Toby Inkster > XML-GRDDL > XML::GRDDL

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NAME ^

XML::GRDDL - transform XML and XHTML to RDF

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#.

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:

SEE ALSO ^

XML::GRDDL::Transformation, XML::GRDDL::Namespace, XML::GRDDL::Profile, XML::GRDDL::Transformation::RDF_EASE::Functional, XML::Saxon::XSLT2.

HTML::HTML5::Parser, RDF::RDFa::Parser, HTML::Microformats.

JSON::GRDDL.

http://www.w3.org/TR/grddl/.

http://www.perlrdf.org/.

This module is derived from Swignition http://buzzword.org.uk/swignition/.

AUTHOR ^

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE ^

Copyright 2008-2012 Toby Inkster

This 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.

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