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Action Cable Connection Base

For every WebSocket connection the Action Cable server accepts, a Connection object will be instantiated. This instance becomes the parent of all of the channel subscriptions that are created from there on. Incoming messages are then routed to these channel subscriptions based on an identifier sent by the Action Cable consumer. The Connection itself does not deal with any specific application logic beyond authentication and authorization.

Here’s a basic example:

module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_user

    def connect
      self.current_user = find_verified_user
      logger.add_tags current_user.name
    end

    def disconnect
      # Any cleanup work needed when the cable connection is cut.
    end

    private
      def find_verified_user
        User.find_by_identity(cookies.encrypted[:identity_id]) ||
          reject_unauthorized_connection
      end
  end
end

First, we declare that this connection can be identified by its current_user. This allows us to later be able to find all connections established for that current_user (and potentially disconnect them). You can declare as many identification indexes as you like. Declaring an identification means that an attr_accessor is automatically set for that key.

Second, we rely on the fact that the WebSocket connection is established with the cookies from the domain being sent along. This makes it easy to use signed cookies that were set when logging in via a web interface to authorize the WebSocket connection.

Finally, we add a tag to the connection-specific logger with the name of the current user to easily distinguish their messages in the log.

Pretty simple, eh?

Methods
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Included Modules

Attributes

[R] env
[R] logger
[R] protocol
[R] server
[R] subscriptions
[R] worker_pool

Class Public methods

new(server, env, coder: ActiveSupport::JSON)

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 67
def initialize(server, env, coder: ActiveSupport::JSON)
  @server, @env, @coder = server, env, coder

  @worker_pool = server.worker_pool
  @logger = new_tagged_logger

  @websocket      = ActionCable::Connection::WebSocket.new(env, self, event_loop)
  @subscriptions  = ActionCable::Connection::Subscriptions.new(self)
  @message_buffer = ActionCable::Connection::MessageBuffer.new(self)

  @_internal_subscriptions = nil
  @started_at = Time.now
end

Instance Public methods

beat()

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 147
def beat
  transmit type: ActionCable::INTERNAL[:message_types][:ping], message: Time.now.to_i
end

close(reason: nil, reconnect: true)

Close the WebSocket connection.

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 120
def close(reason: nil, reconnect: true)
  transmit(
    type: ActionCable::INTERNAL[:message_types][:disconnect],
    reason: reason,
    reconnect: reconnect
  )
  websocket.close
end

handle_channel_command(payload)

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 109
def handle_channel_command(payload)
  run_callbacks :command do
    subscriptions.execute_command payload
  end
end

send_async(method, *arguments)

Invoke a method on the connection asynchronously through the pool of thread workers.

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 131
def send_async(method, *arguments)
  worker_pool.async_invoke(self, method, *arguments)
end

statistics()

Return a basic hash of statistics for the connection keyed with identifier, started_at, subscriptions, and request_id. This can be returned by a health check against the connection.

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 138
def statistics
  {
    identifier: connection_identifier,
    started_at: @started_at,
    subscriptions: subscriptions.identifiers,
    request_id: @env["action_dispatch.request_id"]
  }
end

Instance Private methods

cookies()

The cookies of the request that initiated the WebSocket connection. Useful for performing authorization checks.

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 187
def cookies # :doc:
  request.cookie_jar
end

request()

The request that initiated the WebSocket connection is available here. This gives access to the environment, cookies, etc.

Source: show | on GitHub 

# File actioncable/lib/action_cable/connection/base.rb, line 178
def request # :doc:
  @request ||= begin
    environment = Rails.application.env_config.merge(env) if defined?(Rails.application) && Rails.application
    ActionDispatch::Request.new(environment || env)
  end
end