Building StarSync: realtime chat, editor sync, and code execution

Realtime collaboration workspaces require highly responsive synchronizations. When I designed StarSync, my goal was to combine DMs, room presence, shared text/code editing, and a canvas whiteboard into a single, cohesive experience.

The Realtime Sync Strategy

Instead of using higher-level abstractions like Socket.IO, I chose to work with native ws WebSockets on the backend. This decision kept overhead minimal and let me design custom frame protocols for:

• Collaborative Monaco Editor synchronization
• Active rooms typing indicator broadcasts
• Online presence tracking

// Example WebSocket message dispatcher
socket.send(JSON.stringify({
  type: 'presence:update',
  payload: { userId, roomState }
}));

Running Code Safely in Docker

For safe execution of C, C++, Python, and TypeScript inside the Monaco editor, I integrated the backend with a Docker-based Piston runtime executor. Code is isolated inside brief sandboxed processes to prevent malicious operations from hitting the main servers.