NAME

Plack::Middleware::Precompressed - serve pre-gzipped content to compression-enabled clients

VERSION

version 1.103

SYNOPSIS

 use Plack::Builder;

 builder {
     enable 'Precompressed', match => qr!\.js\z!;
     $handler;
 };

DESCRIPTION

Plack::Middleware::Precompressed is an alternative (or rather, complement) to middlewares like Deflater, which will compress response bodies on the fly. For dynamic resources, that behaviour is necessary, but for static resources it is a waste: identical entities will be compressed over and over. Instead, Precompressed allows you to compress static resources once, e.g. as part of your build process, and then serve the compressed resource in place of the uncompressed one for compression-enabled clients.

To do so, by default it appends a ".gz" suffix to the "PATH_INFO" and tries to serve that. If that fails, it will then try again with the unmodified URI.

Note: this means requests for resources that are not pre-compressed will always be dispatched twice. You are are advised to use either the "match" parameter or the Conditional middleware or something of the sort, to prevent requests from passing through this middleware unnecessarily.

CONFIGURATION OPTIONS

"match"

Specifies a regex that must match the "PATH_INFO" to trigger the middleware.

"rules"

A callback that is expected to transform the path instead of using the default behaviour of appending ".gz" to the file path. "PATH_INFO" will be aliased to the $_ variable, so you can do something like this:

 enable 'Precompressed', match => qr!\.js\z!, rules => sub { s!^/?!/z/! };

This example will prepend "/z/" to file paths instead of appending ".gz" to them.

"env_keys"

An array of PSGI environment key names. If you specify any, then the "rules" callback will receive a reference to a hash with just these keys, aliased to the values in the PSGI environment that will be passed to the wrapped app. You can modify these values to modify the environment it will see. This allows you do to something like this:

 enable 'Precompressed', env_keys => [ 'HTTP_HOST' ],
        rules => sub { $_[0]{'HTTP_HOST'} = 'gzip.assets.example.com' };

This somewhat peculiar interface is necessary so the middleware can abstract away the details of trying to copy as little data as possible during a request.

SUBCLASSING

If you reuse a particular configuration of Plack::Middleware::Precompressed in many projects, you can avoid repeating the same configuration in each of them by subclassing this middleware and overriding the "rewrite" and "env_keys" methods.

The "rewrite" method will be called just as the "rules" callback would be.

The "env_keys" method should return an array reference and will have the same effect on the "rewrite" method as the configuration option on the "rules" callback.

AUTHOR

Aristotle Pagaltzis <pagaltzis@gmx.de>

COPYRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.