Learn: Collaborative Systems

Understanding the concepts behind real-time collaborative editing

Real-Time Synchronization

How changes are instantly broadcast to all connected clients using WebSocket connections.

WebSockets establish a persistent connection between client and server, enabling bidirectional communication. When one user edits text, the change is captured, transformed if needed, and broadcast to all other clients.

Distributed State Management

Managing document state across multiple machines without a single point of truth.

Each client maintains a local copy of the document state. Edits are sent as operations (insert, delete) with metadata. The server coordinates these operations and ensures all clients converge to the same state.

Conflict Resolution

Handling simultaneous edits from different users on the same content.

When two users edit at the same position, conflicts arise. Common strategies: Last-Write-Wins (simple), Operational Transformation (complex), or CRDT (conflict-free). This editor uses operational transformation with timestamps.

TCP vs UDP

Understanding the difference between reliable and unreliable protocols.

TCP ensures ordered, reliable delivery of messages (like WebSocket). UDP is faster but provides no guarantees. WebSocket uses TCP underneath, ensuring no edits are lost.

Consensus Algorithms

How systems agree on a single truth in the presence of failures.

Simple consensus: the server is the authority. More complex: Raft, Paxos, Byzantine Fault Tolerance. For our editor, the server acts as the single source of truth for edit ordering.

Cursor Tracking

Displaying other users' cursor positions and selections in real-time.

Each user's cursor position is sent to the server with edit operations. The server broadcasts cursor positions to all clients, allowing you to see where others are editing.