Converters

From n² wiki

1 Download
2 Intro
3 API Overview
4 Usage:
5 Questions, Suggestions, Bug Reports

[edit] Download

svn co http://n2.talis.com/svn/playground/kwijibo/converters/

[edit] Intro

Converters is a PHP library of classes for converting RDF/XML and SPARQL/XML into PHP data structures. RDF/XML can be converted into an associative array structure following the RDF/JSON Specification (and filtered, modified, and reserialised as RDF/XML and Turtle), SPARQL is converted into an associative array similar to the SPARQL JSON serialisation specification.

[edit] API Overview

RDFXML
      ->value() // an RDF/XML string
      ->to_triples()
      ->to_resources() //needs namespaces array 

Triples
      ->value() // an array of triples, as returned by the ARC RDF/XML parser
      ->to_resources()

ResourcesArray
      ->value() // an associative array like the RDF/JSON structure
      ->to_rdfxml()
      ->to_turtle()
      ->to_resource($uri) // creates and returns a ResourceArray object of the 
      ->filter_by_language($lang) //returns resources with only literals of the same, or unspecified, language
      ->filter_by_object_value($value) // returns only resources with a given object value.

ResourceArray
      ->value() // an associative array like the RDF/JSON structure, containing only one resource
      ->property($property_qname) // returns the value of the given property of this resource.
      ->get_title() //returns the foaf:name, dc:title, or rdfs:label of the resource 

SPARQL_XML
      ->value() // an XML document string
      ->to_boolean() //returns a boolean from an ASK query result document
      ->to_array() // returns an associative array from a select query result
URI
      ->value() // a URI string
      ->to_qname() //needs namespaces array
      ->to_term() // returns the part of the uri after the last # or /
      ->to_namespace() returns the part of the URI up to and including the last # or /
Qname
      ->value() // a qname, eg: 'rdf:type'
      ->to_uri() //needs namespaces array
      ->to_eRDF_value() // replaces the first : for a - .

[edit] Usage:


$namespaces = array (
   'rdf' => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
   'sioc' => 'http://rdfs.org/sioc/ns#',
   'dc' => 'http://purl.org/dc/elements/1.1/',
   'terms' => 'http://purl.org/dc/terms/',
   'foaf' => 'http://xmlns.com/foaf/spec/',
   'rdfs' => 'http://www.w3.org/2000/01/rdf-schema#',
   'rss' => 'http://purl.org/rss/1.0/',
   'owl' => 'http://www.w3.org/2002/07/owl#',
   'rel' => 'http://purl.org/vocab/relationship/',
   'ibis' => 'http://dannyayers.com/2003/12/ibis.rdfs#',
   'doap' => 'http://usefulinc.com/ns/doap#',
   'frbr' => 'http://purl.org/vocab/frbr/core#',
 );

You can optionally pass in an array of namespace prefixes when you initiate the Convertor class. Alternatively (or as well), you can supply namespaces as a second parameter to methods that can (or need to) use prefixes (such as to_qname())

The RDFXML converter needs the ARC RDF/XML parser, available from: the Semsol website


$arc2_location = 'lib/arc2/ARC2.php'; //default path

$Converter = new Converter($namespaces, $arc2_location);

$ResourcesObject = $Converter->RDFXML->to_resources($rdfxml_string);

$resources_assoc_array = $ResourcesObject->value();

$resources_assoc_array ==  array(
	'http://example.org/test/JohnSmith'=>
		array(
			'http://xmlns.com/foaf/spec/name' => 	
					array(
							array('type'=>'literal','value'=>'John Smith')
						),
			'http://xmlns.com/foaf/spec/mbox' => array(
								array('type'=>'uri','value'=>'mailto:john@example.org')
						),	
			'http://www.w3.org/2000/01/rdf-schema#label' => array(
						array('type'=>'literal','value'=>'Label','lang'=>'en-gb')
						),	
			),

	); // true

$ResourceObject = $ResourcesObject->to_resource('http://example.org/test/JohnSmith');

$ResourcesObject->get_title() == 'John Smith'; // true

$Convert->URI->to_qname('http://xmlns.com/foaf/spec/name')->value() == 'foaf:name'; //true

$Convert->URI->to_term('http://xmlns.com/foaf/spec/name') == 'name'; //true