7+1 tips about [Android] App Modularization | droidcon Madrid 19

Nowadays, App modularization is a technique largely adopted that gives lots of advantages. But how to approach it?
This talk will not focus on the pro and cons of modularization but instead on the approach and the process to achieve it. In particular, I want to share the approach that I followed to modularize an existing application and a new one. I want also to share the failures and all the struggles that came in my head while approaching the process.

Transcript

1. 7+1 tips about [Android] App Modularization droidcon Madrid 19 - @marcoGomier
2. ! What this talk is not about • 101 about modularization • Pro and cons droidcon Madrid 19 - @marcoGomier
3. ! What this talk is about • 101 about modularization • Pro and cons • Approach and process • Failure and struggles droidcon Madrid 19 - @marcoGomier
4. Marco Gomiero ! Mobile Engineer @ Uniwhere "# $ Co-Lead @ GDG Venezia ! Stalking info • Twitter: @marcoGomier • Github: prof18 • Website: marcogomiero.com droidcon Madrid 19 - @marcoGomier
5. Uniwhere We use data to make students' journey from college to the job market less stressful • ! Started in 2015 as MVP • " Lots of iterations • # Time for [more] solid architecture droidcon Madrid 19 - @marcoGomier
7. Modularization in few words droidcon Madrid 19 - @marcoGomier
8. Modularization in few words emojis droidcon Madrid 19 - @marcoGomier
9. Modularization in few words emojis • ! Simple development • "# Split responsibilities • $ Reusable modules Source: https://speakerdeck.com/beraldofilippo/the-clean-cut?slide=10
10. Modularization in few words emojis • ! Dynamic features modules • " Faster Builds • # Simple test automation Source: https://speakerdeck.com/beraldofilippo/the-clean-cut?slide=10
12. 1 Read and study how to do droidcon Madrid 19 - @marcoGomier
13. Doing some research is always a good start droidcon Madrid 19 - @marcoGomier
14. Jeroen Mols's series about modularization 1. Modularization - Why you should care 2. Modularization - A successful architecture 3. Modularization - Real-life example 4. Modularization - How to approach 5. Modularization - Lessons learned https://jeroenmols.com/blog/
15. Talk @ Google I/O '19 youtube.com/watch?v=PZBg5DIzNww
16. Plaid github.com/android/plaid
17. Article about Plaid https://medium.com/androiddevelopers/a-patchwork-plaid-monolith-to-modularized-app-60235d9f212e
18. 2 Sketch your features droidcon Madrid 19 - @marcoGomier
19. Sketching "un-confuse" your ideas droidcon Madrid 19 - @marcoGomier
20. Monolithic Application └── app └── src └── main └── java └── com.prof18.myapplication ├── DashboardFragment.kt ├── HomeFragment.kt ├── MainActivity.kt ├── NotificationsFragment.kt ├── ProfileActivity.kt └── ProfileSettingsActivity.kt droidcon Madrid 19 - @marcoGomier
22. How to decide what is a feature? droidcon Madrid 19 - @marcoGomier
26. Think a feature as a flow of screens [in the same context] droidcon Madrid 19 - @marcoGomier
27. 3 Decide your architecture droidcon Madrid 19 - @marcoGomier
28. There is not a "right way" droidcon Madrid 19 - @marcoGomier
29. Modularized App Architecture droidcon Madrid 19 - @marcoGomier
30. Library Modules • Android or Pure Kotlin library • Never depend on feature or app • A library can depend on another droidcon Madrid 19 - @marcoGomier
31. Feature Modules • Android library • Never depend on other features or app • Depends on one or more libraries droidcon Madrid 19 - @marcoGomier
32. App Module • Android application • Link all the modules together • Depends on other features and library droidcon Madrid 19 - @marcoGomier
33. Monolithic Application └── app └── src └── main └── java └── com.prof18.myapplication ├── DashboardFragment.kt ├── HomeFragment.kt ├── MainActivity.kt ├── NotificationsFragment.kt ├── ProfileActivity.kt └── ProfileSettingsActivity.kt droidcon Madrid 19 - @marcoGomier
34. Modularized App [1] ├── app │ └── src │ └── main │ └── java │ └── com.prof18.myapplication │ └── MainActivity.kt │ droidcon Madrid 19 - @marcoGomier
35. Modularized App [2] └── features ├── home │ └── src │ └── main │ └── java │ └── com.prof18.myapplication.features.home │ ├── DashboardFragment.kt │ ├── HomeActivity.kt │ ├── HomeFragment.kt │ └── NotificationsFragment.kt └── profile └── src └── main └── java └── com.prof18.myapplication.features.profile ├── ProfileActivity.kt └── ProfileSettingsActivity.kt droidcon Madrid 19 - @marcoGomier
36. How about navigation? droidcon Madrid 19 - @marcoGomier
37. How about navigation? • Within a feature -> "Classic way", e.g. explicit intent, navigation component • Between features -> Implicit intent droidcon Madrid 19 - @marcoGomier
38. Between features navigation Declare the implicit intent in the Manifest <activity android:name="com.prof18.filmatic.features.home.ui.HomeActivity" android:theme="@style/AppTheme.NoActionBar"> <intent-filter> <action android:name="com.prof18.filmatic.features.home" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </activity> droidcon Madrid 19 - @marcoGomier
39. Between features navigation Create an object to help you with the boilerplate object Actions { fun openHomeIntent(context: Context): Intent = internalIntent(context, "com.prof18.filmatic.features.home") private fun internalIntent(context: Context, action: String) = Intent(action).setPackage(context.packageName) } droidcon Madrid 19 - @marcoGomier
40. How to modularize an existent project? droidcon Madrid 19 - @marcoGomier
41. Pull Code Up • Treat the old code "as a library" and then create new modules • A gentle process droidcon Madrid 19 - @marcoGomier
