/ 
WWW-CheckGzip-0.03
River stage zero No dependents
/ WWW::CheckGzip

NAME

WWW::CheckGzip - check web pages for correct gzipping of content

SYNOPSIS

# This example demonstrates use with the Test::More testing framework.
use Test::More;
use WWW::CheckGzip;
my $wc = WWW::CheckGzip->new (\& mycheck);
$wc->check ('http://www.piedpiper.com');
done_testing ();
exit;

sub mycheck
{
    my ($ok, $message) = @_;
    ok ($ok, $message);
}

produces output

ok 1 - successfully got compressed http://www.piedpiper.com
ok 2 - got content encoding
ok 3 - content encoding is gzip
ok 4 - http://www.piedpiper.com correctly gzipped
ok 5 - compression made it smaller
ok 6 - successfully got uncompressed http://www.piedpiper.com
ok 7 - Did not get content encoding
ok 8 - http://www.piedpiper.com not gzipped when requesting ungzipped
1..8

(This example is included as synopsis.pl in the distribution.)

VERSION

This documents version 0.03 of WWW::CheckGzip corresponding to git commit 18f7c39b6111935af7a67f0f22ef172f30a2e88e released on Thu Aug 17 17:43:51 2017 +0900.

DESCRIPTION

This module offers a way to check a web page for correct gzip compression. It tests the following, in the order given:

Page OK with compression

The web page is retrievable with an Accept-Encoding header set.

If the page is not retrievable, "check" calls the test callback, then returns and does no further actions.

Header OK

When sent a request with an Accept-Encoding header containing the string gzip, the web page responds with a content encoding header.

Header is gzip

The content encoding header of the response is gzip.

Content is in gzip format

The content of the web page's response is in the gzip format. This is checked using "gunzip" in Gzip::Faster.

Content is smaller

The size of the uncompressed content of the web page is larger than it is when compressed. This test will fail, for example, if gzip encoding is wrongly used to compress images or extremely small web pages.

Page OK without compression

The web page is retrievable without an Accept-Encoding header set.

Response has no gzip header

The web page does not send a gzip header if the Accept-Encoding header is not set.

Content is not compressed

The web page does not gzip compress the content when Accept-Encoding header is not sent. This is checked using "gunzip" in Gzip::Faster.

METHODS

new

my $wc = WWW::CheckGzip->new (\& test_sub);

Create a new object. The argument is a code reference to a subroutine of your choosing. The subroutine should take two arguments, a boolean $ok indicating whether the test was successful, and a string $message containing a descriptive message about the test. See "SYNOPSIS" for an example using the Test::More testing framework.

If you do not supply a function, a default function which prints the results to standard output is used. The return value is a blessed WWW::CheckGzip object.

check

$wc->check ('http://www.hooli.xyz');

Check the URL given as the argument. The tests call the callback supplied to "new". There is no return value. If no URL is supplied, a warning is printed and the function returns.

DEPENDENCIES

Carp

This is used to report user errors.

"gunzip" in Gzip::Faster

This is used to test whether the page content is in the gzip format or not.

LWP::UserAgent

This is used to retrieve the web page. However, this module deliberately does not use the built in methods of libwww-perl such as "decoded_content" in HTTP::Response, but explicitly does its own testing of the headers and the content returned.

LIMITATIONS

GET only

As of version 0.03, the module currently only does GET requests.

SCRIPT

A script checkgzip in the distribution checks web pages given to it on the command line:

checkgzip http://www.lemoda.net/

SEE ALSO

CPAN Modules

I'm not aware of any other module which explicitly checks for gzip-related problems from a web page.

WWW::Mechanize::GZip

This module retrieves gzip content from web pages.

Online gzip checkers

http://www.computerhandlung.de/www-mechanize-gzip.htm

By the author of WWW::Mechanize::GZip.

http://www.whatsmyip.org/http-compression-test/

Online AJAX checker with noises and colours.

https://varvy.com/tools/gzip/

Another AJAX checker.

https://developers.google.com/speed/pagespeed/insights/

Google PageSpeed Insights has compression checking as one of its facilities. For whatever reason it doesn't actually tell you if the page is compressed correctly, but only lets you know if there is a problem.

HISTORY

I created this module to have a simple command-line script or module for checking that gzip compression of my own web pages was working correctly.

On 6 March 2017, I suggested the module on PrePAN: http://prepan.org/module/nYdTCdrkEGF. Unfortunately it didn't get any responses. Initially I was planning to fork "WWW::Mechanize::GZip", and the old commits in the github repository contain some code from that module.

On 16 August 2017 I completely rewrote the module to remove the "WWW::Mechanize::GZip" parts and released version 0.01 to CPAN. The methodology the module currently uses is based on my web page: https://www.lemoda.net/compression/lwp-use-gzip/index.html.

AUTHOR

Ben Bullock, <bkb@cpan.org>

COPYRIGHT & LICENCE

This package and associated files are copyright (C) 2017 Ben Bullock.

You can use, copy, modify and redistribute this package and associated files under the Perl Artistic Licence or the GNU General Public Licence.