public override string[] GetAvailableRevisions()
        {
            //encrypt login and password
            string loginName = "";
            string pass = "";
            getloginAndPass(UserId, ref loginName, ref pass);

            string _url = getWSUrl(this.Url);

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

            return repo.GetAvailableRevisions(loginName, pass);
        }