Search appointment by ICal in EWS Managed

Question

Hi all,
First of all, i have tried with the solution of henning however it dont seems to be the correct one... (http://www.infinitec.de/post/2009/04/13/Searching-a-meeting-with-a-specific-UID-using-Exchange-Web-Services-2007.aspx)
We have in our application the UniqueId of an appointment stored. So via this way we have an reference to the correct appointment of a user.
When we create a meeting we create based on the impersonated user. After that we iterate on all the attendees, impersonate each and get the appointment based on ICal.
With the solution of Henning, it seems that not always the correct Uid will be catched. Here is my code:
private Appointment FindAppointmentByICalUid(string iCalUid)
var filter = new SearchFilter.IsEqualTo
PropertyDefinition = new ExtendedPropertyDefinition
(DefaultExtendedPropertySet.Meeting, 0x03, MapiPropertyType.Binary),
Value = GetObjectIdStringFromUid(iCalUid) //Hex value converted to byte and base64 encoded
var view = new ItemView( 1 ) { PropertySet = new PropertySet( BasePropertySet.FirstClassProperties ) };
return _exchangeServer.FindItems(WellKnownFolderName.Calendar, filter, view).Items.FirstOrDefault() as Appointment;
/// <summary>
/// Gets the object id string from uid.
/// <remarks>The UID is formatted as a hex-string and the GlobalObjectId is displayed as a Base64 string.</remarks>
/// </summary>
/// <param name="iCalUid">The ICalUid</param>
/// <returns></returns>
private string GetObjectIdStringFromUid(string iCalUid)
var buffer = new byte[iCalUid.Length / 2];
for (int i = 0; i < iCalUid.Length / 2; i++)
var hexValue = byte.Parse(iCalUid.Substring(i * 2, 2), System.Globalization.NumberStyles.AllowHexSpecifier);
buffer[i] = hexValue;
return Convert.ToBase64String(buffer);

Answer 1

You might want to have a read of
http://blogs.msdn.com/b/mstehle/archive/2009/09/02/ews-uid-not-always-the-same-for-orphaned-instances-of-the-same-meeting.aspx which might be the problem your talking about.
Cheers
Glen