Service for Asynchronous Client calls (polling, callback)

[Alan Rickmoore]

I am a WebService learner and digging through all this stuff isn't easy with all that maybe-outdated-but-still-usable technology floating around. Here's my thing.

My goal is to create a WebService that can be called to perform a time-consuming task. This should be done asynchronously since the client is required to continue working. On my way to achieve this I have stumbled upon JAX-WS 2.0 and it's possibility to create web services via annotation. It also allows asynchronous calls with the @oneway annotation.

Now, I to my understanding (and from several different sources on the web) it seems like I need a server working synchronously which returns a Response<?> (for a polling approach). For a callback approach it seem to be needing an AsyncHandler and sometimes a Future<?>.

Here's how that is supposed to look:

@WebService
public class MyService{
	
	@WebMethod
	public String getStuff(String inputString){
		return doStuff(inputString); //synchronous call
	}
	
	@WebMethod
	public Response<String> getStuffAsync(String inputString){
		return null; //some sources say this isn't even called
	}
	
	@WebMethod
	public Future<?> getStuffAsync(String inputString, AsyncHandler<String> callbackHandler){
		return null; //some sources say this isn't even called
	}
}

Here's the endpoint code:

public class Publisher {
	
	public static void main(String[] args) {
		Object implementor = new MyService();
		String adress = "http://localhost:8080/services";
		
		Endpoint endpoint = Endpoint.publish(adress, implementor);
		
		JOptionPane.showMessageDialog( null, "Exit server" );
		
	    endpoint.stop(); 
	}
	
}

I am using Java 1.6.0_26 and Eclipse Indigo with WTP. I have not actively deployed this code to any server, I am just running this Publisher class above. Everything was working fine until either Response, Future or AsyncHandler are added to the code.

Before that the WSDL was retrievable via http://localhost:8080/services?wsdl. I was able to run a client based on this code using wsimport from a *.bat like this:

wsimport -d ..\src -keep -p test http://localhost:8080/services?wsdl

Now it's giving me this exception, which means I don't even get to the point where my Publisher generates the WSDL:

11.10.2011 08:28:12 com.sun.xml.internal.ws.model.RuntimeModeler getRequestWrapperClass
INFO: Dynamically creating request wrapper Class test.jaxws.GetStuff
11.10.2011 08:28:12 com.sun.xml.internal.ws.model.RuntimeModeler getResponseWrapperClass
INFO: Dynamically creating response wrapper bean Class test.jaxws.GetStuffResponse
11.10.2011 08:28:12 com.sun.xml.internal.ws.model.RuntimeModeler getRequestWrapperClass
INFO: Dynamically creating request wrapper Class test.jaxws.GetStuffAsync
11.10.2011 08:28:12 com.sun.xml.internal.ws.model.RuntimeModeler getResponseWrapperClass
INFO: Dynamically creating response wrapper bean Class test.jaxws.GetStuffAsyncResponse
Exception in thread "main" javax.xml.ws.WebServiceException: Unable to create JAXBContext
	at com.sun.xml.internal.ws.model.AbstractSEIModelImpl.createJAXBContext(Unknown Source)
	at com.sun.xml.internal.ws.model.AbstractSEIModelImpl.postProcess(Unknown Source)
	at com.sun.xml.internal.ws.model.RuntimeModeler.buildRuntimeModel(Unknown Source)
	at com.sun.xml.internal.ws.server.EndpointFactory.createSEIModel(Unknown Source)
	at com.sun.xml.internal.ws.server.EndpointFactory.createEndpoint(Unknown Source)
	at com.sun.xml.internal.ws.api.server.WSEndpoint.create(Unknown Source)
	at com.sun.xml.internal.ws.api.server.WSEndpoint.create(Unknown Source)
	at com.sun.xml.internal.ws.transport.http.server.EndpointImpl.createEndpoint(Unknown Source)
	at com.sun.xml.internal.ws.transport.http.server.EndpointImpl.publish(Unknown Source)
	at com.sun.xml.internal.ws.spi.ProviderImpl.createAndPublishEndpoint(Unknown Source)
	at javax.xml.ws.Endpoint.publish(Unknown Source)
	at test.Publisher.main(Publisher.java:12)
Caused by: java.security.PrivilegedActionException: com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 2 counts of IllegalAnnotationExceptions
javax.xml.ws.Response is an interface, and JAXB can't handle interfaces.
	this problem is related to the following location:
		at javax.xml.ws.Response
		at public javax.xml.ws.Response test.jaxws.GetStuffAsyncResponse._return
		at test.jaxws.GetStuffAsyncResponse
javax.xml.ws.Response does not have a no-arg default constructor.
	this problem is related to the following location:
		at javax.xml.ws.Response
		at public javax.xml.ws.Response test.jaxws.GetStuffAsyncResponse._return
		at test.jaxws.GetStuffAsyncResponse

