Kerb5Context ( String host, String service, String name, int userLifetime, int contextLifetime, String realm ) throws GSSException {
        GSSManager manager = GSSManager.getInstance();
        GSSCredential clientCreds = null;
        Oid mechOid = JGSS_KRB5_MECH_OID;
        if ( realm != null ) {
            this.serviceName = manager.createName(service + "/" + host + "@" + realm, JGSS_KRB5_NAME_OID, mechOid);
        }