PHP Manual GZip Encoding

Question

I was testing my website with Page Speed and the result was around 70/100. Enable Compression was the first and most important factor in slowing it down.

I know that

Answer 1

I'd suggest to use http://php.net/manual/de/function.ob-gzhandler.php, this works out of the box for me:

In my index.php I just place this before some output:

    /**
     * Enable GZIP-Compression for Browser that support it.
     */
    ob_start("ob_gzhandler");

And it encodes it!

Answer 2

A few things:

1. You probably want to add another header: header('Content-Encoding: gzip');

2. You are using ob_end_clean, which deletes all echoed/printed content without sending it to the browser. Depending on what you're trying to do, you may want to use ob_flush instead.

3. To make sure your output is buffered and handled (and compressed if you use PHP's output buffering compression), make sure all echo/print statements are placed BETWEEN the ob_start and ob_flush sttements.

--and then try it again :)

Answer 3

Well, I think it's because you're trying to compress an empty string.

I took your script as you gave it, and ran it in FF and IE.

Both failed, and FF said that there was an issue (like you described).

However, I then noticed $data is an empty string.

When I set $data = "Some test data."; at the top of the file it worked immediately (browser displayed "Some test data."), and checking in Firebug, I can see the correct headers.

Content-Encoding    gzip
Content-Length  68
Vary    Accept-Encoding
Content-Type    text/html

Edit: Also, just to point out, your if ($supportsGzip) { is a bit odd, because your else condition should actually echo out $data, not $content.

Edit: Okay, based on your revised function above, there are two key problems.

The primary problem has to do with the fact that you're wiping out your headers by calling ob_end_clean(). A comment on the PHP Docs states that "ob_end_clean() does discard headers".

This means any headers you set before calling ob_end_clean() will get wiped. Also, your revised function doesn't send a gzip encoding header, either.

I must say that there is probably no need to even use ob_start and related functions here, either. Try the following:

function _compress( $data ) {

    $supportsGzip = strpos( $_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip' ) !== false;


    if ( $supportsGzip ) {
        $content = gzencode( trim( preg_replace( '/\s+/', ' ', $data ) ), 9);
        header('Content-Encoding: gzip');
    } else {
        $content = $data;
    }

    $offset = 60 * 60;
    $expire = "expires: " . gmdate("D, d M Y H:i:s", time() + $offset) . " GMT";

    header("content-type: text/html; charset: UTF-8");
    header("cache-control: must-revalidate");
    header( $expire );
    header( 'Content-Length: ' . strlen( $content ) );
    header('Vary: Accept-Encoding');

    echo $content;

}

_compress( "Some test data" );

This works in IE and FF, but I didn't have time to test other browsers.

If you really must use ob_start and related functions, make sure you set your headers after you call ob_end_clean().