A WSDL requires input for processing

Although I have the WSDL successfully loaded into SoapUI, but the structure was incorrect. Following is the SOAP request message generated by default when the WSDL first loaded into SoapUI:

<soap:envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
   <soap:header/>
   <soap:body>
</soap:Envelope>

I'll get an error message says line -1: null when I validate on this request message. To fix this error, I must have at least one element in the body tag. Here is the new WSDL code for the input:

...

<wsdl:types>
  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://helloWorld.huahsin.org/">
    <xsd:element name="Input"/>
  </xsd:schema>
</wsdl:types>

< wsdl:message name="HelloWorldRequest">
  < wsdl:part name="parameters" element="tns:Input"/>
< /wsdl:message>
...

Now the SOAP request message will look like this:

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:hel="http://helloWorld.huahsin.org/">
   <soap:Header/>
   <soap:Body>
      <hel:Input>?</hel:Input>
   </soap:Body>
</soap:Envelope>

In the real world, it is impossible to have this empty SOAP request message, some input would require to pass in for processing. For the sake of this experiment, I would need a name and an age field. The name field is a mandatory field, whereas age field is optional.

...

<wsdl:types>
  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://helloWorld.huahsin.org/">
    <xsd:element name="Input">
      <xsd:complexType>
        <xsd:sequence>
          <xsd:element name="name" type="xsd:string" minOccurs="1"/>
          <xsd:element name="age" type="xsd:integer" minOccurs="0"/>
        </xsd:sequence>
      </xsd:complexType>
    </xsd:element>
  </xsd:schema>
</wsdl:types>

With this new WSDL design, the SOAP message now will be much better and complete:

< soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:hel="http://helloWorld.huahsin.org/">
   <soap:Header/>
   <soap:Body>
      <hel:Input>
         <name>?</name>
         <!--Optional:-->
         <age>?</age>
      </hel:Input>
   </soap:Body>
</soap:Envelope>