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What You Need to Know About Thin-Client Computing

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A few years ago, IBM introduced thin clients as alternatives to PCs or dumb terminals, but few companies really bought them because those thin clients were expensive yet not powerful enough to be useful. However, more affordable, more powerful systems are now available, and the concept of thin client computing has resurfaced. Today, many midrange IT managers are seriously considering this desktop solution. This article answers the most frequently asked questions about thin clients in the midrange.

Q: Why Move from a PC to a Thin Client?

A: The PC revolution brought tremendous computing power and freedom to end users in the corporate world, including a wide variety of supported applications, customization of user preferences, unrestricted Web access and file transfer capabilities, etc. Today, corporate management has come to realize that this type of freedom has its drawbacks, such as unstable and inconsistent operating environments, poor backup control, and reduced end-user productivity due to Web surfing and other distractions that PCs enable. All these drawbacks lead to higher maintenance costs, system vulnerability, and lower employee performance.

In addition, there's the instability of the platform, and we're not talking about system crashes, although we could be. Not only does the hardware become obsolete (higher-performance CPUs are required to run new applications), but also the operating systems typically need updating every three years. Remember Windows 95, 98, 4.0, NT, 2000? Figure in the licensing fees, the time the system administrator spends updating each workstation, the downtime this causes other employees while their workstations are out of commission, and the additional time required to learn each new revision, and you end up with quite a sizeable price tag!

While thin clients and Ethernet terminals were originally designed to work solely with server-based applications, there is a growing trend toward using 5250/3270 emulation alongside server-based applications. This trend, along with the aforementioned concerns about the PC operating environment, has generated new interest in terminal computing, specifically in the field of thin clients.

Q: Why Thin Clients and Text-Based Terminals?

A: Thin-client and text-based Ethernet terminals have become widely accepted since IBM stopped manufacturing dumb terminals. While 5250 emulation via PCs is also a popular method for bringing midrange applications to LAN and remote users, the PC option has three basic drawbacks: high total cost of ownership (TCO), security issues, and virus concerns. In direct contrast to PCs, thin clients and text-based terminals are inexpensive to purchase and maintain, and they solve configuration and administration issues through centralized management:

  • Central User Management--The system administrator manages the accounts the thin-client terminals use. A major benefit is that since all applications are run from the server, there is no local installation and maintenance of software applications at the thin client. Furthermore, since all user data and files reside on the server, central backup is possible, thereby freeing the user of this task.
  • Central Configuration--Thin-client terminals are simple to configure, either locally or remotely. The user specifies a host connection with the address of the server. The user can either request a normal Windows Desktop or specify an application on the server to run. Security is enhanced because the system administrator can restrict which applications the user can run on a particular terminal.

Q: Thin-Client or Text-Based Terminal: How to Decide?

A: Not all applications require thin clients. For data entry, terminals and text-based terminals (also known as Ethernet terminals) can fit the bill. When users need access to both iSeries and other server applications and the Internet, thin clients are appropriate.

Data Entry

Both twinax and Ethernet text-based terminals are suitable for data entry applications.

Twinax terminals are generally easier to set up and may already be in place. They can be connected easily in a TCP/IP environment by implementing a pure TCP/IP controller, which improves their performance and simplifies management of the devices. Email is available to Twinax users via the controller. Wide area network (WAN) connections using only TCP/IP are normally much more efficient and reliable than mixed SNA and TCP/IP protocols. Often, swapping out SNA-based controllers (such as 53 and 5494 models) is the most economical way to stabilize twinax users in a TCP/IP environment. New installations, however, can choose among twinax via Cat 5 cable to an Active Star hub; a controller with built-in RJ45 connectors via a balun, or Ethernet-based terminals.

Ethernet text-based terminals allow simple configuration and present the user with few additional options; therefore, they are the easiest to manage. Many of these terminals offer remote administration, which can help with configuration and management in general. Email support for text-based terminals normally requires some software on the AS/400 or iSeries server. Another approach is to provide email access via a thin client, which is discussed below.

5250 and PC-Based Applications

Many companies are looking to offer more functionality to their users than text-based terminals can provide. Desktop applications such as Microsoft Office (Word, Excel, etc.), will require server-based connections. In this case, thin clients--either "dumb" or "intelligent"--are appropriate.

"Dumb" thin clients simply act as terminals, allowing access from desktops to server-based applications.

Today's new generation of "intelligent" thin clients include built-in emulation software for access to a range of systems and applications on the server, such as the iSeries; Lotus Notes; WebSphere; email; a full-function browser such as Mozilla Firefox or a full-blown Microsoft Internet Explorer that supports JVM, Flash, and XML; and pop-up window support. These intelligent thin clients are served up with Linux or Windows XPe operating systems.

