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Google I/O Android App

2021 Update

Due to global events, Google I/O 2020 was canceled and Google I/O 2021 is an online-only event, so the companion app hasn't been updated since 2019. However, the iosched team has continued adding several architecture improvements to its codebase. The general look and feel of the app is unchanged, and the app still uses the data from Google I/O 2019.

Major improvements implemented in 2021:

• Migration from LiveData to Kotlin Flows to observe data.
• Support for large screens and other form factors.
• Migration from SharedPreferences to Jetpack DataStore.
• (Experimental) Partial migration to Jetpack Compose (in the compose branch)

Description

Google I/O is a developer conference with several days of deep technical content featuring technical sessions and hundreds of demonstrations from developers showcasing their technologies.

This project is the Android app for the conference.

Running the app

The project contains a staging variant that replaces some modules at compile time so they don't depend on remote services such as Firebase. This allows you to try out and test the app without the API keys.

Features

The app displays a list of conference events - sessions, office hours, app reviews, codelabs, etc. - and allows the user to filter these events by event types and by topics (Android, Firebase, etc.). Users can see details about events, and they can star events that interest them. Conference attendees can reserve events to guarantee a seat.

Other features include a Map of the venue, informational pages to guide attendees during the conference in Info, and time-relevant information during the conference in Home.

Development Environment

The app is written entirely in Kotlin and uses the Gradle build system.

To build the app, use the gradlew build command or use "Import Project" in Android Studio. Android Studio Arctic Fox or newer is required and may be downloaded here.

Architecture

The architecture is built around Android Architecture Components and follows the recommendations laid out in the Guide to App Architecture. Logic is kept away from Activities and Fragments and moved to ViewModels. Data is observed using Kotlin Flows and the Data Binding Library binds UI components in layouts to the app's data sources.

The Repository layer handles data operations. IOSched's data comes from a few different sources - user data is stored in Cloud Firestore (either remotely or in a local cache for offline use), user preferences and settings are stored in DataStore, conference data is stored remotely and is fetched and stored in memory for the app to use, etc. - and the repository modules are responsible for handling all data operations and abstracting the data sources from the rest of the app.

A lightweight domain layer sits between the data layer and the presentation layer, and handles discrete pieces of business logic off the UI thread. See the .\*UseCase.kt files under shared/domain for examples.

The Navigation component is used to implement navigation in the app, handling Fragment transactions and providing a consistent user experience.

Room is used for Full Text Search using Fts4 to search for a session, speaker, or codelab.

UI tests are written with Espresso and unit tests use Junit4 with Mockito when necessary.

The Jetpack Benchmark library makes it easy to benchmark your code from within Android Studio. The library handles warmup, measures your code performance, and outputs benchmarking results to the Android Studio console. We added a few benchmark tests around critical paths during app startup - in particular, the parsing of the bootstrap data. This enables us to automate measuring and monitoring initial startup time. Here is an example from a benchmark run:

Started running tests

Connected to process 30763 on device 'google-pixel_3'.
benchmark:
benchmark:    76,076,101 ns BootstrapConferenceDataSourceBenchmark.benchmark_json_parsing
Tests ran to completion.

Dependency Injection is implemented with Hilt. For more details on migrating from dagger-android to Hilt, read the (migration article.

ViewPager2 offers enhanced functionality over the original ViewPager library, such as right-to-left and vertical orientation support. For more details on migrating from ViewPager to ViewPager2, please see this migration guide.

Firebase

The app makes considerable use of the following Firebase components:

• Cloud Firestore is our source for all user data (events starred or reserved by a user). Firestore gave us automatic sync and also seamlessly managed offline functionality for us.
• Firebase Cloud Functions allowed us to run backend code. The reservations feature heavily depended on Cloud Functions working in conjuction with Firestore.
• Firebase Cloud Messaging let us inform the app about changes to conference data on our server.
• Remote Config helped us manage in-app constants.

For 2020, the implementation was migrated to the Firebase Kotlin extension (KTX) libraries to write more idiomatic Kotlin code when calling Firebase APIs. To learn more, read this Firebase blog article on the Firebase KTX libraries.

Kotlin

The app is entirely written in Kotlin and uses Jetpack's Android Ktx extensions.

Asynchronous tasks are handled with coroutines. Coroutines allow for simple and safe management of one-shot operations as well as building and consuming streams of data using Kotlin Flows.

All build scripts are written with the Kotlin DSL.

Copyright

Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.