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Stevan Little > Web-Machine-0.05 > Web::Machine::Resource



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Module Version: 0.05   Source   Latest Release: Web-Machine-0.17


Web::Machine::Resource - A base resource class


version 0.05


  package HelloWorld::Resource;
  use strict;
  use warnings;

  use parent 'Web::Machine::Resource';

  sub content_types_provided { [{ 'text/html' => 'to_html' }] }

  sub to_html {
              <title>Hello World Resource</title>
              <h1>Hello World</h1>


This is the core representation of the web resource in Web::Machine. It is this object which is interrogated through the state machine. It is important not to think of this as an instance of a single object, but as a web representation of a resource, there is a big difference.

For now I am keeping the docs short, but much more needs to be written here. Below you will find a description of each method this object provides and what is expected of it. These docs were lovingly stolen from the ruby port of webmachine.


init( \%args )

This method is called right after the object is blessed and it is passed reference to the original %args that were given to the constructor.

The default method is a no-op, so there is no need to call the SUPER method, however it is still recommended to ensure proper initialization.


Does the resource exist?

Returning a false value will result in a '404 Not Found' response.

Defaults to true.


Is the resource available?

Returning a false value will result in a '503 Service Not Available' response.

Defaults to true.

If the resource is only temporarily not available, add a 'Retry-After' response header in the body of the method.

is_authorized ( ?$authorization_header )

Is the client or request authorized?

Parameter $authorization_header is the contents of the 'Authorization' header sent by the client, if present.

Returning anything other than true will result in a '401 Unauthorized' response. If a string is returned, it will be used as the value in the 'WWW-Authenticate' response header, which can also be set manually.

Defaults to true.


Is the request or client forbidden?

Returning a true value will result in a '403 Forbidden' response.

Defaults to false.


If the resource accepts POST requests to nonexistent resources, then this should return true.

Defaults to false.


If the request is malformed, this should return true, which will result in a '400 Malformed Request' response.

Defaults to false.

uri_too_long( $uri )

If the URI is too long to be processed, this should return true, which will result in a '414 Request URI Too Long' response.

Defaults to false.

known_content_type( $content_type )

If the 'Content-Type' on PUT or POST is unknown, this should return false, which will result in a '415 Unsupported Media Type' response.

The $content_type provided should be an instance of HTTP::Headers::ActionPack::MediaType.

Defaults to true.

valid_content_headers( $content_headers )

Parameter $content_header is a HASH ref of the Request headers that begin with prefix 'Content-'. It will contain instances of HTTP::Headers::ActionPack::MediaType, HTTP::Headers::ActionPack::MediaTypeList and HTTP::Headers::ActionPack::PriorityList based on the headers included. See HTTP::Headers::ActionPack for details of the mappings.

If the request includes any invalid Content-* headers, this should return false, which will result in a '501 Not Implemented' response.

Defaults to false.

valid_entity_length( $length )

Parameter $length is a number indicating the size of the request body.

If the entity length on PUT or POST is invalid, this should return false, which will result in a '413 Request Entity Too Large' response.

Defaults to true.


If the OPTIONS method is supported and is used, this method should return a HASH ref of headers that should appear in the response.

Defaults to {}.


HTTP methods that are allowed on this resource. This must return an ARRAY ref of strings in all capitals.

Defaults to ['GET','HEAD'].

HTTP methods that are known to the resource. Like allowed_methods, this must return an ARRAY ref of strings in all capitals. One could override this callback to allow additional methods, e.g. WebDAV.

Default includes all standard HTTP methods, ['GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'TRACE', 'CONNECT', 'OPTIONS'].


This method is called when a DELETE request should be enacted, and should return true if the deletion succeeded.

Defaults to false.


This method is called after a successful call to delete_resource and should return false if the deletion was accepted but cannot yet be guaranteed to have finished.

Defaults to true.


If POST requests should be treated as a request to put content into a (potentially new) resource as opposed to a generic submission for processing, then this method should return true. If it does return true, then create_path will be called and the rest of the request will be treated much like a PUT to the path returned by that call.

Default is false.


This will be called on a POST request if post_is_create? returns true. The path returned should be a valid URI part following the dispatcher prefix.


This will be called after create_path but before setting the Location response header, and is used to determine the root URI of the new resource.

Default is nil, which uses the URI of the request as the base.


If post_is_create? returns false, then this will be called to process any POST request. If it succeeds, it should return true.


This should return an ARRAY of HASH ref pairs where the key is name of the media type and the value is a CODE ref of a method which can provide a resource representation in that media type.

For example, if a client request includes an 'Accept' header with a value that does not appear as a first element in any of the return pairs, then a '406 Not Acceptable' will be sent.

Default is an empty ARRAY ref.


Similarly to content_types_provided, this should return an ARRAY of mediatype/handler pairs, except that it is for incoming resource representations -- for example, PUT requests. Handler functions usually want to use $request->body to access the incoming entity.


If this is anything other than undef, it must be an ARRAY of pairs where each pair key is the charset name and the pair value is a CODE ref converter which is an arity-1 method which will be called on the produced body in a GET and ensure that it is in Charset.

Default is undef.


This should return a list of language tags provided by the resource. Default is the empty Array, in which the content is in no specific language.


This should return a HASH of encodings mapped to encoding methods for Content-Encodings your resource wants to provide. The encoding will be applied to the response body automatically by Webmachine.

Default includes only the 'identity' encoding.


If this method is implemented, it should return a list of strings with header names that should be included in a given response's Vary header. The standard conneg headers (Accept, Accept-Encoding, Accept-Charset, Accept-Language) do not need to be specified here as Webmachine will add the correct elements of those automatically depending on resource behavior.

Default is [].


If this returns true, the client will receive a '409 Conflict' response. This is only called for PUT requests.

Default is false.


If this returns true, then it is assumed that multiple representations of the response are possible and a single one cannot be automatically chosen, so a 300 Multiple Choices will be sent instead of a 200.

Default is false.


If this resource is known to have existed previously, this method should return true.

Default is false.


If this resource has moved to a new location permanently, this method should return the new location as a String or URI.

Default is to return false.


If this resource has moved to a new location temporarily, this method should return the new location as a String or URI.

Default is to return false.


This method should return the last modified date/time of the resource which will be added as the Last-Modified header in the response and used in negotiating conditional requests. This should be in the form of an instance of HTTP::Headers::ActionPack::DateHeader.

Default is undef.


If the resource expires, this method should return the date/time it expires. This should be in the form of an instance of HTTP::Headers::ActionPack::DateHeader.

Default is nil.


If this returns a value, it will be used as the value of the ETag header and for comparison in conditional requests.

Default is undef.

finish_request( $metadata )

This method is called just before the final response is constructed and sent. It is passed the collected $metadata from the FSM, which may or may not have information in it.

The return value is ignored, so any effect of this method must be by modifying the response.


Stevan Little <>


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.

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