JAX-WS Guide

Introduction to JAX-WS
Introduction to JAXB
Developing JAX-WS Web services
1. From a JavaBean (bottom-up)
2. From a WSDL document (top-down)
Packaging and deploying a JAX-WS service
1. Developing a JAX-WS client from a WSDL document
2. Developing a dynamic client using JAX-WS APIs
Developing JAX-WS clients
Running a JAX-WS client
Invoking JAX-WS Web services asynchronously
Using handlers in JAX-WS Web services
Enabling HTTP session management support for JAX-WS applications
Enabling MTOM

Introduction to JAX-WS

JAX-WS 2.0 is a new programming model that simplifies application development through support of a standard, annotation-based model to develop Web Service applications and clients. The JAX-WS 2.0 specification strategically aligns itself with the current industry trend towards a more document-centric messaging model and replaces the remote procedure call programming model as defined by JAX-RPC. JAX-WS is the strategic programming model for developing Web services and is a required part of the Java Platform, Enterprise Edition 5 (Java EE 5). The implementation of the JAX-WS programming standard provides the following enhancements for developing Web services and clients:

Better platform independence for Java applications.
Using JAX-WS APIs, development of Web services and clients is simplified with better platform independence for Java applications. JAX-WS takes advantage of the dynamic proxy mechanism to provide a formal delegation model with a pluggable provider. This is an enhancement over JAX-RPC, which relies on the generation of vendor-specific stubs for invocation.
Annotations
JAX-WS introduces support for annotating Java classes with metadata to indicate that the Java class is a Web service. JAX-WS supports the use of annotations based on the Metadata Facility for the Java Programming Language (JSR 175) specification, the Web Services Metadata for the Java Platform (JSR 181) specification and annotations defined by the JAX-WS 2.0 specification. Using annotations within the Java source and within the Java class simplifies development of Web services by defining some of the additional information that is typically obtained from deployment descriptor files, WSDL files, or mapping metadata from XML and WSDL files into the source artifacts.

For example, you can embed a simple @WebService tag in the Java source to expose the bean as a Web service.
```
      @WebService 

      public class QuoteBean implements StockQuote {

             public float getQuote(String sym) { ... }

      }
```
The @WebService annotation tells the server runtime to expose all public methods on that bean as a Web service. Additional levels of granularity can be controlled by adding additional annotations on individual methods or parameters. Using annotations makes it much easier to expose Java artifacts as Web services. In addition, as artifacts are created from using some of the top-down mapping tools starting from a WSDL file, annotations are included within the source and Java classes as a way of capturing the metadata along with the source files.
Using annotations also improves the development of Web services within a team structure because you do not need to define every Web service in a single or common deployment descriptor as required with JAX-RPC Web services. Taking advantage of annotations with JAX-WS Web services allows parallel development of the service and the required metadata.
Invoking Web services asynchronously
With JAX-WS, Web services are called both synchronously and asynchronously. JAX-WS adds support for both a polling and callback mechanism when calling Web services asynchronously. Using a polling model, a client can issue a request, get a response object back, which is polled to determine if the server has responded. When the server responds, the actual response is retrieved. Using the callback model, the client provides a callback handler to accept and process the inbound response object. Both the polling and callback models enable the client to focus on continuing to process work without waiting for a response to return, while providing for a more dynamic and efficient model to invoke Web services.

