How they implemented?
How they implemented?
The implementation depends on the browser you use. IE, Edge and Safari are still using Java applet which implies installing Java. Chrome, Firefox and Opera already use HTML5/JavaScript (noVNC). See https://www.profitbricks.com/help/Remote_Console for more details.
I recommend to use the noVNC based access to the remote console: You don't need to install Java which brings in new vulnerabilties, it has a lower footprint and, personally, I found it to be faster.