Action Cable for real-time WebSocket communication

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                  class NotificationsChannel < ApplicationCable::Channel
  def subscribed
    stream_for current_user
  end

  def unsubscribed
    stop_all_streams
  end
end

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

    def connect
      self.current_user = find_verified_user
    end

    private

    def find_verified_user
      token = request.params[:token]
      payload = JwtService.decode(token)

      if payload && (user = User.find_by(id: payload['user_id']))
        user
      else
        reject_unauthorized_connection
      end
    end
  end
end

                  class Notification < ApplicationRecord
  belongs_to :user

  after_create_commit :broadcast_notification

  private

  def broadcast_notification
    NotificationsChannel.broadcast_to(
      user,
      {
        id: id,
        message: message,
        created_at: created_at,
        read: false
      }
    )
  end
end

Action Cable brings WebSocket support to Rails, enabling real-time features like live notifications, collaborative editing, or chat systems. Clients subscribe to channels that broadcast updates when server-side events occur. I use Redis as the pub/sub backend so messages propagate across multiple application servers. Each channel class defines subscribed and unsubscribed lifecycle hooks, and broadcast happens via ActionCable.server.broadcast. Authentication happens during the connection handshake using the same session-based or token-based approach as HTTP requests. The key challenge is scaling—WebSockets hold persistent connections, so I often isolate Action Cable servers from HTTP servers to optimize resource allocation independently.

Alex Kumar

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Action Cable for real-time WebSocket communication

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