For example, a Web service interface might have methods for both synchronous and asynchronous requests. Asynchronous requests are identified in bold below:
```
      @WebService
      public interface CreditRatingService {
            // sync operation
            Score      getCreditScore(Customer customer);
            // async operation with polling
            Response<Score> getCreditScoreAsync(Customer customer);
            // async operation with callback
            Future<?> getCreditScoreAsync(Customer customer, 
               AsyncHandler<Score> handler);
      }
```
The asynchronous invocation that uses the callback mechanism requires an additional input by the client programmer. The callback is an object that contains the application code that will be executed when an asynchronous response is received. The following is a code example for an asynchronous callback handler:
```
      CreditRatingService svc = ...;

      Future<?> invocation = svc.getCreditScoreAsync(customerFred,
        new AsyncHandler<Score>() {
           public void handleResponse (
               Response<Score> response)
             {
               Score score = response.get();
               // do work here...
             }
         }
      );
```
The following is a code example for an asynchronous polling client:
```
      CreditRatingService svc = ...;
      Response<Score> response = svc.getCreditScoreAsync(customerFred);

      while (!response.isDone()) {
                // do something while we wait
      }

      // no cast needed, thanks to generics
      Score score = response.get();
```
Using resource injection
JAX-WS supports resource injection to further simplify development of Web services. JAX-WS uses this key feature of Java EE 5 to shift the burden of creating and initializing common resources in a Java runtime environment from your Web service application to the application container environment itself. JAX-WS provides support for a subset of annotations that are defined in JSR-250 for resource injection and application lifecycle in its runtime.
Axis2 supports the JAX-WS usage of the @Resource annotation for resource injection. The @Resource annotation is defined by the JSR-250, Common Annotations specification that is included in Java Platform, Enterprise Edition 5 (Java EE 5). By placing the @Resource annotation on a service endpoint implementation, you can request a resource injection and collect the javax.xml.ws.WebServiceContext interface related to that particular endpoint invocation. When the endpoint sees the @Resource annotation, the endpoint adds the annotated variable with an appropriate value before the servlet is placed into service. From the WebServiceContext interface, you can collect the MessageContext for the request associated with the particular method call using the getMessageContext() method.

The following example illustrates using the @Resource annotation for resource injection:
```
@WebService
public class MyService {
    
    @Resource
    private WebServiceContext ctx;

    public String echo (String input) {
        …
    }
     
}
```
Refer to sections 5.2.1 and 5.3 of the JAX-WS 2.0 specification for more information on resource injection.
Data binding with Java Architecture for XML Binding (JAXB) 2.0
JAX-WS leverages the JAXB 2.0 API and tools as the binding technology for mappings between Java objects and XML documents. JAX-WS tooling relies on JAXB tooling for default data binding for two-way mappings between Java objects and XML documents.
Dynamic and static clients
The dynamic client API for JAX-WS is called the dispatch client (javax.xml.ws.Dispatch). The dispatch client is an XML messaging oriented client. The data is sent in either PAYLOAD or MESSAGE mode. When using the PAYLOAD mode, the dispatch client is only responsible for providing the contents of the <soap:Body> and JAX-WS adds the <soap:Envelope> and <soap:Header> elements. When using the MESSAGE mode, the dispatch client is responsible for providing the entire SOAP envelope including the <soap:Envelope>, <soap:Header>, and <soap:Body> elements and JAX-WS does not add anything additional to the message. The dispatch client supports asynchronous invocations using a callback or polling mechanism.
The static client programming model for JAX-WS is the called the proxy client. The proxy client invokes a Web service based on a Service Endpoint interface (SEI) which must be provided.
Support for Message Transmission Optimized Mechanism (MTOM)
Using JAX-WS, you can send binary attachments such as images or files along with Web services requests. JAX-WS adds support for optimized transmission of binary data as specified by Message Transmission Optimization Mechanism (MTOM).
Multiple data binding technologies
JAX-WS exposes the following binding technologies to the end user: XML Source, SOAP Attachments API for Java (SAAJ) 1.3, and Java Architecture for XML Binding (JAXB) 2.0. XML Source enables a user to pass a javax.xml.transform.Source into the runtime which represents the data in a Source object to be processed. SAAJ 1.3 now has the ability to pass an entire SOAP document across the interface rather than just the payload itself. This is done by the client passing the SAAJ SOAPMessage object across the interface. JAX-WS leverages the JAXB 2.0 support as the data binding technology of choice between Java and XML.
Support for SOAP 1.2
Support for SOAP 1.2 has been added to JAX-WS 2.0. JAX-WS supports both SOAP 1.1 and SOAP 1.2 so that you can send binary attachments such as images or files along with Web services requests. JAX-WS adds support for optimized transmission of binary data as specified by MTOM.
New development tools
JAX-WS provides the wsgen and wsimport command-line tools for generating portable artifacts for JAX-WS Web services. When creating JAX-WS Web services, you can start with either a WSDL file or an implementation bean class. If you start with an implementation bean class, use the wsgen command-line tool to generate all the Web services server artifacts, including a WSDL file if requested. If you start with a WSDL file, use the wsimport command-line tool to generate all the Web services artifacts for either the server or the client. The wsimport command line tool processes the WSDL file with schema definitions to generate the portable artifacts, which include the service class, the service endpoint interface class, and the JAXB 2.0 classes for the corresponding XML schema.
Introduction to JAXB
Java Architecture for XML Binding (JAXB) is a Java technology that provides an easy and convenient way to map Java classes and XML schema for simplified development of Web services. JAXB leverages the flexibility of platform-neutral XML data in Java applications to bind XML schema to Java applications without requiring extensive knowledge of XML programming.

