/ 
CGI-Buffer-0.56
River stage zero No dependents
/ CGI::Buffer

NAME

CGI::Buffer - Verify and Optimise CGI Output

VERSION

Version 0.56

SYNOPSIS

CGI::Buffer verifies the HTML that you produce by passing it through HTML::Lint.

CGI::Buffer optimises CGI programs by compressing output to speed up the transmission and by nearly seamlessly making use of client and server caches.

To make use of client caches, that is to say to reduce needless calls to your server asking for the same data, all you need to do is to include the package, and it does the rest.

use CGI::Buffer;
# ...

To also make use of server caches, that is to say to save regenerating output when different clients ask you for the same data, you will need to create a cache. But that's simple:

    use CGI::Buffer;
    use CHI;

    # Put this at the top before you output anything
    CGI::Buffer::init(
	cache => CHI->new(driver => 'File')
    );
    if(CGI::Buffer::is_cached()) {
	exit;
    }

    # ...

SUBROUTINES/METHODS

init

Set various options and override default values.

    # Put this toward the top of your program before you do anything
    # By default, generate_tag and compress_content are both ON and
    # optimise_content and lint_content are OFF.  Set optimise_content to 2 to
    # do aggressive JavaScript optimisations which may fail.
    use CGI::Buffer;
    CGI::Buffer::init(
	generate_etag => 1,	# make good use of client's cache
	generate_last_modified => 1,	# more use of client's cache
	compress_content => 1,	# if gzip the output
	optimise_content => 0,	# optimise your program's HTML, CSS and JavaScript
	cache => CHI->new(driver => 'File'),	# cache requests
	cache_key => 'string',		# key for the cache
	stats_file => '/tmp/stats',	# File to keep statistics of CGI::Buffer
	lint->content => 0,	# Pass through HTML::Lint
    );

If no cache_key is given, one will be generated which may not be unique. The cache_key should be a unique value dependent upon the values set by the browser.

The cache object will be an instantiation of a class that understands get, set, created_at and is_valid, such as CHI.

To generate a last_modified header, you must give a cache object.

Init allows a reference of the options to be passed. So both of these work: use CGI::Buffer; #... CGI::Buffer::init(generate_etag => 1); CGI::Buffer::init({ generate_etag => 1 });

Generally speaking, passing by reference is better since it copies less on to the stack.

Alternatively you can give the options when loading the package: use CGI::Buffer { optimise_content => 1 };

set_options

Synonym for init, kept for historical reasons.

is_cached

Returns true if the output is cached. If it is then it means that all of the expensive routines in the CGI script can be by-passed because we already have the result stored in the cache.

    # Put this toward the top of your program before you do anything

    # Example key generation - use whatever you want as something
    # unique for this call, so that subsequent calls with the same
    # values match something in the cache
    use CGI::Info;
    use CGI::Lingua;

    my $i = CGI::Info->new();
    my $l = CGI::Lingua->new(supported => ['en']);

    # To use server side caching you must give the cache argument, however
    # the cache_key argument is optional - if you don't give one then one will
    # be generated for you
    CGI::Buffer::init(
	cache => CHI->new(driver => 'File'),
	cache_key => $i->domain_name() . '/' . $i->script_name() . '/' . $i->as_string() . '/' . $l->language()
    );
    if(CGI::Buffer::is_cached()) {
	# Output will be retrieved from the cache and sent automatically
	exit;
    }
    # Not in the cache, so now do our expensive computing to generate the
    # results
    print "Content-type: text/html\n";
    # ...

AUTHOR

Nigel Horne, <njh at bandsman.co.uk>

BUGS

When using Template, ensure that you don't use it to output to STDOUT, instead you will need to capture into a variable and print that. For example:

my $output;
$template->process($input, $vars, \$output) || ($output = $template->error());
print $output;

Can produce buggy JavaScript if you use the <!-- HIDING technique. This is a bug in <JavaScript::Packer>, not CGI::Buffer. See https://github.com/nevesenin/javascript-packer-perl/issues/1#issuecomment-4356790

Mod_deflate can confuse this when compressing output. Ensure that deflation is off for .pl files:

SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|pl)$ no-gzip dont-vary

Please report any bugs or feature requests to bug-cgi-buffer at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=CGI-Buffer. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SEE ALSO

HTML::Packer, HTML::Lint

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc CGI::Buffer

You can also look for information at:

ACKNOWLEDGEMENTS

The inspiration and code for some if this is cgi_buffer by Mark Nottingham: http://www.mnot.net/cgi_buffer.

LICENSE AND COPYRIGHT

The licence for cgi_buffer is:

"(c) 2000 Copyright Mark Nottingham <mnot@pobox.com>

This software may be freely distributed, modified and used,
provided that this copyright notice remain intact.

This software is provided 'as is' without warranty of any kind."

The reset of the program is Copyright 2011-2012 Nigel Horne, and is released under the following licence: GPL