Does value of ICalRecurrenceId ever change for each instance of recurring meeting

Question

I want to import all the meetings for a number of users into a database. I'm using the EWS Managed API and C#

When I import meetings from each mailbox, I might encounter the same meeting multiple times if each of the users have been invited to that meeting.

For single instance meetings I can use the value of ICalUid to get the unique ID of the meeting and so I will be able to only store one instance of it.

However, for recurring meetings it is not clear what additional field I should use (along with ICalUid) to identity each instance of a recurring meeting series.

Can I reliably use ICalRecurrenceId? Will this value ever change? Will it be consistent when the meeting instance is imported from multiple mailboxes? Is there a better field that I can/should use to meet my needs?

Note - I've looked at using the ItemId field but this returns a different value when the same meeting is returned from different mailboxes. I need to be able to identity a meeting instance regardless of what mailbox it was imported from.

Answer 1

This question has been here for years but I hope this answer gives some information for people who need.

• ICalUid: is the UID of the meeting and will not be changed across calendars.
• ICalRecurrenceId: is the original start time of each occurrence of the recurrence meeting.
• All the occurrences of a recurrence meeting will have same ICalUid but ICalRecurrenceId will be different.
• On start time modification of an occurrence, ICalUid and ICalRecurrenceId will not be changed.
• On start time modification of a recurrence meeting, ICalUid will be retained but the ICalRecurrenceId will be changed for all occurrences

So to resolve your problem, the combination of the two values will be good enough.