php - PHP で特定の XML ノードにアクセスする

Question

以下のコードのような xml リクエストがあり、レスポンスに含まれるノード RATE の値のみを PHP 変数に格納したいと考えています。

どうすればそれを達成できますか？

$zip = 90002;
$pounds = 0.1;
$shippingMode = "Express";
$url = "http://production.shippingapis.com/shippingAPI.dll";

$devurl ="testing.shippingapis.com/ShippingAPITest.dll";
$service = "RateV4";
$xml = rawurlencode("<RateV4Request USERID='USER' >
<Revision/>
     <Package ID='1ST'>
          <Service>$shippingMode</Service>
          <ZipOrigination>10025</ZipOrigination>
          <ZipDestination>".$zip."</ZipDestination>
          <Pounds>".$pounds."</Pounds>
          <Ounces>0</Ounces>
          <Container></Container>
          <Size>REGULAR</Size>
          <Width></Width>
          <Length></Length>
          <Height></Height>
          <Girth></Girth>
     </Package>
</RateV4Request>");
$request = $url . "?API=" . $service . "&xml=" . $xml;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$request);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_HTTPGET, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$result = curl_exec($ch);
curl_close($ch);

応答は次のようになります。RATE 値を取得するだけです。

<?xml version="1.0" encoding="UTF-8"?>
<RateV4Response>
     <Package ID="1ST">
          <ZipOrigination>44106</ZipOrigination>
          <ZipDestination>20770</ZipDestination>
          <Pounds>1</Pounds>
          <Ounces>8</Ounces>
          <Container>NONRECTANGULAR</Container>
          <Size>LARGE</Size>
          <Width>15</Width>
          <Length>30</Length>
          <Height>15</Height>
          <Girth>55</Girth>
          <Zone>3</Zone>
          <Postage CLASSID="1">
               <MailService>Priority Mail&lt;sup&gt;&amp;reg;&lt;/sup&gt;</MailService>
               <Rate>24.85</Rate>
          </Postage>
     </Package>
</RateV4Response>   

---

最新のコード

$zip = 90002;
$pounds = 0.1;
$shippingMode = "Express";
function USPSParcelRate($pounds,$zip,$shippingMode) {
$url = "http://production.shippingapis.com/shippingAPI.dll";

$devurl ="testing.shippingapis.com/ShippingAPITest.dll";
$service = "RateV4";
$userid = "023TAHAR4995";
$xml = rawurlencode("<RateV4Request USERID='023TAHAR4995' >
<Revision/>
     <Package ID='1ST'>
          <Service>$shippingMode</Service>
          <ZipOrigination>10025</ZipOrigination>
          <ZipDestination>".$zip."</ZipDestination>
          <Pounds>".$pounds."</Pounds>
          <Ounces>0</Ounces>
          <Container></Container>
          <Size>REGULAR</Size>
          <Width></Width>
          <Length></Length>
          <Height></Height>
          <Girth></Girth>
     </Package>
</RateV4Request>");
$request = $url . "?API=" . $service . "&xml=" . $xml;
// send the POST values to USPS
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$request);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_HTTPGET, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
// parameters to post


$result = curl_exec($ch);
curl_close($ch);
$response = new SimpleXMLElement($result);

echo $response->RateV4Response->Package->Postage->Rate;

}
USPSParcelRate($pounds,$zip, $shippingMode);