composer.json

{
    "require": {
        "hoa/file": "0.14.12.10"
    }
}

main.php

<?php
require_once "vendor/autoload.php";

$file = new \Hoa\File\Read('https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css');

$file->on('progress', function () {

	echo 'Hello';
});

echo md5($file->readAll());