Instead of passing a URL, we can pass the XML content to this class (either you
 want to use CURL, Socks or fopen to retrieve it first) and instead of using 
 array, I'm using separator '|' to identify which data to get (in order to make 
 it short to retrieve a complex XML data). Here is my class with built-in fopen 
 which you can pass URL or you can pass the content instead :
p/s : thanks to this great help page.
<?php
class xx_xml {
 // XML parser variables
 var $parser;
 var $name;
 var $attr;
 var $data = array();
 var $stack = array();
 var $keys;
 var $path;
 
 // either you pass url atau contents. 
 // Use 'url' or 'contents' for the parameter
 var $type;
 // function with the default parameter value
 function xx_xml($url='http://www.example.com', $type='url') {
 $this->type = $type;
 $this->url = $url;
 $this->parse();
 }
 
 // parse XML data
 function parse()
 {
 $data = '';
 $this->parser = xml_parser_create();
 xml_set_object($this->parser, $this);
 xml_set_element_handler($this->parser, 'startXML', 'endXML');
 xml_set_character_data_handler($this->parser, 'charXML');
 xml_parser_set_option($this->parser, XML_OPTION_CASE_FOLDING, false);
 if ($this->type == 'url') {
 // if use type = 'url' now we open the XML with fopen
 
 if (!($fp = @fopen($this->url, 'rb'))) {
 $this->error("Cannot open {$this->url}");
 }
 while (($data = fread($fp, 8192))) {
 if (!xml_parse($this->parser, $data, feof($fp))) {
 $this->error(sprintf('XML error at line %d column %d', 
 xml_get_current_line_number($this->parser), 
 xml_get_current_column_number($this->parser)));
 }
 }
 } else if ($this->type == 'contents') {
 // Now we can pass the contents, maybe if you want 
 // to use CURL, SOCK or other method.
 $lines = explode("\n",$this->url);
 foreach ($lines as $val) {
 if (trim($val) == '')
 continue;
 $data = $val . "\n";
 if (!xml_parse($this->parser, $data)) {
 $this->error(sprintf('XML error at line %d column %d', 
 xml_get_current_line_number($this->parser), 
 xml_get_current_column_number($this->parser)));
 }
 }
 }
 }
 function startXML($parser, $name, $attr) {
 $this->stack[$name] = array();
 $keys = '';
 $total = count($this->stack)-1;
 $i=0;
 foreach ($this->stack as $key => $val) {
 if (count($this->stack) > 1) {
 if ($total == $i)
 $keys .= $key;
 else
 $keys .= $key . '|'; // The saparator
 }
 else
 $keys .= $key;
 $i++;
 }
 if (array_key_exists($keys, $this->data)) {
 $this->data[$keys][] = $attr;
 } else
 $this->data[$keys] = $attr;
 $this->keys = $keys;
 }
 function endXML($parser, $name) {
 end($this->stack);
 if (key($this->stack) == $name)
 array_pop($this->stack);
 }
 function charXML($parser, $data) {
 if (trim($data) != '')
 $this->data[$this->keys]['data'][] = trim(str_replace("\n", '', $data));
 }
 function error($msg) {
 echo "<div align=\"center\">
 <font color=\"red\"><b>Error: $msg</b></font>
 </div>";
 exit();
 }
}
?>

And example of retrieving XML data:
p/s: example use to retrieve weather
<?php
include_once "xx_xml.class.php";
// Im using simple curl (the original is in class) to get the contents
$pageurl = "http://xml.weather.yahoo.com/forecastrss?p=MYXX0008&u=c";
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt ($ch, CURLOPT_URL, $pageurl );
$thecontents = curl_exec ( $ch );
curl_close($ch);
// We want to pass only a ready XML content instead of URL
// But if you want to use URL , skip the curl functions above and use this 
// $xx4 = new xx_xml("url here",'url');
$xx4 = new xx_xml($thecontents,'contents'); 
// As you can see, we use saparator '|' instead of long array
$Code = $xx4->data ['rss|channel|item|yweather:condition']['code'] ;
$Celcius = $xx4->data ['rss|channel|item|yweather:condition']['temp'] ;
$Text = $xx4->data ['rss|channel|item|yweather:condition']['text'] ;
$Cityname = $xx4->data ['rss|channel|yweather:location']['city'] ;
?>

Hope this helps.