Axis2 provides JAXB 2.0 standards.

JAXB is an XML to Java binding technology that supports transformation between schema and Java objects and between XML instance documents and Java object instances. JAXB consists of a runtime application programming interface (API) and accompanying tools that simplify access to XML documents. JAXB also helps to build XML documents that both conform and validate to the XML schema.

JAXB provides the xjc schema compiler tool, the schemagen schema generator tool, and a runtime framework. You can use the xjc schema compiler tool to start with an XML schema definition (XSD) to create a set of JavaBeans that map to the elements and types defined in the XSD schema. You can also start with a set of JavaBeans and use the schemagen schema generator tool to create the XML schema. Once the mapping between XML schema and Java classes exists, XML instance documents can be converted to and from Java objects through the use of the JAXB binding runtime API. Data stored in XML documents can be accessed without the need to understand the data structure. You can then use the resulting Java classes to assemble a Web services application.

JAXB annotated classes and artifacts contain all the information needed by the JAXB runtime API to process XML instance documents. The JAXB runtime API supports marshaling of JAXB objects to XML and unmarshaling the XML document back to JAXB class instances. Optionally, you can use JAXB to provide XML validation to enforce both incoming and outgoing XML documents to conform to the XML constraints defined within the XML schema.

JAXB is the default data binding technology used by the Java API for XML Web Services (JAX-WS) 2.0 tooling and implementation within this product. You can develop JAXB objects for use within JAX-WS applications.

You can also use JAXB independently of JAX-WS when you want to leverage the XML data binding technology to manipulate XML within your Java applications.

The following diagram illustrates the JAXB architecture.
Developing JAX-WS Web services
Developing a JAX-WS Web service from a JavaBean (bottom-up development)
When developing a JAX-WS Web service starting from JavaBeans, you can use a bean that already exists and then enable the implementation for JAX-WS Web services. The use of annotations simplifies the enabling of a bean for Web services. Adding the @WebService annotation to the bean defines the application as a Web service and how a client can access the Web service. JavaBeans can have a service endpoint interface, but it is not required. Enabling JavaBeans for Web services includes annotating the bean and the optional service endpoint interface, assembling all artifacts required for the Web service, and deploying the application into Axis2. You are not required to develop a WSDL file because the use of annotations can provide all of the WSDL information necessary to configure the service endpoint or the client. It is, however, a best practice to develop a WSDL file.
1. Develop a service endpoint interface.
2. Java API for XML-Based Web Services (JAX-WS) supports two different service endpoint implementations types, the standard JavaBeans service endpoint interface and a new Provider interface to enable services to work at the XML message level. By using annotations on the service endpoint or client, you can define the service endpoint as a Web service.
  
