Gem for Pusher Channels

This Gem provides a Ruby interface to the Pusher HTTP API for Pusher Channels.

Build Status

Installation and Configuration

Add pusher to your Gemfile, and then run bundle install

gem 'pusher'

or install via gem

gem install pusher

After registering at https://dashboard.pusher.com/, configure your Pusher Channels app with the security credentials.

Instantiating a Pusher Channels client

Creating a new Pusher Channels client can be done as follows.

require 'pusher'

channels_client = Pusher::Client.new(
  app_id: 'your-app-id',
  key: 'your-app-key',
  secret: 'your-app-secret',
  cluster: 'your-app-cluster',
  use_tls: true
)

The cluster value will set the host to api-<cluster>.pusher.com. The use_tls value is optional and defaults to false. It will set the scheme and port. Custom scheme and port values take precendence over use_tls.

If you want to set a custom host value for your client then you can do so when instantiating a Pusher Channels client like so:

require 'pusher'

channels_client = Pusher::Client.new(
  app_id: 'your-app-id',
  key: 'your-app-key',
  secret: 'your-app-secret',
  host: 'your-app-host'
)

If you pass both host and cluster options, the host will take precendence and cluster will be ignored.

Finally, if you have the configuration set in an PUSHER_URL environment variable, you can use:

channels_client = Pusher::Client.from_env

Global configuration

Configuring Pusher can also be done globally on the Pusher class.

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

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 encrypted to true. Issuing this command is going to reset port value if it was previously specified.

Pusher.encrypted = true

As of version 0.12, SSL certificates are verified when using the synchronous http client. If you need to disable this behaviour for any reason use:

Pusher.default_client.sync_http_client.ssl_config.verify_mode = OpenSSL::SSL::VERIFY_NONE

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
  channels_client.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 published to one or more channels (limited to 10) in one API call:

channels_client.trigger('channel', 'event', foo: 'bar')
channels_client.trigger(['channel_1', 'channel_2'], 'event_name', foo: 'bar')

An optional fourth argument may be used to send additional parameters to the API, for example to exclude a single connection from receiving the event.

channels_client.trigger('channel', 'event', {foo: 'bar'}, {socket_id: '123.456'})

Batches

It's also possible to send multiple events with a single API call (max 10 events per call on multi-tenant clusters):

channels_client.trigger_batch([
  {channel: 'channel_1', name: 'event_name', data: { foo: 'bar' }},
  {channel: 'channel_1', name: 'event_name', data: { hello: 'world' }}
])

Deprecated 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 has been replaced by channels_client.trigger which supports one or multiple channels.

Getting information about the channels in your Pusher Channels app

This gem provides methods for accessing information from the Pusher HTTP API. The documentation also shows an example of the responses from each of the API endpoints.

The following methods are provided by the gem.

  • channels_client.channel_info('channel_name') returns information about that channel.

  • channels_client.channel_users('channel_name') returns a list of all the users subscribed to the channel.

  • channels_client.channels returns information about all the channels in your Pusher application.

Asynchronous requests

There are two main reasons for using the _async methods:

  • In a web application where the response from the Pusher Channels HTTP API is not used, but you'd like to avoid a blocking call in the request-response cycle
  • Your application is running in an event loop and you need to avoid blocking the reactor

Asynchronous calls are supported either by using an event loop (eventmachine, preferred), or via a thread.

The following methods are available (in each case the calling interface matches the non-async version):

  • channels_client.get_async
  • channels_client.post_async
  • channels_client.trigger_async

It is of course also possible to make calls to the Pusher Channels HTTP API via a job queue. This approach is recommended if you're sending a large number of events.

With EventMachine

  • Add the em-http-request gem to your Gemfile (it's not a gem dependency).
  • Run the EventMachine reactor (either using EM.run or by running inside an evented server such as Thin).

The _async methods return an EM::Deferrable which you can bind callbacks to:

channels_client.get_async("/channels").callback { |response|
  # use reponse[:channels]
}.errback { |error|
  # error is an instance of Pusher::Error
}

A HTTP error or an error response from pusher will cause the errback to be called with an appropriate error object.

Without EventMachine

If the EventMachine reactor is not running, async requests will be made using threads (managed by the httpclient gem).

An HTTPClient::Connection object is returned immediately which can be interrogated to discover the status of the request. The usual response checking and processing is not done when the request completes, and frankly this method is most useful when you're not interested in waiting for the response.

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

channels_client.authenticate('private-my_channel', 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:

channels_client.authenticate('presence-my_channel', 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 = channels_client.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