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Thursday, October 14, 2010

Zend_Soap_Client and PHP http client do not share same native code

I was told by a senior PHP consultant that he can not successfully make Zend_Soap_Client call over the SSL. He runs his code on Zend Server running on i Series. Then, I told him that, if I were him, I will try to write a normal HTTP client to access the WSDL file over SSL first. The reason for me to approach in this way because,

  • SOAP is built on the top HTTP. So, SSL should not be business of SOAP. In other words, SOAP client shall rely on the HTTP client implement.
  • I THOUGHT that Zend_Soap_Client uses same native code as PHP http client.

However, I was wrong. He tested and found that he was able to do file_get_contents and retrieve https:// content from the server. Then, I started to trace the source code of Zend_Soap_Client. I found,
  1. Zend_Soap_Client is a wrapper around PHP SOAP extension.
  2. PHP SOAP is a thin layer. It quickly goes to native code at file called soap.php.
  3. Native c code of soap.php has its own logical to deal with proxy and SSL. Click Here to see C source code.
So, I was wrong. I can not regard that Zend_Soap_Client can support SSL just because PHP Http client can support SSL. They probably uses different version of native http client code. From this discussion, I get deeper understanding about architecture of PHP. I will probably write a article to compare Java and PHP.

BTW, PHP 5.3 version of Zend Server 5.0.2 on iSeries does not support Zend_Soap_Client to access web service over the SSL. However, Zend_Soap_Client work with SSL when the Zend Server was rolled back to version 5.0.1 . Zend_Soap_Client coming with Zend server 5.0.4 can be used to access Web service over one-way SSL. I have not tried mutual SSL with Zend_Soap_Client yet. But, it sounds not easy.

Also, to test Zend_Soap_Client access over one-way SSL can be as simple as below,

try {
 $soap_url = ''; 
 $soap_client = new SoapClient ( $soap_url);
 var_dump ( $soap_client -> __getFunctions () );
} catch ( Exception $e ) {
 print_r ( $e );
 exit ();

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