Product Reviews

Occasionally, you discover a piece of software which alters the way you work. VNC is one such product and, best of all, it doesn't cost a bean.

VNC, which stands for Virtual Network Computing, is the product of a research laboratory jointly funded by Olivetti and Oracle. Basically, it's a method of controlling one computer from another over a network. But to those people whose initial response is to sigh 'Oh, like Timbuktu', don't turn the page yet - VNC has the potential to be more flexible and work on a wider set of machines than Timbuktu ever did.

VNC comes as two distinct components: a Server and a Viewer. The Server is run on the computer you want to be able to control; it operates in the background, waiting for connections. The Viewer is the actual control application; run it, connect to the 'served' computer, and you'll see the contents of its screen in a window on your desktop. Move the mouse, type at the keyboard, and it's just as though you were performing those actions on the remote machine itself - in other words, complete control.

The current Mac version of the Viewer is classified as a beta, and the Server is an alpha at present, but both - especially the Viewer - work extremely well. Over three weeks of intensive use, the Viewer crashed no more than any other Mac application - and far less than most. The Server, although it still has a few glitches, also performed well, with only the occasional crash.

VNC keeps information about the connection on the Server rather than at the client end. This means you can be connected using a Viewer at work, close the connection, go home, connect from your home machine (VNC uses TCP/IP, so it'll work over the Internet) and the screen will appear just as you left it, even if you were in the middle

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of editing a document, composing an email, or whatever.

This is what you'd expect from such a program - after all, if no-one else had used the served Mac in the interim, why wouldn't the screen be just the same? But the great thing about VNC is that Servers and Viewers are available not only for the Mac, but also for Windows (95/98 and NT) and Unix boxes. So you can control whatever machine you want from your Mac, and vice versa. On Unix boxes in particular, the fact that information is held by the Server is fantastic; unlike with a standard X Windows session, you can disconnect, reconnect from somewhere else, and the session is exactly as you left it. No need to log out - just disconnect and reconnect later. For this reason alone, VNC can completely replace X Windows servers for both Windows machines and Macs.

VNC works superbly over a local area network, and even performs reasonably across a dial-up Internet connection. When used in this way, it's not quite as fast as a standard X Windows system, but it's not far off. And if your connection is dropped halfway through your work, as it often is when using the Internet, you can just reconnect and carry on exactly where you left off. It's hard to explain just how useful this is until you've tried it - at which point you'll never want to go back to using a standard X client again. (Actually, VNC uses X as its underlying windowing system, so you can run whatever Unix window manager you want if you're connected to a Unix box.)

As if this wasn't enough, you don't even need the VNC Viewer software to control a remote machine. If it has the Server running, you can also connect to it using any Java-compatible Web browser. By pointing your Web browser to the correct port (for example, by connecting to http://mycomputer.mydomain.com:5800), a small Java applet (30K or so) downloads to your browser, and the contents of the remote machine can then be seen - and controlled - via your browser's window.

VNC is a superb piece of software. The Servers for Windows and Unix are robust and efficient, the Mac Server is very close to the same standard, and the Mac Viewer is rock-solid (as are those for other platforms, including, believe it or not, Windows CE). If you need remote control of a machine on your network, be it a Mac, Windows PC or Unix box, VNC is fast, user-friendly, robust - and free.