Web::Machine::Resource - A base resource class
version 0.15
package HelloWorld::Resource; use strict; use warnings; use parent 'Web::Machine::Resource'; sub content_types_provided { [{ 'text/html' => 'to_html' }] } sub to_html { q{<html> <head> <title>Hello World Resource</title> </head> <body> <h1>Hello World</h1> </body> </html>} }
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 documentation 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. Your resource classes should extend the base Web::Machine::Resource class, overriding its methods as necessary. Sane defaults are provided for most methods, but you will want to create a content_types_provided method, as without this your resource will not be able to return any useful content.
content_types_provided
The documentation was lovingly stolen from the ruby port of webmachine.
init( \%args )
This method is called right after the object is blessed and it is passed a reference to the original %args that were given to the constructor. By default, these will include request (Plack::Request) and response (Plack::Response) arguments.
%args
request
response
If your resource is instantiated via Web::Machine then the contents of its resource_args parameter will be appended to the Web::Machine::Resource constructor arguments and made available to init:
resource_args
init
use strict; use warnings; use Web::Machine; { package HelloWorld::Resource; use strict; use warnings; use JSON::XS qw[ encode_json ]; use parent 'Web::Machine::Resource'; sub init { my $self = shift; my $args = shift; # Plack::Request # my $request = $args->{request}; # Plack::Response # my $response = $args->{response}; $self->{json} = exists $args->{json} ? $args->{json} : {}; } sub content_types_provided { [ { 'application/json' => 'to_json' } ] } sub to_json { my $self = shift; encode_json( $self->{json} ); } } Web::Machine->new( resource => 'HelloWorld::Resource', resource_args => [ json => { message => 'Hello World!', }, ], )->to_app;
Returns the Plack::Request (or subclass) request object for the current request.
Returns the Plack::Response (or subclass) response object for the current request.
resource_exists
Does the resource exist?
Returning a false value will result in a '404 Not Found' response.
Defaults to true.
service_available
Is the resource available?
Returning a false value will result in a '503 Service Not Available' response.
If the resource is only temporarily not available, add a 'Retry-After' response header in the body of the method.
is_authorized ( ?$authorization_header )
Is the client or request authorized?
Parameter $authorization_header is the contents of the 'Authorization' header sent by the client, if present.
$authorization_header
Returning anything other than 1 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.
forbidden
Is the request or client forbidden?
Returning a true value will result in a '403 Forbidden' response.
Defaults to false.
allow_missing_post
If the resource accepts POST requests to nonexistent resources, then this should return true.
malformed_request
If the request is malformed, this should return true, which will result in a '400 Malformed Request' response.
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.
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 value of $content_type is derived from the Plack::Request object and will therefore be an instance of the HTTP::Headers::ActionPack::MediaType class.
$content_type
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.
$content_header
If the request includes any invalid Content-* headers, this should return false, which will result in a '501 Not Implemented' response.
valid_entity_length( $length )
Parameter $length is a number indicating the size of the request body.
$length
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.
options
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 {}.
allowed_methods
HTTP methods that are allowed on this resource. This must return an ARRAY ref of strings in all capitals.
Defaults to ['GET','HEAD'].
['GET','HEAD']
known_methods
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'].
['GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'TRACE', 'CONNECT', 'OPTIONS']
delete_resource
This method is called when a DELETE request should be enacted, and should return true if the deletion succeeded.
delete_completed
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.
post_is_create
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.
create_path
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.
create_path_after_handler
This changes the behavior of create_path so that it will fire after the content handler has processed the request body. This allows the creation of paths that are more tightly tied to the newly created entity.
base_uri
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.
process_post
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 the name of the media type and the value is a CODE ref (or name 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.
The order of HASH ref pairs in the ARRAY is important. If no specific content type is requested (the client does not send an Accept header) then the first content type in the ARRAY will be used as the default.
Accept
Default is an empty ARRAY ref.
content_types_accepted
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.
$request->body
charsets_provided
This specifies the charsets that your resource support. Returning a value from this method enables content negotiation based on the client's Accept-Charset header.
The return value from this method must be an ARRAY ref. Each member of that array can be either a string or a HASH ref pair value. If the member is a string, it must be a valid character set name for the Encode module. Web::Machine will call encode() on the body using this character set if you set a body.
encode()
sub charsets_provided { return [ qw( UTF-8 ISO-8859-1 shiftjis ) ]; }
If you return a HASHREF pair, the key must be a character set name and the value must be a CODE ref. This CODE ref will be called as a method on the resource object. It will receive a single parameter, a string to be encoded. It is expected to return a scalar containing bytes, not characters. This will be used to encode the body you provide.
sub charsets_provided { return [ { 'UTF-8' => sub { my $self = shift; my $string = shift; return make_some_bytes($string),; }, }, { 'ISO-8859-1' => sub { my $self = shift; my $string = shift; return strip_non_ascii($string),; }, }, ]; }
The character set name will be appended to the Content-Type header returned the client.
If a client specifies the same preference for two or more character sets that your resource provides, then Web::Machine chooses the first character set in the returned ARRAY ref.
CAVEAT: Note that currently Web::Machine does not support the use of encodings when the body is returned as a CODE ref. This is a bug to be remedied in the future.
Web::Machine
Default is an empty list.
default_charset
If the client does not provide an Accept-Charset header, this sub is called to provide a default charset. The return value must be either a string or a hashref consisting of a single pair, where the key is a character set name and the value is a subroutine.
This works just like the charsets_provided() method, except that you can only return a single value.
charsets_provided()
languages_provided
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.
encodings_provided
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 Web::Machine.
Default includes only the 'identity' encoding.
variances
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 content negotiation headers (Accept, Accept-Encoding, Accept-Charset, Accept-Language) do not need to be specified here as Web::Machine will add the correct elements of those automatically depending on resource behavior.
Default is [].
is_conflict
If this returns true, the client will receive a '409 Conflict' response. This is only called for PUT requests.
multiple_choices
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.
previously_existed
If this resource is known to have existed previously, this method should return true.
moved_permanently
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.
moved_temporarily
If this resource has moved to a new location temporarily, this method should return the new location as a String or URI.
last_modified
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.
expires
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.
generate_etag
If this returns a value, it will be used as the value of the ETag header and for comparison in conditional requests.
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.
$metadata
The return value is ignored, so any effect of this method must be by modifying the response.
Stevan Little <stevan.little@iinteractive.com>
Andreas Marienborg <andreas.marienborg@gmail.com>
Andrew Nelson <anelson@cpan.org>
Arthur Axel 'fREW' Schmidt <frioux@gmail.com>
Carlos Fernando Avila Gratz <cafe@q1software.com>
Dave Rolsky <autarch@urth.org>
Fayland Lam <fayland@gmail.com>
George Hartzell <hartzell@alerce.com>
Gregory Oschwald <goschwald@maxmind.com>
Jesse Luehrs <doy@tozt.net>
John SJ Anderson <genehack@genehack.org>
Mike Raynham <enquiries@mikeraynham.co.uk>
Mike Raynham <mike.raynham@spareroom.co.uk>
Olaf Alders <olaf@wundersolutions.com>
Thomas Sibley <tsibley@cpan.org>
This software is copyright (c) 2014 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.
To install Web::Machine, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Web::Machine
CPAN shell
perl -MCPAN -e shell install Web::Machine
For more information on module installation, please visit the detailed CPAN module installation guide.