How to display Real-Time notifications (via Icons) in WordPress

I'm trying to use icons to communicate messages between an Admin and the site's Registered Users (both collectively and individually):

1. An Admin to posts a message in some type of back-end interface (Custom Post Type, maybe?)
2. The Admin can designate the individual user(s) or all users (for a site-wide messages)
3. The user(s) see the all the message since the user last logged in via a well recognizable bell icon with numbers indicating the number of new messages.
4. See my example video from a bootstrap template.

I have searched the web, but all i'm getting back is information on Push notifications, which is not what i'm trying to do.

Any guidance would be greatly appreciated.