<?php
$collections = array(
    'Marc Rutkowski' => 'marc',
    'Olivier Parmentier' => 'olivier'
);
$xsl = new DOMDocument;
$xsl->load('collection.xsl');
// Configure le transformateur
$proc = new XSLTProcessor;
$proc->importStyleSheet($xsl); // attachement des règles xsl
foreach ($collections as $name => $file) {
    // Chargement de la source XML
    $xml = new DOMDocument;
    $xml->load('collection_' . $file . '.xml');
    $proc->setParameter('', 'owner', $name);
    $proc->transformToURI($xml, 'file:///tmp/' . $file . '.html');
}
?>