Some day, it may be possible to accommodate the needs of workers with a Java-oriented network computer (NC). Early efforts by Corel Corp. show great promise and virtually every major application house, including Microsoft Corp., have Java development projects under way.

Today, though, the need to support Windows applications is high on the list of requirements for most network managers contemplating the deployment of NCs. Windows application servers, based on a multiuser Windows NT from Citrix Systems, let NCs display any application that will run under NT. Citrix markets its own product, WinFrame, which relies on their Intelligent Console Architecture (ICA) protocol to display Windows applications on any device capable of running an ICA client. Citrix markets ICA clients for DOS and Windows. HDS Network Systems, Insignia Solutions and Tektronix have ported ICA client to other platforms.

Several vendors provide a licensed version of WinFrame with a few of their own value-added features. Over the past several months, we have worked with WinFrame in our labs, as well as with Insignia's Ntrigue, Tektronix's WinDD, and Network Computing Devices' (NCD) WinCenter, all of which are based on WinFrame. Each adds its own twist-support for Mac, Java or Unix ICA clients, an X Window client or some combination of all these capabilities. In addition to the Citrix varia nts, Exodus Technologies offers Nterprise, its own Windows application server that includes no Citrix code. Offering connectivity in an X environment only, Nterprise provides a solid so lution for environments with Unix machines or terminals that support X Windows.

Although each of the NC vendors supports its own preferred Windows application platform based on a WinFrame derivative, we successfully connected NCD's HMX, HDS @workStation, and Boundless Technologies' XL to our Nterprise server with good results.

The Java Alternative

Java-based application suites are the other solution for delivering productivity applications to the NC. We have hands-on experience with only one suite in this arena: Corel Office for Java. Although Corel is likely to be the first to market with such a product, Lotus Development Corp. is planning a similar offering and Microsoft reportedly has a Java-based Office development effort under way-just in case Java really catches on. For NCs based strictly on Java, like the JavaStation, Corel Office for Java provides a full-function productivity suite that runs on a Java virtual machine. In addition, this suite can be deployed to any computer with a Java virtual machine, including all popular desktop systems.

For most of NCs reviewed in this feature, you can choose between a Windows application server and a Java-based suite to provide personal productivity applications. However, because of implementation and migration issues, as well as performance considerations, one or the other will likely stand out as the best solution for your site.

For Windows terminals, such as the Wyse Technology's Winterm 2700T and Boundless TC, the only solution is a Windows server because these machines are essentially ICA display devices with no local Java capabilities. HDS @workstation and HMX have the flexibility of providing connectivity to Windows servers while supporting a local Java virtual machine; your choice will depend on the nature of your environment and the applications you need to support. The JavaStation lends itself to a Java-based suite, but with a Windows server client that runs on a Java virtual machine, you can implement either a Citrix varia nt as well.

Windows Applications Abound

Choosing to use a Windows server on the back end means you get all of the compatibility of a Windows NT environment. However, because the back-end server must host all of your users' applications, it must be a very high-end system. All of the vendors offer guidelines, but figure on no more that 15 to 20 concurrent sessions on a 200-MHz Pentium Pro.

Memory requirements will vary according to the application mix, but a safe bet is 32 MB base memory and at least 12 MB per concurrent user. For a WinFrame server hosting 15 to 20 users, this translates into approximately 256 MB of RAM. That may seem like a lot, but with RAM prices in the $5 per MB range these days, such a configuration will cost about the same as a 32 MB 100-MHz Pentium system did a couple of years ago. Note that though Windows servers give you centralized administration of applications and almost no new training for users, this solution will not provide satisfactory results for processo r-intensive applications, such as computer-aided design (CAD).

All but one of the Windows servers that we looked at provide the basic, multiuser system that Citrix pioneered. Citrix-based servers offer connectivity via the ICA protocol, which is processor-intensive on the server side, but very modest in bandwidth requirements. Nterprise, Ntrigue and WinCenter also offer support for the X protocol as well, which is lighter on server CPU but more demanding in network bandwidth. ICA is hence a much better choice for supporting dialup users or internetworked users who depend on low-bandwidth WAN connections between their workstation and the application server. Currently, ICA is limited to 256 colors and does not support audio. All of the X-based products offer higher pixel density and WinCenter also supports sound capabilities.

No ne of the NT application server products are compatible with NT 4.0. This may be a major obstacle to deployment given the differences in the user interface between the two p roducts. In late February, Microsoft announced that it will include multiuser capabilities in a future version of NT. Whether such a system will be based on Citrix technology is an unknown at this point, but it seems unlikely that you will see an NT 4.0-compatible version of any of these products if a cross-licensing arrangement with Microsoft cannot be reached.

Because a session on an NT server functions in much of the same way as if you were sitting at the console, you have access to all of the features of a Windows NT machine-including full compatibility with every software package that runs on NT. Connectivity is therefore extended to anything NT can connect to, including other NT servers, NetWare, and Unix systems. In fact, NCD's WinCenter and Tektronix's WinDD ship with Network File System (NFS) clients to integrate better with Unix environments.

Using a Windows application server instead of Java-based productivity suites also gives you significant continuity and flexibility for desktop syst ems support. The look and feel is exactly the same as Windows 3.1 and users are authenticated against the Windows server and to any file-and-print servers that they wish to use on the network. Login scripting connects all of the appropriate resources that your users will need. Additionally, there is no need to implement or learn a new printing system, such as Java-based suites will require.

Integrating a Windows application server with your NCs is fairly simple; most even include a way to make the connection with a few mouse clicks. With a bit of configuration file manipulation, HDS @workStation creates a desktop icon. Users click on the icon and they are presented with a Windows NT logon screen, just as if they were sitting at the console. With NCD, it is a little more complicated, requiring a right-mouse click on the desktop to activa te a menu-an operation familiar to X users.

Using a Unix or Macintosh client in this scenario is just as easy. By purchasing an ICA client or an X server, you can host the Windows server desktop on your machine. We have worked with both X and ICA implementations on the Mac and Unix. The functionality is identical to that found in the clients available for NCs.

The Windows terminals, like Wyse WinTerm and Boundless TC, are simply a hardware-based implementation of the ICA client. Thus, they can only connect to a Windows server and you are limited to the ICA protocol only.

To push the envelop of discerning Java-based productivity and Windows servers, Insignia offers a Java-based ICA client. By running a Java applet, you can connect to any Windows server that supports ICA. Although we did not perform exhaustive testing, we ran the Insignia ICA client on a variety of Java-capable machines and found the solution to be acceptable, though somewhat limited. For example, you cannot use local floppy drives or sound devices because of security in the Java implementations.