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The starting point for developing a service consumer (or client) in CXF is a WSDL contract, complete with port type, binding, and service definitions. You can then use the wsdl2java utility to generate the Java stub code from the WSDL contract. The stub code provides the supporting code that is required to invoke operations on the remote service.
For CXF clients, the wsdl2java utility can generate the following kinds of code:

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Basic HelloWorld WSDL contract

#Example1 The below shows the HelloWorld WSDL contract. This contract defines a single port type, Greeter, with a SOAP binding, Greeter_SOAPBinding, and a service, SOAPService, which has a single port, SoapPort.

<?xml version="1.0" encoding="UTF-8"?>
<wsdl:definitions name="HelloWorld" targetNamespace="http://apache.org/hello_world_soap_http" 
    xmlns="http://schemas.xmlsoap.org/wsdl/" 
    xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" 
    xmlns:tns="http://apache.org/hello_world_soap_http"
    xmlns:x1="http://apache.org/hello_world_soap_http/types"
    xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <wsdl:types>
        <schema targetNamespace="http://apache.org/hello_world_soap_http/types" 
            xmlns="http://www.w3.org/2001/XMLSchema"
	    xmlns:tns="http://apache.org/hello_world_soap_http/types"
            elementFormDefault="qualified">
	    <simpleType name="MyStringType">
		<restriction base="string">
		    <maxLength value="30" />
		</restriction>
	    </simpleType>

            <element name="sayHi">
                <complexType/>
            </element>
            <element name="sayHiResponse">
                <complexType>
                    <sequence>
                        <element name="responseType" type="string"/>
                    </sequence>
                </complexType>
            </element>
            <element name="greetMe">
                <complexType>
                    <sequence>
                        <element name="requestType" type="tns:MyStringType"/>
                    </sequence>
                </complexType>
            </element>
            <element name="greetMeResponse">
                <complexType>
                    <sequence>
                        <element name="responseType" type="string"/>
                    </sequence>
                </complexType>
            </element>
            <element name="greetMeOneWay">
                <complexType>
                    <sequence>
                        <element name="requestType" type="string"/>
                    </sequence>
                </complexType>
            </element>
            <element name="pingMe">
                <complexType/>
            </element>
            <element name="pingMeResponse">
                <complexType/>
            </element>
            <element name="faultDetail">
                <complexType>
                    <sequence>
                        <element name="minor" type="short"/>
                        <element name="major" type="short"/>
                    </sequence>
                </complexType>
            </element>
        </schema>
    </wsdl:types>
    <wsdl:message name="sayHiRequest">
        <wsdl:part element="x1:sayHi" name="in"/>
    </wsdl:message>
    <wsdl:message name="sayHiResponse">
        <wsdl:part element="x1:sayHiResponse" name="out"/>
    </wsdl:message>
    <wsdl:message name="greetMeRequest">
        <wsdl:part element="x1:greetMe" name="in"/>
    </wsdl:message>
    <wsdl:message name="greetMeResponse">
        <wsdl:part element="x1:greetMeResponse" name="out"/>
    </wsdl:message>
    <wsdl:message name="greetMeOneWayRequest">
        <wsdl:part element="x1:greetMeOneWay" name="in"/>
    </wsdl:message>
    <wsdl:message name="pingMeRequest">
        <wsdl:part name="in" element="x1:pingMe"/>
    </wsdl:message>
    <wsdl:message name="pingMeResponse">
        <wsdl:part name="out" element="x1:pingMeResponse"/>
    </wsdl:message>		
    <wsdl:message name="pingMeFault">
        <wsdl:part name="faultDetail" element="x1:faultDetail"/>
    </wsdl:message>
    
    <wsdl:portType name="Greeter">
        <wsdl:operation name="sayHi">
            <wsdl:input message="tns:sayHiRequest" name="sayHiRequest"/>
            <wsdl:output message="tns:sayHiResponse" name="sayHiResponse"/>
        </wsdl:operation>
        
        <wsdl:operation name="greetMe">
            <wsdl:input message="tns:greetMeRequest" name="greetMeRequest"/>
            <wsdl:output message="tns:greetMeResponse" name="greetMeResponse"/>
        </wsdl:operation>
        
        <wsdl:operation name="greetMeOneWay">
            <wsdl:input message="tns:greetMeOneWayRequest" 
                name="greetMeOneWayRequest"/>
        </wsdl:operation>

