public List<User> GetOnlineContacts()
 {
     using (ContactsOperations ops = new ContactsOperations())
     {
         return ops.GetOnlineUsers();
     }
 }
 public void ChangeUserStatus(string userHash, bool online)
 {
     using (ContactsOperations ops = new ContactsOperations())
     {
         try
         {
             ops.ChangeUserOnlineState(userHash, online);
         }
         catch (InvalidOperationException e)
         {
             throw new FaultException(e.Message);
         }
     }
 }
 public ContactsStatusNotificationService()
 {
     ops = new ContactsOperations(true, On_UsersCacheChanged);
 }