Expressing Type

There are three ways.

Use the xsi:type attribute on each accessor and reference the appropriate XML Schema type:

<s:Envelope 
  xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" 
  xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" 
  xmlns:xsd="http://www.w3.org/1999/XMLSchema">
  <s:Body>
    <ns1:doSearch>
      <param xsi:type="xsd:string">hello</param>
    </ns1:doSearch>
  </s:Body>
</s:Envelope>

Reference an XML Schema document that defines the data type.

<s:Envelope 
  xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" 
  xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" 
  xmlns:xsd="http://www.w3.org/1999/XMLSchema">
  <s:Body>
    <ns1:doSearch 
      xmlns="myschema.xsd">
      <param>hello</param>
    </ns1:doSearch>
  </s:Body>
</s:Envelope>

Reference some other type of schema document that defines the data type of schema document that defines the data type of element within its definition.

<s:Envelope 
  xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" >
  <s:Body>
    <ns1:doSearch 
      xmlns="urn:some_namespace">
      <param>hello</param>
    </ns1:doSearch>
  </s:Body>
</s:Envelope>
<!--Where urn:some_namespace indicates some namespace-->
<!-- where the value of param elements are strings.-->