title: Optional Message Parts in WSDL
body: <p>In my wsdl:message i got two parameters, firstname and lastname:</p>
  
  <pre><code>&lt;message name="setName"&gt;
    &lt;part name="firstname" type="xsd:string"&gt;&lt;/part&gt;
    &lt;part name="lastname" type="xsd:string"&gt;&lt;/part&gt;
  &lt;/message&gt; 
  </code></pre>
  
  <p>I want to define the "firstname" part as required, and the "lastname" part as optional. 
  How do i do that?</p>