Sinatra::PubSub

PubSub is a little extension to Sinatra that adds basic publish/subscribe streaming using HTML5 Server Sent Events.

For example, clients can subscribe to events like this:

var es = new EventSource('/subscribe');
es.onmessage = function(e) {
  console.log(JSON.parse(e.data));
};

And then you can broadcast events to them like this:

Sinatra::PubSub.publish_all(type: 'tick')

You can subscribe to specific channels:

var es = new EventSource('/subscribe/sites/123');

And publish to them:

Sinatra::PubSub.publish('sites/123', data: 'hi')

Requirements

Add this line to your application's Gemfile:

gem 'sinatra-pubsub'

And then execute:

$ bundle

Or install it yourself as:

$ gem install sinatra-pubsub

Include it in your Sinatra application like so:

require 'sinatra/pubsub'
register Sinatra::PubSub

This creates a /subscribe/* endpoint, which clients can use with EventSource.

You can publish to channels using the Sinatra::PubSub.publish_all(msg) or Sinatra::publish(channel, msg) methods.

Messages will be automatically serialized to JSON - you'll need to parse them on the client. See the ./examples dir for more use-cases.