Real-Time Collaboration Engine

Real-Time Collaboration Engine

Overview

Enables multiple users to collaborate in real-time on shared content with presence awareness and conflict-free updates.

Decision Framework

When to use

• Multiple users editing same content
• Live presence indicators needed
• Real-time data synchronization required

When NOT to use

• Single-user applications
• Batch processing workflows

Trigger Phrases

• "Real-time updates"
• "Live collaboration"
• "Show who's online"
• "Multiple users editing"
• "WebSocket connection"

Technology Options

Presence System

class PresenceManager {
  constructor(channel) {
    this.channel = channel;
    this.users = new Map();
  }

  async join(userId, metadata) {
    this.users.set(userId, {
      ...metadata,
      joinedAt: Date.now(),
      lastSeen: Date.now()
    });
    await this.channel.broadcast('user:joined', { userId, metadata });
  }

  async updateCursor(userId, position) {
    await this.channel.broadcast('cursor:moved', { userId, position });
    this.users.get(userId).lastSeen = Date.now();
  }

  async leave(userId) {
    this.users.delete(userId);
    await this.channel.broadcast('user:left', { userId });
  }

  getActiveUsers() {
    const now = Date.now();
    return Array.from(this.users.entries())
      .filter(([_, u]) => now - u.lastSeen < 30000);
  }
}

Conflict Resolution

Operational Transform

class OTEngine {
  constructor() {
    this.document = '';
    this.revision = 0;
    this.buffer = [];
  }

  apply(operation) {
    // Transform against concurrent operations
    let transformed = operation;
    for (const concurrent of this.buffer) {
      transformed = this.transform(transformed, concurrent);
    }
    this.document = this.execute(transformed);
    this.revision++;
    return transformed;
  }

  transform(op1, op2) {
    // Transform op1 against op2
    if (op1.position <= op2.position) {
      return op1;
    }
    return { ...op1, position: op1.position + op2.length };
  }
}

Connection States

CONNECTING → CONNECTED → DISCONNECTED
     ↓           ↓            ↓
   [retry]    [active]    [reconnect]
     ↓           ↓            ↓
   CONNECTED  SYNCING    CONNECTED

Error Classification