Update the time zone for an appointment by using EWS in Exchange

Learn how to update the time zone for an existing appointment or meeting by using the EWS Managed API or EWS in Exchange.

When an appointment or meeting is created on an Exchange calendar, the time zone used to specify the start and end times is saved as the creation time zone for the appointment. You can change that time zone by using the EWS Managed API or EWS. However, changing the time zone on an appointment has other effects on the start and end time of the appointment.

Time values are stored on the Exchange server in Coordinate Universal Time (UTC). So if an appointment is set to start at 1:00 PM (13:00) in the Eastern time zone (UTC-05:00), that value is stored as 6:00 PM (18:00) on the server, assuming that the time zone is in its standard time phase. When that appointment is viewed in other time zones, the appropriate number of hours is added or subtracted from the UTC value to determine the time zone-specific time. For example, if an appointment has a start time at 1:00 PM Eastern (6:00 PM UTC), and is viewed from a client in the Pacific time zone (UTC-08:00), the time-zone specific start time for that client would be 10:00 AM (18:00 - 08:00).

When you update the time zone of the appointment without updating the start and end time, the server updates the UTC values stored on the server to keep the start and end time as the same time zone-specific times. For example, consider the 1:00 PM Eastern appointment. The time is stored as 18:00 UTC on the server. If the time zone of the appointment is changed to the Pacific time zone, the server shifts the start time to 1:00 PM Pacific (21:00 UTC).

You can change this behavior by explicitly setting the start and end times.

Updating the time zone on an existing appointment by using the EWS Managed API

In the following example, the EWS Managed API is used to update the time zone on an existing appointment to the Central time zone by updating the Appointment.StartTimeZone and Appointment.EndTimeZone properties. If the shiftAppointnment parameter is set to true, the code does not explicitly set the start and end times on the appointment. In this case, the server will shift the start and end times to keep them at the same time zone-relative times in the new time zone. If set to false, the code converts the start and end times explicitly to keep the appointment at the same time in UTC.

This example assumes that the ExchangeService object has been initialized with valid values in the Credentials and Url properties.

static void UpdateAppointmentTimeZone(ExchangeService service, ItemId apptId, bool shiftAppointment)
{
    PropertySet includeTimeZones = new PropertySet(AppointmentSchema.Subject,
                                                   AppointmentSchema.Start,
                                                   AppointmentSchema.ReminderDueBy,
                                                   AppointmentSchema.End,
                                                   AppointmentSchema.StartTimeZone,
                                                   AppointmentSchema.EndTimeZone);
    Appointment apptToUpdate;
    // Load the existing appointment.
    // This will result in a call to EWS.
    try
    {
        apptToUpdate = Appointment.Bind(service, apptId, includeTimeZones);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Error retrieving existing appointment: {0}", ex.Message);
        return;
    }
    Console.WriteLine("Before update:");
    // Output the current start, reminder, end, and time zones.
    Console.WriteLine("  Start: {0}", apptToUpdate.Start);
    Console.WriteLine("  Start time zone: {0}", apptToUpdate.StartTimeZone.DisplayName);
    Console.WriteLine("  Reminder: {0}", apptToUpdate.ReminderDueBy);
    Console.WriteLine("  End: {0}", apptToUpdate.End);
    Console.WriteLine("  End time zone: {0}", apptToUpdate.EndTimeZone.DisplayName);
    // Retrieve the Central time zone.
    TimeZoneInfo centralTZ = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
    // Update the time zones on the appointment.
    apptToUpdate.StartTimeZone = centralTZ;
    apptToUpdate.EndTimeZone = centralTZ;
    if (!shiftAppointment)
    {
        // Set the start and end times explicitly so that the appointment
        // will start and end at the same UTC time.
        // Convert the times to then Central time zone. This
        // will keep them at the same time in UTC.
        // For example, 1:00 PM Eastern becomes 12:00 PM Central.
        DateTime newStartTime = TimeZoneInfo.ConvertTime(
            apptToUpdate.Start, centralTZ);
        DateTime newEndTime = TimeZoneInfo.ConvertTime(
            apptToUpdate.End, centralTZ);
        apptToUpdate.Start = newStartTime;
        apptToUpdate.End = newEndTime;
    }
    try
    {
        // Save the changes. This will result in a call to EWS.
        apptToUpdate.Update(ConflictResolutionMode.AlwaysOverwrite, 
            SendInvitationsOrCancellationsMode.SendToNone);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Error updating appointment: {0}", ex.Message);
        return;
    }
    // Now rebind to the appointment to get the new values.
    Appointment apptAfterUpdate;
    
    try
    {
        // This will result in a call to EWS.
        apptAfterUpdate = Appointment.Bind(service, apptId, includeTimeZones);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Error retrieving existing appointment: {0}", ex.Message);
        return;
    }
    Console.WriteLine("After update:");
    // Output the current start, reminder, end, and time zones.
    Console.WriteLine("  Start: {0}", apptAfterUpdate.Start);
    Console.WriteLine("  Start time zone: {0}", apptAfterUpdate.StartTimeZone.DisplayName);
    Console.WriteLine("  Reminder: {0}", apptAfterUpdate.ReminderDueBy);
    Console.WriteLine("  End: {0}", apptAfterUpdate.End);
    Console.WriteLine("  End time zone: {0}", apptAfterUpdate.EndTimeZone.DisplayName);
}

When the example is used to update an appointment that starts at 1:00 PM Eastern and ends at 2:00 PM Eastern, with the shiftAppointment parameter set to true, and the ExchangeService.TimeZone property set to the Eastern time zone, the output looks like the following.

