Pushing Dynamic Features your Users want as quick as they want them

Many successful Android apps offer multiple features and components that work together to provide a great user experience. Although you want all prospective users to have the ability to install your app, this may not be possible due to limitations in storage and network connection, especially in emerging markets. What if you can deliver new features selectively post-installation, reducing the initial app size, and allowing you to target a wider audience? How did Kotlin enhance your reliability and quick prototyping before shipping a brand new dynamic feature? Now that Kotlin is the first language on the Android platform, you certainly know this was the right choice at the time.

What will the audience learn from this talk?
The good, the bad and lessons learnt we had along the way when building our first Dynamic Feature at Twitter for Android. Technical Design decisions we made, some architecture and implementation details (code samples in Kotlin language) and thinking in behind them. What is a dynamic feature? Why did we choose to make it? How did we make it? What difficulties did we have? What are the next steps?

Transcript

1. Pushing Dynamic Features Your Users Want, As Quick As They Want Them
2. @raulhernandezl Raul Hernandez Lopez Software Engineer @ Twitter raulh82vlc
3. What?
5. Why?
6. Broadcasting with Guests “GO LIVE Together”
7. Guests Call-In “GO LIVE Together”
8. (...don’t want this to change) Twitter has 139M mDAU
9. Twitter Android App - 26.84MB
10. WebRTC library
11. WebRTC library WebRTC is a free, open project that provides mobile applications with Real-Time Communications (RTC) capabilities via simple APIs.
12. WebRTC library Communications Optimisation
13. WebRTC library Communications Optimisation https://webrtc.org/
14. WebRTC library adds 5-7 MB
15. WebRTC library adds 5-7 MB 18.63 %
16. Google advises that for every increase of 3MB in install size there is a 0.5% install failure rate.
17. Emerging markets
18. Need a reliable solution
19. On-demand features?
20. A/B testing
21. How?
22. Modularization
23. Designing separate sections
24. :feature-1 :app
25. :feature-1 :app :feature-2 :feature-n
26. Easier Code reuse
27. Scale across teams
28. Build time reduction
30. Current App modularization lib-webrtc periscope:lib features:lib :app:twitter
31. App modularization lib-webrtc periscope:lib features:lib :app:twitter exclude 'lib/**/libjingle_peerconnection_so.so'
32. App modularization lib-webrtc periscope:lib features:lib :app:twitter webrtc feature module exclude 'lib/**/libjingle_peerconnection_so.so'
33. MUST split feature into a separate module webrtc feature module
34. Steps to start
35. 1. Google Play Store handling Play Store WebRTC dynamic module
36. Lollipop? :app:twitter (Base APK) hdpi & arm64 xhdpi & x86_64 xhdpi & x86 lib_core ... No WebRTC dynamic module Play Store 2. Request to install a dynamic feature
37. Lollipop? :app:twitter (Base APK) Yes x86_64 lib_core ... assets... hdpi WebRTC dynamic module Play Store 2. Request to install a dynamic feature
38. Lollipop? :app:twitter (Base APK) Yes x86_64 lib_core ... assets... hdpi hdpi & arm64 xhdpi & x86_64 xhdpi & x86 lib_core ... No WebRTC dynamic module Play Store 2. Request to install a dynamic feature
39. 3. Handle errors DOWNLOAD NETWORK, PERMISSIONS
40. 3. Handle errors INSTALLATION INSUFFICIENT STORAGE
41. 4. Handle success DOWNLOAD PROGRESS COMPLETION
42. 4. Handle success INSTALLATION LOADING
43. When? Initiate install only when feature is needed
44. When? Initiate install only when feature is needed or Defer install when convenient
45. Designs principles
46. Managing activity states ActivityTracker
47. Generic, to handle future modules as well onResume onPause Generic Implementation ActivityTracker Install Manager
48. Integrates well with Google libraries onResume onPause unregister Split InstallManager register Play Core Library Generic Implementation ActivityTracker Install Manager
49. Functionality waiting for subscribes observes RxJava streams Specific Implementation Integrates well with popular libraries onResume onPause unregister Split InstallManager register Play Core Library Generic Implementation ActivityTracker Install Manager
50. subscribes observes Request Installation / Loading Get Install Manager Event Specific Implementation Install Manager Functionality waiting for Loader Easy to extend
51. - NoDownloadInProgress - DownloadInProgress - Downloaded - Complete subscribes observes Request Installation / Loading Get Install Manager Event Specific Implementation Current State Install Manager Functionality waiting for Loader …and extend...
52. [ 0 - 1.0 ] - NoDownloadInProgress - DownloadInProgress - Downloaded - Complete subscribes observes Request Installation / Loading Get Install Manager Event Specific Implementation Progress Current State Install Manager Functionality waiting for Loader …and extend... even… more
53. Other teams friendly Dynamic features on Twitter for Android!
54. Implementation
56. data classes
57. sealed classes data classes
58. sealed classes nested sealed classes data classes
59. sealed classes smart casting nested sealed classes data classes
60. sealed classes data classes smart casting nested sealed classes object
61. build.gradle ... dynamicFeatures = ':lib:twitter:features:dynamic-features' Base app
