how to parse a secured file in php and make it available in pdf using wkhtmltopdf

wkhtmltopdf.php

//if expected template available in string formate
if($string1)
{
		//write the expected template in a unique html file
    write_file("uploads/$classId/Result-$classId-part$number.html", $string1);
    //make the unique url for the html
    $fileUrl = base_url()."uploads/$classId/Result-$classId-part$number.html";
    //run exec funtion and fee the html link to wkhtml function with requed pdf link(unique)
    exec('"C:\Program Files\wkhtmltopdf\bin\wkhtmltopdf.exe" '.$fileUrl. ' uploads/'.$classId.'/'.$number.".pdf");
    //after execution remove the html file
    unlink("uploads/$classId/Result-$classId-part$number.html");
 }