dougal-software/lib/www/server/ws/index.js

const ws = require('ws');
const URL = require('url');
const db = require('./db');

function start (server, pingInterval=30000) {
	
	const channels = [
		"realtime", "event", "project",
		"preplot_lines", "preplot_points",
		"planned_lines",
		"raw_lines", "raw_shots",
		"final_lines", "final_shots", "info"
	];

	const wsServer = new ws.Server({ noServer: true });
	wsServer.on('connection', socket => {
		socket.alive = true;
		socket.on('pong', function () { this.alive = true; })
		socket.on('message', message => console.log(message));
	});

	server.on('upgrade', (request, socket, head) => {
// 		console.log("Received upgrade request", request.url);
		const url = URL.parse(request.url);
		if (/^\/ws\/?$/.test(url.pathname)) {
			wsServer.handleUpgrade(request, socket, head, socket => {
				wsServer.emit('connection', socket, request);
			});
		}
	});

	db.listen(channels, (data) => {
		wsServer.clients.forEach( (socket) => {
			socket.send(JSON.stringify(data));
		})
	});

	const interval = setInterval( () => {
		wsServer.clients.forEach( (socket) => {
			if (!socket.alive) {
				return socket.terminate();
			}
			socket.alive = false;
			socket.ping();
		})
	}, pingInterval);

	wsServer.on('close', () => clearInterval(interval));

	return wsServer;
}

module.exports = {
	start
}