by , 2:00 PM EDT, October 17th, 2007

Mac OS X 10.5, Leopard, is a triumph of customer-focused engineering, according to Tom Yager at InfoWorld on Wednesday. One of the key elements of Mac OS X's design and success is the concept of frameworks.

"Windows and Linux are designed from the core out, which is to say that they are all about layered kernels, system calls, and APIs, with each layer's purpose being to abstract the layers below it. The layers grow thicker; when a layer gets unmanageably thick, a pretty new abstraction layer is created so that people don't have to deal with the ugly one," Mr. Yager explained.

"Programmers end up having endless entry points with identical purpose and having heated debates about which ones are best. But each way of doing the same thing involves varying dependencies, deprecations, and peculiarities."

In contrast, Mac OS X uses the concept of frameworks. Below the framework remains a simple, stable Unix core. "When developers write to Apple's frameworks, they inherit cross-application integration and operational and interface consistency with no effort. For example, E-Mail, the Address Book, and QuickTime are smart, autonomous objects available to all Mac apps regardless of language and requiring no optional software," Mr. Yager noted.

Best of all, this version of Mac OS X is fully Unix certified. [(SUSv3) and POSIX 1003.1.] Mr. Yager wrote, with obvious glee, "Finally, there's a PC Unix that everyone can love."

In the end, it takes someone deeply familar with the internals of Unix to appreciate what Apple has achieved. "Leopard is a legitimately big deal. It's underhyped compared to iPhone, and yet unlike iPhone, Leopard is a genuine triumph of customer-focused engineering. It's a pleasure and a relief to see that Apple remembers how to deliver open, affordable, standards-based products," the InfoWorld editor and Macintosh expert concluded.

Thanks to TMO reader Orlando Smith for the news tip.