HTTP::Headers::ActionPack(3) HTTP Action, Adventure and Excitement


version 0.09


use HTTP::Headers::ActionPack;
my $pack = HTTP::Headers::ActionPack->new;
my $media_type = $pack->create_header( 'Content-Type' => 'application/xml;charset=UTF-8' );
my $link = $pack->create( 'LinkHeader' => [ '</test/tree>', rel => "up" ] );
# auto-magic header inflation
# for multiple types
$pack->inflate( $http_headers_instance );
$pack->inflate( $http_request_instance );
$pack->inflate( $plack_request_instance );


This is a module to handle the inflation and deflation of complex HTTP header types. In many cases header values are simple strings, but in some cases they are complex values with a lot of information encoded in them. The goal of this module is to make the parsing and analysis of these headers as easy as calling "inflate" on a compatible object (see below for a list).

This top-level class is basically a Factory for creating instances of the other classes in this module. It contains a number of convenience methods to help make common cases easy to write.


This class provides a set of default mappings between HTTP headers and the classes which can inflate them. Here is the list of default mappings this class provides.

  Link                HTTP::Headers::ActionPack::LinkList
  Content-Type        HTTP::Headers::ActionPack::MediaType
  Accept              HTTP::Headers::ActionPack::MediaTypeList
  Accept-Charset      HTTP::Headers::ActionPack::PriorityList
  Accept-Encoding     HTTP::Headers::ActionPack::PriorityList
  Accept-Language     HTTP::Headers::ActionPack::PriorityList
  Date                HTTP::Headers::ActionPack::DateHeader
  Client-Date         HTTP::Headers::ActionPack::DateHeader
  Expires             HTTP::Headers::ActionPack::DateHeader
  Last-Modified       HTTP::Headers::ActionPack::DateHeader
  If-Unmodified-Since HTTP::Headers::ActionPack::DateHeader
  If-Modified-Since   HTTP::Headers::ActionPack::DateHeader
  WWW-Authenticate    HTTP::Headers::ActionPack::WWWAuthenticate
  Authentication-Info HTTP::Headers::ActionPack::AuthenticationInfo
  Authorization       HTTP::Headers::ActionPack::Authorization

NOTE: The 'Client-Date' header is often added by LWP on HTTP::Response objects.


"new( ?%mappings )"
The constructor takes an option hash of header-name to class mappings to add too (or override) the default mappings (see above for details). Each class is expected to have a "new_from_string" method which can parse the string representation of the given header and return an object.
This returns the set of mappings in this instance.
This returns the list of supported classes, which is by default the list of classes included in this modules, but it also will grab any additionally classes that were specified in the %mappings parameter to "new" (see above).
Returns an instance of HTTP::Headers::ActionPack::ContentNegotiation.
"create( $class_name, $args )"
This method, given a $class_name and $args, will inflate the value using the class found in the "classes" list. If $args is a string it will call "new_from_string" on the $class_name, but if $args is an ARRAY ref, it will dereference the ARRAY and pass it to "new".
"create_header( $header_name, $header_value )"
This method, given a $header_name and a $header_value will inflate the value using the class found in the mappings. If $header_value is a string it will call "new_from_string" on the class mapped to the $header_name, but if $header_value is an ARRAY ref, it will dereference the ARRAY and pass it to "new".
"inflate( $http_headers )"
"inflate( $http_request )"
"inflate( $plack_request )"
"inflate( $web_request )"
Given either a HTTP::Headers instance, a HTTP::Request instance, a Plack::Request instance, or a Web::Request instance, this method will inflate all the relevant headers and store the object in the same instance.

In theory this should not negatively affect anything since all the header objects overload the stringification operator, and most often the headers are treated as strings. However, this is not for certain and care should be taken.


Plack Compatibility

We have a test in the suite that checks to make sure that any inflated header objects will pass between HTTP::Request and HTTP::Response objects as well as Plack::Request and Plack::Response objects.

A simple survey of most of the Plack::Handler subclasses shows that most of them will end up properly stringifying these header objects before sending them out. The notable exceptions were the Apache handlers.

At the time of this writing, the solution for this would be for you to either stringify these objects prior to returning your Plack::Response, or to write a simple middleware component that would do that for you. In future versions we might provide just such a middleware (it would likely inflate the header objects on the request side as well).


As mentioned above, all the header objects overload the stringification operator, so normal usage of them should just do what you would expect (stringify in a sensible way). However this is not certain and so care should be taken when passing object headers onto another library that is expecting strings.


Stevan Little <[email protected]>



This software is copyright (c) 2012 by Infinity Interactive, Inc..

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