        <wsdl:operation name="pingMe">
            <wsdl:input name="pingMeRequest" message="tns:pingMeRequest"/>
            <wsdl:output name="pingMeResponse" message="tns:pingMeResponse"/>
            <wsdl:fault name="pingMeFault" message="tns:pingMeFault"/>
        </wsdl:operation> 
    </wsdl:portType>
    <wsdl:binding name="Greeter_SOAPBinding" type="tns:Greeter">
        <soap:binding style="document" 
             transport="http://schemas.xmlsoap.org/soap/http"/>
        
        <wsdl:operation name="sayHi">
            <soap:operation soapAction="" style="document"/>
            <wsdl:input name="sayHiRequest">
                <soap:body use="literal"/>
            </wsdl:input>
            <wsdl:output name="sayHiResponse">
                <soap:body use="literal"/>
            </wsdl:output>
        </wsdl:operation>
        
        <wsdl:operation name="greetMe">
            <soap:operation soapAction="" style="document"/>
            <wsdl:input name="greetMeRequest">
                <soap:body use="literal"/>
            </wsdl:input>
            <wsdl:output name="greetMeResponse">
                <soap:body use="literal"/>
            </wsdl:output>
        </wsdl:operation>
        
        <wsdl:operation name="greetMeOneWay">
            <soap:operation soapAction="" style="document"/>
            <wsdl:input name="greetMeOneWayRequest">
                <soap:body use="literal"/>
            </wsdl:input>
        </wsdl:operation>

        <wsdl:operation name="pingMe">
            <soap:operation style="document"/>
            <wsdl:input>
                <soap:body use="literal"/>
            </wsdl:input>
            <wsdl:output>
                <soap:body use="literal"/>
            </wsdl:output>
            <wsdl:fault name="pingMeFault">
                <soap:fault name="pingMeFault" use="literal"/>
            </wsdl:fault>
        </wsdl:operation>
        
    </wsdl:binding>
    <wsdl:service name="SOAPService">
        <wsdl:port binding="tns:Greeter_SOAPBinding" name="SoapPort">
            <soap:address 
                location="http://localhost:9000/SoapContext/SoapPort"/>
        </wsdl:port>
    </wsdl:service>
</wsdl:definitions>

The Greeter port type from #Example1 defines the following WSDL operations:

• sayHi - has a single output parameter, of xsd:string.
• greetMe - has an input parameter, of xsd:string, and an output parameter, of xsd:string.
• greetMeOneWay - has a single input parameter, of xsd:string. Because this operation has no output parameters, CXF can optimize this call to be a oneway invocation (that is, the client does not wait for a response from the server).
• pingMe - has no input parameters and no output parameters, but it can raise a fault exception.

#Example1 This WSDL also defines a binding, Greeter_SOAPBinding, for the SOAP protocol. In practice, the binding is normally generated
automatically - for example, by running either of the CXF wsdl2soap or wsdl2xml utilities. Likewise, the SOAPService service can be generated automatically by running the CXF wsdl2service utility.

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Where ClientDir is the location of a directory where you would like to put the generated files and
hello_world.wsdl is a file containing the contract shown in #Example1the WSDL above. The -ant option generates an ant build.xml file, for use with the ant build utility. The -client option generates starting point code for a client main() method.

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• org.apache.hello_world_soap_http
  This package name is generated from the http://apache.org/hello_world_soap_httpImage Removed target namespace. All of the WSDL entities defined in this target namespace (for example, the Greeter port type and the SOAPService service) map to Java classes in the corresponding Java package.
• org.apache.hello_world_soap_http.types
  This package name is generated from the http://apache.org/hello_world_soap_http/typesImage Removed target namespace. All of the XML types defined in this target namespace (that is, everything defined in the wsdl:types element of the HelloWorld contract) map to Java classes in the corresponding Java package.

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• Classes representing WSDL entities (in the org.apache.hello_world_soap_http package) - the following classes are generated to represent WSDL entities:
  • Greeter is a Java interface that represents the Greeter WSDL port type. In JAX-WS terminology, this Java interface is a service endpoint interface.
  • SOAPService is a Java class that represents the SOAPService WSDL service element.
  • PingMeFault is a Java exception class (extending java.lang.Exception) that represents the pingMeFault WSDL fault element.
• Classes representing XML types (in the org.apache.hello_world_soap_http.types package) - in the HelloWorld example, the only generated types are the various wrappers for the request and reply messages. Some of these data types are useful for the
  asynchronous invocation model.