  JavaBeans endpoints in JAX-WS are similar to the endpoint implementations in the Java API for XML-based RPC (JAX-RPC) specification. Unlike JAX-RPC, the requirement for a service endpoint interface (SEI) is optional for JavaBeans-based services. JAX-WS services that do not have an associated SEI are regarded as having an implicit SEI, whereas services that have an associated SEI are regarded as having an explicit SEI. The service endpoint interfaces required by JAX-WS are also more generic than the service endpoint interfaces required by JAX-RPC. With JAX-WS, the SEI is not required to extend the java.rmi.Remote interface as required by the JAX-RPC specification.
  
  The JAX-WS programming model also leverages support for annotating Java classes with metadata to define a service endpoint application as a Web service and define how a client can access the Web service. JAX-WS supports annotations based on the Metadata Facility for the Java Programming Language (JSR 175) specification, the Web Services Metadata for the Java Platform (JSR 181) specification and annotations defined by the JAX-WS 2.0 (JSR 224) specification, which includes Java Architecture for XML Binding (JAXB) annotations. Using annotations, the service endpoint implementation can independently describe the Web service without requiring a WSDL file. Annotations can provide all of the WSDL information necessary to configure your service endpoint implementation or Web services client. You can specify annotations on the service endpoint interface used by the client and the server, or on the server-side service implementation class.
  
  To develop a JAX-WS Web service, you must annotate your Java class with the javax.jws.WebService annotation for JavaBeans endpoints or the javax.jws.WebServiceProvider annotation for a Provider endpoint. These annotations define the Java class as a Web service endpoint. For a JavaBeans endpoint, the service endpoint interface or service endpoint implementation is a Java interface or class, respectively, that declares the business methods provided by a particular Web service. The only methods on a JavaBeans endpoint that can be invoked by a Web services client are the business methods that are defined in the explicit or implicit service endpoint interface.
  
  All JavaBeans endpoints are required to have the @WebService (javax.jws.WebService) annotation included on the bean class. If the service implementation bean also uses an SEI, then that endpoint interface must be referenced by the endpointInterface attribute on that annotation. If the service implementation bean does not use an SEI, then the service is described by the implicit SEI defined in the bean.
  
  The JAX-WS programming model introduces the new Provider API, javax.xml.ws.Provider, as an alternative to service endpoint interfaces. The Provider interface supports a more messaging oriented approach to Web services. With the Provider interface, you can create a Java class that implements a simple interface to produce a generic service implementation class. The Provider interface has one method, the invoke method, which uses generics to control both the input and output types when working with various messages or message payloads. All Provider endpoints must be annotated with the @WebServiceProvider (javax.xml.ws.WebServiceProvider) annotation. A service implementation cannot specify the @WebService annotation if it implements the javax.xml.ws.Provider interface.
  
  So the steps involved are:
  
  Identify your service endpoint requirements for your Web services application.
  
  First determine if the service implementation is a JavaBeans endpoint or a Provider endpoint. If you choose to use a JavaBeans endpoint, then determine if you want to use an explicit SEI or if the bean itself will have an implicit SEI.
  A Java class that implements a Web service must specify either the javax.jws.WebService or javax.xml.ws.WebServiceProvider annotation. Both annotations must not be present on a Java class. The javax.xml.ws.WebServiceProvider annotation is only supported on classes that implement the javax.xml.ws.Provider interface.
  
  If you have an explicit service endpoint interface with the Java class, then use the endpointInterface parameter to specify the service endpoint interface class name to the javax.jws.WebService annotation. You can add the @WebMethod annotation to methods of a service endpoint interface to customize the Java-to-WSDL mappings. All public methods are considered as exposed methods regardless of whether the @WebMethod annotation is specified or not. It is incorrect to have an @WebMethod annotation on an service endpoint interface that contains the exclude attribute.
  
