Browser Clients for Apple’s Lion iCal Server - dummies

Browser Clients for Apple’s Lion iCal Server

By John Rizzo

The iCal Server in Lion Server is based on the open CalDAV standard (Calendaring Extensions to webDAV), which means that client calendaring applications must also be CalDAV-compatible. Not surprising, all of Apple’s calendar clients for Mac and iOS (iPhone, iPad, and iPod touch) use CalDAV.

In addition to CalDAV compatibility, some calendar clients are compatible with Mac OS X Server’s push notification service. These include iCal in Mac OS X 10.6 and later, and iOS 3 and later clients.

There are CalDAV clients for Windows, Linux, and older versions of Mac OS X that work with iCal Server to various degrees. The following clients support the CalDAV standard:

  • eM Client: From E&S Software Ltd, this is a commercial messaging client for Windows. In addition to CalDAV and Google Calendar, it supports e-mail, contacts, and tasks.

  • Mozilla Sunbird and Lightning: These are two open source clients available for Mac OS X, Windows, Linux, and Unix. Sunbird is a stand-alone calendar client. Lightning is an extension for the Thunderbird e-mail client. (From the people who bring you the Firefox web browser.)

  • Chandler: From the Open Software Application Foundation, Chandler is an open source calendar and tasks program for Windows, Mac OS X, and Linux.

  • GNOME Evolution: For Linux and Unix, this is an e-mail, calendar, and contact client for users of the GNOME desktop interface. Evolution requires the CalDAV plug-in to be installed.

Of course, the client that is glaringly missing from this list is Microsoft Outlook. Neither the Windows or Mac version supports CalDAV, and neither can be used with iCal Server. There is an open source plug-in for Outlook for Windows — the Outlook Connector Project with Microsoft Outlook — but it hasn’t been updated in over two years. Try at your own risk.

iCal Server and push notification service are based on open standards. The calendaring functionality uses CalDAV, which is based on webDAV, which is based on Hypertext Transfer Protocol (HTTP). The push-subscriber technology uses the Extensible Messaging and Presence Protocol (XMPP), which is based on Extensible Markup Language (XML). XMMP sends a small message (like a tweet) to the client, telling it that new data exists. The client then fetches that data.