SYNOPSIS
High-level interface:
my $grddl = XML::GRDDL->new;
my $model = $grddl->data($xmldoc, $baseuri);
# $model is an RDF::Trine::Model
Low-level interface:
my $grddl = XML::GRDDL->new; my @transformations = $grddl->discover($xmldoc, $baseuri); foreach my $t (@transformations) { # $t is an XML::GRDDL::Transformation my ($output, $mediatype) = $t->transform($xmldoc); # $output is a string of type $mediatype. }
DESCRIPTION
GRDDL is a W3C Recommendation for extracting RDF data from arbitrary XML and XHTML via a transformation, typically written in XSLT. See <http://www.w3.org/TR/grddl/> for more details.This module implements GRDDL in Perl. It offers both a low level interface, allowing you to generate a list of transformations associated with the document being processed, and thus the ability to selectively run the transformation; and a high-level interface where a single RDF model is returned representing the union of the RDF graphs generated by applying all available transformations.
Constructor
- "XML::GRDDL->new"
- The constructor accepts no parameters and returns an XML::GRDDL object.
Methods
- "$grddl->discover($xml, $base, %options)"
-
Processes the document to discover the transformations associated
with it. $xml is the raw XML source of the document, or an
XML::LibXML::Document object. ($xml cannot be ``tag soup'' HTML,
though you should be able to use HTML::HTML5::Parser to
parse tag soup into an XML::LibXML::Document.) $base is the
base URI for resolving relative references.
Returns a list of XML::GRDDL::Transformation objects.
Options include:
-
- force_rel - boolean; interpret XHTML rel=``transformation'' even in the absence of the GRDDL profile.
- strings - boolean; return a list of plain strings instead of blessed objects.
-
- "$grddl->data($xml, $base, %options)"
-
Processes the document, discovers the transformations associated
with it, applies the transformations and merges the results into a
single RDF model. $xml and $base are as per "discover".
Returns an RDF::Trine::Model containing the data. Statement contexts (a.k.a. named graphs / quads) are used to distinguish between data from the result of each transformation.
Options include:
-
- force_rel - boolean; interpret XHTML rel=``transformation'' even in the absence of the GRDDL profile.
- metadata - boolean; include provenance information in the default graph (a.k.a. nil context).
-
- "$grddl->ua( [$ua] )"
- Get/set the user agent used for HTTP requests. $ua, if supplied, must be an LWP::UserAgent.
Constants
These constants may be exported upon request.- "GRDDL_NS"
- "XHTML_NS"
FEATURES
XML::GRDDL supports transformations written in XSLT 1.0, and in RDF-EASE.XML::GRDDL is a good HTTP citizen: Referer headers are included in requests, and appropriate Accept headers supplied. To be an even better citizen, I recommend changing the User-Agent header to advertise the name of the application:
$grddl->ua->default_header(user_agent => 'MyApp/1.0 ');
Provenance information for GRDDL transformations is returned using the GRDDL vocabulary at http://www.w3.org/2003/g/data-view# <http://www.w3.org/2003/g/data-view#>.
Certain XHTML profiles and XML namespaces known not to contain any transformations, or to contain useless transformations are skipped. See XML::GRDDL::Namespace and XML::GRDDL::Profile for details. In particular profiles for RDFa and many Microformats are skipped, as RDF::RDFa::Parser and HTML::Microformats will typically yield far superior results.
BUGS
Please report any bugs to <http://rt.cpan.org/>.Known limitations:
-
Recursive GRDDL doesn't work yet.
That is, the profile documents and namespace documents linked to from your primary document cannot themselves rely on GRDDL.
AUTHOR
Toby Inkster <[email protected]>.COPYRIGHT AND LICENCE
Copyright 2008-2012 Toby InksterThis library is free software; you can redistribute it and/or modify it under the same terms as Perl 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.