Last updated February 17, 2008. Created by Arto on February 10, 2008.
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The RDF API exposes the following Drupal hooks that third-party extension modules can implement to provide extended functionality:
hook_rdf()
Allows modules to take action when RDF statements are inserted or deleted.
Example of usage
<?php
/**
* Implementation of hook_rdf().
*/
function mymodule_rdf($op, $subject, $predicate, $object) {
switch ($op) {
case 'insert':
// A new statement was asserted
break;
case 'delete':
// An existing statement was unasserted
break;
}
}
?>hook_rdf_namespaces()
Defines URI abbreviations for use in CURIEs and QNames.
Example from the RDF API module
<?php
/**
* Implementation of hook_rdf_namespaces().
*/
function rdf_rdf_namespaces() {
return array(
'_' => 'http://bnode.net/',
'rdf' => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
'rdfs' => 'http://www.w3.org/2000/01/rdf-schema#',
'xsi' => 'http://www.w3.org/2001/XMLSchema-instance#',
'xsd' => 'http://www.w3.org/2001/XMLSchema#',
'owl' => 'http://www.w3.org/2002/07/owl#',
'dc' => 'http://purl.org/dc/elements/1.1/',
'dcterms' => 'http://purl.org/dc/terms/',
'dcmitype' => 'http://purl.org/dc/dcmitype/',
);
}
?>hook_rdf_contexts()
Defines contexts, also known as named graphs.
Example from the RDF API module
<?php
/**
* Implementation of hook_rdf_contexts().
*/
function rdf_rdf_contexts() {
return array(
url(NULL, array('absolute' => TRUE)),
);
}
?>hook_rdf_repositories()
Defines RDF repositories.
Example from the RDF DB module
<?php
/**
* Implementation of hook_rdf_repositories().
*/
function rdf_db_rdf_repositories() {
$repos = array();
foreach (rdf_db_get_repository_names() as $name => $table) {
$repos[$name] = array(
'title' => $name,
'type' => 'local',
'persistent' => TRUE,
'mutable' => TRUE,
'enabled' => TRUE,
'statements' => rdf_db_count_repository_triples($name),
'callbacks' => array(
'insert' => array(
'function' => 'rdf_db_rdf_insert',
'arguments' => array($table)
),
'delete' => array(
'function' => 'rdf_db_rdf_delete',
'arguments' => array($table)
),
'query' => array(
'function' => 'rdf_db_rdf_query',
'arguments' => array($table)
),
),
);
}
return $repos;
}
?>hook_rdf_formats()
Defines RDF serialization formats.
Example from the RDF API module
<?php
/**
* Implementation of hook_rdf_formats().
*/
function rdf_rdf_formats() {
return array(
'rdf+php' => array(
'title' => t('RDF/PHP'),
'mime_type' => 'application/vnd.php.serialized',
'encoding' => 'ascii',
'file_ext' => 'txt',
'serialize' => 'rdf_serialize_php',
'unserialize' => 'rdf_unserialize_php',
),
);
}
?>