public bool Exists(ItemIdentifier itemId)
        {
            //encrypt login and password
            string loginName = "";
            string pass = "";
            getloginAndPass(UserId, ref loginName, ref pass);
            string _url = getWSUrl(this.Url);

            RepositoryWebservice repo = new RepositoryWebservice(_url);
            repo.Credentials = new System.Net.NetworkCredential(loginName, pass);

            bool exists = repo.Exists(itemId, loginName, pass);

            repo.Dispose();
            return exists;
        }