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This section describes how to write the code for a simple Java client, based on the WSDL contract from #Example1 above. To implement the client, you need to use the following stub classes:

• Service class (that is, SOAPService).
• Service endpoint interface (that is, Greeter).

Generated service class

#Example2 The below shows the typical outline for a generated service class, ServiceName, which extends the javax.xml.ws.Service base class.

public class ServiceName extends javax.xml.ws.Service
 {
  ...
  public ServiceName(URL wsdlLocation, QName serviceName) { }
  
  public ServiceName() { }

  public Greeter getPortName() { }
  .
  .
  .
}

The ServiceName class in #Example2 defines the following methods:

• Constructor methods - the following forms of constructor are defined:
  • ServiceName(URL wsdlLocation, QName serviceName) constructs a service object based on the data in the serviceName service in the WSDL contract that is obtainable from wsdlLocation.
  • ServiceName() is the default constructor, which constructs a service object based on the service name and WSDL contract that were provided at the time the stub code was generated (for example, when running the CeltiXfire CXF wsdl2java command). Using this constructor presupposes that the WSDL contract remains available at its original location.
• get_PortName_() methods - for every PortName port defined on the ServiceName service, CXF generates a corresponding get_PortName_() method in Java. Therefore, a wsdl:service element that defines multiple ports will generate a service class with multiple get_PortName_() methods.

...

1. The input parameters are mapped to method arguments.
2. The first output parameter is mapped to a return value.
3. If there is more than one output parameter, the second and subsequent output parameters map to method arguments (moreover, the values of these arguments must be passed using Holder types).

For example, #Example3 the below shows the Greeter service endpoint interface, which is generated from the Greeter port type defined in #Example1. For simplicity, #Example3 omits the standard JAXB and JAX-WS annotations.

/* Generated by WSDLToJava Compiler. */

package org.objectweb.hello_world_soap_http;
  ...
public interface Greeter
 {
  public java.lang.String sayHi();
  
  public java.lang.String greetMe(java.lang.String requestType);

  public void greetMeOneWay(java.lang.String requestType);

  public void pingMe() throws PingMeFault;
}

Client main function

#Example4 shows the Here is Java code that implements the HelloWorld client. In summary, the client connects to the SoapPort port on the SOAPService service and then proceeds to invoke each of the operations supported by the Greeter port type.

package demo.hw.client;

import java.io.File;
import java.net.URL;
import javax.xml.namespace.QName;
import org.apache.hello_world_soap_http.Greeter;
import org.apache.hello_world_soap_http.PingMeFault;
import org.apche.hello_world_soap_http.SOAPService;

public final class Client {

  private static final QName SERVICE_NAME = 
    new QName("http://apache.org/hello_world_soap_http", 
    "SOAPService");

  private Client()
  {
  }

  public static void main(String args[]) throws Exception
  {
    if (args.length == 0)
    {
      System.out.println("please specify wsdl");
      System.exit(1);
    }

    URL wsdlURL;
    File wsdlFile = new File(args[0]);
    if (wsdlFile.exists())
    {
      wsdlURL = wsdlFile.toURL();
    }
    else
    {
      wsdlURL = new URL(args[0]);
    }

    System.out.println(wsdlURL);
    SOAPService ss = new SOAPService(wsdlURL, SERVICE_NAME);
    Greeter port = ss.getSoapPort();
    String resp;

    System.out.println("Invoking sayHi...");
    resp = port.sayHi();
    System.out.println("Server responded with: " + resp);
    System.out.println();

    System.out.println("Invoking greetMe...");
    resp = port.greetMe(System.getProperty("user.name"));
    System.out.println("Server responded with: " + resp);
    System.out.println();

    System.out.println("Invoking greetMeOneWay...");
    port.greetMeOneWay(System.getProperty("user.name"));
    System.out.println("No response from server as method is OneWay");
    System.out.println();

    try {
      System.out.println("Invoking pingMe, expecting exception...");
      port.pingMe();
    } catch (PingMeFault ex) {
      System.out.println("Expected exception: PingMeFault has occurred.");
      System.out.println(ex.toString());
    }
    System.exit(0);
  }
}

The Client.main() function from #Example4 proceeds as follows:</para>

1. The CXF runtime is implicitly initialized - that is, provided the CXF runtime classes are loaded. Hence, there is no need to call a special function in order to initialize CXF.
2. The client expects a single string argument that gives the location of the WSDL contract for HelloWorld. The WSDL location is stored in wsdlURL.

