public static AuthenticationSessionModel Instance()
        {
            if (_authenticationSessionModel == null)
            {
                _authenticationSessionModel = new AuthenticationSessionModel();
            }

            return _authenticationSessionModel;
        }
 public static AuthenticationSessionModel Instance(OATSDBEntities iDb)
 {
     if (_authenticationSessionModel == null)
     {
         _authenticationSessionModel = new AuthenticationSessionModel();
         _authenticationSessionModel.db = iDb;
     }
     return _authenticationSessionModel;
 }