Please, imagine a context that user import a .ics file on iCalendar application (e.g. Outlook, Google Calendar...) and after that, the events on .ics had some informations changed (hour/date changed, event cancelled...). The user receive other .ics file on email with event's informations up to date; he must import again and this time, the out of date events must be updated in order that user always has up to date events with only one .ics file. All information must be reflect in a single import.
How can I create this .ics file in order that a iCalendar application understand it and do the job?
Edited
Keeping in mind the context above: One user (let's call 'First User') receive a .ics file (let's call 'first.ics') by email with up to date events. The events was changed. The second.ics file was sent by email, but this time, for the First User and the Second User (a new user that don't import first.ics file).
How can I create this second.ics file in order that a iCalendar application understand it and do the job for First User and Second User?
This two users must have the same information up to date.
Neeryk,
The only way that you can have updates populate automatically to a users calendar application with a SINGLE step, is to have them 'SUBSCRIBE' to an ics url/file, NOT import.
If they subscribe to a URL it is of course visible in their calendar application AND the application will usually check periodically for updates. The system producing the ics file can then update that url and the events in it (make sure you have unique id's and use sequence numbers). The users calendar app will pickup the update on it's next check and show the changes.
If they 'import' the event then calendar applications do not check for updates. The only way to update would be to re-import.