LocalChat (lchat)

A peer-to-peer chat application for Android using Wi-Fi Aware (NAN - Neighbor Awareness Networking) technology. Chat with nearby users without internet or traditional Wi-Fi access points.

Overview

Package Name: com.mattintech.lchat
Min SDK: API 26 (Android 8.0)
Technology: Wi-Fi Aware (NAN)

Features

Core Functionality

• Dual Mode Operation: Single APK that can function as both host and client
• Direct P2P Communication: No internet or router required
• Real-time Messaging: Instant message delivery to nearby devices
• Auto-discovery: Automatically find and connect to nearby chat rooms
• Session Management: Maintain chat sessions while devices are in range

User Features

• Create or join chat rooms
• Set custom nicknames
• View active users in range
• Message history (session-based)
• Material Design 3 interface
• Background service for persistent connections

Technical Requirements

Android Permissions

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.NEARBY_WIFI_DEVICES" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

Architecture

Single APK Design

The app operates in two modes within a single application:

1. Host Mode - Publishes a chat service for others to discover
2. Client Mode - Subscribes to discover available chat services

Key Components

• WifiAwareManager - Core Wi-Fi Aware functionality
• PublishConfig - Configuration for hosting chat rooms
• SubscribeConfig - Configuration for discovering chat rooms
• WifiAwareSession - Manages aware connections
• NetworkSpecifier - Establishes data paths between devices

Data Flow

1. Discovery Phase

   • Host publishes service with room name
   • Clients subscribe to discover services
   • Service discovery triggers connection UI

2. Connection Phase

   • Client requests connection to host
   • Host accepts/manages connections
   • Bidirectional data path established

3. Communication Phase

   • Messages sent over established data path
   • All connected clients receive messages
   • Host manages client list and broadcasting

Project Structure

lchat/
├── app/
│   ├── src/main/java/com/mattintech/lchat/
│   │   ├── MainActivity.kt
│   │   ├── network/
│   │   │   ├── WifiAwareManager.kt
│   │   │   ├── ChatService.kt
│   │   │   └── MessageHandler.kt
│   │   ├── ui/
│   │   │   ├── ChatFragment.kt
│   │   │   ├── LobbyFragment.kt
│   │   │   └── adapters/
│   │   ├── data/
│   │   │   ├── Message.kt
│   │   │   ├── User.kt
│   │   │   └── ChatRepository.kt
│   │   └── utils/
│   └── src/main/res/
├── gradle/
└── build.gradle.kts

Development Roadmap

Phase 1: Foundation

• Basic Android project setup
• Wi-Fi Aware permission handling
• Simple host/client mode switching

Phase 2: Core Messaging

• Message sending/receiving
• User management
• Basic UI implementation

Phase 3: Enhanced Features

• Message persistence
• Reconnection handling
• Advanced UI features

Phase 4: Polish

• Error handling
• Performance optimization
• UI/UX refinements

Building

./gradlew assembleDebug

Testing

Wi-Fi Aware requires physical devices for testing (API 26+). Emulator support is limited.

License

[To be determined]