In depth with Apple's Snow Leopard Server

I've worked with various versions of Apple's Mac OS X Server for nearly a decade now. Each new release has brought major advances to the company's server software in terms of overall features, performance and ease of administration. The most recent iteration, version 10.6 — a.k.a. Snow Leopard Server — is no exception.

It offers a number of advances compared to Leopard Server (v. 10.5), which was released two years ago.

These changes include performance gains, improvements to several collaboration tools introduced in Leopard Server, enhanced simple administration for non-technical users and new features designed for mobile access and for supporting the iPhone.

And if those aren't reasons enough to be happy about the upgrade, the fact that Apple cut the price of its server OS in half, to $499 — and continues to make it available with no client access licenses — makes it well-worth considering. It can serve nicely as either an upgrade from previous versions or as a replacement for other server platforms. In this article, I'll focus on the major additions and changes that Apple has made in version 10.6.

Clearing away administrative confusion

One of the features introduced in Leopard Server was a simplified administration tool called Server Preferences. Server Preferences was designed for workgroups or small businesses to manage some of the core services — file sharing, e-mail accounts, Web hosting and other collaborative tools, and centralized backup using Apple's Time Machine — available in Leopard Server.

This management happened from a simple utility that was designed along the same lines as Mac OS X's familiar System Preferences utility, but with Server Preferences, a user with only moderate technical skills could set up and easily manage a server without having to dig through the primary Mac OS X Server administrative tools.

Within Server Preferences in Leopard Server, Apple drew clear delineations between three different types of configuration:

One for small businesses with no large infrastructure

One where a server was installed for a specific department or project and where user accounts were imported from a larger directory system within the network (such as Microsoft's Active Directory or Apple's Open Directory)

An advanced mode where experienced systems administrators had full access to Apple's GUI and command-line tools for managing each and every service available

However, there was no easy way to switch between the two simplified modes and the advanced mode. You could convert a server to advanced mode by launching one of the advanced admin tools, but once you did, you couldn't go back to the simpler Server Preferences.

This left a fair amount of confusion for IT departments setting up a departmental or workgroup server in a larger organization as well as for novice administrators wanting to implement additional services not supported by Server Preferences. The descriptions of the various modes were also a bit confusing to novice administrators.

Now, though, in Snow Leopard Server, the switching restriction has been removed, along with all language relating to the selection of one of the three modes that Leopard Server imposed.

Apple has retained Server Preferences, and it's largely unchanged from a user interface perspective. Snow Leopard Server has also retained the ability to import and augment records from a different directory system to support user access to services without requiring schema modifications on the larger existing directory system that is already in use within an organization.

The result: IT staff or consultants can now create more complex configurations for novice administrators while still supporting management in Server Preferences. For any small business or department of a larger business, this means they can have the best of both worlds — either on their own if they have the know-how or with the occasional help of a systems administrator or consultant to do the more technical tasks.

Better collaboration

Another set of features introduced in Leopard Server was a series of collaborative tools. Beyond the basic mail server and Jabber instant messaging service, Apple introduced a shared calendaring solution called iCal Server that was based on the open CalDAV standard and that supported other CalDAV clients beyond Apple's iCal. Other tools in Leopard Server included a wiki and blog server that allowed users to easily collaborate through a Web-based interface that can edit content, track changes and let users know when content impacting them is modified. It also makes tagging and searching for resources very simple.

All of these were great steps, but they still had a slightly less than polished look when Leopard Server first shipped. Many of these improved in stability and performance after the first couple of updates to Leopard Server.

In Snow Leopard Server, all of the collaborative tools have significantly matured and now live up to the promise that they offered in Leopard Server. Read on to learn more.

Revamped mail services

One of the big changes Apple made was to move its mail server to be based on the open-source Dovecot, which provides Unix/Linux mail servers with a broader range of features than Apple's previous mail software. New features include the ability to have more complex server-based filtering; this allows mail to be filtered into specific mailboxes by the server rather than a mail client, resulting in better client performance and sorting being applied regardless of the computer or device being used to access mail.

Another new feature is the use of vacation or out-of-office replies. Apple also improved the Webmail interface available to users; previous iterations relied on a very basic implementation of the common Squirrelmail tool.

Address Book Server

The biggest addition on the collaborative tools front is Address Book Server, to help share contacts and manage personal contacts using the relatively new CardDAV standard. This is a big improvement in many ways because previously the only option for shared contacts was through the use of LDAP. While LDAP was a viable solution if you needed to only retrieve contact information, it offered little in the way of editing contacts.

CardDAV is still somewhat of an emerging standard, with a limited number of clients that support it aside from Mac OS X's Address Book in Snow Leopard. Still, it is a step in the right direction and it shows that Apple is committed to developing collaborative tools that are based on open standards, as it did with iCal Server support.

Enhanced Calendar Server

Speaking of iCal Server, the shared calendaring got a number of updates in Snow Leopard Server. iCal Server in Leopard provided limited functionality for inviting multiple members to events. Also, it was difficult to access iCal Server from systems without CalDAV clients, including Apple's own iPhone.

iCal Server — dubbed iCal Server 2 in Snow Leopard Server — now has a better-performing and more streamlined user experience. Configuring clients to access the server is simpler. And features including invitations and viewing the availability of rooms, other resources and other users are both easier and more consistent.

Apple's also added support for the iPhone; this was a combination of both the iPhone OS 3 update released this summer, which introduced CalDAV support, as well as the server enhancements. Web-based access to calendars is also now possible with the revamped wiki server.

Another addition is the iCal Server Utility. This utility existed in a somewhat different form in Mac OS X Leopard as the Directory application. This application originally took the form of a central directory that all Leopard users could access. In that iteration, it offered the ability to look up users, contacts, locations and resources such as projectors, printers and even company cars. It also allowed users to create ad-hoc groups for collaboration.

As intriguing as Directory was, it was in no way cross-platform or accessible from the Web. Only Leopard users could access it; users of earlier Mac OS X versions as well as other platforms were out of luck. There was also a fair amount of work required when populating the data into Directory, which given a limited client base made it hard to fully justify the effort in most organizations.

Now, as iCal Server Utility, the tool is now aimed at server systems administrators and can be used only to populate resources and locations. Once these are populated using iCal Server Utility, users will be able to reserve rooms and other resources via iCal, any third-party CalDAV client or iCal Server's new Web interface. Users cannot add new rooms or resources through these tools, however; that task remains in the hands of systems administrators.

The somewhat scaled-back approach may seem like a step backwards from Directory's overarching vision. However, it is actually a positive step because for contacts, Apple has introduced Address Book Server, which is based on open standards and is supported by tools on additional platforms. This provides for much of the general use that Directory was intended to achieve and requires less effort.