3. A new port object (which enables you to access the remote server endpoint) is created in two steps, as shown in the following code fragment:

   Code Block
   SOAPService ss = new SOAPService(wsdlURL, SERVICE_NAME); Greeter port = ss.getSoapPort();

   To create a new port object, you first create a service object (passing in the WSDL location and service name) and then call the appropriate get PortName () method to obtain an instance of the particular port you need. In this case, the SOAPService service supports only the SoapPort port, which is of Greeter type.

4. The client proceeds to call each of the methods supported by the Greeter service endpoint interface.
5. In the case of the pingMe() operation, the example code shows how to catch the PingMeFault fault exception.

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• Request context - on the client side, the request context enables you to set properties that affect outbound messages. Request context properties are applied to a specific port instance and, once set, the properties affect every subsequent operation invocation made on the port, until such time as a property is explicitly cleared. For example, you might use a request context property to set a connection timeout or to initialize data for sending in a header.</para>
• Response context - on the client side, you can access the response context to read the property values set by the inbound message from the last operation invocation. Response context properties are reset after every operation invocation. For example, you might access a response context property to read header information received from the last inbound message.

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To set a particular request context property, <replaceable>ContextPropertyName</replaceable> ContextPropertyName, to the value, PropertyValue, use the code shown in #Example4.here:

// Set request context property.
java.util.Map<String, Object> requestContext =
  ((javax.xml.ws.BindingProvider)port).getRequestContext();
requestContext.put(ContextPropertyName, PropertyValue);

// Invoke an operation.
port.SomeOperation();

...

To retrieve a particular response context property, ContextPropertyName, use the code shown in #Example5.here:

// Invoke an operation.
port.SomeOperation();

// Read response context property.
java.util.Map<String, Object> responseContext =
  ((javax.xml.ws.BindingProvider)port).getResponseContext();
PropertyType propValue = (PropertyType) responseContext.get(ContextPropertyName);

...

CXF supports the following context properties:

Asynchronous Invocation Model

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Contract for asynchronous example

#Example6 The following example shows the WSDL contract that is used for the asynchronous example. The contract defines a single port type, GreeterAsync, which contains a single operation, greetMeSometime.

<wsdl:definitions xmlns="http://schemas.xmlsoap.org/wsdl/"
                  xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
                  xmlns:tns="http://apache.org/hello_world_async_soap_http"
                  xmlns:xmlns:x1="http://apache.org/hello_world_async_soap_http/types"
                  xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
                  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                  targetNamespace="http://apache.org/hello_world_async_soap_http"
                  name="HelloWorld">
    <wsdl:types>
        <schema targetNamespace="http://apache.org/hello_world_async_soap_http/types"
                xmlns="http://www.w3.org/2001/XMLSchema"
                xmlns:x1="http://apache.org/hello_world_async_soap_http/types"
                elementFormDefault="qualified">
            <element name="greetMeSometime">
                <complexType>
                    <sequence>
                        <element name="requestType" type="xsd:string"/>
                    </sequence>
                </complexType>
            </element>
            <element name="greetMeSometimeResponse">
                <complexType>
                    <sequence>
                        <element name="responseType" type="xsd:string"/>
                    </sequence>
                </complexType>
            </element>      
        </schema>
    </wsdl:types>
    <wsdl:message name="greetMeSometimeRequest">
        <wsdl:part name="in" element="x1:greetMeSometime"/>
    </wsdl:message>
    <wsdl:message name="greetMeSometimeResponse">
        <wsdl:part name="out" element="x1:greetMeSometimeResponse"/>
    </wsdl:message>
    <wsdl:portType name="GreeterAsync">
        <wsdl:operation name="greetMeSometime">
            <wsdl:input name="greetMeSometimeRequest" 
                message="tns:greetMeSometimeRequest"/>
            <wsdl:output name="greetMeSometimeResponse" 
                message="tns:greetMeSometimeResponse"/>
        </wsdl:operation>
    </wsdl:portType>
    <wsdl:binding name="GreeterAsync_SOAPBinding" type="tns:GreeterAsync">
        <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
        <wsdl:operation name="greetMeSometime">
            <soap:operation style="document"/>
            <wsdl:input>
                <soap:body use="literal"/>
            </wsdl:input>
            <wsdl:output>
                <soap:body use="literal"/>
            </wsdl:output>
        </wsdl:operation>
    </wsdl:binding>
    <wsdl:service name="SOAPService">
        <wsdl:port name="SoapPort" binding="tns:GreeterAsync_SOAPBinding">
            <soap:address 
                location="http://localhost:9000/SoapContext/SoapPort"/>
        </wsdl:port>
    </wsdl:service>
</wsdl:definitions>

