Thin-Client Computing

But SBC environments cannot be installed overnight. It takes time and effort to transition from fat to thin clients and lay the necessary foundation in server processors. And thin architecture is not for everyone. Scalability is a problem on the server side. You'll need to add memory and processing power for the clients and applications being used. If your users spend more time processing and less time viewing the results, thin is probably not for you. But if your users work predominantly on tasks that do not require intense processing, server-based computing should be on your wish list.

Twiggy in the Enterprise

To date, thin clients have had a thin presence in the corporate world. PC makers and distributors have sold us on fat for homes and schools, and that's what we've come to expect at work. Giving end users what they expect ensures user buy-in and reduces the need for training.

Despite advances in technology and manufacturing that have lowered the cost of fat clients, however, all is not a bargain. Factor in the cost of management, service and support, and you'll see those costs greatly exceed the purchase price of the computer. For $1,000, you can purchase a PC with a gigahertz processor, a gigabit NIC and a hard disk with more space than the average user can manage during his or her tenure of employment, if not lifetime. But the initial cost is just the tip of the TCO over the life cycle of the machine. Maintenance and application management ratchet the TCO up considerably.

Not so with thin clients, which offer reduced costs in desktop maintenance and application management because the applications are built and saved in a centrally located, server-based environment. Thin clients are assured of accessing the most recent version of applications installed on servers every time they are connected to the network. From a server administrator's point of view, thin-client upgrades are as close as it gets to zero administration on the desktop.

Beyond savings on the desktop, consider the cost of upgrading your branch offices, which must replicate centrally located resources--directory, application, database and mail services. By switching to thin clients, you could save much more than the cost of fat clients.If you implement a thin client network, you must provision the proper server-based resources, or you will impoverish your processing power. Work with your hardware and thin-client software providers to scope out the correct resources. Map out the number of processors and the amount of memory required for servers based on the number of users and applications. Determine if you can use Linux or Sun Microsystems Solaris applications (both are a good fit for thin clients). If you use Windows, you can take advantage of Microsoft Terminal Services and Citrix MetaFrame software to categorize applications as low, medium or high priority. Then look at the network; you may need to implement load balancers and WAN accelerators. Finally, to size your SBC environment properly and ensure you have enough processing power, use a benchmark program like Mercury Interactive's LoadRunner or a server-sizing tool from your hardware vendor.Thin clients come in a variety of packages and sizes. Most consist of a small device to house the thin-client software and a mechanism to boot an OS from ROM or an image housed on a remote server. That device will have audio and video graphics support as well as ports for a keyboard and mouse. Make sure your package includes all the needed peripherals, but remember that adding devices to your thin clients will make them fat and may increase your support needs.

Thin clients comprise three broad categories: X Terminals, Windows-based terminals (WBT) and Sun Rays. X Terminals have the look and feel of the old dumb terminals that served as conduits to midrange and mainframe servers. An X Terminal computer provides an X Window to server-based applications on Linux or Unix. It runs a local X server process and applies local fonts for display. This setup requires more CPU and memory than most thin clients do. In addition, X Terminals need to maintain state with their server-based sessions.

WBTs run Windows OSs--Windows NT, 2000, XP--and support the ICA and RDP protocols. Linux can be used with ICA and RDP to run the latest Windows apps. WBTs boot an OS from ROM or a server-based image and render apps running on servers. Unlike X Terminals, WBTs make use of thin-client software, like Microsoft Terminal Services and/or Citrix clients. Although rendering an app onto a WBT is less burdensome than displaying it in an X Terminal, it still involves client resources that demand computing power and memory.

Sun Ray thin clients are specific to the Solaris OS. Unlike the X Terminal or WBT, the Sun Ray is stateless: Each Sun Ray client contains a firmware module that lets it communicate and receive display commands and data from Sun Ray servers. Sun Rays also support smartcard technology that can be used for authentication to the device and the network. In addition, smartcards can support application and storage. They can be encoded with a JVM (Java Virtual Machine) to power Java Applets as well (see "Sun Ray Architecture," above).

Both X Terminals and WBTs can use low-end or low-cost computers as thin-client devices. PCs and Macintosh computers can each host Citrix, X server software and other thin-client software. Low-end PCs can support Microsoft Terminal Services clients--one way to keep aging computers in service--but they still require the same desktop support associated with fat clients.Dedicated thin-client devices can relieve desktop support as long as you keep thin clients lean and mean. If you add local browsers with plug-ins and software, you'll need increased processing power and more memory. If you add peripheral devices, expect to visit the desktop periodically to support them.

Sean Doherty is a technology editor and lawyer based at our Syracuse University Real-World Labs®. Write to him at [email protected].

Post a comment or question on this story.

1) Is the OS compatible with your server?

2) Is there an OS upgrade scheme?

3) Does it boot from ROM or server image?4) Are its applications and storage server-based or local?

5) How much RAM does it require?

6) What network protocols does it support?

7) Are peripherals included or supported?

8) What is its mean time between failures?9) What is its warranty period?

For details and prices on specific makes and models, use our Interactive Buyer's Guide charts at www.nwc.com/1424/1424ibg1.html