class Koala::Facebook::RealtimeUpdates

Attributes

api[R]

The application API interface used to communicate with Facebook. @return [Koala::Facebook::API]

app_access_token[R]
app_id[R]
secret[R]

Public Instance Methods

list_subscriptions(options = {}) click to toggle source

List all active subscriptions for this application.

@param options (see Koala::HTTPService.make_request)

@return [Array] a list of active subscriptions

# File lib/koala/realtime_updates.rb, line 82
def list_subscriptions(options = {})
  @api.graph_call(subscription_path, {}, "get", options)
end
subscribe(object, fields, callback_url, verify_token, options = {}) click to toggle source

Subscribe to realtime updates for certain fields on a given object (user, page, etc.). See {developers.facebook.com/docs/reference/api/realtime the realtime updates documentation} for more information on what objects and fields you can register for.

@note Your callback_url must be set up to handle the verification request or the subscription will not be set up.

@param object a Facebook ID (name or number) @param fields the fields you want your app to be updated about @param callback_url the URL Facebook should ping when an update is available @param verify_token a token included in the verification request, allowing you to ensure the call is genuine

(see the docs for more information)

@param options (see Koala::HTTPService.make_request)

@raise A subclass of Koala::Facebook::APIError if the subscription request failed.

# File lib/koala/realtime_updates.rb, line 56
def subscribe(object, fields, callback_url, verify_token, options = {})
  args = {
    :object => object,
    :fields => fields,
    :callback_url => callback_url,
  }.merge(verify_token ? {:verify_token => verify_token} : {})
  # a subscription is a success if Facebook returns a 200 (after hitting your server for verification)
  @api.graph_call(subscription_path, args, 'post', options)
end
subscription_path() click to toggle source

The Facebook subscription management URL for your application.

# File lib/koala/realtime_updates.rb, line 141
def subscription_path
  @subscription_path ||= "#{@app_id}/subscriptions"
end
unsubscribe(object = nil, options = {}) click to toggle source

Unsubscribe from updates for a particular object or from updates.

@param object the object whose subscriptions to delete.

If no object is provided, all subscriptions will be removed.

@param options (see Koala::HTTPService.make_request)

@raise A subclass of Koala::Facebook::APIError if the subscription request failed.

# File lib/koala/realtime_updates.rb, line 73
def unsubscribe(object = nil, options = {})
  @api.graph_call(subscription_path, object ? {:object => object} : {}, "delete", options)
end
validate_update(body, headers) click to toggle source

Public: As a security measure, all updates from facebook are signed using X-Hub-Signature: sha1=XXXX where XXX is the sha1 of the json payload using your application secret as the key.

Example:

# in Rails controller
# @oauth being a previously defined Koala::Facebook::OAuth instance
def receive_update
  if @oauth.validate_update(request.body, headers)
    ...
  end
end
# File lib/koala/realtime_updates.rb, line 127
def validate_update(body, headers)
  unless @secret
    raise AppSecretNotDefinedError, "You must init RealtimeUpdates with your app secret in order to validate updates"
  end

  if request_signature = headers['X-Hub-Signature'] || headers['HTTP_X_HUB_SIGNATURE'] and
     signature_parts = request_signature.split("sha1=")
    request_signature = signature_parts[1]
    calculated_signature = OpenSSL::HMAC.hexdigest('sha1', @secret, body)
    calculated_signature == request_signature
  end
end

Public Class Methods

meet_challenge(params, verify_token = nil) { |params| ... } click to toggle source

As a security measure (to prevent DDoS attacks), Facebook sends a verification request to your server after you request a subscription. This method parses the challenge params and makes sure the call is legitimate.

@param params the request parameters sent by Facebook. (You can pass in a Rails params hash.) @param verify_token the verify token sent in the {subscribe subscription request}, if you provided one

@yield verify_token if you need to compute the verification token

(for instance, if your callback URL includes a record ID, which you look up
and use to calculate a hash), you can pass meet_challenge a block, which
will receive the verify_token received back from Facebook.

@return the challenge string to be sent back to Facebook, or false if the request is invalid.

# File lib/koala/realtime_updates.rb, line 99
def self.meet_challenge(params, verify_token = nil, &verification_block)
  if params["hub.mode"] == "subscribe" &&
      # you can make sure this is legitimate through two ways
      # if your store the token across the calls, you can pass in the token value
      # and we'll make sure it matches
      ((verify_token && params["hub.verify_token"] == verify_token) ||
      # alternately, if you sent a specially-constructed value (such as a hash of various secret values)
      # you can pass in a block, which we'll call with the verify_token sent by Facebook
      # if it's legit, return anything that evaluates to true; otherwise, return nil or false
      (verification_block && yield(params["hub.verify_token"])))
    params["hub.challenge"]
  else
    false
  end
end
new(options = {}) click to toggle source

Create a new RealtimeUpdates instance. If you don’t have your app’s access token, provide the app’s secret and Koala will make a request to Facebook for the appropriate token.

@param options initialization options. @option options :#app_id the application’s ID. @option options :#app_access_token an application access token, if known. @option options :secret the application’s secret.

@raise ArgumentError if the application ID and one of the app access token or the secret are not provided.

# File lib/koala/realtime_updates.rb, line 25
def initialize(options = {})
  @app_id = options[:app_id]
  @app_access_token = options[:app_access_token]
  @secret = options[:secret]
  unless @app_id && (@app_access_token || @secret) # make sure we have what we need
    raise ArgumentError, "Initialize must receive a hash with :app_id and either :app_access_token or :secret! (received #{options.inspect})"
  end

  # fetch the access token if we're provided a secret
  if @secret && !@app_access_token
    oauth = Koala::Facebook::OAuth.new(@app_id, @secret)
    @app_access_token = oauth.get_app_access_token
  end

  @api = API.new(@app_access_token)
end