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 0.05 of WWW::CheckGzip corresponding to git commit c2e1c0b7f8722fa48778c1027ae79c3019348a0b released on Wed Oct 4 11:01:08 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.
TESTING
In order to not cause problems for testers, this module does not attempt to connect to the internet during its tests. To run the module's tests with a real web site, set the environment variable WEBSITE to a real website you know to be well-behaved with regards to gzip compression. For example, on a Unix-like system,
export WEBSITE=http://www.hooli.xyz
make test
# clean up if necessary as follows
export WEBSITE=
will cause the module to attempt to connect to the given web site and check its compression.
The tests will fail if the web site does not use gzip correctly, so using your local web server may cause test failures which are not this module's fault.
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.
- HTTP::Tiny
-
This is used to retrieve the web page. Until version 0.04, LWP::UserAgent was used.
LIMITATIONS
SCRIPT
A script checkgzip in the distribution checks web pages given to it on the command line:
checkgzip http://www.lemoda.net/
"No output" indicates success, so that this can be used by, for example cron jobs.
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.
About compression on the web
- web-gzip
-
Some scripts by the author of this module related to compression of static content (content which does not change with each request, such as JavaScript files).
- Compressing CGI output with Perl and Gzip::Faster
-
A very simple demonstration of compression using CGI (the common gateway interface) and Gzip::Faster.
- Gzip handler in Go
-
Similar to the above, but for the Go language.
- Compressing CGI output with Perl
-
Another Perl example, this time using the IO::Compress::Gzip module instead of Gzip::Faster.
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 used was based on my web page https://www.lemoda.net/compression/lwp-use-gzip/index.html.
On 1 October 2017, for version 0.04, I changed from LWP::UserAgent to HTTP::Tiny at the suggestion of a blog commentator.
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.