Our solution needs to understand Exchange Fast Transfer Stream like the m:data at below for calendar:
<m:ExportItemsResponseMessage ResponseClass="Success">
<m:ResponseCode>NoError</m:ResponseCode>
<m:ItemId Id="AAMkAGYzZjZmRiUsidkC+NAAAAY89GAAA=" ChangeKey="FwAAAA=="/>
<m:Data>
AQAAAAgAAAAAAAAALgBlAHgAdABlAHMAdAAuAG0AaQBjAHIAbwBzAG8AZgB0AC4A
YwBvAG0AAABTAE0AVABQAAAAVQBzAGUAcgAyAEAAYQB1AGoAaQBuAGcALQBkAG8AbQAuAGUA
eAB0AGUAcwB0AC4AbQBpAGMAcgBvAHMAbwBmAHQALgBjAG8AbQAAALCE/jlMAAAAVQBzAGUA
cgAyAEAAYQB1AGoAaQBuAGcALQBkAG8AbQAuAGUAeAB0AGUAcwB0AC4AbQBpAGMAcgBvAHMA
bwBmAHQALgBjAG8AbQAAAAMAADkAAAAAAwD+DwYAAAADAARAAwACQAMADkA=
</m:Data>
</m:ExportItemsResponseMessage>
I found out that MS protocol document around this [MS-OXWSBTRF]: Bulk Transfer Web Service Protocol, however it doesn't talk about how to parse the m:Data element. I did base64 decoding on it and it would become partially readable although not all the information though. I also found this link Exchange 2010 EWS ExportItems Data field where a parser was written by Glen Scales although it is not available at CodePlex any more. I also found out outlook redemption could import this into outlook although I didn't see if it could parse it and make it available for our program to use. Plus it would require outlook installation.
Any insights would be highly appreciated.
[Update on Aug 27]. Our goal is to be able to move calendars from other platforms such as google and yahoo into Exchange Online. When we created the appointment for both organizer and attendee via EWS, we are facing some challenges in reestablish the relationship and we are seeing this issue when organizer sends update to attendee.
Basically attendee would see the message "The meeting request was updated after this message was sent. You should open a later update or open the item on the calendar" for both update and cancel message. Any insights here for what MAPI properties to fix would be greatly appreciated as well.
However we are able to move calendars successful with Exchange Web Services export and import via FTS and that is why we are looking for how to generate FTS stream via Outlook Redemption and then use EWS to import those FTS data into Exchange Online side.
However if outlook redemption could allow us to import ics file directly into end user mailbox, that would be even better where we found out that service account needs full access to all mailboxes. From my manual testing, manual importing ics files into both organizer and attendee mailbox are able to re-establish the relationship. Again, it would be really appreciated for any suggestions for above "The meeting request was updated after this message was sent. You should open a later update or open the item on the calendar".
The format is indeed undocumented. It is essentially a list of properties separated by page breaks (to be able to send/receive it in chunks while parsing).
Redemption (I am its author) supports that format through RDOMail.SaveAs
/ Import
; the format type is olFTS
.
You can also see the FST data in OutlookSpy (I am also its author) - click GetItem button on the EWS section of the OutlookSpy ribbon, go to the ExportItems tab. To import an FTS stream, click GetFolder | UploadItems.