Action Cable provides a realtime websocket connection between the browser and your Rails app backed by a Redis pubsub connection.
Jumpstart Pro comes with Action Cable connections preconfigured to work with Devise's authentication mechanism called Warden. It will also tag the logs with the User ID for ease of debugging.
You can run rails g channel my_channel to create a new Action Cable channel. This will generate the Ruby class and Javascript file for your channel.
Check out the GoRails screencast episodes on Action Cable and the Action Cable Rails Guide for more information on how to use Action Cable.