Gzip Output¶

What does it do?¶

When using big Javascript files, the delay of execution, caused by the loading time, may be nerve-racking for your customers and the end users. So there are are a lot of tools, that compress the files by restructuring them, like Jsmin (shipped with Typo3 4.2), YUI Compressor or Packer. Those tools reduce the size of a big JS file already a lot, but using Gzip compression reduces the files even A LOT more. Typo3 can do this for regular pages, but not for external files like Javascripts or CSS files. So you could use mod_compress or mod_deflate for this. If this webserver modules are not available you can use this extension, to get the job done with PHP.

Additionally you can tell the client, how long a file may remain in the browser/proxy – cache before it needs to be reloaded from the server. Typo3 Core has some .htaccess files, which show you how to use this for images (like icons) in the backend. Of course you can use this for your javascripts too, but it requires mod_expires to be installed. This extension will send those caching headers for you too.

So, what does it do? It gzips files and sends them to the client with caching headers.

You can use this for your files, using a PHP class, a simple Typoscript or (the simple way) by doing a URL rewrite. Much of the code of this extension is based upon a sample PHP file, written by Julien Lecomte. For more information on this issue, please visit his blog

Requirements¶

To make this work you need at least PHP 5.0, because the main class of this tool has methods, declared as protected, public and final. You will get a parse error when trying to use it with PHP 4.x

This tool makes use of the eID feature of TYPO3 which is available since version 4.0, so it won't work with 3.x

To get the full advantage of the caching headers feature, you will need the pecl_http extension for PHP, but most of the tool will work without it.

Which headers are sent¶

There are several checks before the actual sending of the file.

Is the request a vaild eID request with all parameters needed? Is it a TYPO3 process at all?If not, the script ends with a 400 – Bad Request header.

Is the file inside the allowed paths (a simple security check)?If not, a 403 – Forbidden header is send

Does the request wants an existing file?If not, the script quits with a 404 – Not found header

Has the file already be sent, but expired?If yes, and the file didn't change in between, a 304 – Not modified header is sent, so the client still takes the cached file. (Works only of pecl_http extension is installed!)

If the script didn't quit yet, the following headers are sent with the content (Customisable at the extension manager):

• Last-ModifiedThe last modified date of the file itself
• ExpiresThe current date + x days (Defined during installation. Defaults to seven days, but it can be a good idea to use a “never expire” header, by setting it to eg.: 300 days)
• The Etag
• The Pragma header is set to “public”
• And Cache-Control headers which complete the Expires header

Note: To calculate the max-age header, Gzip now uses the current timestamp instead of the last modified timestamp of a file, so there is no problem with old files.

Additional Note¶

The API currently supports adding CSS and Javascript files, but you can use it for more files using a simple URL rewrite. This is explained in the “Configuration” chapter.

It's actually not a good idea to use gzipping and an advanced compressing script together (like Packer by Dean Edwards), because the gain of speed while transfering maybe lost, if the browser has to decompress it twice. You should consider using a less “aggressive” compressor like JSMin or YUI Compressor .

PHP¶

This is pretty simple, just get an instance of the script, call the url method and give the path to your file as first parameter. For performance resons, the class is not loaded by default but there is a loader function available.

Example:

// My file I want to compres
$file = t3lib_extMgm::siteRelPath('myExtKey') . 'res/coolCalenderApp.js';

// Load and compress it
$gzip = tx_gzip_load();
$compressed_file = $gzip->url($file);

// Add to header
$GLOBALS['TSFE']->additionalHeaderData[] = '<script type=”text/javascript” src=”'.$compressed_file.'”></script>';

This example will take the file, save a gzipped version to typo3temp/gzip and give back an url to index.php with the needed params set. The method supports a secound parameter: $fullURI. Set this to true to prepend the index.php with the URL of the set page. This method also supports the EXT: prefix

So:

$file = 'EXT:myext/res/big.js';
$gzip = tx_gzip_load();

// Will usally return
// index.php?eID=tx_gzip_ouput&uri=typo3conf%2Fext%2Fmyextt%2Frest%2Fbig.js
$gzip->url($file);

// And this will return
// http://www.domain.tld/index.php?eID=tx_gzip_ouput&uri=typo3conf%2Fext%2Fmyextt%2Frest%2Fbig.js
$gzip->url($file, TRUE);

I developed this for the frontend, but though I did not much testing with the backend yet, it should work without problems. At least when using the $fullURI option

URL Rewrite¶

Note: The example below and inside the example files rewrite both frontend and backend URLs. I made some testing without running into troubles with that. The backend was even faster!

Inside the doc folder of this extension there is the file example.htaccess which contains a complete rewrite setup for Gzip and RealURL which succeeded on all systems I tested yet. just take a look.

It simply adds two lines, which takes every .css or .js file, and puts them to the gzip script. This looks like this:

RewriteCond  %{REQUEST_FILENAME} .*\.(css|js)$
RewriteRule .*  index.php?eID=tx_gzip_output [L]

I recently fell in love with lighty (lighttpd). So a rewrite configuration for this tool was needed and here it is:

...
        url.rewrite-once = (
                "^.*\.(js|css)$" => "index.php?eID=tx_gzip_output",
        )
...

Inside the doc folder you will find an example file (lighttpd- rewrite.conf) which contains the example above together with a tested RealURL configuration.

After some testing I feel like to prefer this method over calling $gzip->url();, simply for two reasons:

You don't have to take care of the availability of tx_gzip while writing your own code

Since the URI changes, relative links to external files in CSS files (eg: background images) are currently broken.