(PHP 5)
DOMDocument::relaxNGValidateSource — Performs relaxNG validation on the document
Performs » relaxNG validation on the document based on the given RNG source.
A string containing the RNG schema.
Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.
Took me a while to get a working example.  Here it is:
<?php
# enable warnings
ini_set( 'track_errors', 1);
ini_set('error_reporting', E_ALL | E_STRICT);
# this is a sample relaxNG definition
$rng = <<<EOT
<?xml version="1.0" encoding="UTF-8"?>
<grammar ns="" xmlns="http://relaxng.org/ns/structure/1.0"
  datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <start>
    <element name="apple">
      <element name="pear">
        <data type="NCName"/>
      </element>
    </element>
  </start>
</grammar>
EOT;
# well formed xml, but invalid per schema
# too many pears
$bad_xml =<<<EOT
<?xml version="1.0"?>
<apple>
  <pear>Pear</pear>
  <pear>Pear</pear>
</apple>
EOT;
# well formed xml and valid per schema
$good_xml =<<<EOT
<?xml version="1.0"?>
<apple>
  <pear>Pear</pear>
</apple>
EOT;
# this function does the work, it tests the relaxNG in the string $rng
# against the xml in string $xml
Function relaxNG ( $xml, $rng ) {
        $dom_xml = new DomDocument;
        $dom_xml->loadXML($xml);
                        
        if ( $dom_xml->relaxNGValidateSource ( $rng ) ) {
                echo "Good\n";
        } else {
                echo $php_errormsg . "\n";
        }
}       
# test the good xml, will echo:
#    Good
relaxNG ($good_xml, $rng);
                        
# test the bad xml, will echo:
#    Did not expect element pear there
relaxNG ($bad_xml, $rng);
?>
results:
Good
Did not expect element pear there