sWM: Why do companies want to run Windows applications on Linux, or Windows and Linux together?
Curtin: Linux is more efficient in its use of hardware. Those who are running Windows are being forced to upgrade hardware. They're also just spending too much administering and managing. By lifting up Windows applications and sticking Linux underneath, they get better uptime. Linux also has better remote administration tools. It's more easily accessible from the network to do configuration, servicing, support and updating. You also improve security of the overall system by introducing Linux. Linux is as much Unix as you can get, so it has the security and robustness of Unix. So, there's security, reliability, manageability. There are the productivity benefits of starting and stopping faster, and it's less buggy.
sWM: How does emulation work?
Curtin: We call what we do integration and virtualization, but it achieves the effect of emulation. We require systems to run on the Intel platform, the Microsoft native environment. DOS instruction sets access directly through the processor, and the host services are integrated with Linux. The applications write to the Linux file system. The applications are managed by the Linux task scheduler. So, the device drivers are virtualized: the keyboard, mouse, video, sound and printer. Microsoft thinks it's talking to a Microsoft keyboard or display, but we virtualize it into a Linux interface.
sWM: What is the difference between various emulation technologies?
Curtin: There's us, VMWare and WINE. VMWare offers you a complete virtual machine. The file system and kernel are virtualized. You're running a complete OS in a virtual machine. Virtual machine architecture allows you to reduce your hardware cost and have one support professional run Novell, Mac, Windows 95, Windows 98, Windows NT and Linux.
The full emulation architecture is WINE. If you're running Word or PowerPoint, for example, there's literally tens of thousands of calls those applications make. WINE takes all those application calls. It tries to create a pseudo interface on the Linux side, so it maps the Windows application call into Linux. So, it thinks it's writing to Windows, but there's no Windows involved. It completely removes Windows, and the applications write directly to Linux. We're in the middle.
We use part virtual machine, part emulation and part integration. We leverage the DOS piece of the Linux OS and the Windows integration piece.
sWM: When would you use emulation over VMWare's virtual machine?
Curtin: Well, complete emulation is not going to work. VMWare can be used in three markets. One is in support departments, where they have to support multiple operating systems but don't want to buy and maintain hardware for every single OS. The second is the development environment, where they want to develop in one environment and test in another. Again, they want to save on hardware. The third is like the mainframe on a PC model, where you create different virtual machines to host multiple servers on one machine. That's what IBM is doing with Linux on the mainframe.
sWM: Is Linux being adopted by enterprises more frequently now?
Curtin: There's no doubt a lot of enterprises are using Linux legitimately. A lot have adopted it in the periphery: the mail server, the Web server or the firewall. Companies are starting to run back office applications on it, too. As far as the desktop, it hasn't seemed like the best thing to do. We see people actually scrapping the whole fat desktop model and go to a thin client model. And those thin clients are more likely to be running Linux. We haven't seen any 50,000-seat enterprises go to Linux, though.
sWM: Do you have any tips to running Window applications on Linux?
Curtin: It's pretty straightforward. Move as much of your state, which is your applications, data, configurations, and all your settings, to the server to break the desktop hardware upgrade cycle. Then, all your future processor investments and licensing management can be done centrally. You won't have to live in this decentralized world.
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