  If you have an implicit service endpoint interface with the Java class, then the javax.jws.WebService annotation will use the default values for the serviceName, portName, and targetNamespace parameters. To override these default values, specify values for these parameters in the @WebService annotation. If the @WebMethod annotation is not specified, all public methods are exposed including the inherited methods with the exception of methods inherited from java.lang.Object. The exclude parameter of the @WebMethod annotation can be used to control which methods are exposed.
  
  If you are using the Provider interface, use the javax.xml.ws.WebServiceProvider annotation on the Provider endpoint.
  
  Annotate the service endpoints.
  
  Implement your service.
  
  When using a bottom-up approach to develop JAX-WS Web services, use the wsgen command-line tool when starting from a service endpoint implementation. The wsgen tool processes a compiled service endpoint implementation class as input and generates the following portable artifacts:
  
  any additional Java Architecture for XML Binding (JAXB) classes that are required to marshal and unmarshal the message contents. The additional classes include classes that are represented by the @RequestWrapper annotation and the @ResponseWrapper annotation for a wrapped method.
  
  a WSDL file if the optional -wsdl argument is specified. The wsgen command does not automatically generate the WSDL file. The WSDL file is automatically generated when you deploy the service endpoint.
  
  You are not required to develop a WSDL file when developing JAX-WS Web services using the bottom-up approach of starting with JavaBeans. The use of annotations provides all of the WSDL information necessary to configure the service endpoint or the client. Axis2 supports WSDL 1.1 documents that comply with Web Services-Interoperability (WS-I) Basic Profile 1.1 specifications and are either Document/Literal style documents or RPC/Literal style documents. Additionally, WSDL documents with bindings that declare a USE attribute of value LITERAL are supported while the value, ENCODED, is not supported. For WSDL documents that implement a Document/Literal wrapped pattern, a root element is declared in the XML schema and is used as an operation wrapper for a message flow. Separate wrapper element definitions exist for both the request and the response.
  
  To ensure the wsgen command does not miss inherited methods on a service endpoint implementation bean, you must either add the @WebService annotation to the desired superclass or you can override the inherited method in the implementation class with a call to the superclass method. Implementation classes only expose methods from superclasses that are annotated with the @WebService annotation.
  
  Note: The wsgen command does not differentiate the XML namespace between multiple XMLType annotations that have the same @XMLType name defined within different Java packages. When this scenario occurs, the following error is produced:
  
  Error: Two classes have the same XML type name .... Use @XmlType.name and @XmlType.namespace to assign different names to them...
  This error indicates you have class names or @XMLType.name values that have the same name, but exist within different Java packages. To prevent this error, add the @XML.Type.namespace class to the existing @XMLType annotation to differentiate between the XML types.
3. Develop the Java artifacts.
4. Package and deploy your service.
Developing a JAX-WS Web service from a WSDL document (top-down development)
You can use a top-down development approach to create a JAX-WS Web service with an existing WSDL file using JavaBeans.

You can use the JAX-WS tool, wsimport, to process a WSDL file and generate portable Java artifacts that are used to create a Web service. The portable Java artifacts created using the wsimport tool are:
- Service endpoint interface (SEI)
- Service class
- Exception class that is mapped from the wsdl:fault class (if any)
- Java Architecture for XML Binding (JAXB) generated type values which are Java classes mapped from XML schema types
Run the
wsimport -keep -verbose wsdl_URL
command to generate the portable artifacts. The -keep option tells the tool not to delete the generated files, and the -verbose option tells it to list the files that were created. The ObjectFactory.java file that is created contains factory methods for each Java content interface and Java element interface generated in the associated package. The package-info.java file takes the targetNamespace value and creates the directory structure.

