jeremyvdw / pusher-gem

Gem for adding Pusher support into your application

Pusher gem

Installation & Configuration

Add pusher to your Gemfile, and then run bundle install

gem 'pusher'

or install via gem

gem install pusher

After registering at http://pusher.com configure your app with the security credentials.

Global

The most standard way of configuring Pusher is to do it globally on the Pusher class.

Pusher.app_id = 'your-pusher-app-id'
Pusher.key = 'your-pusher-key'
Pusher.secret = 'your-pusher-secret'

Global configuration will automatically be set from the PUSHER_URL environment variable if it exists. This should be in the form http://KEY:[email protected]/apps/APP_ID. On Heroku this environment variable will already be set.

If you need to make requests via a HTTP proxy then it can be configured

Pusher.http_proxy = 'http://(user):(password)@(host):(port)'

By default API requests are made over HTTP. HTTPS can be used by setting

Pusher.encrypted = true

Instantiating a Pusher client

Sometimes you may have multiple sets of API keys, or want different configuration in different parts of your application. In these scenarios, a pusher client may be configured:

pusher_client = Pusher::Client.new({
  app_id: 'your-pusher-app-id',
  key: 'your-pusher-key',
  secret: 'your-pusher-secret'
})

This client will have all the functionality listed on the main Pusher class (which proxies to a client internally).

Interacting with the Pusher service

The Pusher gem contains a number of helpers for interacting with the service. As a general rule, the library adheres to a set of conventions that we have aimed to make universal.

Handling errors

Handle errors by rescuing Pusher::Error (all errors are descendants of this error)

begin
  Pusher.trigger('a_channel', 'an_event', {:some => 'data'})
rescue Pusher::Error => e
  # (Pusher::AuthenticationError, Pusher::HTTPError, or Pusher::Error)
end

Logging

Errors are logged to Pusher.logger. It will by default log at info level to STDOUT using Logger from the standard library, however you can assign any logger:

Pusher.logger = Rails.logger

Publishing events

An event can be sent to Pusher in in the following ways:

# on the Pusher class
Pusher.trigger('channel_name', 'event_name', {some: 'data'})
Pusher.trigger(['channel_1', 'channel_2'], 'event_name', {some: 'data'})

# or on a pusher_client
pusher_client.trigger(['your_channels'], 'your_event_name', {some: 'data'})

Note: the first channels argument can contain multiple channels you'd like your event and data payload to go to. There is a limit of 100 on the number of channels this can contain.

An optional fourth argument of this method can specify a socket_id that will be excluded from receiving the event (generally the user where the event originated -- see http://pusher.com/docs/publisher_api_guide/publisher_excluding_recipients for more info).

Original publisher API

Most examples and documentation will refer to the following syntax for triggering an event:

Pusher['a_channel'].trigger('an_event', {:some => 'data'})

This will continue to work, but will be replaced as the canonical version by Pusher.trigger which supports multiple channels.

Generic requests to the Pusher REST API

Aside from triggering events, the REST API also supports a number of operations for querying the state of the system. A reference of the available methods is available at http://pusher.com/docs/rest_api.

All requests must be signed by using your secret key, which is handled automatically using these methods:

# using the Pusher class
Pusher.get('url_without_app_id', params)

# using a client
pusher_client.post('url_without_app_id', params)

Note that you don't need to specify your app_id in the URL, as this is inferred from your credentials. As with the trigger method above, _async can be suffixed to the method name to return a deferrable.

Asynchronous requests

If you are running your application in an evented environment, you may want to use the asynchronous versions of the Pusher API methods to avoid blocking. The convention for this is to add the suffix _async to the method, e.g. trigger_async or post_async.

You need to be running eventmachine to make use of this functionality. This is already the case if, for example, you're deploying to Heroku or using the Thin web server. You will also need to add em-http-request to your Gemfile.

When using an asynchronous version of a method, it will return a deferrable.

Pusher.trigger_async(['a_channel'], 'an_event', {
  :some => 'data'
}, socket_id).callback {
  # Do something on success
}.errback { |error|
  # error is a instance of Pusher::Error
}

Authenticating subscription requests

It's possible to use the gem to authenticate subscription requests to private or presence channels. The authenticate method is available on a channel object for this purpose and returns a JSON object that can be returned to the client that made the request. More information on this authentication scheme can be found in the docs on http://pusher.com

Private channels

Pusher['private-my_channel'].authenticate(params[:socket_id])

Presence channels

These work in a very similar way, but require a unique identifier for the user being authenticated, and optionally some attributes that are provided to clients via presence events:

Pusher['presence-my_channel'].authenticate(params[:socket_id], {
  user_id: 'user_id',
  user_info: {} # optional
})

Receiving WebHooks

A WebHook object may be created to validate received WebHooks against your app credentials, and to extract events. It should be created with the Rack::Request object (available as request in Rails controllers or Sinatra handlers for example).

webhook = Pusher.webhook(request)
if webhook.valid?
  webhook.events.each do |event|
    case event["name"]
    when 'channel_occupied'
      puts "Channel occupied: #{event["channel"]}"
    when 'channel_vacated'
      puts "Channel vacated: #{event["channel"]}"
    end
  end
  render text: 'ok'
else
  render text: 'invalid', status: 401
end