So we wanted to integrate a websockets server within our REST api for which we were using HapiJS. I was previously using Socket.IO solution for websockets and I was very happy with it. So we decided to use it with our REST server in a single codebase.
But we faced a problem with several solutions:
We wanted an action, which happens in the REST api (like a POST request), to trigger an event which will tell the sockets server to send some new info to selected clients which are connected.
To implement this you have several solutions:
- Separate the two servers and make the talk to each other using RabbitMQ . This is the hardest and trickiest solution.
- Use the Socket.IO-Emitter. But it requires you to have a Redis database so you can talk to the sockets server. Not nice solution.
- Use an ordinary client to connect to the Socket.IO server. But do you have to open a connection each time a request is made? It sounds bad.
- Use HapiNES – sockets implementation specific for Hapi with option to communicate between each other. I haven’t tried this because I wanted to stick with Socket.IO.
- Use the NodeJS EventEmitter to send events from the one server to the other. I didn’t know about this. Thanks to Matt Harrison for answering my question.
I decided to use the 5-th option to communicate through the built-in EventEmitter. And it worked as Matt’s example is showing. Here is the example:
var Hapi = require('hapi');
// Make an event emitter for managing communication
// between hapi and socket.io code
var EventEmitter = require('events');
var notifier = new EventEmitter();
// Setup API + WS server with hapi
var server = new Hapi.Server();
server.register(require('inert'), function () {});
server.connection({ port: 4000, labels: ['api'] });
server.connection({ port: 4001, labels: ['ws'] });
var apiServer = server.select('api');
var wsServer = server.select('ws');
apiServer.route({
method: 'GET',
path: '/',
handler: function (request, reply) {
reply.file('index.html');
}
});
apiServer.route({
method: 'GET',
path: '/action',
handler: function (request, reply) {
notifier.emit('action', { time: Date.now() });
reply('ok');
}
});
// Setup websocket stuff
var io = require('socket.io')(wsServer.listener);<!DOCTYPE html>
io.on('connection', function (socket) {
// Subscribe this socket to `action` events
notifier.on('action', function (action) {
socket.emit('action', action);
});
});
server.start(function () {
console.log('Server started');
});
Here is a basic HTML page:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<script src="http://localhost:4001/socket.io/socket.io.js"></script>
</head>
<body>
<script>
var socket = io('http://localhost:4001');
socket.on('action', function (action) {
console.log(action);
});
</script>
</body>
</html>
Make Things Happen 