You must now provide an implementation for the SEI created by the tool.
Packaging and deploying a JAX-WS service
Axis2 provides two mechanisms for deploying JAX-WS services:
1. The service may be packaged and deployed as an AAR, just like any other service within Axis2. Like with all AARs, a services.xml file containing the relevant metadata is required for the service to deploy correctly.
2. The service may be packaged in a jar file and placed into the servicejars directory. The JAXWSDeployer will examine all jars within that directory and deploy those classes that have JAX-WS annotations which identify them as Web services.
Developing JAX-WS clients
The Java API for XML-Based Web Services (JAX-WS) Web service client programming model supports both the Dispatch client API and the Dynamic Proxy client API. The Dispatch client API is a dynamic client programming model, whereas the static client programming model for JAX-WS is the Dynamic Proxy client. The Dispatch and Dynamic Proxy clients enable both synchronous and asynchronous invocation of JAX-WS Web services.

Dispatch client: Use this client when you want to work at the XML message level or when you want to work without any generated artifacts at the JAX-WS level.

Dynamic Proxy client: Use this client when you want to invoke a Web service based on a service endpoint interface.

Dispatch client
XML-based Web services use XML messages for communications between Web services and Web services clients. The JAX-WS APIs provide high-level methods to simplify and hide the details of converting between Java method invocations and their associated XML messages. However, in some cases, you might desire to work at the XML message level. Support for invoking services at the XML message level is provided by the Dispatch client API. The Dispatch client API, javax.xml.ws.Dispatch, is a dynamic JAX-WS client programming interface. To write a Dispatch client, you must have expertise with the Dispatch client APIs, the supported object types, and knowledge of the message representations for the associated WSDL file. The Dispatch client can send data in either MESSAGE or PAYLOAD mode. When using the javax.xml.ws.Service.Mode.MESSAGE mode, the Dispatch client is responsible for providing the entire SOAP envelope including the <soap:Envelope>, <soap:Header>, and <soap:Body> elements. When using the javax.xml.ws.Service.Mode.PAYLOAD mode, the Dispatch client is only responsible for providing the contents of the <soap:Body> and JAX-WS includes the payload in a <soap:Envelope> element.

The Dispatch client API requires application clients to construct messages or payloads as XML which requires a detailed knowledge of the message or message payload. The Dispatch client supports the following types of objects:

javax.xml.transform.Source: Use Source objects to enable clients to use XML APIs directly. You can use Source objects with SOAP or HTTP bindings.

JAXB objects: Use JAXB objects so that clients can use JAXB objects that are generated from an XML schema to create and manipulate XML with JAX-WS applications. JAXB objects can only be used with SOAP or HTTP bindings.

javax.xml.soap.SOAPMessage: Use SOAPMessage objects so that clients can work with SOAP messages. You can only use SOAPMessage objects with SOAP bindings.

javax.activation.DataSource: Use DataSource objects so that clients can work with Multipurpose Internet Mail Extension (MIME) messages. Use DataSource only with HTTP bindings.

For example, if the input parameter type is javax.xml.transform.Source, the call to the Dispatch client API is similar to the following code example:

Dispatch<Source> dispatch = … create a Dispatch<Source> Source request = … create a Source object Source response = dispatch.invoke(request);
The Dispatch parameter value determines the return type of the invoke() method.

The Dispatch client is invoked in one of three ways:

Synchronous invocation for requests and responses using the invoke method

Asynchronous invocation for requests and responses using the invokeAsync method with a callback or polling object

One-way invocation using the invokeOneWay methods

Refer to Chapter 4, section 3 of the JAX-WS 2.0 specification for more information on using a Dispatch client.

Dynamic Proxy client
The static client programming model for JAX-WS is the called the Dynamic Proxy client. The Dynamic Proxy client invokes a Web service based on a Service Endpoint Interface (SEI) which must be provided. The Dynamic Proxy client is similar to the stub client in the Java API for XML-based RPC (JAX-RPC) programming model. Although the JAX-WS Dynamic Proxy client and the JAX-RPC stub client are both based on the Service Endpoint Interface (SEI) that is generated from a WSDL file , there is a major difference. The Dynamic Proxy client is dynamically generated at run time using the Java 5 Dynamic Proxy functionality, while the JAX-RPC-based stub client is a non-portable Java file that is generated by tooling. Unlike the JAX-RPC stub clients, the Dynamic Proxy client does not require you to regenerate a stub prior to running the client on an application server for a different vendor because the generated interface does not require the specific vendor information.