	at java.security.AccessController.doPrivileged(Native Method)
	... 12 more
Caused by: com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 2 counts of IllegalAnnotationExceptions
javax.xml.ws.Response is an interface, and JAXB can't handle interfaces.
	this problem is related to the following location:
		at javax.xml.ws.Response
		at public javax.xml.ws.Response test.jaxws.GetStuffAsyncResponse._return
		at test.jaxws.GetStuffAsyncResponse
javax.xml.ws.Response does not have a no-arg default constructor.
	this problem is related to the following location:
		at javax.xml.ws.Response
		at public javax.xml.ws.Response test.jaxws.GetStuffAsyncResponse._return
		at test.jaxws.GetStuffAsyncResponse

	at com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException$Builder.check(Unknown Source)
	at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(Unknown Source)
	at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(Unknown Source)
	at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(Unknown Source)
	at com.sun.xml.internal.bind.v2.ContextFactory.createContext(Unknown Source)
	at com.sun.xml.internal.bind.api.JAXBRIContext.newInstance(Unknown Source)
	at com.sun.xml.internal.ws.developer.JAXBContextFactory$1.createJAXBContext(Unknown Source)
	at com.sun.xml.internal.ws.model.AbstractSEIModelImpl$1.run(Unknown Source)
	at com.sun.xml.internal.ws.model.AbstractSEIModelImpl$1.run(Unknown Source)
	... 13 more

From what I know this tells me JAXB isn't able to work with these interfaces because it can't translate them. But if that's the case, why do I find tutorials with this code at IBM and Apache Axis 2?


Thanks for your help.

[H Paul]

KEY: The features you're looking for is from the Client side only - Client ASYNCHRONOUS invocation.

You will be clarified by these 2 links:
http://jax-ws.java.net/nonav/2.1.4/docs/UsersGuide.html
http://jax-ws.java.net/nonav/2.1.4/docs/asynch.html

Simplified as below:

1.
http://jax-ws.java.net/nonav/2.1.4/samples/fromwsdl/etc/AddNumbers.wsdl
wsimport this wsdl and you (client) can make a SYNCHRONOUS call.

the generated service endpoint interface DO NOT have async methods.


3. if you (client) want to make a ASYNCHRONOUS call to the web service provider (polling or callback)

http://jax-ws.java.net/nonav/2.1.4/docs/asynch.html

In order to generate a service endpoint interface with asynchronous methods the following binding declaration file will be passed to wsimport

   <bindings
       xmlns:xsd="http://www.w3.org/2001/XMLSchema"
       xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
       wsdlLocaption="http://localhost:8080/jaxws-async/addnumbers?WSDL"
       xmlns="http://java.sun.com/xml/ns/jaxws">
       <bindings node="wsdl:definitions">
           <package name="async.client"/>
           <enableAsyncMapping>true</enableAsyncMapping>
       </bindings>
   </bindings>

	These 2 methods will added service endpoint interface    

       //async polling Method
       public Response<AddNumbersResponse> addNumbers(int number1, int number2);
       //async callback Method
       public Future<?> addNumbers(int number1, int number2, AsyncHandler<AddNumbersResponse>);

These 2 allow you (client) to invoke a web service provider ASYNCHRONOUSLY from the client only.