Q: Dumb or Intelligent Thin Client?

A: The best way to choose the most appropriate thin client for your organization is to determine the functionality you require and then find the most cost-effective solution by matching a specific operating system to those requirements. There is a direct relationship between the thin client's operating system, its support for various applications, and the cost of the solution.

The scale ranges from "dumb" requirements, which are minimal and can be addressed by the most inexpensive devices, to "intelligent" requirements, which demand support for more sophisticated applications and more familiar operating environments. Dumb thin client requirements are minimal. You'll need a connection to Citrix or Microsoft Terminal Server. A Web browser is unimportant, but embedded emulation software may matter.
Intelligent thin client requirements are more extensive. You'll need a Java-enabled Web browser, an email client, and desktop application icons to access server-based office software. And embedded applications are essential.

Q: Windows-Based or Linux-Based Intelligent Thin Client?

A: Thin clients are based on one of three operating systems: Microsoft Windows CE.Net, Microsoft Windows XPe, or Linux. Following is a description of the features and pros and cons of each.

Windows CE.Net-Based Thin Client


  • Internet Explorer IE. 6 browser (compact version)
  • Remote Desktop Protocol (RDP) for all Windows servers
  • Independent Computing Architecture (ICA) Citrix neighborhood
  • Acrobat Reader
  • Office Viewer
  • Embedded emulation
  • POP 3 email
  • VPN client


  • Windows CE.Net is inexpensive
  • Small footprint
  • Faster and more stable than Windows CE


  • Poor performance of embedded applications
  • No direct access to the file server
  • Weak Internet capabilities
  • Only the compact Internet Explorer IE.6
  • No JVM
  • No Flash
  • Limited JavaScript
  • No Linux option

Windows XPe-Based Thin Client


  • Internet Explorer 6 (full version)
  • Macromedia Flash
  • RDP
  • ICA Citrix Neighborhood
  • Adobe Acrobat Reader
  • 5250e Embedded Terminal/Printer emulation
  • Microsoft Office viewers
  • Outlook Express
  • Media Player
  • Open Office (requires larger storage)


  • Internet Explorer 6
  • Ability to embed almost any current Windows application to reside on the terminal
  • Ability to be part of a Microsoft Domain (with drive mappings, etc.)
  • Familiar Windows desktop
  • Latest Microsoft OS (probably most stable)
  • Windowing support
  • File server support without requiring a TSCAL
  • JVM support with all browsers
  • Macromedia Flash support
  • Browser windows work correctly


  • Price (operating system costs $90 per copy)
  • Requires more expensive hardware, more memory, faster CPU

Linux-Based Thin Client


  • Multiple emulations (5250e, 3270e, VT 100, Wyse 60, SUN, HP, SCO, ANSI, VT220, VT420, VT510, VT520, X Term, and Telnet with SSH)
  • X-Windows client
  • RDP (fully Microsoft Server 2003-compliant)
  • ICA (Citrix)
  • Tarantella (Citrix-type product for Linux, provides compression for better communication with server-based apps)
  • Choice of browser (with JVM and Flash support)
  • Firefox
  • Mozilla 1.6
  • Netscape (on request)
  • POP 3 email client
  • Real Adobe Acrobat Reader
  • Open Office


  • Windowing support
  • Windows-type interface
  • High performance with embedded applications
  • X-Windows support
  • File server support without requiring a TSCAL
  • JVM support with all browsers
  • Macromedia Flash support
  • Browser windows work correctly


  • Requires more memory
  • Requires more CPU
  • Linux is an unfamiliar environment
  • No Microsoft Internet Explorer browser

Q: What Is a Thin PC?

A: A new approach to providing thin clients is to convert existing PCs to thin clients with inexpensive software. Companies that seek to recycle obsolete PCs or that want to maintain the PCs they're using yet increase security are candidates for this approach to thin-client computing.

Q: Briefly, What Are the Benefits of Thin Clients?

A: Thin clients provide fully manageable desktop computing that is secure, easy to deploy, and economical. Linux-based thin clients offer a real alternative to the Microsoft desktop environment and its associated upgrade cycle. The hardware is reliable and does not need to be replaced every few years. Embedded emulation software provides server independence and high performance. Power consumption is low--good both for the environment and the budget. Data is much more secure because there is no exposure to viruses. Last but not least, thin clients have a rapid ROI and low TCO.

Martin Pladgeman is president of BOSaNOVA Inc., Master Distributor for BOScom products in North America.



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