public static LiteralControl XmlFileTransform(string xmlfile, string xslfile)
        {
            XslTransform xslt;
            XPathDocument xml;
            StringWriter writer = new StringWriter();
            try
            {
                xml = new XPathDocument(new XmlTextReader(xmlfile));

                xslt = new XslTransform();
                xslt.Load(xslfile);
                xslt.Transform(xml, null, writer, null);

                return new LiteralControl(writer.ToString());
            }
            catch(Exception e)
            {
                writer.Write(e.Message);
            }
            return null;
        }