How to add required attendees in appoitment in microsoft crm - dynamics-crm-4

Question

I added a new contact in microsoft dynamics 4.0 from C#. How to required attendees from code? I created a contact like this. now how to add this contact as required attendees for selected appointment ?
CRM.CrmService service = GetService();
var contactResult = new contact
{
emailaddress1 = userContact.Email
};
var requestContact = new RetrieveDuplicatesRequest
{
BusinessEntity = contactResult
,
MatchingEntityName = EntityName.contact.ToString()
,
PagingInfo = new PagingInfo
{
PageNumber = 1,
Count = 1
}
};
bool blnEmailExists = false;
try
{
var response = (RetrieveDuplicatesResponse)
service.Execute(requestContact);
foreach (contact contactItem in response.DuplicateCollection.BusinessEntities)
{
blnEmailExists = true;
contactResult.contactid = new Key();
contactResult.contactid.Value = new Guid(contactItem.contactid.Value.ToString());
contactResult.firstname = userContact.FirstName;
contactResult.lastname = userContact.LastName;
contactResult.fullname = userContact.FullName;
contactResult.mobilephone = userContact.PhoneNumber;
contactResult.description = userContact.Description;
service.Update(contactResult);
}
if (!blnEmailExists)
{
contactResult.firstname = userContact.FirstName;
contactResult.lastname = userContact.LastName;
contactResult.fullname = userContact.FullName;
contactResult.mobilephone = userContact.PhoneNumber;
contactResult.description = userContact.Description;
Guid contactId = service.Create(contactResult);
if (!string.IsNullOrEmpty(userContact.Notes))
AppendToNotesSection(userContact.Notes, contactId, service);
}
}
catch (System.Web.Services.Protocols.SoapException ex)
{
throw new Exception(ex.Message);
}
Thanks

Answer 1

Through activityParty it can be updated, atlast i found it and fixed.
CRM.CrmService service = GetService();
appointment appointment = (appointment)service.Retrieve(EntityName.appointment.ToString(), activityid, new AllColumns());
if(appointment == null)
{
throw new ArgumentNullException("Invalid Appointment");
}
contact contact = RegisterContact(userContact, service);
activityparty[] activityParty = new activityparty[appointment.requiredattendees.Length + 1];
activityParty[0] = new activityparty();
activityParty[0].partyid = new Lookup();
activityParty[0].partyid.Value = contact.contactid.Value;
activityParty[0].partyid.type = "contact";
Int16 index = 1;
foreach (var item in appointment.requiredattendees)
{
//for avoiding duplicates
if (item.partyid.Value != contact.contactid.Value)
{
activityParty[index] = new activityparty();
activityParty[index].partyid = item.partyid;
activityParty[index].partyid.Value = item.partyid.Value;
activityParty[index].partyid.type = item.partyid.type;
index++;
}
}
appointment.requiredattendees = activityParty;
try
{
service.Update(appointment);
}
catch (System.Web.Services.Protocols.SoapException ex)
{
Console.WriteLine(ex.Message + ". " + ex.Detail.InnerText);
}