websocket server to push updates

andy-haynes · May 11, 2020 · 8d681f9 · 8d681f9
1 parent 781991e
commit 8d681f9
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Showing 3 changed files with 31 additions and 5 deletions.
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -19,7 +19,8 @@
     "lodash": "^4.17.10",
     "moment": "^2.24.0",
     "node-pid-controller": "^1.0.1",
-    "rpio": "1.3.0"
+    "rpio": "1.3.0",
+    "ws": "^7.2.3"
   },
   "devDependencies": {
     "chai": "^4.1.2",

diff --git a/src/server.js b/src/server.js
@@ -1,15 +1,35 @@
 const bodyParser = require('body-parser');
 const express = require('express');
+const moment = require('moment');
+const WebSocket = require('ws');
+
+const BROADCAST_UPDATE_INTERVAL = moment.duration(5, 'seconds').asMilliseconds();
 
 const app = express();
 app.use(bodyParser.json());
 
-function initializeServer({ port }, controller) {
-  app.get('/alive', (req, res, next) => {
-    res.json({ alive: true });
-    next();
+function initializeWebSocketServer(controller, port) {
+  const wss = new WebSocket.Server({ port });
+  let updateInterval;
+
+  wss.on('connection', (ws) => {
+    updateInterval = setInterval(() => {
+      ws.send(JSON.stringify({
+        update: controller.getUpdate(),
+      }));
+    }, BROADCAST_UPDATE_INTERVAL);
   });
 
+  wss.on('close', () => {
+    if (updateInterval) {
+      clearInterval(updateInterval);
+    }
+  });
+}
+
+function initializeServer({ port }, controller) {
+  initializeWebSocketServer(controller, 4000);
+
   app.get('/update', (req, res, next) => {
     const lastUpdate = controller.getUpdate();
     res.json({ lastUpdate });