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NAME
RDF::Generator::HTTP - Generate RDF from a HTTP message
SYNOPSIS
use LWP::UserAgent;
my $ua = LWP::UserAgent->new;
my $response = $ua->get('http://search.cpan.org/');
use RDF::Generator::HTTP;
use RDF::Trine qw(iri);
my $g = RDF::Generator::HTTP->new(message => $response,
graph => iri('http://example.org/graphname'),
blacklist => ['Last-Modified', 'Accept']);
my $model = $g->generate;
print $model->size;
my $s = RDF::Trine::Serializer->new('turtle', namespaces =>
{ httph => 'http://www.w3.org/2007/ont/httph#',
http => 'http://www.w3.org/2007/ont/http#' } );
$s->serialize_model_to_file(\*STDOUT, $model);
DESCRIPTION
This module simply takes a HTTP::Message object, and based on its content,
especially the content the HTTP::Header object(s) it contains, creates a
simple RDF representation of the contents. It is useful chiefly for
recording data when crawling resources on the Web, but it may also have
other uses.
Constructor
`new(%attributes)`
Moose-style constructor function.
Attributes
These attributes may be passed to the constructor to set them, or called
like methods to get them.
`message`
A HTTP::Message (or subclass thereof) object to generate RDF for.
Required.
`blacklist`
An `ArrayRef` of header field names that you do not want to see in the
output.
`whitelist`
An `ArrayRef` of the only header field names that you want to see in
the output. The whitelist will be ignored if the blacklist is set.
`graph`
You may pass an optional graph name to be used for all triples in the
output. This must be an object of RDF::Trine::Node::Resource.
`ns`
An URI::NamespaceMap object containing namespace prefixes used in the
module. You should probably not override this even though you can.
`request_subject`
An RDF::Trine::Node object containing the subject of any statements
describing requests. If unset, it will default to a blank node.
`response_subject`
An RDF::Trine::Node object containing the subject of any statements
describing responses. If unset, it will default to a blank node.
Methods
The above attributes all have read-accessors by the same name.
`blacklist`, `whitelist` and `graph` also has writers and predicates,
which is used to test if the attribute has been set, by prefixing `has_`
to the attribute name.
This class has two methods:
`generate ( [ $model ] )`
This method will generate the RDF. It may optionally take an
RDF::Trine::Model as parameter. If it exists, the RDF will be added to
this model, if not, a new Memory model will be created and returned.
`ok_to_add ( $field )`
This method will look up in the blacklists and whitelists and return
true if the given field and value may be added to the model.
EXAMPLES
For an example of what the module can be used to create, consider the
example in the "SYNOPSIS", which at the time of this writing outputs the
following Turtle:
@prefix http: <http://www.w3.org/2007/ont/http#> .
@prefix httph: <http://www.w3.org/2007/ont/httph#> .
[] a http:RequestMessage ;
http:hasResponse [
a http:ResponseMessage ;
http:status "200" ;
httph:client_date "Sun, 14 Dec 2014 21:28:21 GMT" ;
httph:client_peer "207.171.7.59:80" ;
httph:client_response_num "1" ;
httph:connection "close" ;
httph:content_length "3643" ;
httph:content_type "text/html" ;
httph:date "Sun, 14 Dec 2014 21:28:21 GMT" ;
httph:link "<http://search.cpan.org/uploads.rdf>; rel=\"alternate\"; title=\"RSS 1.0\"; type=\"application/rss+xml\"", "<http://st.pimg.net/tucs/opensearch.xml>; rel=\"search\"; title=\"SearchCPAN\"; type=\"application/opensearchdescription+xml\"", "<http://st.pimg.net/tucs/print.css>; media=\"print\"; rel=\"stylesheet\"; type=\"text/css\"", "<http://st.pimg.net/tucs/style.css?3>; rel=\"stylesheet\"; type=\"text/css\"" ;
httph:server "Plack/Starman (Perl)" ;
httph:title "The CPAN Search Site - search.cpan.org" ;
httph:x_proxy "proxy2"
] ;
http:method "GET" ;
http:requestURI <http://search.cpan.org/> ;
httph:user_agent "libwww-perl/6.05" .
NOTES
HTTP Vocabularies
There have been many efforts to create HTTP vocabularies (or ontologies),
where the most elaborate and complete is the HTTP Vocabulary in RDF 1.0
<http://www.w3.org/TR/HTTP-in-RDF/>. Nevertheless, I decided not to
support this, but rather support an older and much less complete
vocabulary that has been in the Tabulator
<https://github.com/linkeddata/tabulator-firefox> project, with the
namespace prefixes <http://www.w3.org/2007/ont/http#> and
<http://www.w3.org/2007/ont/httph#>. The problem of modelling HTTP is that
headers modify each other, so if you want to record the HTTP headers so
that they can be used in an actual HTTP dialogue afterwards, they have to
be in a container so that the order can be reconstructed. Moreover, there
is a lot of microstructure in the values, and that also adds complexity if
you want to translate all that to RDF. That's what the former vocabulary
does. However, for now, all the author wants to do is to record them, and
then neither of these concerns are important. Therefore, I opted to go for
a much simpler vocabulary, where each field is a simple predicate. That is
not to say that the former approach isn't valid, it is just not something
I need now.
BUGS
This is a very early release, but it works for the author.
Please report any bugs to
<https://github.com/kjetilk/p5-rdf-generator-http/issues>.
AUTHOR
Kjetil Kjernsmo <kjetilk@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2014 by Kjetil Kjernsmo.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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