例）

$dom = new domDocument;
$dom->load('books.xml'); // XML文書読み込み

$root = $dom->documentElement;
$books = $root->childNodes;

foreach($books as $book)
{
    if(@$book->nodeName == 'book')
    {
        $content = $book->childNodes;
        foreach ($content as $elem)
        {
            if(@$elem->nodeName == 'name')
            {
                $author = $elem->nodeValue;
            }
            if(@$elem->nodeName == 'publish')
            {
                $title = $elem->nodeValue;
            }
        }
    }
}