Abstract: A client-server-communication system comprises a public network (1), especially the Internet, a server computer (2) running at least one server application which provides a graphical user interface, wherein the server application creates basic GUI data to be processed by a graphics processing unit (7) for controlling said graphical user interface, which basic GUI data at least include a set of geometric basic primitives, and a client computer (3) including a graphics processing unit (7), connectable to the server computer (2) via the public network (1), and running a browser program (5) which is HTML5 capable, in which browser program (5) a client-side-script-program (9) including a WebSocket protocol (10) is running, which receives and interprets the basic GUI data and from these basic GUI data renders drawing instructions as graphics content for being processed by the graphics processing unit (7) of the client computer (3).