The introspection callback function should return an XML string with the following format:
<?xml version='1.0'?>
<introspection version='1.0'>
<methodList>
<methodDescription name='introspection.hello'>
<author>Dan Libby</author>
<purpose>greets the caller and demonstrates use of introspection mechanism</purpose>
<signatures>
<signature>
<params>
<value type='string' name='name'>name of the caller</value>
</params>
<returns>
<value type='string'>a greeting to the caller</value>
</returns>
</signature>
</signatures>
<see><item>system.listMethods</item></see>
<examples/>
<errors>
<item>returns fault code 1 if the caller's name is not specified</item>
</errors>
<notes>
<item>this is a lame example</item>
<item>example of multiple notes</item>
</notes>
<bugs/>
<todo/>
</methodDescription>
</methodList>
</introspection>