Get value from specific key in XML output from REST API - php

Question

I am making a simple web-based application that shows the arrival time (in minutes) of trains arriving at the metro station near my home.
Metro (The subway in Washington, DC) has released an API that allows developers to access this information: http://developer.wmata.com/docs/read/GetRailStationInfo
When I use the example code from the link above I get a list of tagged text like this:
<AIMPredictionResp xmlns="http://www.wmata.com" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<Trains>
<AIMPredictionTrainInfo>
<Car>6</Car>
<Destination>NewCrltn</Destination>
<DestinationCode>D13</DestinationCode>
<DestinationName>New Carrollton</DestinationName>
<Group>1</Group>
<Line>OR</Line>
<LocationCode>K03</LocationCode>
<LocationName>Virginia Square</LocationName>
<Min>7</Min>
</AIMPredictionTrainInfo>
</Trains>
All I want to display is the minutes wrapped in the < Min > < /Min > tag. What's the best way to go about this? Is there a PHP script that I can write that will pull just that number? If so, could you please point me in the right direction?
Thanks!
UPDATE:
Thank you all very much. I have tried an example from the tutorial you sent, but when I switch my URL (with key) in it does not display anything.
<?php
$trainInfo = simplexml_load_file("api.wmata.com/StationPrediction.svc/GetPrediction/_KEYXXXXXXXX);
print $trainInfo->AIMPredictionTrainInfo->LocationName;
print $trainInfo->AIMPredictionTrainInfo->Min;
?>

Answer 1

The direction you want to be pulled in is SimpleXML
EXAMPLE (not tested):
<?php
$xml = new SimpleXMLElement($my_input_xml);
echo $xml->getMin() . "<br>";
?>
Here are some other good tutorials:
http://php.net/manual/en/simplexml.examples-basic.php
http://www.phpeveryday.com/articles/PHP-SimpleXML-Tutorial-P846.html
'Hope that helps!

Answer 2

Here comes an example using DOMXPath (tested). Important is to register the default namespace:
$data = <<<EOF
<?xml version="1.0"?>
<AIMPredictionResp xmlns="http://www.wmata.com" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<Trains>
<AIMPredictionTrainInfo>
<Car>6</Car>
<Destination>NewCrltn</Destination>
<DestinationCode>D13</DestinationCode>
<DestinationName>New Carrollton</DestinationName>
<Group>1</Group>
<Line>OR</Line>
<LocationCode>K03</LocationCode>
<LocationName>Virginia Square</LocationName>
<Min>7</Min>
</AIMPredictionTrainInfo>
</Trains>
</AIMPredictionResp>
EOF;
$doc = new DOMDocument();
$doc->loadXML($data);
$selector = new DOMXPath($doc);
$selector->registerNamespace(
'default',
'http://www.wmata.com'
);
$query = '//default:Min';
foreach($selector->query($query) as $node) {
var_dump($node->nodeValue);
}
Output:
string(1) "7"