Notes - Build a Modular Android App Architecture (Google I/O'19)

f:id:shaunkawano:20190509003256p:plain

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本記事は、Build a Modular Android App Architecture (Google I/O'19)の記事です。

Why Modularize your app?

People can specialize in certain sections of the application
Maintainability
- grouping layouts based on features
Faster compilation
Faster CI
- Only modified module and the modules that depend on that module need to be tested.
- How we do it in AndroidX
  - Discover dependency graph
  - Find changed fines from Git History
  - Execute all testes of affected modules
  - URL: goo.gle/androidx-dependency-tracker
Good for business
- Smaller APKs using the Android App bundle
Isolated feature testing

How to modularize?

Dynamic Feature Module

App can't depend on modules; modules depend on app
onDemand="false", onDemand="true"
Feature Modularization

Layer modularization

Plaid Features
- Persistence
- API client / Authentication
- Custom Styling Library
- Feed UI
- Post UI

Isolation via modules

api vs implementation
- if module is provided through api all of the public api are available for all the modules depending on that module.
- if module is provided through implementation then all the modules depending on that module cannot see any public api

Feature modularization

Encapsulation
Possibility for dynamic delivery

Layer modularization

Isolation to your app
Structure to your app

If you are starting from the monolithic app

Start with layer modularization

Working with dynamic feature modules

Navigation
- starting activity
  - setClassName
- starting fragment
- Class.forName()..
  - Needs ProGuard
  - No runtime performance hits

=> Currently working on it with navigation jetpack library to make this navigation as natural as possible.

Databases

One common database
- Pros
  - Very easy to maintain database connection
  - Easy to share tables
- Cons
  - No isolation between modules
  - Feature specific entities are in shared domain
One database per module
- Pros
  - Isolation between modules
- Cons
  - Database connection maintenance
  - Duplicate data
A hybrid approach