The Dynamic Proxy instances extend the java.lang.reflect.Proxy class and leverage the Dynamic Proxy function in the base Java Runtime Environment Version 5. The client application can then provide an interface that is used to create the proxy instance while the runtime is responsible for dynamically creating a Java object that represents the SEI.

The Dynamic Proxy client is invoked in one of three ways:

Synchronous invocation for requests and responses using the invoke method

Asynchronous invocation for requests and responses using the invokeAsync method with a callback or polling object

One-way invocation using the invokeOneWay methods

Refer to Chapter 4 of the JAX-WS 2.0 specification for more information on using Dynamic Proxy clients.

Developing a JAX-WS client from a WSDL document
Java API for XML-Based Web Services (JAX-WS) tooling supports generating Java artifacts you need to develop static JAX-WS Web services clients when starting with a Web Services Description Language (WSDL) file.

The static client programming model for JAX-WS is the called the dynamic proxy client. The dynamic proxy client invokes a Web service based on a service endpoint interface that is provided. After you create the proxy, the client application can invoke methods on the proxy just like a standard implementation of those interfaces. For JAX-WS Web service clients using the dynamic proxy programming model, use the JAX-WS tool, wsimport, to process a WSDL file and generate portable Java artifacts that are used to create a Web service client.

Create the following portable Java artifacts using the wsimport tool:

Service endpoint interface (SEI)

Service class

Exception class that is mapped from the wsdl:fault class (if any)

Java Architecture for XML Binding (JAXB) generated type values which are Java classes mapped from XML schema types

The steps to creating a dynamic proxy client are:

(Optional) If you are using WSDL or schema customizations, use the -b option with the wsimport command to specify an external binding files that contain your customizations.

For example: wsimport -b binding.xml wsdlfile.wsdl.

You can customize the bindings in your WSDL file to enable asynchronous mappings or attachments. To generate asynchronous interfaces, add the client-side only customization enableAsyncMapping binding declaration to the wsdl:definitions element or in an external binding file that is defined in the WSDL file. Use the enableMIMEContent binding declaration in your custom client or server binding file to enable or disable the default mime:content mapping rules. For additional information on custom binding declarations, see chapter 8 the JAX-WS specification.

Run the wsimport -keep wsdl_URL command to generate the portable client artifacts. Use the -verbose option to see a list of generated files when you run the command.

Best practice: When you run the wsimport tool, the location of your WSDL file must either be omitted or point to a valid WSDL document. A best practice for ensuring that you produce a JAX-WS Web services client that is portable to other systems is to package the WSDL document within the application module such as a Web services client Java archive (JAR) file or a Web archive (WAR) file. You can specify a relative URI for the location of your WSDL file by using the-wsdllocation annotation attribute. For example, if your MyService.wsdl file is located in the META-INF/wsdl/ directory, then run the wsimport tool and use the -wsdllocation option to specify the value to be used for the location of the WSDL file.

wsimport -keep -wsdllocation=META-INF/wsdl/MyService.wsdl

Developing a dynamic client using JAX-WS APIs
JAX-WS provides a new dynamic Dispatch client API that is more generic and offers more flexibility than the existing Java API for XML-based RPC (JAX-RPC)-based Dynamic Invocation Interface (DII). The Dispatch client interface, javax.xml.ws.Dispatch, is an XML messaging oriented client that is intended for advanced XML developers who prefer to work at the XML level using XML constructs. To write a Dispatch client, you must have expertise with the Dispatch client APIs, the supported object types, and knowledge of the message representations for the associated WSDL file.