42. Pull Code Down • Hold the app together and then extract new modules • A more aggressive process droidcon Madrid 19 - @marcoGomier
44. Pull Code Up 1. Create new module core 2. All existing code into core 3. New app module that decides what to open 4. Extract a new feature from core 5. … droidcon Madrid 19 - @marcoGomier
46. droidcon Madrid 19 - @marcoGomier
48. Change of strategy: Pull Code Down 1. Maintain all the code in the existent app module 2. Move [some] common code to the core module 3. Start creating new features and libraries droidcon Madrid 19 - @marcoGomier
49. 4 Fail as fast as you can droidcon Madrid 19 - @marcoGomier
50. Fail as fast as you can • It's ok to fail during this process • Keep pushing • Allocate a big initial push to get things started droidcon Madrid 19 - @marcoGomier
51. After failure things get better — me droidcon Madrid 19 - @marcoGomier
52. After failure things get better worse — also me droidcon Madrid 19 - @marcoGomier
53. String resources • Each module has its strings • Common strings on core module • ! for separation of concerns • " to maintain with a "translation platform" droidcon Madrid 19 - @marcoGomier
54. String resources • Each module has its strings • Common strings on core module • All strings on core module droidcon Madrid 19 - @marcoGomier
55. 5 Use Dependency Injection. droidcon Madrid 19 - @marcoGomier
56. Let's introduce Dagger while modularizing — me droidcon Madrid 19 - @marcoGomier
58. Dagger in a multi-module project https://proandroiddev.com/using-dagger-in-a-multi-module-project-1e6af8f06ffc
59. Dagger in a multi-module project droidcon Madrid 19 - @marcoGomier
60. New to Dagger? https://developer.android.com/training/dependency-injection/dagger-android
61. How to approach a no Dagger project? • Start gently with some [common] dependencies • Continue with more dependencies droidcon Madrid 19 - @marcoGomier
62. 6 Modules configurations. droidcon Madrid 19 - @marcoGomier
63. Modules configuration We need a smart way to handle dependencies and configurations across all modules droidcon Madrid 19 - @marcoGomier
64. SDK Configuration subprojects { afterEvaluate { project -> if (project.hasProperty('android')) { android { buildToolsVersion Config.buildTools compileSdkVersion Config.compileSdk defaultConfig { minSdkVersion Config.minSdk targetSdkVersion Config.targetSdk testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" } compileOptions { sourceCompatibility Config.javaVersion targetCompatibility Config.javaVersion } } } } } droidcon Madrid 19 - @marcoGomier
65. SDK Configuration object Config { val minSdk = 21 val compileSdk = 29 val targetSdk = 29 val javaVersion = JavaVersion.VERSION_1_8 val buildTools = "29.0.0" } droidcon Madrid 19 - @marcoGomier
66. Dependency Management object Versions { val appcompat = "1.0.2" val design = "1.0.0" val cardview = "1.0.0" ... } object Deps { val appcompat = "androidx.appcompat:appcompat:${Versions.appcompat}" val design = "com.google.android.material:material:${Versions.design}" val cardview = "androidx.cardview:cardview:${Versions.cardview}" ... } droidcon Madrid 19 - @marcoGomier
67. Dependency Management dependencies { implementation Deps.appcompat implementation Deps.retrofit implementation Deps.gson ... } droidcon Madrid 19 - @marcoGomier
68. Common dependencies: dependencies { implementation Deps.appcompat implementation Deps.constraintLayout implementation Deps.design implementation Deps.vectorDrawable implementation Deps.timber } apply from: '../../shared_dependencies.gradle' droidcon Madrid 19 - @marcoGomier
69. Dependencies Update https://github.com/ben-manes/gradle-versions-plugin
70. Dependencies Update ./gradlew dependencyUpdates ------------------------------------------------------------ : Project Dependency Updates (report to plain text file) ------------------------------------------------------------ The following dependencies are using the latest milestone version: - androidx.cardview:cardview:1.0.0 - androidx.constraintlayout:constraintlayout:2.0.0-beta3 - androidx.emoji:emoji-bundled:1.0.0 .... The following dependencies have later milestone versions: - androidx.appcompat:appcompat [1.1.0 -> 1.2.0-alpha01] https://developer.android.com/jetpack/androidx - androidx.browser:browser [1.0.0 -> 1.2.0-rc01] https://developer.android.com/jetpack/androidx - androidx.core:core-ktx [1.0.1 -> 1.2.0-rc01] droidcon Madrid 19 - @marcoGomier
71. 7 Decide your approach. droidcon Madrid 19 - @marcoGomier
72. What approach to follow? A big sprint? Small chunks of work? droidcon Madrid 19 - @marcoGomier
73. My approach • Start with preliminaries • move common code/resources to a [or many] core module[s] • Setup the navigation between features • … • Start by modularizing a single feature droidcon Madrid 19 - @marcoGomier
74. My approach • Ship that feature [after testing, QA, etc. ] • Start modularizing more features droidcon Madrid 19 - @marcoGomier
75. 8 Create a pet project to try stuff droidcon Madrid 19 - @marcoGomier
76. Architecture and modularization require an initial research droidcon Madrid 19 - @marcoGomier
77. Conclusions droidcon Madrid 19 - @marcoGomier
78. Conclusions • Plan a big initial push to get things started • It's a long [and difficult] journey but it totally worth it • Don't be afraid to fail droidcon Madrid 19 - @marcoGomier
80. into modularization! droidcon Madrid 19 - @marcoGomier
82. Thanks Q&A droidcon Madrid 19 - @marcoGomier
83. Thanks Q&A • @marcoGomier • github.com/prof18 • marcogomiero.com droidcon Madrid 19 - @marcoGomier