I've been trying to make sense of the current state-of-play of calendar and event publishing standards. Two things have motiviated me to look at this.
1) I'm fed up of Outlook for holding events and appointments for the whole family. Outlook is meant for one person hosted in a corporate environment and just doesn't do the family scenario very well. It's viewing options are pretty restricted. For instance, in month view it munges Saturday and Sunday into one little box (like nothing happens on a weekend!) while weekdays get their own boxes. I'd like to find a new solution. Rather than a PIM, call it a FIM - a Family Information Manager.
2) The Internet is a great tool for finding out what's on but it's a lot of work. I would love an effortless way to discover events that are going on without me having to do all the searching and filtering. Think of it as Google for events. This is an obvious and ancient problem so I assumed the Internet had evolved a practical solution by now just waiting for me to look it up.
Looking for PIM's, I didn't find a better alternative than Outlook. The next best seemed to be Above & Beyond 2004 but again, it's focused on the corporate scenario and the UI is basic. On the Mac, there's Apple's iCal which looks pretty but is no good to me. Dead end.
So what about standards? Well, there's iCalendar which is RFC2445 and published way back in 1998. From a quick scan, it's seem to be primarily an exchange format between PIMs and pretty comprehensive. Apple uses it and iCalShare promotes sharing files in this format.
There was IETF work to bring iCal into the XML world and calling it xCal but I gather it's dead.
Looking around some more I found that Ray Ozzie had posted about the same issue last year and I learned about Upcoming. Yet another place to manually search for events and very little help to discover or get notified of events that you would probably like to know about.
I also found the recently launched RSSCalendar.com beta. Nice simple idea for event publication and syndication. However it embeds the event information as HTML in the RSS 2.0 description and then provides links to iCal or vCal data. It allows broad reach and can be pretty handy if there's several well known publishers of events that you want to manually monitor.
However, still hadn't found a solution for elegant aggregation of events or discovering new events. I want something like radicalendar personlised just for my interests.
There's RdfCalendar which would seem to be the right direction for the semantic web since it makes the event information transparent and searchable. However, it's somewhere on the horizon.
Meanwhile, a simplistic approach is the RSS Events Module which extends the RSS feed format with an event name space and five new elements to describe the event. At least this means the event is no longer opaque in the feed and a smart client could start doing something with it.
I found a good summary of these standards as part of a proposed calendar extensions to webdav and a summary of what's going on with iCal. The impression I get is that iCal rules on the desktop and is still the best standard. Meanwhile RDF Calendar or an RDF version of iCal is the future. In the meantime, we'll get by with some RDF inside RSS to describe events.