> ## Documentation Index > Fetch the complete documentation index at: https://mintlify.com/jitsi/lib-jitsi-meet/llms.txt > Use this file to discover all available pages before exploring further. # Architecture Overview > Understanding lib-jitsi-meet's architecture and design patterns lib-jitsi-meet is a JavaScript library that provides WebRTC functionality, XMPP communication, and media handling for Jitsi Meet clients. This page explains its core architecture and design principles. ## Module Organization The library follows a modular design with clear separation of concerns: ### Core API Layer The main public API is exposed through these core classes: * **JitsiMeetJS.ts** - Main library entry point exposing the public API * **JitsiConnection.ts** - XMPP connection management and authentication * **JitsiConference.js** - Video conference session representation * **JitsiParticipant.ts** - Conference participant abstraction * **JitsiTrack/JitsiLocalTrack/JitsiRemoteTrack** - Media track management ### RTC Module (`/modules/RTC/`) Handles all WebRTC functionality: * **Core WebRTC features**: Track management and screen sharing * **TraceablePeerConnection.js** - Enhanced PeerConnection with debugging capabilities * **RTCUtils.js** - Browser compatibility and WebRTC utilities The RTC module provides a clean abstraction over browser WebRTC APIs with built-in compatibility handling. ### XMPP Module (`/modules/xmpp/`) Implements XMPP/Jingle protocol for signaling: * **ChatRoom.js** - Multi-user chat room with presence management * **JingleSessionPC.js** - Jingle protocol for media negotiation * **SignalingLayerImpl.js** - Abstraction layer for signaling * **Strophe plugins** - Protocol extensions (disco, ping, stream-management, etc.) This module uses a custom Jitsi fork of `strophe.js` as the XMPP client library. ### E2EE Module (`/modules/e2ee/`) Provides end-to-end encryption: * **End-to-end encryption** using insertable streams and SFrame * **Worker.js** - Web worker for E2EE processing (separate webpack entry) * **OlmAdapter.js** - Integration with Olm for key management ### Quality Control Module (`/modules/qualitycontrol/`) Manages video quality and codec selection: * **Video quality adaptation** and codec selection * **ReceiveVideoController/SendVideoController** - Stream management ### Service Layer (`/service/`) Provides type-safe constants and events: * Type-safe constants, events, and enums * Well-defined event system used throughout the library ## Architecture Layers ### Signaling vs Media Layers lib-jitsi-meet maintains a clean separation between two fundamental layers: **Signaling Layer (XMPP)** * Handles session establishment and negotiation * Manages participant presence and room membership * Coordinates media capabilities between peers * Uses XMPP with Jingle extensions * Supports both BOSH and WebSocket transports **Media Layer (WebRTC)** * Manages actual media streams (audio/video) * Handles peer-to-peer connections when applicable * Controls media quality and bandwidth * Processes media through the TraceablePeerConnection This separation allows the signaling layer to use XMPP while the media layer uses WebRTC, providing flexibility and maintainability. ## Event-Driven Architecture The library extensively uses the EventEmitter pattern throughout all modules: ```typescript theme={null} // Example: JitsiConnection extends EventEmitter functionality class JitsiConnection { addEventListener(event: JitsiConnectionEvents, listener: (...args: any[]) => void): void { this.xmpp.addListener(event, listener); } } ``` Key characteristics: * **Consistent event handling** across all components * **Typed events** defined in the `/service/` directory * **Event parameters** and timing documented in JSDoc comments * **State change notifications** for all significant operations ### Common Event Patterns All major classes follow this pattern: 1. **Connection Events**: `CONNECTION_ESTABLISHED`, `CONNECTION_FAILED`, `CONNECTION_DISCONNECTED` 2. **Conference Events**: `CONFERENCE_JOINED`, `USER_JOINED`, `TRACK_ADDED` 3. **Track Events**: `TRACK_MUTE_CHANGED`, `TRACK_AUDIO_LEVEL_CHANGED` 4. **Media Events**: `REMOTE_TRACK_ADDED`, `LOCAL_TRACK_STOPPED` ## Design Patterns ### Protocol Abstraction Clean separation between XMPP signaling and WebRTC media: * **SignalingLayerImpl** provides an abstraction for signaling operations * **XMPP details** are hidden behind higher-level APIs * **WebRTC integration** uses TraceablePeerConnection for enhanced debugging ### Modular Design * **Self-contained modules** with minimal cross-dependencies * **Clear interfaces** between components * **Consistent error handling** and reporting across modules ### Browser Compatibility * **webrtc-adapter** integration for cross-browser support * **RTCUtils** abstraction for capability detection * **Feature detection** rather than browser detection where possible ## Build Architecture The library supports dual output formats: * **UMD bundle** (`dist/umd/`) - For browser `