Invoke a single port async service using JAX-WS and WS-Addressing

I was looking over the WSTF pages and found the use cases that include a single port reply to another address. I did wonder if you could safely invoke this using JAX-WS. So I decided to find out.

To make things simple I used the following hello world with addressing turned on. Note this is not a true asynchronous service as the rely is sent before the server returns with a 202 code; but it is close enough for the purposes of this presentation.

@Addressing
@WebService
public class Hello {

    @Action(input="http://project1/Hello/sayHello"
            output="http://project1/Hello/sayHelloReponse")
    public String sayHello(String name) {
        return name;
    }
}

So I published this service and then generated a client to another project. We need to create a suitable callback service so first of all you have to find the port SEI:

@WebService(wsdlLocation="HelloService.wsdl", targetNamespace="http://project1/",
  name="Hello")
@XmlSeeAlso(
  { project1.ObjectFactory.class })
public interface Hello
{
  @WebMethod
  @Action(input="http://project1/Hello/sayHelloRequest", output="http://project1/Hello/sayHelloResponse")
  @ResponseWrapper(localName="sayHelloResponse", targetNamespace="http://project1/",
    className="project1.SayHelloResponse")
  @RequestWrapper(localName="sayHello", targetNamespace="http://project1/",
    className="project1.SayHello")
  @WebResult(targetNamespace="")
  public String sayHello(@WebParam(targetNamespace="", name="arg0")
    String arg0);
}

Then I used Refactor->Duplicate to create a copy and converted the interface into a class. As you can see you need to turn the interface in-side out. The changes I made are:

• Remove WSDL declaration in @WebService, a new one will be create for response part
• Remove output action and replace with input with the output value
• Make method one way
• Add @Addressing modifier
• Make the return value the only parameter, moving over any WebResult values to WebParam.

If would be really nice to have this done automatically when the usingAddressing tag is found in the WSDL, perhaps it would be possible to extend the web services generation tool to do this.

@WebService(targetNamespace = "http://project1/", name = "Hello")
@XmlSeeAlso( { ObjectFactory.class })
@Addressing
public class HelloCallback {
    @WebMethod
    @Action(input = "http://project1/Hello/sayHelloResponse")
    @RequestWrapper(localName = "sayHelloResponse",
                     targetNamespace = "http://project1/",
                     className = "project1.SayHelloResponse")
    @Oneway
    public void sayHello(@WebParam(targetNamespace = "", name = "return")
        String ret) {
        
        System.out.println(ret);
        
    }
}

And then the code is really quite simple, in this case we publish the endpoint and then invoke the service. Note we use the @OneWayFeature to populate the required WS-Addressing features, this is a bit naughty as it is part of the -RI and doesn't support faults. For the purposes of this blog though it makes the code a mite easier to read.

The other thing to note is that the call to sayHello returns a "null" object, you can use the MessageContext to check the response code if you want to confirm a 202; but otherwise the rest of the action is deferred to the callback class at this point.

public static void main(String[] args) {
    helloService = new HelloService();
    
    
    Endpoint e = Endpoint.publish(
        "http://localhost:7890/endpoint",
        new HelloCallback());
    

    WSEndpointReference replyTo = new WSEndpointReference(e.getEndpointReference());


    Hello hello = helloService.getHelloPort(new WebServiceFeature[] {
      new OneWayFeature(true, replyTo)});


    // This method will return null
    //
    
    Object ret = hello.sayHello("Bob");

    // Check the message response code
    //

    Integer responseCode = (Integer)     
        ((BindingProvider)hello).getReponseContext()
            .get(MessageContext.HTTP_RESPONSE_CODE);  
}

One final note is that you need to force the client to exit as Endpoint.publish create a non-daemon thread.