System.IO.Stream        stream;
TextStreamIo            io;
System.IO.StreamReader  reader;
XML                     fileContent;

io = TextStreamIo::constructForWrite();
io.writeExp(str2con(<String value/record>)));

stream = io.getStream();
stream.Position = 0;
reader = new System.IO.StreamReader(stream);
filecontent = reader.ReadToEnd();

//save file on local folder
//File::SendStringAsFileToUser(str content, str fileName, System.Text.Encoding encoding = System.Text.Encoding::get_UTF8(), ClassName fileUploadStrategyClassName = classstr(FileUploadTemporaryStorageStrategy))
File::SendStringAsFileToUser(fileContent, 'MyTextFile');