feat: SSE implementation for real-time event streaming with logging

[rahulwebend]

This PR adds Server-Sent Events (SSE) support to enable clients to subscribe and receive real-time events pushed from the server.

Features implemented:

• Clients can connect to /api/sse/stream endpoint and receive server updates in real time.
• Support for sending arbitrary named events with JSON payloads to individual or multiple connected clients.
• Connection lifecycle logging (connect, disconnect, error) into logs/connections.log.
• Graceful handling of client disconnections.
• SSE headers set to ensure proper event streaming and prevent caching.

Changes Made

1. Frontend Updates

   • BroadcastPanel: Displays user list with online/offline status in dropdown.
   • SubscriberPanel: Shows received events (message, ping, broadcast) in real time.

2. Backend Integration

   • Centralized SSE manager to maintain active client connection lifecycle.
   • Clients are identified by userId if provided, otherwise by client.id.
   • Heartbeat ensures connection remains open and is monitored.
   • Disconnections are handled in req.signal.addEventListener("abort").

3. Client Management

   • Maintains a list of connected clients.
   • Supports sending messages to:
     • A single client by id
     • Broadcast to all connected clients

4. Robust Error Handling & Logging

   • All SSE connect/disconnect, broadcast, and send actions are wrapped with try/catch and logged using logToFile.
   • Logs:
     • New connections with timestamp & client ID
     • Disconnections with timestamp & client ID
     • Errors during connection/disconnection

5. API Enhancements

   • GET /api/sse/stream now returns correct connection stream and cleans up on client abort.
   • POST /api/sse/send supports targeted user messages or global broadcast.
   • GET /api/users to fetch all user’s with connectivity status.

Additional Notes

• SSE keeps a single HTTP connection open for each client — efficient for server → client push.
• Heartbeats (ping) are sent every 25 seconds to prevent timeouts and detect dead connections.
• Log file grows over time; consider log rotation for production.

Preview

screenrecord.webm