Question

I have a page on a remote server that returns a single xml value

<?xml version="1.0" ?><Tracker>12345</Tracker>

How do I go about getting the value 12345 or whatever is in the tag into a PHP variable?
I know I can’t do something as simple as:

<?php
    $var = http://www.www.com/file.php;
    echo $var;   //12345
?>

I’m new to the entire idea of creating a web service – I think that’s what this should be.?.

Answer 1

You have to go in two steps :

• Get the XML string from the remote server
  • with curl, for instance
  • or with file_get_contents
• and, then, parse that XML to extract the data
  • with simplexml_load_string for instance

Note that those two steps can be merged as one, using simplexml_load_file, if the configuration of your server allows you to do that.

Once you have that XML in a PHP variable, using SimpleXML, it’s quite easy to get the value you want. For instance :

$string = '<?xml version="1.0" ?><Tracker>12345</Tracker>';
$xml = simplexml_load_string($string);
echo (string)$xml;

Will get you

12345

And getting the content of that XML from the remote URL can be as simple as :

$string = file_get_contents('http://your-remote-url');

And if you can do that, you can also use that remote URL directly with SimpleXML :

$xml = simplexml_load_file('http://your-remote-url');
echo (string)$xml;

But this will only work if allow_url_fopen is enabled in your server’s configuration.

If allow_url_fopen is disabled on your server, you can get the XML from the remote server using curl ; something like this should do the trick, for instance :

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://your-remote-url");
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$string = curl_exec($ch);
curl_close($ch);

And, then, you can still use simplexml_load_string, as I did in my first example.

(If using curl, take a look at the documentation of curl_setopt : there are several options that might interest your — for instance, to specify timeouts)