Android App

This guide covers building and contributing to the KayakNet Android app.

Overview

The Android app provides:

• Full KayakNet connectivity
• Chat (rooms and DMs)
• Marketplace browsing
• Domain lookup
• Native Android experience

Tech Stack

• Language: Kotlin
• UI: Jetpack Compose
• Architecture: MVVM
• Networking: Ktor HTTP client
• Build: Gradle

Project Structure

android/
├── app/
│   ├── src/main/
│   │   ├── java/com/kayaknet/
│   │   │   ├── MainActivity.kt
│   │   │   ├── KayakNetApp.kt
│   │   │   ├── ui/
│   │   │   │   ├── screens/
│   │   │   │   │   ├── HomeScreen.kt
│   │   │   │   │   ├── ChatScreen.kt
│   │   │   │   │   ├── MarketScreen.kt
│   │   │   │   │   └── DomainsScreen.kt
│   │   │   │   └── theme/
│   │   │   │       └── Theme.kt
│   │   │   └── network/
│   │   │       └── KayakNetClient.kt
│   │   ├── res/
│   │   │   ├── drawable/
│   │   │   └── values/
│   │   └── AndroidManifest.xml
│   └── build.gradle.kts
├── build.gradle.kts
└── settings.gradle.kts

Building

Prerequisites

• Android Studio Hedgehog (2023.1.1) or later
• JDK 17
• Android SDK (API 34)

Build Steps

# Clone repository
git clone https://github.com/KayakNet/KayakNet.git
cd KayakNet/android

# Build debug APK
./gradlew assembleDebug

# Output: app/build/outputs/apk/debug/app-debug.apk

Build Release APK

# Create signing key (first time only)
keytool -genkey -v -keystore kayaknet.keystore \
  -alias kayaknet -keyalg RSA -keysize 2048 -validity 10000

# Build release
./gradlew assembleRelease

# Output: app/build/outputs/apk/release/app-release.apk

GitHub Actions

Automated builds via GitHub Actions:

# .github/workflows/android.yml
name: Build Android APK

on:
  push:
    branches: [main]
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Set up JDK 17
        uses: actions/setup-java@v4
        with:
          java-version: '17'
          distribution: 'temurin'
      - name: Build APK
        run: |
          cd android
          chmod +x gradlew
          ./gradlew assembleDebug
      - name: Upload APK
        uses: actions/upload-artifact@v4
        with:
          name: kayaknet-debug
          path: android/app/build/outputs/apk/debug/app-debug.apk

Architecture

Network Communication

The app communicates with the KayakNet backend via HTTP:

class KayakNetClient(private val baseUrl: String) {
    private val client = HttpClient(CIO) {
        install(ContentNegotiation) {
            json()
        }
    }
    
    suspend fun getChatRooms(): List<ChatRoom> {
        return client.get("$baseUrl/api/chat/rooms").body()
    }
    
    suspend fun sendMessage(room: String, content: String) {
        client.post("$baseUrl/api/chat/send") {
            setBody(FormDataContent(Parameters.build {
                append("room", room)
                append("content", content)
            }))
        }
    }
}

Bootstrap Connection

val bootstrapUrl = "http://203.161.33.237:8080"
val client = KayakNetClient(bootstrapUrl)

UI with Jetpack Compose

@Composable
fun ChatScreen(viewModel: ChatViewModel) {
    val messages by viewModel.messages.collectAsState()
    
    Column {
        LazyColumn(modifier = Modifier.weight(1f)) {
            items(messages) { msg ->
                MessageItem(msg)
            }
        }
        MessageInput(onSend = { viewModel.sendMessage(it) })
    }
}

Features Implementation

Chat

• Rooms list from /api/chat/rooms
• Messages from /api/chat/history
• Send via POST /api/chat/send
• Polling for updates (1s interval)

Marketplace

• Listings from /api/market/listings
• Details from /api/market/listing?id=X
• Categories and search supported

Domains

• Lookup via /api/domains/lookup?domain=X
• My domains from /api/domains/mine

Testing

Unit Tests

./gradlew test

Instrumented Tests

./gradlew connectedAndroidTest

Manual Testing

1. Install APK on device/emulator
2. Ensure KayakNet node is running
3. App should connect automatically

Known Issues

No Local Node

The Android app connects to the bootstrap node, not a local node. This means:

• Relies on bootstrap availability
• No local proxy mode
• Limited offline capability

Future: Embedded Node

Planned: Embed Go node using gomobile:

gomobile bind -target=android ./pkg/mobile

Contributing

Code Style

• Kotlin conventions
• Compose best practices
• Clear naming
• Comments for complex logic

Pull Requests

1. Fork repository
2. Create feature branch
3. Test on multiple devices
4. Submit PR with description

Troubleshooting

Build Fails

# Clean and rebuild
./gradlew clean
./gradlew assembleDebug

Connection Issues

• Verify bootstrap is running
• Check internet connectivity
• Try with VPN if needed

UI Issues

• Check Compose version compatibility
• Verify Material3 components
• Test on different screen sizes