Server initiated server-client websocket messages in nodejs? - node.js

Question

I have a node js app that receives data from a sensor device via POST requests. It also serves frontend to monitor that data. I want it to send data updates via websocket to all connected clients
Here's what I came up with:
const express = require('express');
const app = express();
const expressWs = require('express-ws')(app);
const ws = expressWs.getWss('/ws');
function sendAll(data) {
ws.clients.forEach(function each(client) {
client.send(JSON.stringify(data));
});
}
setInterval(async () => {
try {
let message = { message: 'dataUpdated', data: { foo: 'bar } };
sendAll(message);
} catch (err) {
console.error(err);
}
}, 1000 * 5);
app.use(express.static('./static/'));
// tell the app to parse HTTP body messages
app.use(bodyParser.json());
// routes
const apiRoutes = require('./api/routes/api-routes');
app.use('/api', apiRoutes);
module.exports = app;
I can use the sendAll function to broadcast data. But I'd like to be able to also use this function inside apiRoutes where I process the incoming requests from the sensor. How can I pass it there, or maybe get access to the expressWs instance and create same function in the included api-routes file?

Answer 1

The solution turned out to be quite simple =)
const express = require('express');
const app = express();
const expressWs = require('express-ws')(app);
const ws = expressWs.getWss('/ws');
export function wsBroadcast(data) {
ws.clients.forEach(function each(client) {
client.send(JSON.stringify(data));
});
}
app.use(express.static('./static/'));
// tell the app to parse HTTP body messages
app.use(bodyParser.json());
// routes
const apiRoutes = require('./api/routes/api-routes');
app.use('/api', apiRoutes);
module.exports = app;
And then just import it in the file that needs it to broadcast messages:
import express from 'express';
import { wsBroadcast } from '../server';
const router = express.Router();
router.post('/data', (req, res) => {
wsBroadcast({ message: 'gotData', data: req.body });
...