main uk germany Feature 1 @Orbycius
25. src main uk germany Feature 1 @Orbycius
26. src main uk germany Feature 1 Feature 2 @Orbycius
27. src main uk germany Feature 1.1 Feature 2 @Orbycius
28. src main uk germany Feature 1.1 Feature 2 @Orbycius
29. src main uk germany Feature 1.1 Feature 2 @Orbycius
30. Author: Marcos Holgado <…@sky.uk> Date: Bug fix for tab colours... again Tue Oct 17 09:36:44 2017 +0100 @Orbycius
31. 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 @Orbycius
32. 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 @Orbycius
33. Long build times Change one break many Painful to work with It doesn’t scale … @Orbycius
34. Convincing people is hard @Orbycius
35. Convincing people out of your team is hard @Orbycius
36. “The Vision” @Orbycius
37. Showcase App @Orbycius
38. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
39. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
40. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
41. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
42. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
43. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
44. What is a module? @Orbycius
45. Feature modules Core @Orbycius
46. Feature modules Core @Orbycius
47. @Orbycius
48. Inputs @Orbycius
49. Inputs Outputs @Orbycius
50. Inputs Outputs listeners() @Orbycius
51. Inputs Outputs listeners() App @Orbycius
52. Inputs Outputs listeners() App implements @Orbycius
53. What is a feature? @Orbycius
54. Inputs Outputs App Article List @Orbycius
55. Inputs Outputs ArticleListActivity App Article List @Orbycius
56. Inputs Outputs ArticleListActivity App Article List ArticleWebViewActivity? @Orbycius
57. Inputs Outputs App Article List onArticleClick() Article Reader Inputs Outputs @Orbycius
58. Inputs Outputs App implements Article List onArticleClick() Article Reader Inputs Outputs @Orbycius
59. Inputs Outputs App implements Article List onArticleClick() Article Reader Inputs Outputs @Orbycius
60. The first module @Orbycius
61. App @Orbycius
62. App Streaming @Orbycius
63. App Streaming @Orbycius
64. App Streaming Live TV @Orbycius
65. App Streaming Live TV @Orbycius
66. App Streaming Live TV @Orbycius
67. Extremely complicated feature @Orbycius
68. Extremely complicated feature Hard deadline @Orbycius
69. Extremely complicated feature Hard deadline Mainly done by one person @Orbycius
70. Extremely complicated feature Hard deadline Mainly done by one person Very bad 1st example @Orbycius
71. Start with the easiest @Orbycius
72. @Orbycius
73. Splash Screen @Orbycius
74. Start with the most valuable @Orbycius
75. Integrate ASAP @Orbycius
76. @Orbycius
77. @Orbycius
78. Don’t compromise your modules @Orbycius
79. Dependency Injection @Orbycius
80. App Streaming Live TV Streaming player @Orbycius
81. App Streaming Live TV Core Streaming player @Orbycius
82. App Streaming Live TV Core Streaming player @Orbycius
83. App Streaming Live TV Core Streaming player @Orbycius
84. App Streaming Live TV Core Streaming player User @Orbycius
85. App Streaming Live TV Core Streaming player User User @Orbycius
86. App Streaming Live TV Core Streaming player User User @Orbycius
87. App Streaming Live TV Core Streaming player User User @Orbycius
88. Dagger to the rescue @Orbycius
89. Dagger to the rescue ? @Orbycius
90. Dagger vs Koin @Orbycius
91. If you don’t want to understand it, don’t use it @Orbycius
92. SODD @Orbycius
93. Stack Overflow Driven Development @Orbycius
94. @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 @Orbycius
95. @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 @Orbycius
96. @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 @Orbycius
97. 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() @Orbycius
98. 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() @Orbycius
99. 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() @Orbycius
100. public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } ModuleHelper getModuleHelper(); @Orbycius
101. public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } ModuleHelper getModuleHelper(); @Orbycius
102. public interface ModuleMain { void initialise(); void terminate(); BaseNavObjectRegistrar getNavObjectRegistrar(); } public interface ModuleHelper { void setCoreComponent(CoreComponent coreComponent); CoreComponent getCoreComponent(); } ModuleHelper getModuleHelper(); @Orbycius
103. Subcomponents @Orbycius
104. App 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 @Orbycius
105. App 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 @Orbycius
106. App 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 @Orbycius
107. App Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent @Orbycius
108. App Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent @Orbycius
109. App Streaming .plus(streamingSubcomponent) .inject(this) @Component(modules = [AppModule::class]) interface AppComponent { fun inject(mainActivity: MainActivity) fun plus( ) } streamingComponent: StreamingSubcomponent appComponent @Orbycius
110. Subcomponents @Orbycius
111. Subcomponents @Orbycius
112. @Component( modules = StreamingModule.class, dependencies = CoreComponent.class ) public interface StreamingComponent { } @Orbycius