Before update:
  Start: 6/20/2014 1:00:00 PM
  Start time zone: (UTC-05:00) Eastern Time (US & Canada)
  Reminder: 6/20/2014 1:00:00 PM
  End: 6/20/2014 2:00:00 PM
  End time zone: (UTC-05:00) Eastern Time (US & Canada)
After update:
  Start: 6/20/2014 2:00:00 PM
  Start time zone: (UTC-06:00) Central Time (US & Canada)
  Reminder: 6/20/2014 2:00:00 PM
  End: 6/20/2014 3:00:00 PM
  End time zone: (UTC-06:00) Central Time (US & Canada)

When the example is used to update the same appointment with the shiftAppointment parameter set to false, and with the TimeZone property again set to the Eastern time zone, the output looks a little different.

Before update:
  Start: 6/20/2014 1:00:00 PM
  Start time zone: (UTC-05:00) Eastern Time (US & Canada)
  Reminder: 6/20/2014 1:00:00 PM
  End: 6/20/2014 2:00:00 PM
  End time zone: (UTC-05:00) Eastern Time (US & Canada)
After update:
  Start: 6/20/2014 1:00:00 PM
  Start time zone: (UTC-06:00) Central Time (US & Canada)
  Reminder: 6/20/2014 1:00:00 PM
  End: 6/20/2014 2:00:00 PM
  End time zone: (UTC-06:00) Central Time (US & Canada)

Notice that the start and end times did not change. This is because the times are being interpreted in the Eastern time zone (because the TimeZone property is set to the Eastern time zone), and the time values were updated to prevent the appointment from shifting.

Updating the time zone on an existing appointment by using EWS

The following example EWS UpdateItem operation request updates the time zone on an appointment. This example only updates the StartTimeZone and EndTimeZone elements, so the server will shift the start and end times of the appointment to keep it at the same time-zone-relative time in the new time zone. The value of the ItemId element is shortened for readability.

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" 
    xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" 
    xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange2010" />
  </soap:Header>
  <soap:Body>
    <m:UpdateItem ConflictResolution="AlwaysOverwrite" SendMeetingInvitationsOrCancellations="SendToNone">
      <m:ItemChanges>
        <t:ItemChange>
          <t:ItemId Id="AAMkADA5..." ChangeKey="DwAAABYA..." />
          <t:Updates>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:StartTimeZone" />
              <t:CalendarItem>
                <t:StartTimeZone Id="Central Standard Time" />
              </t:CalendarItem>
            </t:SetItemField>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:EndTimeZone" />
              <t:CalendarItem>
                <t:EndTimeZone Id="Central Standard Time" />
              </t:CalendarItem>
            </t:SetItemField>
          </t:Updates>
        </t:ItemChange>
      </m:ItemChanges>
    </m:UpdateItem>
  </soap:Body>
</soap:Envelope>

The following example request updates the time zone of the appointment, and also updates the start and end times by explicitly setting the Start and End elements. The value of the ItemId element is shortened for readability.

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" 
    xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" 
    xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange2010" />
  </soap:Header>
  <soap:Body>
    <m:UpdateItem ConflictResolution="AlwaysOverwrite" SendMeetingInvitationsOrCancellations="SendToNone">
      <m:ItemChanges>
        <t:ItemChange>
          <t:ItemId Id="AAMkADA5..." ChangeKey="DwAAABYA..." />
          <t:Updates>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:StartTimeZone" />
              <t:CalendarItem>
                <t:StartTimeZone Id="Central Standard Time" />
              </t:CalendarItem>
            </t:SetItemField>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:EndTimeZone" />
              <t:CalendarItem>
                <t:EndTimeZone Id="Central Standard Time" />
              </t:CalendarItem>
            </t:SetItemField>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:Start" />
              <t:CalendarItem>
                <t:Start>2014-06-20T17:00:00.000Z</t:Start>
              </t:CalendarItem>
            </t:SetItemField>
            <t:SetItemField>
              <t:FieldURI FieldURI="calendar:End" />
              <t:CalendarItem>
                <t:End>2014-06-20T18:00:00.000Z</t:End>
              </t:CalendarItem>
            </t:SetItemField>
          </t:Updates>
        </t:ItemChange>
      </m:ItemChanges>
    </m:UpdateItem>
  </soap:Body>
</soap:Envelope>

See also