Calling $doc->dump_mem or $doc->dump_file with format set to true seems to corrupt the internal representation of the XML document, removing all writespace-only text nodes, which alters the structure of the document. It doesn't affect the document object in the same request, but all subsequent requests that access an identical XML doc -- even on a different page -- will see the altered structure instead of the structure actually present in the original doc.

Workaround: set format to false

Config:  './configure' '--with-apxs=/opt/apache/bin/apxs' '--with-dom' '-with-dom-xslt' '--with-dom-exslt' '--prefix=/opt' '--with-zlib'

Demo script:

<?php

$xml = "<?xml version=\"1.0\"?>
<motel>
<roaches>
<roach state=\"alive\"/>
<roach state=\"dead\"/>
<roach state=\"dead\"/>
</roaches>
</motel>";

$doc = domxml_open_mem($xml);
echo "First listing:<br>\n";
list_roaches($doc);

/*
  Calling dump mem with format set to true
  alters the in-memory copy the xml file, even
  across reloads of the page!

  With the whitespace stripped, the structure
  of the document changes.
 */
$foo = $doc->dump_mem(true);

echo "After doc->dump_mem called:<br>\n";
list_roaches($doc);

echo "Now, reload to see error<br>\n";

function list_roaches ($doc)
{
  $root         = $doc->document_element(); 
  $first_child  = $root->first_child();
  $roaches_el   = $first_child->next_sibling();
 
  if ($roaches_el) {
    $roaches_list = $roaches_el->get_elements_by_tagname("roach");
    for ($i = 0; $i < count($roaches_list); $i++) {
      echo " Roach $i is " . $roaches_list[$i]->get_attribute("state")
	. "<br>\n";
    }
  } else {
    echo "No sibling of first child found!<br><xmp>\n";
    echo $doc->dump_mem();
    echo "</xmp>\n";
  }
}

?>