Integration

Hi.
I have webservice which doesn't need input message. For example stack cleaner.

<wsdl:message name="eraseStackRequest">
</wsdl:message>
<wsdl:message name="eraseStackResponse">
<wsdl:part element="impl:result" name="result"/>
</wsdl:message>
<wsdl:portType name="Stack">
<wsdl:operation name="eraseStack">
<wsdl:input message="impl:eraseStackRequest" name="eraseStackRequest"/>
<wsdl:output message="impl:eraseStackResponse" name="eraseStackResponse"/>
</wsdl:operation>
</wsdl:portType>
<wsdl:binding name="StackSOAPSoapBinding" type="impl:Stack">
<wsdlsoap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
<wsdl:operation name="eraseStack">
<wsdlsoap:operation soapAction=""/>
<wsdl:input name="eraseStackRequest">
<wsdlsoap:body use="literal"/>
</wsdl:input>
<wsdl:output name="eraseStackResponse">
<wsdlsoap:body use="literal"/>
</wsdl:output>
</wsdl:operation>

Is there possibility call this service from BPEL. JDeveloper require input message.
When I create input variable and assign value to it, I get error.

Thanks.