Technology | Cost of Ownership | Thin Client | Thin Computing | Network Computing | Server Based | RDP | Zero Client

Zero Client and Thin Client Technology: History, Use and Critical Comparison

Definition and Description

The zero client ("station") is a set of components (monitor, keyboards, mouse), none of which have independently programmable intelligence, that relies on a centralized CPU ("Host PC") for all program execution and information processing. The connection between the zero client and the Host PC is a direct, point-to-point connection that operates at bus speed, requiring no network protocol. Zero clients are typically implemented in clusters, using a "star-like" configuration around the Host PC.

Each cluster can function either as a network component of a distributed computing system or as self-contained, small-group system. When combined with the high performance of the bus-speed delivery system, zero client technology offers an unequalled platform for small-group, transactional-based systems accessing a shared database.

Since a zero client uses low-cost component hardware, with no local intelligence or processing, its cost per seat is similar to that of network computers. Likewise, zero clients offer a single point location - the Host PC - for upgrade, maintenance and support, thus drastically reducing licensing and lifetime system costs.

Definition of Zero Client

A traditional PC has a single display adapter, a single mouse port and a single keyboard controller. A zero client PC Host has multiple display adapters, multiple mouse ports and multiple keyboard controllers. Through system software that resides on the PC Host, multiple virtual machines or sessions are created, each associated with a display adapter, a mouse and a keyboard. Input for the session is read directly from its mouse and keyboard; output is written directly to its display adapter. As in any computing architecture, there are both hardware and software components involved to deliver this advanced functionality.

Key Components of Zero Client Technology

• Host PC - Standard PC with multiple display adapters

• Local Station - Standard (or USB) input and output devices
(e.g. monitor, mouse, keyboard, audio, Touch Screen, serial, etc.)

• High Speed Delivery System - Direct connection or extension

• Software Component - Multiuser Software, such as Applica for Windows

Thin Client Compared to Zero Client

Thin client technology has received a lot of attention in recent years. In support of an industry focus upon expense reduction and improved manageability of desktop computing, the computer industry has drawn from the experience of the mini/mainframe model of host and terminal. With the thin client architecture, the application moved back to a multiuser host, which transmitted the display information to an intelligent device for presentation to the user.

However, the thin client model ignored a crucial change that occurred in the application domain with adoption of Windows as a standard platform: the move from a character-based to a graphical user interface. The client station must now do substantially more processing than the old "dumb" terminal. Higher bandwidth links are also required for the graphical information. When multimedia is added to the application equation, the effectiveness of thin client technology is severely reduced.

Zero client technology differs from thin client technology in client hardware requirements, display data processing and the data delivery system. A comparison of the processing of graphical commands points to some key differences.

As a baseline, on a standalone PC, Windows passes graphical commands directly to a display driver that interprets them and updates the display.

Summary

The zero client architecture combines key aspects of the thin client, the NC and the personal computer. As in the thin client model, Windows applications (including browsers) execute on a shared Host PC. This reduces cost and improves control and manageability. As in the NC model, the zero client stations are lowest cost, secure and environmentally efficient. As in the personal computer model, the display adapter resides in the same computer as the application. This preserves performance because it eliminates the need for a network transmission protocol that degrades CPU processing and injects delays due to network overhead. When all the strengths and weaknesses of each desktop configuration alternative are considered, the zero client technology offers flexible and valuable options to users seeking minimized costs of ownership and improved control.

Applica U2Lite Applica U2Lite locally supports an additional station attached to the Host PC with USB Keyboard and USB Mouse support. Independent audio can be added with the Applica USB Sound Adapter. Applica U2Lite is the least expensive solution for local station support such as kiosks and home use.	ApplicaDS ApplicaDS is combination of hardware and software that allows many users to use one Windows PC simultaneously and independently! All users have their own Windows desktop and can work completely independent - with no perceptible performance degradation.	Applica UGroup Applica UGroup allows the addition of 4 extra remote users to the primary user's computer by connecting an additional set of standard keyboard, mouse and monitor as well as other devices using USB technology.