java.lang.IllegalArgumentException: webservices.CurrencyConversion is not an interface - web-services

Question

I have build a simple web services in my JSF projects. I have tested the web services that I created with a java application and its works fine. After that, I tried to call the method in web service to my managedBean to works with jsf. An exception was occur as below:
javax.faces.el.EvaluationException: java.lang.IllegalArgumentException: webservices.CurrencyConversion is not an interface
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
This is my webservice code :
package webservices;
import javax.jws.WebService;
import javax.jws.WebMethod;
import javax.jws.WebParam;
#WebService(serviceName = "CurrencyConversion")
public class CurrencyConversion {
String listCurrency[] = {"MYR", "EUR", "USD", "SGD", "AUD", "HKD", "CNY", "TWD"};
double listRate[] = {0.258667, 1.22903, 1.000000, 0.762768, 0.766570, 0.127416, 0.159005, 0.0343023};
String origin = null;
String destination = null;
double oriRate;
double destRate;
double convertRate;
double amount = 1.0;
#WebMethod(operationName = "convertCurrency")
public double convertCurrency(#WebParam(name = "origin") String origin,#WebParam(name = "destination") String destination) {
double convertRate = 0.0;
for (int i = 0; i < listCurrency.length; i++){
if (origin.equals(listCurrency[i])) {
oriRate = listRate[i];
i = i + listCurrency.length;
}
}
for (int i = 0; i < listCurrency.length; i++){
if (destination.equals(listCurrency[i])) {
destRate = listRate[i];
i = i + listCurrency.length;
}
}
convertRate = amount * (oriRate / destRate);
return convertRate;
}
}
This is the way I call the web service method:
String origin = null;
String destination =null;
double convertRate = 0.0;
public String getOrigin() {
return origin;
}
public String getDestination() {
return destination;
}
public void setOrigin(String origin) {
this.origin = origin;
}
public void setDestination(String destination) {
this.destination = destination;
}
public double getConvertRate() {
return convertRate;
}
public void setConvertRate(double convertRate) {
this.convertRate = convertRate;
}
public void convert() {
convertRate = convertCurrency(origin, destination);
}
private double convertCurrency(java.lang.String origin, java.lang.String destination) {
// Note that the injected javax.xml.ws.Service reference as well as port objects are not thread safe.
// If the calling of port operations may lead to race condition some synchronization is required.
webservices.CurrencyConversion port = service.getCurrencyConversionPort();
return port.convertCurrency(origin, destination);
}
And lastly the jsf I writed:
<h:selectOneMenu value = "#{courseworkBean.origin}" class="listbox">
<f:selectItem itemValue = "MYR" itemLabel = "MYR" />
<f:selectItem itemValue = "EUR" itemLabel = "EUR" />
<f:selectItem itemValue = "USD" itemLabel = "USD" />
<f:selectItem itemValue = "SGD" itemLabel = "SGD" />
<f:selectItem itemValue = "AUD" itemLabel = "AUD" />
<f:selectItem itemValue = "HKD" itemLabel = "HKD" />
<f:selectItem itemValue = "CNY" itemLabel = "CNY" />
<f:selectItem itemValue = "TWD" itemLabel = "TWD" />
</h:selectOneMenu>
<h:selectOneMenu value = "#{courseworkBean.destination}" class="listbox">
<f:selectItem itemValue = "MYR" itemLabel = "MYR" />
<f:selectItem itemValue = "EUR" itemLabel = "EUR" />
<f:selectItem itemValue = "USD" itemLabel = "USD" />
<f:selectItem itemValue = "SGD" itemLabel = "SGD" />
<f:selectItem itemValue = "AUD" itemLabel = "AUD" />
<f:selectItem itemValue = "HKD" itemLabel = "HKD" />
<f:selectItem itemValue = "CNY" itemLabel = "CNY" />
<f:selectItem itemValue = "TWD" itemLabel = "TWD" />
</h:selectOneMenu>
<h:commandButton class="cmdbutton" value = "Submit" action = "#{courseworkBean.convert()}" />
<h:outputText value="#{courseworkBean.getConvertRate()}" />
</h:form>
</h:body>
I tried to find several solutions but nothing is worked for me. Please tell me what's wrong for my code and thank you.