- htmlspecialchars: documentation ( source)
<?php
$oXMLWriter = new XMLWriter;
$oXMLWriter->openMemory();
$oXMLWriter->startDocument('1.0', 'UTF-8');
$oXMLWriter->startElement('test');
$oXMLWriter->writeAttribute('value', "Just <span style=\"color:red\">testing</span>:漢字");
$oXMLWriter->text('Hello, World!');
$oXMLWriter->endElement();
$oXMLWriter->endDocument();
echo htmlspecialchars($oXMLWriter->outputMemory(TRUE));