Calling web service from oracle forms fails with ORA_JAVA.JAVA_ERROR

Question

Problem Description:
I'm following the steps as per the doc:
http://www.oracle.com/technology/products/forms/htdocs/10gr2/howto/webservicefromforms/ws_10_1_3_from_forms.html
to create a java stub to call external web service and then use java importer in oracle forms to call this web service from oracle forms.
WSDL for external web service used is http://www.webservicex.net/CurrencyConverter.asmx?wsdl
Calling the web service using JDeveloper works fine but from Oracle Forms returns ORA_JAVA.JAVA_ERROR; Unable to call out to Java, Invalid object type for argument 1
The code from oracle form to call web service is as below:
DECLARE
jo ora_java.jobject;
rv ora_java.jobject;
ex ora_java.jobject;
outString varchar2(2000);
BEGIN
jo:= CurrencyConvertorStub.new;
--This will get the exchange rate from US Dollars to UK Sterling.
rv:= CurrencyConvertorStub.ConversionRate(jo,'CAD','USD');
message (float_.floatValue(RV));
EXCEPTION
WHEN ORA_JAVA.JAVA_ERROR then
message('Unable to call out to Java, ' ||ORA_JAVA.LAST_ERROR);
WHEN ORA_JAVA.EXCEPTION_THROWN then
ex := ORA_JAVA.LAST_EXCEPTION;
outString := Exception_.toString(ex);
message(outString);
END;
Any help/ideas on this is greatly appreciated. Thanks.

Answer 1

Yes, it is the message line - so basically this call fails => rv:= CurrencyConvertorStub.ConversionRate(jo,'CAD','USD'); and control goes in the exception block
WHEN ORA_JAVA.JAVA_ERROR then
message('Unable to call out to Java, ' ||ORA_JAVA.LAST_ERROR);
Below is the code from java stub that was generated using JDeveloper by using web services stub/skeleton and associating the WSDL
public Double ConversionRate(String FromCurrency, String ToCurrency) throws Exception
URL endpointURL = new URL(endpoint);
Envelope requestEnv = new Envelope();
Body requestBody = new Body();
Vector requestBodyEntries = new Vector();
String wrappingName = "ConversionRate";
String targetNamespace = "http://www.webserviceX.NET/";
Vector requestData = new Vector();
requestData.add(new Object[] {"FromCurrency", FromCurrency});
requestData.add(new Object[] {"ToCurrency", ToCurrency});
requestBodyEntries.addElement(toElement(wrappingName, targetNamespace, requestData));
requestBody.setBodyEntries(requestBodyEntries);
requestEnv.setBody(requestBody);
Message msg = new Message();
msg.setSOAPTransport(m_httpConnection);
msg.send(endpointURL, "http://www.webserviceX.NET/ConversionRate", requestEnv);
Envelope responseEnv = msg.receiveEnvelope();
Body responseBody = responseEnv.getBody();
Vector responseData = responseBody.getBodyEntries();
return (Double)fromElement((Element)responseData.elementAt(0), java.lang.Double.class);
}