Get the organizer's calendar appointment using EWS for Exchange 2010

Question

I have an synchronization application with sync appointments with Exchange 2010, and i have some questions.

1. UserA creates an appointment and add UserB as atten

Answer 1

For anyone coming after me - here is the details on how this works. I'll also post reference to my blog with source files.

In short - appointments are tied together using the UID property. This property is also termed as the CleanUniqueIdentifier. While this example code could be adjusted based on a "bug" fix referenced in the blog post below, this source code is done because the requirements are to work with => 2007 SP1.

This assumes you have some prior knowledge of what the EWS is and how to use it (EWS API). This also is building off of blog post "EWS: UID not always the same for orphaned instances of the same meeting" and post "Searching a meeting with a specific UID using Exchange Web Services 2007"

Required setup for this to work:

1. User account that can be a "Delegate" or has "Impersonation" privileges for respective accounts.

Problem: Each "appointment" in exchange has a unique id (Appointment.Id) that is the exact instance identifier. Having this id, how can one find all related instances (recurring or attendee requests) in a calendar?

The code below outlines how this can be accomplished.

[TestFixture]
public class BookAndFindRelatedAppoitnmentTest
{
  public const string ExchangeWebServiceUrl = "https://contoso.com/ews/Exchange.asmx";

  [Test]
  public void TestThatAppointmentsAreRelated()
  {
    ExchangeService service = GetExchangeService();

    //Impersonate the user who is creating the Appointment request
    service.ImpersonatedUserId = new ImpersonatedUserId( ConnectingIdType.PrincipalName, "Test1" );
    Appointment apptRequest = CreateAppointmentRequest( service, new Attendee( "Test2@contoso.com" ) );

    //After the appointment is created, we must rebind the data for the appointment in order to set the Unique Id
    apptRequest = Appointment.Bind( service, apptRequest.Id );

    //Impersonate the Attendee and locate the appointment on their calendar
    service.ImpersonatedUserId = new ImpersonatedUserId( ConnectingIdType.PrincipalName, "Test2" );
    //Sleep for a second to let the meeting request propogate YMMV so you may need to increase the sleep for this test
    System.Threading.Thread.Sleep( 1000 );
    Appointment relatedAppt = FindRelatedAppointment( service, apptRequest );

    Assert.AreNotEqual( apptRequest.Id, relatedAppt.Id );
    Assert.AreEqual( apptRequest.ICalUid, relatedAppt.ICalUid );
  }

  private static Appointment CreateAppointmentRequest( ExchangeService service, params Attendee[] attendees )
  {
    // Create the appointment.
    Appointment appointment = new Appointment( service )
    {
      // Set properties on the appointment.
      Subject = "Test Appointment",
      Body = "Testing Exchange Services and Appointment relationships.",
      Start = DateTime.Now,
      End = DateTime.Now.AddHours( 1 ),
      Location = "Your moms house",
    };

    //Add the attendess
    Array.ForEach( attendees, a => appointment.RequiredAttendees.Add( a ) );

    // Save the appointment and send out invites
    appointment.Save( SendInvitationsMode.SendToAllAndSaveCopy );

    return appointment;
  }

  /// <summary>
  /// Finds the related Appointment.
  /// </summary>
  /// <param name="service">The service.</param>
  /// <param name="apptRequest">The appt request.</param>
  /// <returns></returns>
  private static Appointment FindRelatedAppointment( ExchangeService service, Appointment apptRequest )
  {
    var filter = new SearchFilter.IsEqualTo
    {
      PropertyDefinition = new ExtendedPropertyDefinition
        ( DefaultExtendedPropertySet.Meeting, 0x03, MapiPropertyType.Binary ),
      Value = GetObjectIdStringFromUid( apptRequest.ICalUid ) //Hex value converted to byte and base64 encoded
    };

    var view = new ItemView( 1 ) { PropertySet = new PropertySet( BasePropertySet.FirstClassProperties ) };

    return service.FindItems( WellKnownFolderName.Calendar, filter, view ).Items[ 0 ] as Appointment;
  }

  /// <summary>
  /// Gets the exchange service.
  /// </summary>
  /// <returns></returns>
  private static ExchangeService GetExchangeService()
  {
    //You can use AutoDiscovery also but in my scenario, I have it turned off      
    return new ExchangeService( ExchangeVersion.Exchange2007_SP1 )
    {
      Credentials = new System.Net.NetworkCredential( "dan.test", "Password1" ),
      Url = new Uri( ExchangeWebServiceUrl )
    };
  }

  /// <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="id">The uid.</param>
  /// <returns></returns>
  private static string GetObjectIdStringFromUid( string id )
  {
    var buffer = new byte[ id.Length / 2 ];
    for ( int i = 0; i < id.Length / 2; i++ )
    {
      var hexValue = byte.Parse( id.Substring( i * 2, 2 ), System.Globalization.NumberStyles.AllowHexSpecifier );
      buffer[ i ] = hexValue;
    }
    return Convert.ToBase64String( buffer );
  }
}