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Customization enables you to modify the way the wsdl2java utility generates stub code. In particular, it enables you to modify the WSDL-to-Java mapping and to switch on certain features. Here, customization is used to switch on the asynchronous invocation feature. Customizations are specified using a binding declaration, which you define using a jaxws:bindings tag (where the jaxws prefix is tied to the http://java.sun.com/xml/ns/jaxwsImage Removed namespace). There are two alternative ways of specifying a binding declaration:

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This section considers only the first approach, the external binding declaration. The template for a binding declaration file that switches on asynchronous invocations is shown in #Example7.next:

<bindings xmlns:xsd="http://www.w3.org/2001/XMLSchema"
          xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
          wsdlLocation="<at:var at:name="WSDL_LOCATION" />/hello_world_async.wsdl"
          xmlns="http://java.sun.com/xml/ns/jaxws">
  <bindings node="wsdl:definitions">
    <enableAsyncMapping>true</enableAsyncMapping>
  </bindings>
</bindings>

<para>Where Where AffectedWSDLContract specifies the URL of the WSDL contract that is affected by this binding declaration. The AffectedNode is an XPath value that specifies which node (or nodes) from the WSDL contract are affected by this binding declaration. You can set AffectedNode to wsdl:definitions, if you want the entire WSDL contract to be affected. The {jaxws:enableAsyncMapping}} element is set to true to enable the asynchronous invocation feature.

For example, if you want to generate asynchronous methods only for the GreeterAsync port type, you could specify <bindings node="wsdl:definitions/wsdl:portType@name='GreeterAsync'"> in the preceding binding declaration.

...

When you run the wsdl2java command, you specify the location of the binding declaration file using the -b option. After generating the stub code in this way, the GreeterAsync service endpoint interface (in the file GreeterAsync.java) is defined as shown in #Example8.below:

/* Generated by WSDLToJava Compiler. */
package org.apache.hello_world_async_soap_http;
...
import java.util.concurrent.Future;
import javax.xml.ws.AsyncHandler;
import javax.xml.ws.Response;
...
public interface GreeterAsync {

  public Future<?> greetMeSometimeAsync(
    java.lang.String requestType,
    AsyncHandler<org.apache.hello_world_async_soap_http.myorg.types.GreetMeSometimeResponse> asyncHandler
  );

  public Response<org.pache.hello_world_async_soap_http.myorg.types.GreetMeSometimeResponse> greetMeSometimeAsync(
    java.lang. String requestType
  );

  public java.lang.String greetMeSometime(
    java.lang. String requestType
  );
}

In addition to the usual synchronous method, greetMeSometime(), two asynchronous methods are also generated for the greetMeSometime operation, as follows:

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Implementing an asynchronous client with the polling approach

#Example9 The below sample illustrates the polling approach to making an asynchronous operation call. Using this approach, the client invokes the
operation by calling the special Java method, _OperationName_Async(), that returns a javax.xml.ws.Response<T> object, where T is the type of the operation's response message. The Response<T> object can be polled at a later stage to check whether the operation's response message has arrived.

package demo.hw.client;

import java.io.File;
import java.util.concurrent.Future;

import javax.xml.namespace.QName;
import javax.xml.ws.Response;

import org.apache.hello_world_async_soap_http.GreeterAsync;
import org.apache.hello_world_async_soap_http.SOAPService;
import org.apche.hello_world_async_soap_http.types.GreetMeSometimeResponse;

public final class Client {
  private static final QName SERVICE_NAME
    = new QName("http://objectweb.org/hello_world_async_soap_http", "SOAPService");

  private Client() {}

  public static void main(String args[]) throws Exception {
    ...
    // Polling approach:
    Response<GreetMeSometimeResponse> greetMeSomeTimeResp =
      port.greetMeSometimeAsync(System.getProperty("user.name"));
      while (!greetMeSomeTimeResp.isDone()) {
        Thread.sleep(100);
      }
      GreetMeSometimeResponse reply = greetMeSomeTimeResp.get();
      ...
      System.exit(0);
  }
}

