php处理复杂xml

<?php
$xml = <<< XML
<?xml version="1.0" encoding="utf-8"?>
<epp xmlns="urn:ietf:params:xml:ns:epp-1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd">
  <response>
    <result code="1000">
      <msg>Command completed successfully</msg>
    </result>
    <resData>
      <domain:chkData xmlns:domain="urn:ietf:params:xml:ns:domain-1.0" xsi:schemaLocation="urn:ietf:params:xml:ns:domain-1.0 domain-1.0.xsd">
        <domain:cd>
          <domain:name avail="0">qq.com</domain:name>
          <domain:reason>Domain exists</domain:reason>
        </domain:cd>
        <domain:cd>
          <domain:name avail="1">baidu.com</domain:name>
          <domain:reason>Domain exists</domain:reason>
        </domain:cd>
      </domain:chkData>
    </resData>
    <trID>
      <clTRID>REQ-001-0000000074</clTRID>
      <svTRID>649334436-1440642163169</svTRID>
    </trID>
  </response>
</epp>
XML;

$x = simplexml_load_string($xml);
echo intval($x->response->result["code"]), "\n";
echo strval($x->response->result->msg), "\n";
$ns = $x->response->resData->getNamespaces(true);
$cds = $x->response->resData->children($ns["domain"])->chkData->cd;
foreach ($cds as $key => $value) {
    echo intval($value->name->attributes()["avail"]), strval($value->name), strval($value->reason), "\n";
}