title: What is 'any' in wsdl and how i can call a wsdl function using php?
body: <p>This code is a small part of my wsdl. Here I haven't understood    </p>
  
  <pre><code>&lt;s:sequence&gt;
      &lt;s:any/&gt;
  &lt;/s:sequence&gt;
  </code></pre>
  
  <p>Please tell me what is this </p>
  
  <pre><code>&lt;s:element name="CalculStudents"&gt;
      &lt;s:complexType&gt;
          &lt;s:sequence&gt;
              &lt;s:element minOccurs="0" maxOccurs="1" name="doc"&gt;
                  &lt;s:complexType mixed="true"&gt;
                      &lt;s:sequence&gt;
                          &lt;s:any/&gt;
                      &lt;/s:sequence&gt;
                  &lt;/s:complexType&gt;
              &lt;/s:element&gt;
          &lt;/s:sequence&gt;
      &lt;/s:complexType&gt;
  &lt;/s:element&gt;
  </code></pre>
  
  <p>using php I am calling this function  below is my code   </p>
  
  <pre><code> $client = new SoapClient("some.wsdl");
   $params = array("any"=&gt;'');
   $result = $client-&gt;CalculStudents(array('doc'=&gt;$params));
  </code></pre>
  
  <p>but it's throwing an error </p>
  
  <pre><code> Exception Error! Server was unable to process 
   request.Object reference not set to an instance of an object.
  </code></pre>
  
  <p>Tell me how to solve this. Is this a php calling mistake or wsdl is wrong?</p>