Cancel appointment and associated resources in Outlook when created using EWS Managed API

Question

I am using the EWS Managed API to create appoitments on Exchange 2010.

Appointment appointment = new Appointment(exchangeService);

appointment.Subject = "Sample meeting";
appointment.Body = "Sample meeting body";
appointment.Start = bookingInfo.from;
appointment.End = bookingInfo.from.AddMinutes(bookingInfo.duration);

appointment.Location = meetingRoom.displayName;
appointment.Resources.Add(<my_room_mail>);

// Send the meeting request to all attendees and save a copy in the Sent Items folder.
appointment.Save(SendInvitationsMode.SendToAllAndSaveCopy);

This piece of code create effectively an appoitment in my Outlook but the Meeting Room included as a resource is marked as a "tentative" (not really accepted). So when I want to delete the meeting, the meeting room stay booked (busy/tentative) for the slot and it is impossible to delete the tentative.

If I delete the appoitment from the EWS code (using the appoitment ID), it works as expected, the room is effectively free.

Appointment appointment = Appointment.Bind(exchangeService, new ItemId(itemId));
appointment.Delete(DeleteMode.MoveToDeletedItems);

Do you have any idea of what is the problem ? Outlook right ? Bad appoitment creation or resource booking ?

Answer 1

Ok, I understand that Direct Booking is not compatible with EWS/OWA/Mobile solutions (and also with Outlook 2010/2013 without register tweak).

Direct Booking and Resource Booking Attendant (Auto Accept feature) are conflicting technologies, and if enabled together, unexpected behavior in calendar processing and item consistency can occur.

Check this for more details :

• http://msexchangeanswers.blogspot.fr/2009/08/outlook-direct-booking-vs-auto-accept_17.html
• http://exchangeserverinfo.net/2013/05/remove-auto-accept-from-outlook-for-all-room-mailbox/

Answer 2

The resource room needs to auto-accept the invitation, so it loses its tentative status. Then when you delete the appointment from your calendar, it should automatically send cancellation to the room. There is a setting on the delete to do this, and I forget off the top of my head if it's the default or not, but I think the initial issue is why the room is not configured to accept or reject the invite sent.