<?php

$url = 'http://www.feedforall.com/sample.xml';
$xml = @simplexml_load_file($url);
$articles = array();

if ($xml) {
    foreach ($xml->channel->item as $item) {
        $articles[] = sprintf(
            '<li><a href="%s">%s</a><br>%s</li>' . PHP_EOL,
            $item->link,
            $item->title,
            mb_strimwidth($item->description, 0, 120, '...', 'UTF-8')
        );
    }
} else {
    $articles[] = '<li>取得失敗</li>';
}

shuffle($articles);

foreach ($articles as $article) {
    echo $article;
}