NODE JS introduction: socket polling

nodejs/.env.example

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+# Node.js real-time server config
+# Copy this file to .env and fill in the values
+
+# Port the Node.js server listens on
+PORT=3000
+
+# Secret key — PHP sends this in x-emit-secret header to authenticate /emit calls
+# Use a long random string in production
+EMIT_SECRET=

nodejs/package.json

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+{
+  "name": "mn3wms-realtime",
+  "version": "1.0.0",
+  "description": "Real-time event server for MN3 WMS",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js"
+  },
+  "dependencies": {
+    "express": "^4.18.0",
+    "socket.io": "^4.7.0",
+    "dotenv": "^16.0.0"
+  }
+}

nodejs/server.js

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+require('dotenv').config();
+
+const express    = require('express');
+const { createServer } = require('http');
+const { Server } = require('socket.io');
+
+const app        = express();
+const httpServer = createServer(app);
+const io         = new Server(httpServer, {
+    cors: { origin: '*' }
+});
+
+app.use(express.json());
+
+// ── /emit ─────────────────────────────────────────────────────────────────────
+// PHP calls this after any significant action.
+// Body: { event, data, company_id }
+//
+app.post('/emit', (req, res) => {
+    const secret = req.headers['x-emit-secret'];
+    if (secret !== process.env.EMIT_SECRET) {
+        return res.status(403).json({ ok: false, message: 'Forbidden' });
+    }
+
+    const { event, data, company_id } = req.body;
+    if (!event || !company_id) {
+        return res.status(400).json({ ok: false, message: 'event and company_id required' });
+    }
+
+    // Broadcast only to the room for this company
+    io.to(`company_${company_id}`).emit(event, data);
+
+    console.log(`[emit] company=${company_id} event=${event}`, data);
+    res.json({ ok: true });
+});
+
+// ── WebSocket connections ─────────────────────────────────────────────────────
+// Each browser tab connects here on page load.
+// It joins a room named company_<id> so events stay isolated per company.
+//
+io.on('connection', (socket) => {
+    const company_id = socket.handshake.query.company_id;
+
+    if (!company_id) {
+        socket.disconnect();
+        return;
+    }
+
+    socket.join(`company_${company_id}`);
+    console.log(`[connect] socket=${socket.id} company=${company_id}`);
+
+    socket.on('disconnect', () => {
+        console.log(`[disconnect] socket=${socket.id}`);
+    });
+});
+
+// ── Start ─────────────────────────────────────────────────────────────────────
+const PORT = process.env.PORT || 3000;
+httpServer.listen(PORT, () => {
+    console.log(`Node.js real-time server running on port ${PORT}`);
+});