Question

Suppose that the action performed by the procedure , which is called by the webservice , is equivalent to a void method , should it always return a value anyway ?

Answer 1

From WSDL point of view you have two choices:

1:

<wsdl:types>
  ...
  <xs:element name="method1" type="x:MyType1" />
  ...

<wsdl:message name="msg1_1">
  <wsdl:part name="input" element="tns:method1" />
</wsdl:message>

<wsdl:portType name="MyInterface">
  <wsdl:operation name="method1">
    <wsdl:input name="req" message="tns:msg1_1" />
  </wsdl:operation>
  ...

2:

<wsdl:types>
  ...
  <xs:element name="method2" type="x:MyType2" />
  <xs:element name="method2Response">
    <xs:complexType>
      <xs:sequence />
    </xs:complexType>
  </xs:element>
  ...

<wsdl:message name="msg2_1">
  <wsdl:part name="input" element="tns:method2" />
</wsdl:message>
<wsdl:message name="msg2_1">
  <wsdl:part name="output" element="tns:method2Response" />
</wsdl:message>

<wsdl:portType name="MyInterface">
  <wsdl:operation name="method2">
    <wsdl:input name="req" message="tns:msg2_1" />
    <wsdl:output name="res" message="tns:msg2_2" />
  </wsdl:operation>
  ...

With option 1 you get One-way Operation which may sometimes be a problem becase the client’s call returns without the knowledge of comleting the server-side method.

With option 2 you have normal Request-response Operation, you just get (almost) empty SOAP response.

(all above examples use document/literal/wrapped convention)

From implementation point of view, if you use e.g. Apache CXF with JAX-WS you end up with standard, void-returning methods.