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.
Instantiating a Pusher client
Creating a new Pusher client
can be done as follows.
pusher_client = Pusher::Client.new(
app_id: 'your-pusher-app-id',
key: 'your-pusher-key',
secret: 'your-pusher-secret'
)
If you want to set a custom host
value for your client then you can do so when instantiating a Pusher client like so:
pusher_client = Pusher::Client.new(
app_id: 'your-pusher-app-id',
key: 'your-pusher-key',
secret: 'your-pusher-secret',
host: 'your-pusher-host'
)
If you created your app in a different cluster to the default cluster, you must pass the cluster
option as follows:
pusher_client = Pusher::Client.new(
app_id: 'your-pusher-app-id',
key: 'your-pusher-key',
secret: 'your-pusher-secret',
cluster: 'your-app-cluster'
)
This will set the host
to api-<cluster>.pusher.com
. 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:
pusher_client = Pusher::Client.from_env
Global
Configuring Pusher can also be done 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
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
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 published to one or more channels (limited to 10) in one API call:
Pusher.trigger('channel', 'event', foo: 'bar')
Pusher.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.
Pusher.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):
Pusher.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 Pusher.trigger
which supports one or multiple channels.
Using the Pusher REST API
This gem provides methods for accessing information from the Pusher REST API. The documentation also shows an example of the responses from each of the API endpionts.
The following methods are provided by the gem.
Pusher.channel_info('channel_name')
returns information about that channel.Pusher.channel_users('channel_name')
returns a list of all the users subscribed to the channel.Pusher.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 Pusher 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):
Pusher.get_async
Pusher.post_async
Pusher.trigger_async
It is of course also possible to make calls to pusher via a job queue. This approach is recommended if you're sending a large number of events to pusher.
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:
Pusher.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
Pusher.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:
Pusher.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 = 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