On Fri, 5 Mar 2010 22:21:58 +0000 Chris G <cl@isbd.net> wrote:

After having a hard time trying to 'synchronize' a couple of applications which use iCalendar .ics files I had a little Google around to see if I could understand the problems I'm having.

I think quite a lot of the problem is that what I call synchronization is quite different (and rather more than) what everyone else means by the word.

There are so many possibilities I can see where confusion can set in. As an example it is possible to have a "Cloud" service where a calendar is maintained by a central server and the various clients can see, create, delete and edit events. There is no synchronisation here because the data is held centrally. Calendar synchronisation would have become popular in the days when PDAs couldn't expect to have their own network access but would rely on synchronising with a PC application. In a typical corporate environment that PC application would be using centrally held data whereas for a typical home user the data would be locally stored on the PC. These days, of course, many PDAs have WiFi and even those that don't may be part of a mobile phone and can this synchronise with a cloud service for example Google Calendar for Android, Exchange for Windows Mobile etc. It is still useful to have local data on the PDA though for times when the network is not available.

For example I found several places with quotes like the following:-

How to sync your google calendar with Evolution The access is read-only which means you cannot add events in Evolution and have them show up in your google calendar, but your events in google calendar will be available in Evolution for you to read.

I am sure two way access to Google calendar from Evolution now works but I'm not sure if it is really synchronisation which would imply, for example, being able to create an event in a Google calendar from within Evolution when the network is down and have the event added to the Google master version when the network comes back, or whether it is effectively a cache.

What I'm actually trying to do is to allow two people on a LAN to share a .ics file saved on a server, hardly hi-tech, but I'm really finding it well nigh impossible. A section of a whiteboard would be easier at the moment.

Surely .ics files are not designed to be multi-user. I would expect you would want a server that can maintain a calendar and enable it to be accessed via an open standard protocol and then have the various clients use that. Any .ics file could be imported and it would be useful to be able to export the calendar to be able to move it to a different server in the future. HTH, Steve.