4. Some IDE will generate these 2 async methods or have an option during the web service client generation to create
these 2 asyn methods.

[H Paul]

Here is 1 quick test:

Server side on GlassFish 3x

package test.provider.async;

import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebResult;
import javax.jws.WebService;

@WebService(name = "EndpointSEI", targetNamespace = "http://async.provider.test/")
public interface EndpointSEI
{
   @WebMethod
   @WebResult(name = "result")
   public String echo(@WebParam(name = "what") String what);
}


package test.provider.async;

import javax.jws.WebService;

@WebService(targetNamespace = "http://async.provider.test/",
		endpointInterface = "test.provider.async.EndpointSEI", 
		portName = "EndpointSIBPort", 
		serviceName = "EndpointSIBService")
public class EndpointSIB implements EndpointSEI
{

	@Override
	public String echo(String what) {
		// TODO Auto-generated method stub
		return what;
	}




}

Client side (eclipse ide, Apache CXF and the binding file for ide for client side artifacts generation)

<?xml version="1.0" encoding="UTF-8"?>
<bindings
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
    wsdlLocaption="http://elephant:8080/GlassFishMetroWS/EndpointSIBService?wsdl"
    xmlns="http://java.sun.com/xml/ns/jaxws">
    <bindings node="wsdl:definitions">
        <package name="async.client"/>
        <enableAsyncMapping>true</enableAsyncMapping>
    </bindings>
</bindings>



Code generated:

package async.client;

import java.util.concurrent.Future;
import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebResult;
import javax.jws.WebService;
import javax.xml.bind.annotation.XmlSeeAlso;
import javax.xml.ws.Action;
import javax.xml.ws.AsyncHandler;
import javax.xml.ws.RequestWrapper;
import javax.xml.ws.Response;
import javax.xml.ws.ResponseWrapper;

/**
 * This class was generated by Apache CXF 2.4.2
 * 2011-10-11T12:16:27.437-07:00
 * Generated source version: 2.4.2
 * 
 */
@WebService(targetNamespace = "http://async.provider.test/", name = "EndpointSEI")
@XmlSeeAlso({test.provider.async.ObjectFactory.class})
public interface EndpointSEI {

    @RequestWrapper(localName = "echo", targetNamespace = "http://async.provider.test/", className = "test.provider.async.Echo")
    @ResponseWrapper(localName = "echoResponse", targetNamespace = "http://async.provider.test/", className = "test.provider.async.EchoResponse")
    @WebMethod(operationName = "echo")
    public Response<test.provider.async.EchoResponse> echoAsync(
        @WebParam(name = "what", targetNamespace = "")
        java.lang.String what
    );

    @RequestWrapper(localName = "echo", targetNamespace = "http://async.provider.test/", className = "test.provider.async.Echo")
    @ResponseWrapper(localName = "echoResponse", targetNamespace = "http://async.provider.test/", className = "test.provider.async.EchoResponse")
    @WebMethod(operationName = "echo")
    public Future<?> echoAsync(
        @WebParam(name = "what", targetNamespace = "")
        java.lang.String what,
        @WebParam(name = "asyncHandler", targetNamespace = "")
        AsyncHandler<test.provider.async.EchoResponse> asyncHandler
    );

    @WebResult(name = "result", targetNamespace = "")
    @Action(input = "http://async.provider.test/EndpointSEI/echoRequest", output = "http://async.provider.test/EndpointSEI/echoResponse")
    @RequestWrapper(localName = "echo", targetNamespace = "http://async.provider.test/", className = "test.provider.async.Echo")
    @WebMethod
    @ResponseWrapper(localName = "echoResponse", targetNamespace = "http://async.provider.test/", className = "test.provider.async.EchoResponse")
    public java.lang.String echo(
        @WebParam(name = "what", targetNamespace = "")
        java.lang.String what
    );
}