<?php
$reader = new XMLReader();
$reader->XML('<lineup>
        <headend headendId="something">
        <name>some name</name>
        <ids>ids</ids>
        <codes>codes</codes>
        </headend>
        </lineup>');

while($reader->read())
{
        if($reader->nodeType == XMLREADER::ELEMENT && $reader->localName == 'headend')
        {
                $headend = (string)$reader->getAttribute('headendId');
                echo $headend;
        }
}

something