Dissection of a XML-RPC Response - PHP

Do you want your Perl code on one server to call your PHP functions on another? "Impossible!" you say? Not with XML-RPC. XML-RPC is a standard way for any application to make requests and recieve responses from methods written in any language. Interested? I knew you would be.

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By: Lucas Marshall

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December 20, 2001

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And here's the response to the call:

HTTP/1.1 200 OK
Connection: close
Content-Length: 191
Content-Type: text/xml
Date: Tue, 18 Dec 2001 14:23:52 GMT
Server: xmlrpc-epi-php/0.2 (PHP)
<?xml version='1.0' encoding="iso-8859-1" ?>
<methodResponse>
<params>
<param>
<value>
<string>Hello Lucas. How are you today?</string>
</value>
</param>
</params>
</methodResponse>

With your newly found knowledge of XML-RPC calls, it is easy to decipher standard responses. Normal responses consist of <params> container with <param> elements (and all they are heir to) sent inside <methodResponse> tags, but there is another type of response - a fault:

HTTP/1.1 200 OK
Connection: close
Content-Length: 356
Content-Type: text/xml
Date: Tue, 18 Dec 2001 13:52:25 GMT
Server: Apache/1.3.20
<?xml version='1.0' encoding="iso-8859-1" ?>
<methodResponse>
<fault>
<value>
<struct>
<member>
<name>faultCode</name>
<value>
<int>4</int>
</value>
</member>
<member>
<name>faultString</name>
<value>
<string>Too many parameters.</string>
</value>
</member>
</struct>
</value>
</fault>
</methodResponse>

As you can see, a fault response consists of a <methodResponse> containing a <fault> which contains a <value> which is a <struct> containing two elements, one named <faultCode>, an <int> and one named <faultString>, a <string>.

Please note that a response cannot contain both a <params> container and a <fault> container.

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