How to setup push notifications using WebSockets?

This tutorial presents the basic steps to implement live synchronisation of records between clients.

Currently, it relies on a plugin that sends events through WebSockets using Pusher.com.

Note

Another plugin is under construction for WebPush: Kinto/kinto-webpush

Setup a Pusher account

  • Go to https://pusher.com
  • Create a new app
  • Get your app credentials (app_id, key, secret)

Configure Kinto

The plugin is already installed in the Docker image. But if you run the Python version, first install it:

$ pip install kinto-pusher

As explained in the settings section, add these lines to setup a listener, and be notified of record updates per collection:

kinto.includes = kinto_pusher

kinto.event_listeners = pusher
kinto.event_listeners.pusher.use = kinto_pusher.listener
kinto.event_listeners.pusher.resources = record
kinto.event_listeners.pusher.channel = {bucket_id}-{collection_id}-{resource_name}

pusher.app_id = <pusher-app-id>
pusher.key = <pusher-key>
pusher.secret = <pusher-secret>
pusher.cluster = eu

And (re)start Kinto with this new configuration.

Test Pusher events

Now that Kinto runs locally and is configured to send events to Pusher, you should be able to see them in the Debug Console of your Pusher dashboard.

For example, with httpie, create an account and create an arbitrary record in the default bucket:

$ echo '{"data":{"password":"s3cr3t"}}' | \
    http POST http://localhost:8888/v1/accounts/alice
$ echo '{"data":{"name":"bob"}}' | \
    http POST http://localhost:8888/v1/buckets/default/collections/tasks/records --auth alice:s3cr3t

This created a record, and you should see the generated event in the dashboard.

Consume events in JavaScript

The Pusher documentation is full of examples for a variety of languages. For JavaScript, just add the Pusher library to your page:

<script src="//js.pusher.com/3.0/pusher.min.js"></script>

And listen to the events:

// Pusher credentials
var pusher_key = 'your key';

var pusher = new Pusher(pusher_key, {
  encrypted: true
});

// The channel name. It should match the setting
// `kinto.event_listeners.pusher.channel`
var channelName = bucket_id + '-' + collection_id + '-record';

var channel = pusher.subscribe(channelName);
channel.bind('create', function(data) {
  console.log("New records created", data);
});
channel.bind('update', function(data) {
  console.log("Records updated", data);
});
channel.bind('delete', function(data) {
  console.log("Records deleted", data);
});

Demos

We’ve made several demos with live sync.

For example, open these in several browser windows and observe the live changes:

More demos are available.