113. App Streaming Core interface CoreComponentProvider { CoreComponent provideCoreComponent(); } interface AppComponentProvider { AppComponent provideAppComponent(); } interface StreamingComponentProvider { StreamingComponent provideStComponent(); } @Orbycius
114. App Streaming Core interface CoreComponentProvider { CoreComponent provideCoreComponent(); } interface AppComponentProvider { AppComponent provideAppComponent(); } interface StreamingComponentProvider { StreamingComponent provideStComponent(); } class SkySportsApplication extends Application implements CoreComponentProvider, AppComponentProvider { } @Orbycius
115. 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; } } @Orbycius
116. 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() @Orbycius
117. 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() @Orbycius
118. 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() @Orbycius
119. 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() @Orbycius
120. 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() @Orbycius
121. public class PlayerActivity extends AppCompatActivity { @Inject Utility utility; @Inject User user; @Override protected void onCreate(Bundle savedInstanceState) { StreamingInjectHelper.provideStreamingComponent( getApplicationContext() ).inject(this); } } @Orbycius
122. 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"); } } } @Orbycius
123. Understand what you do Share knowledge @Orbycius
124. KI S S @Orbycius
125. K I S S Keep It Simple Stupid @Orbycius
126. Too smart to fail? @Orbycius
127. If the team can’t understand it, you already failed @Orbycius
128. @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(); } @Orbycius
129. @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; } @Orbycius
130. public class Config implements Parcelable { /** * Config Sections */ private final Map<String, ConfigSection> sections; } @Orbycius
131. 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(); } @Orbycius
132. 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; } @Orbycius
133. 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(); } @Orbycius
134. 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"; } @Orbycius
135. 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; } @Orbycius
136. “Deleted a lot of classes around config because, let's be honest, is just a json so why over complicating it?” @Orbycius
137. “Deleted a lot of classes around config because, let's be honest, is just a json so why over complicating it?” @Orbycius
138. Core @Orbycius
139. Core do you need it? @Orbycius
140. App Streaming Core User User @Orbycius
141. App Streaming Core User User @Orbycius
142. App Streaming Core User About @Orbycius
143. App Streaming Core User About other_libraries @Orbycius
144. App Streaming Core About other_libraries User User @Orbycius
145. App Streaming Core User User @Orbycius
146. App Streaming Core User User Streaming @Orbycius
147. Treat each module* as a library *feature module @Orbycius
148. Treat each module* as a library… maybe @Orbycius
149. Testing @Orbycius
150. Showcase App @Orbycius
151. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 @Orbycius
152. Showcase App @Orbycius
153. Showcase App @Orbycius
154. Sample Apps @Orbycius
155. Feature 1 Feature 2 Feature 3 Feature 4 Feature 5 Feature 6 Feature 7 Feature 8 Feature 9 @Orbycius
156. Resource conflicts @Orbycius
157. App Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming') @Orbycius
158. App Streaming Core <TextView android:text="@string/test"/> <string name="test">My test</string> implementation project(path: ':core') implementation project(path: ':streaming') My test @Orbycius
159. App 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> @Orbycius
160. App 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> @Orbycius
161. App 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') @Orbycius
162. App 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') @Orbycius
163. App 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> @Orbycius
164. App 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> @Orbycius
165. android { compileSdkVersion androidCompileSdkVersion defaultConfig { minSdkVersion androidMinSdkVersion targetSdkVersion androidTargetSdkVersion versionCode 1 versionName "1.0" } } @Orbycius
166. android { compileSdkVersion androidCompileSdkVersion defaultConfig { minSdkVersion androidMinSdkVersion targetSdkVersion androidTargetSdkVersion versionCode 1 versionName "1.0" } resourcePrefix 'my_prefix' } @Orbycius
167. <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`' ? ! @Orbycius
168. <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`' ? ! @Orbycius
169. Android Studio Scopes @Orbycius
170. @Orbycius
171. @Orbycius
172. @Orbycius
173. Recap @Orbycius
174. App is the glue that holds all together @Orbycius
175. Treat your feature modules as libraries @Orbycius
176. “Everything should be as simple as possible, but not simpler” Albert Einstein @Orbycius
177. @Orbycius THANKS https://github.com/marcosholgado/dagger-playground (blog) http://bit.ly/android-module (slides) http://bit.ly/dcberlin19-modularization