This seems to be the week to think about Linux. First, as you’ll see in the news section of this newsletter, Red Hat is now shipping the Linux Independent Computing Architecture (ICA) client with its version of Linux. You can download this software for free from the Citrix Web site, but now Red Hat users don’t have to go to the trouble of downloading the client—they’ve already got it. "So what?" I hear you cry. Okay, think of it this way: The sellers of an open-source OS think it's desirable to include a tool that lets Linux users easily run Microsoft applications. You can think of this development as either a triumph for Microsoft or, as I prefer, a triumph for true interoperability. You can use the OS you need when you need it, but you’re not prevented from using the abilities of another OS from the same desktop—no reboot required.

This week also marks the anniversary of Eric S. Raymond’s publication of the first of the "Halloween Documents." If you’re not familiar with these documents (published here), they’re a collection of internal Microsoft white papers, the first of which discusses the threat to Microsoft’s space in the server market from open-source software, such as Linux. Halloween is here again, and Linux is not only a potential challenger to Windows’ place on the desktop, it’s on the desktop. You can’t see it most of the time, you might not even know it’s there, but an increasing number of Windows-based terminals (WBTs) are using Linux as a local OS for connecting to a terminal server.

In September 1998, Citrix released the Linux-compatible ICA client, giving WBT manufacturers the option of using Linux as the client-side OS. Since then, several Linux-based WBTs have emerged. In fact, Boca Research just announced its Linux-based WBT contribution, which includes a Java-based version of the RDP display protocol so the terminal server doesn’t have to have MetaFrame installed.

Why Linux? WBTs are slowly becoming more multifunctional. A year or so ago, many people assumed that the network computer was dead. It wasn’t dead then and it isn’t now—it’s just been assimilated into the WBT design as a more powerful WBT, one that needs a more mature client-side OS than Windows CE can provide. Linux is good for the same marketplace that Microsoft is targeting with its Windows NT 4.0 Embedded WBTs.

Linux has several advantages when it comes to a client-side OS. First, it’s flexible. If you’re a manufacturer building the better WBT based on Windows CE or NT 4.0 Embedded and you want to include some functionality that the OS doesn’t support, you’re out of luck. If you’re using Linux (or your own OS), you can modify the kernel to add that support. Second, Linux has a relatively small memory footprint, and when you’re talking about an OS stored in flash memory, size matters. Third, it’s cheaper to license than Microsoft OSs. Because licensing fees represent a good chunk of the cost of a WBT, that’s important.

This isn’t to say that Linux is inherently a better OS for the WBT environment. Whether it’s the best one will depend on the job the WBT is meant for. The marketplace is split between the dumb terminal WBTs and the PC-wannabe WBTs, and the OSs are not equal when it comes to serving those different markets. The point is that, only a year after the publication of Microsoft’s concerns about the threat from Linux as a server OS, Linux as a client OS is contributing to the success of multiuser NT. Interesting twist.