The X Factor

The graphical X Window System can be found in a wide variety of commercial settings, but it is most often found in technical, scientific, and manufacturing environments. X Window applications have become so commonplace that to introduce a workstation (or workstation operating system) into an organization, it must be able to run X Window applications. This review looks at the following X Window products for Windows NT: eXceed by Hummingbird Communications, eXalt by Intergraph Corporation, Reflection X by Walker Richer & Quinn, Inc. (WRQ), and XoftWare/32 by AGE Logic.

History of X
The X Window user interface is a simple, easy-to-use graphical interface that is similar to the graphical application interfaces provided by Windows, Windows NT, and Macintosh System 7. The specifications for the X Window System were developed at the Massachusetts Institute of Technology (MIT) under Project Athena. These specifications were subsequently handed over to the non-profit X Consortium, which now maintains ownership and distribution rights.

The current version of the X Window specifications is "11" (hence, the nickname "X11"). They have undergone a number of revisions. For example, X11R3 refers to the third revision, X11R5 to the fifth, and X11R6 to the sixth (and current) revision. The revisions are, for the most part, backward-compatible, although there are a few bugs with X11R3 that are outside the specifications.

The X11 specifications describe fonts, window controls, and client/server interactions that allow it to operate across platforms and UNIX implementations. Despite the breadth of these specifications, however, some UNIX vendors have added proprietary extensions to their X11 implementations (just as they have with UNIX). For example, Hewlett-Packard (HP), Digital Equipment, and IBM have each developed proprietary X tools that use custom fonts. As a result, some X programs are not compatible across platforms.

An important part of X11 is the Window Manager, a software module responsible for the appearance and control of individual X Window programs in the display area. More than two dozen Window Managers have been developed for X11. Some of the more common ones are the Universal Window Manager (UWM), the Tab Window Manager (TWM--an earlier version of TWM was called Tom's Window Manager), and the Motif Window Manager (MWM). Most Window Managers are public-domain products, although some UNIX vendors have developed proprietary Window Managers. These include HP's HP VUE, Digital's DECwindows, and IBM's AIXwindows.

The proprietary extensions result in situations where an X Window product can run the full range of "standard" X11 programs but may not be able to run mission-critical X programs that depend on proprietary extensions. Consider this a word of caution, and make sure you can achieve the interoperability you need when you choose X Window software.

X in the Lab
Terminology is often a stumbling block when dealing with the X Window System. In particular, the system that is displaying the X application is called a "server," and the system where the binary program for the X application resides (and actually runs) is called the "client." Under the X terminology, an X Window terminal, for example, is really a server. Keeping this in mind, you might find it easier to think of products called "X Servers" as X Window terminal emulators.

The X Window server products I ran through the lab had several common operating requirements and features. For example, all the products ran as native Windows NT applications (no underlying services were installed), and all of them required an SVGA display subsystem configured for 256-color support (or better). More importantly, all of these products shared two key capabilities:

• The ability to run X Window programs on the NT desktop--Each X Window program appears in a standard NT window and supports standard NT controls.
• The ability to run X Window programs in a single NT window--You must access that specific NT window to access the individual X Window programs running in it.

Running X Window programs on the NT desktop offers the most natural fit with the NT environment. The X Window programs support the same controls as normal Windows programs, and, in more general terms, have the same look and feel as native NT programs. This approach also provides the best performance.

The performance advantage of using the NT desktop for X programs is based on running them under a single NT window. For most of the products, you must run a remote Window Manager (e.g., TWM, UWM, MWM, etc.) to manage the X programs that will display in the single window. (One product I reviewed, Hummingbird's eXceed, provides an optional local Window Manager for handling the single window environment, but unfortunately that's the exception--not the rule.)

When a remote Window Manager is used, every mouse click and control option is handled remotely. This often delivers less than ideal performance. Still, if you need to create an X Window environment that looks and acts exactly like it does on a UNIX system, this is really your only choice.

The two major areas where the X Window software products differ are in how X Window programs are launched on a remote system and how X Window fonts are handled. The second topic, fonts, is actually a broad one that addresses which fonts are included, how they are stored, and what proprietary fonts, if any, are included.

Finally, all the products I reviewed share one common oversight--program launching is blind. In other words, none of the products displays any error messages generated by the remote system in response to font incompatibilities, command errors, or incorrect parameters, although some do include a simple progress monitor. For this reason, you might want to use Microsoft's Telnet or Remote Shell (RSH) facility until you get the hang of command initiation--you don't really have to use a product's launch facility to start X programs.

The following reviews give brief reports of my experiences with each product in the lab. For product comparisons, see the table on page 62.

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