62. build.gradle ... apply plugin: 'com.android.dynamic-feature' Dynamic feature
63. AndroidManifest.xml <manifest package="com.twitter.webrtcnative" ... <dist:module dist:instant="false" dist:onDemand="true" dist:title="@string/dynamic_feature_module_name"> <dist:fusing dist:include="true"/> </dist:module> <application android:hasCode="false" tools:ignore="AllowBackup,GoogleAppIndexingWarning,MissingApplicationIcon"> </application> </manifest>
64. interface DynamicDeliveryInstallManager { fun installDynamicModule(moduleName: String) fun isDynamicModuleInstalled(moduleName: String): Boolean fun loadDynamicModule(moduleName: String) ... }
65. interface DynamicDeliveryInstallManager { ... fun register(moduleName: String) fun unregister(moduleName: String) fun isRegistered(moduleName: String): Boolean ... }
66. interface DynamicDeliveryInstallManager { ... fun observeDynamicModuleState(moduleName: String): Observable<DynamicDeliveryInstallManagerEvent> }
67. override fun installDynamicModule(moduleName: String) { if (isDynamicModuleInstalled(moduleName)) { loadDynamicModule(moduleName) return } val request = SplitInstallRequest.newBuilder() .addModule(moduleName) .build() manager.startInstall(request) eventPublishSubject.onNext(DownloadStart(moduleName)) }
68. override fun installDynamicModule(moduleName: String) { if (isDynamicModuleInstalled(moduleName)) { loadDynamicModule(moduleName) return } val request = SplitInstallRequest.newBuilder() .addModule(moduleName) .build() manager.startInstall(request) eventPublishSubject.onNext(DownloadStart(moduleName)) }
69. override fun loadDynamicModule(moduleName: String) { val config = getConfigFromModuleName(moduleName) try { splitInstallDelegate.load(appContext, config) eventPublishSubject .onNext(LoadComplete(moduleName)) loadedModuleNames.add(moduleName) } catch (error: Error) { eventPublishSubject .onNext(Error.LoadError(moduleName, error)) } }
70. override fun load( appContext: Context, config: DynamicFeatureConfig ) { if (config.binaryName.isNotEmpty()) { SplitInstallHelper .loadLibrary(appContext, config.binaryName) } }
71. override fun loadDynamicModule(moduleName: String) { val config = getConfigFromModuleName(moduleName) try { splitInstallDelegate.load(appContext, config) eventPublishSubject .onNext(LoadComplete(moduleName)) loadedModuleNames.add(moduleName) } catch (error: Error) { eventPublishSubject .onNext(Error.LoadError(moduleName, error)) } }
72. override fun observeDynamicModuleState(moduleName: String): Observable<DynamicDeliveryInstallManagerEvent> { if (loadedModuleNames.contains(moduleName)) { return Observable.just( DynamicDeliveryInstallManagerEvent.LoadComplete(moduleName)) } return eventPublishSubject .onErrorReturn { Error.UnknownError(moduleName, it) } .filter { it.moduleName == moduleName } .takeUntil { it is DynamicDeliveryInstallManagerEvent.LoadComplete } }
73. override fun observeDynamicModuleState(moduleName: String): Observable<DynamicDeliveryInstallManagerEvent> { if (loadedModuleNames.contains(moduleName)) { return Observable.just( DynamicDeliveryInstallManagerEvent.LoadComplete(moduleName)) } return eventPublishSubject .onErrorReturn { Error.UnknownError(moduleName, it) } .filter { it.moduleName == moduleName } .takeUntil { it is DynamicDeliveryInstallManagerEvent.LoadComplete } }
74. sealed class DynamicDeliveryInstallEvent(open val moduleName: String) { … sealed class Error(override val moduleName: String, open val throwable: Throwable) : DynamicDeliveryInstallManagerEvent(moduleName) { … data class LoadError(override val moduleName: String, override val throwable: Throwable) : Error(moduleName, throwable) } … }
75. sealed class DynamicDeliveryInstallEvent(open val moduleName: String) { … data class Progress( override val moduleName: String, val progress: Float ) : DynamicDeliveryInstallManagerEvent(moduleName) … }
76. sealed class DynamicDeliveryInstallEvent(open val moduleName: String) { … data class InstallComplete( override val moduleName: String ) : DynamicDeliveryInstallManagerEvent(moduleName) data class LoadComplete( override val moduleName: String ) : DynamicDeliveryInstallManagerEvent(moduleName) … }
77. WEBRTC_MODULE_NAME = "webrtcnative"; WEBRTC_BINARY_NAME = "jingle_peerconnection_so"; @ApplicationScope @Provides @IntoMap @NotNull @DynamicDeliveryActivityKey(BroadcastFullscreenActivity.class) static List<String> provideBroadcastFullscreenActivityModules() { return ListBuilder.build( WEBRTC_MODULE_NAME ); } Dependency Injection
78. override fun logEvent(event: DynamicDeliveryInstallManagerEvent) { when (event) { … is InstallComplete -> { scribeHelper .scribeDynamicDeliveryInstallSuccess(createItemProvider()) } … } Analytics
79. Install only when the “GO LIVE Together” button is tapped
80. Install only when the “GO LIVE Together” button is tapped
81. Analytics
82. Results
83. No decline in user numbers
84. Prevented 18.63% APK size increase (5 MB)
85. “GO LIVE Together” on Twitter for Android
86. Lessons learned
87. Issues with Android’s beta features
88. Gradle module issues
89. KitKat / Older devices
90. Collaboration
91. Synchronisation issues
92. Synchronisation issues
93. Synchronisation issues
94. Issues when developing
95. Next Steps
96. Defer installation
97. Conditional installation
98. Thank you.
99. Questions? @raulhernandezl raulh82vlc