The greetMeSometimeAsync() method invokes the greetMeSometimes operation, transmitting the input parameters to the remote service and returning a reference to a javax.xml.ws.Response<GreetMeSometimeResponse> object. The Response class is defined by extending the standard java.util.concurrency.Future<T> interface, which is specifically designed for polling the outcome of work performed by a concurrent thread. There are essentially two basic approaches to polling using the Response object:

• Non-blocking polling - before attempting to get the result, check whether the response has arrived by calling the non-blocking
  Response<T>.isDone() method. For example:

  Code Block
  Response<GreetMeSometimeResponse> greetMeSomeTimeResp = ...; if (greetMeSomeTimeResp.isDone()) { GreetMeSometimeResponse reply = greetMeSomeTimeResp.get(); }

  
  

• Blocking polling - call Response<T>.get() right away and block until the response arrives (optionally specifying a timeout). For example, to poll for a response, with a 60 second timeout:

  Code Block
  Response<GreetMeSometimeResponse> greetMeSomeTimeResp = ...; GreetMeSometimeResponse reply = greetMeSomeTimeResp.get( 60L, java.util.concurrent.TimeUnit.SECONDS );

  
  

Implementing an asynchronous client with the callback approach

An alternative approach to making an asynchronous operation invocation is to implement a callback class, by deriving from the
javax.xml.ws.AsyncHandler interface. This callback class must implement a handleResponse() method, which is called by the CXF runtime to notify the client that the response has arrived. #Example10 The following shows an outline of the AsyncHandler interface that you need to implement.

package javax.xml.ws;

public interface AsyncHandler<T>
{
  void handleResponse(Response<T> res);
}

In this example, a callback class, TestAsyncHandler, is defined as shown in #Example11below.

package demo.hw.client;

import javax.xml.ws.AsyncHandler;
import javax.xml.ws.Response;

import org.apache.hello_world_async_soap_http.types.GreetMeSometimeResponse;

public class TestAsyncHandler implements AsyncHandler<GreetMeSometimeResponse> {
  private GreetMeSometimeResponse reply;

  public void handleResponse(Response<GreetMeSometimeResponse> response) {
    try {
      reply = response.get();
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }

  public String getResponse() {
    return reply.getResponseType();
  }
}

The implementation of handleResponse() shown in #Example11 simply gets the response data and stores it in a member variable, reply. The extra getResponse() method is just a convenience method that extracts the sole output parameter (that is, responseType) from the response.

#Example12 illustrates the callback approach to making an asynchronous operation call. Using this approach, the client invokes the operation by calling the special Java method, _OperationName_Async(), that returns a java.util.concurrency.Future<?> object and takes an extra parameter of AsyncHandler<T>.

...

package demo.hw.client;

import java.io.File;
import java.util.concurrent.Future;

import javax.xml.namespace.QName;
import javax.xml.ws.Response;

import org.apache.hello_world_async_soap_http.GreeterAsync;
import org.apache.hello_world_async_soap_http.SOAPService;
import org.apache.hello_world_async_soap_http.types.GreetMeSometimeResponse;

public final class Client {
  private static final QName SERVICE_NAME
    = new QName("http://apache.org/hello_world_async_soap_http", "SOAPService");

  private Client() {}

  public static void main(String args[]) throws Exception {
    ...
    // Callback approach
    TestAsyncHandler testAsyncHandler = new TestAsyncHandler();
    System.out.println("Invoking greetMeSometimeAsync using callback object...");
    Future<?> response = port.greetMeSometimeAsync(System.getProperty("user.name"), testAsyncHandler);
    while (!response.isDone()) {
      Thread.sleep(100);
    }
    resp = testAsyncHandler.getResponse();
    ...
    System.exit(0);
  }
}

The Future<?> object returned by greetMeSometimeAsync() can be used only to test whether or not a response has arrived yet - for example, by calling response.isDone(). The value of the response is only made available to the callback object, testAsyncHandler.