Lab 5 : PHP and SOAP

The only SOAP requests I’ve ever made were made on the .NET platform. They’re not that much of a beast on .NET, but it wasn’t exactly a cake walk either. So I had been bracing myself for the worst trying to implement it in PHP.

I should explain that my lab 5 client connects to a PHP service that in turn makes the SQS requests, etc. I initially wanted to implement an SQS library in Actionscript (and probably will in the future when I’m not pressed by deadlines) but I decided it was too ambitious for the amount of time I wanted to spend on this lab. So alas, a PHP service also handles my SOAP request to WHOIS.

Anyway, I was expecting SOAP on PHP to be a seriously complex affair. Here’s my code that makes the request:

$client = new SOAPClient("http://www.webservicex.net/whois.asmx?WSDL");
$params = array('HostName' => $_GET['url']);
$whois = $client->GetWhoIS($params);

Granted, it would have required about 2 more lines if there wasn’t a URL to the WSDL, but it doesn’t get much simpler than that. I should mention that this requires that PHP SOAP be enabled (uncomment a line in your php.ini if you’re running Windows; recompile from source using ‘enable-soap’ if you’re running Linux). I didn’t have to recompile, thanks once again to Remi Collet (the French guy who has yum rpms for all this stuff, see my previous post).

Well, the SQS library I’m using is pretty old and doesn’t have a means of querying the queue for the number of messages. So, I thought I’d try sending a SOAP message to Amazon to get it. Amazon’s WSDL is a little more complex, and I probably could have gotten it to work if I wanted to play around with the messages for another hour or so. It turned out to be a miserable failure, and I resorted to my old tricks: (file_get_contents()) which worked perfectly. Here’s the code I used, which shows the query string needed to get the number of messages:

$timestamp = gmdate('Y-m-d\TH:i:s\Z');
$qs = "http://queue.amazonaws.com/A3N3IV5XJH079S/processing" .
  "?Action=GetQueueAttributes" .
  "&Attribute=ApproximateNumberOfMessages" .
  "&AWSAccessKeyId=[AMAZON_ACCESS_KEY]" .
  "&Version=2007-05-01" .
  "&Timestamp=" . urlencode($timestamp) .
  "&Signature=" . urlencode(constructSig('GetQueueAttributes' . $timestamp));
$response = file_get_contents($qs);

The constructSig is the same method I listed in a previous post.

Here are a few links that were helpful:
SQS Query and SOAP API
Getting SQS Attributes
SQS WSDL