Apple's desktop Macs are incomparably well suited for the full range of uses from general productivity to technical and creative design, with the entire user skill and requirements spectrum covered by a rich, engaging, intuitive platform. It took Apple several years to get its head out of hardware long enough to perfect its client software. But the combination of broad feature set and usability that Apple brings to desktops, with the idea that one can sit down and start working immediately, didn't stand a chance of making it to servers.
Apple has brought its unique brand of richness and simplicity to servers. OS X Leopard Server is the fifth generation of the software half of Apple's server platform. This time around, Apple took what is a unique and bold approach for a UNIX server. Leopard Server continues the OS X Server tradition of delivering platform-independent file/print, e-mail, Web, and network edge services (such as stateful firewall, VPN, proxy, virus, and spam filtering). But it is as easy to set up and run as a desktop. Truly; the typical Mac user could get a Leopard Server going, because the default administrative interface is a match for a Mac's System Preferences.
Leopard Server breaks from the previous Mac server, and all server practices in general, in another regard. It takes the core server capabilities that I described in the preceding paragraph for granted, and places a completely new emphasis on cutting edge network collaboration that includes blog, wiki, instant messaging, calendar and scheduling, and address book (which Apple refers to as Directory). Sure, that's a trick that Linux or Windows can pull off, but Apple's spin is unique. These services are turnkey simple, but even in a turnkey setting, Leopard Server's services are loaded with features and integrated to an extent that one finds, well, on a Mac desktop. If you can wrap your mind around this idea, then you won't be surprised that Apple has supplied templates and default behaviors that make the services you put on the air look professionally designed from minute zero. Leopard Server passes the true turnkey sniff test by supporting all of its services without requiring custom coding or scripting.
Open and mighty
Apple, which has been known to approach challenges by inventing proprietary wheels, went full-bore on public standards with Leopard Server. Standouts among Leopard Server's standard standards are CalDAV shared calendars, Jabber/XMPP, Apache 2.2, Ruby on Rails with Mongrel and Capistrano, IPSec and PPTP VPN, RSS, and Kerberos. Apple went proprietary only on the underlying plumbing of management GUIs. SNMPv3 is supported for monitoring with open tools. Apple's bullish on security, and some of the secrets it keeps are in customers' interest.
Although Leopard Server has the outward appearance of a gentle, unintimidating client that magically makes collaboration, general server, and edge services appear on your network, it wears its UNIXness with pride. Leopard Server is UNIX with a U, the real deal, with Open Group UNIX 03 certification for the first time in OS X history. That puts Leopard Server in the rarified company of AIX, Solaris, and HP-UX. The Big Three is now the Big Four. The point is, if you're concerned that Apple's having brought client ease of use to servers means that UNIX gearheads have to clear a lot of brush to work their craft, don't worry about it. Leopard Server is source-level compatibility with any UNIX software in the wild, or at least that which adheres to UNIX standards. Further, a full set of commands -- including command-line administration of its entire feature set -- means that Leopard Server is both pretty to look at and well-muscled, a fine specimen all around.
For the short rack
If Leopard Server has a shortcoming, it is its limited scalability. This is a legitimate concern for IT, but then IT is neither Apple's target for Leopard Server nor the most likely purchaser of turnkey, user-friendly servers. Again, Leopard Server passes muster in the general purpose category, and linking in Apple's Xsan SAN filesystem opens Leopard Server's intrinsic scalability. But the turnkey features that make Leopard Server so appealing don't scale with the use of the GUI tools. The tools themselves fall short of an experienced admin's expectations, especially with regard to real-time reporting. Apple thoughtfully made all of its admin tools operable remotely so that you don't have to resort to VNC or a remote shell; the console administrative GUI runs on any Mac client, and the tools are free. But when a remote management connection goes down mid-session, the admin tools handle it poorly. There is no notification that the link to the server has been cut. Rather, stale stats persist on-screen until the admin tool is restarted, at which point a broken connection is reported.
Leopard Server does all of the things that Tiger Server did, with modernization that's particularly visible in its default security and the GUI interfaces that operate it. You'll also find that often-used features like the setting up of network shares have been moved to top-level management interfaces. Leopard Server is a much easier OS to run even when your requirements exceed that which the desktop-like GUI can manage.