We’ve been using this calendar server for quite a while now and without any incidents, failures or operational problems. I shall probably upgrade it to the 1.0 in a short while, but seeing how reliable our 0.13svn system has been I’m a bit reticent  – you know the old adage; “if it ain’t broke, don’t fix it!”.

So, what’s a calendar server then?

Think of google calendar or something similar that allows you run multiple calendars and decide who gets to see what bits of your life story.

Cosmo is one of these. It supports various communications methods including the public IETF standard CalDAV protocol to talk to calendaring clients (iCal, Sunbird, Lightning…) and it also has a built-in web interface so you can access your calendar when away from your desk/laptop computers.

The neat thing about the way Cosmo works is the way you manage and publish your separate calendars (called collections). You issue tickets that can be everlasting or time-limited and can provide full read/write access, read-only access or just show free/busy status, and you can send these tickets to as many people as you like – no need for creating accounts and passwords for the recipients.

Here’s a screenshot of Mozilla Thunderbird using the Lightning (calendaring) plugin. All the data is resident on our Chandler calendar server and is accessed via the CalDAV protocol.

The list down the left shows the various calendar collections to which I have access and the main screen shows all the events and tasks color coded for the month of June.

Here’s a similar shot but of the Cosmo UI in a web browser.

Cosmo is a Java application that runs in a Tomcat server. We have ours running on my little low power VIA C7N server and it has been running happily for a year or so with no interruption to service.

Interestingly, Google has just made available a CalDAV interface to their calendar system too. It is a bit rough around the edges currently and is only supposed to support Apple’s iCal client but thanks to a comment from Roberto via the cosmo mailing list, I made a brief test with Lightning using CalDAV and it appears to work O.K. But don’t take my word for it: in Sunbird or Lightning, use the following URL to talk to your Google calendar:

https://www.google.com/calendar/dav/UserName@gmail.com/events

It’s alright, although managing multiple collections, or calendars, with Google is no where near as easy as it is using Cosmo. But being able to now collate all your calendars into your desktop with Lightning and CalDAV is great!