เขียน php กับ webserice ทำยังไงเหรอครับ คือจะใช้ REST แต่ไม่รู้จะทำไงดี บอกหน่อยดิ

<?php
function build_query_string(array $params) {
 $query_string = http_build_query($params);
 return $query_string;
}

function curl_get($url) {
 $client = curl_init($url);
 curl_setopt($client, CURLOPT_RETURNTRANSFER, true);
 $response = curl_exec($client);
 curl_close($client);
 return $response;
}

$url = 'http://............................./rss.xml';
$response = curl_get($url);
$xml = simplexml_load_string($response , 'SimpleXMLElement', LIBXML_NOCDATA);
$base_url = 'http://.........................................';
foreach ($xml->channel->item as $item) {
 echo '<h2>' . $item->title . '</h2>'. "\n";
 $params = array (
 'appid' => 'YahooDemo',
 'query' => $item->title,
 'results' => 2,
 'language' => 'en'
 );
 $url = "$base_url?" . build_query_string($params);
 $response = curl_get($url);
 $xml = simplexml_load_string($response);
 echo '<ul>' ."\n";
 foreach ($xml->Result as $news) {
 echo '<li><a href=\'' . $news->Url . '\'/>' . $news->Title . '</a></li>' . "\n";
 }
 echo '</ul>' ."\n";
}
?>