The Dispatch API can send data in either PAYLOAD or MESSAGE mode. When using the PAYLOAD mode, the Dispatch client is only responsible for providing the contents of the <soap:Body> and JAX-WS includes the input payload in a <soap:Envelope> element. When using the MESSAGE mode, the Dispatch client is responsible for providing the entire SOAP envelope.

The Dispatch client API requires application clients to construct messages or payloads as XML and requires a detailed knowledge of the message or message payload. The Dispatch client can use HTTP bindings when using Source objects, Java Architecture for XML Binding (JAXB) objects, or data source objects. The Dispatch client supports the following types of objects:

javax.xml.transform.Source: Use Source objects to enable clients to use XML APIs directly. You can use Source objects with SOAP and HTTP bindings.

JAXB objects: Use JAXB objects so that clients can use JAXB objects that are generated from an XML schema to create and manipulate XML with JAX-WS applications. JAXB objects can only be used with SOAP and HTTP bindings.

javax.xml.soap.SOAPMessage: Use SOAPMessage objects so that clients can work with SOAP messages. You can only use SOAPMessage objects with SOAP version 1.1 or SOAP version 1.2 bindings.

javax.activation.DataSource: Use DataSource objects so that clients can work with Multipurpose Internet Mail Extension (MIME) messages. Use DataSource only with HTTP bindings.

The Dispatch API uses the concept of generics that are introduced in Java Runtime Environment Version 5. For each of the invoke() methods on the Dispatch interface, generics are used to determine the return type.

The steps to creating a dynamic client are:

Determine if you want your dynamic client to send data in PAYLOAD or MESSAGE mode.

Create a service instance and add at least one port to it. The port carries the protocol binding and service endpoint address information.

Create a Dispatch<T> object using either the Service.Mode.PAYLOAD method or the Service.Mode.MESSAGE method.

Configure the request context properties on the javax.xml.ws.BindingProvider interface. Use the request context to specify additional properties such as enabling HTTP authentication or specifying the endpoint address.

Compose the client request message for the dynamic client.

Invoke the service endpoint with the Dispatch client either synchronously or asynchronously.

Process the response message from the service.

The following example illustrates the steps to create a Dispatch client and invoke a sample EchoService service endpoint.

String endpointUrl = ...; QName serviceName = new QName("http://org/apache/ws/axis2/sample/echo/", "EchoService"); QName portName = new QName("http://org/apache/ws/axis2/sample/echo/", "EchoServicePort"); /** Create a service and add at least one port to it. **/ Service service = Service.create(serviceName); service.addPort(portName, SOAPBinding.SOAP11HTTP_BINDING, endpointUrl); /** Create a Dispatch instance from a service.**/ Dispatch<SOAPMessage> dispatch = service.createDispatch(portName, SOAPMessage.class, Service.Mode.MESSAGE); /** Create SOAPMessage request. **/ // compose a request message MessageFactory mf = MessageFactory.newInstance(SOAPConstants.SOAP_1_1_PROTOCOL); // Create a message. This example works with the SOAPPART. SOAPMessage request = mf.createMessage(); SOAPPart part = request.getSOAPPart(); // Obtain the SOAPEnvelope and header and body elements. SOAPEnvelope env = part.getEnvelope(); SOAPHeader header = env.getHeader(); SOAPBody body = env.getBody(); // Construct the message payload. SOAPElement operation = body.addChildElement("invoke", "ns1", "http://org/apache/ws/axis2/sample/echo/"); SOAPElement value = operation.addChildElement("arg0"); value.addTextNode("ping"); request.saveChanges(); /** Invoke the service endpoint. **/ SOAPMessage response = dispatch.invoke(request); /** Process the response. **/

Running a JAX-WS client
A JAX-WS client may be started from the command line like any other Axis2-based client, including through the use of the axis2 shell scripts in the bin directory of the installed runtime.

Invoking JAX-WS Web services asynchronously
Java API for XML-Based Web Services (JAX-WS) provides support for invoking Web services using an asynchronous client invocation. JAX-WS provides support for both a callback and polling model when calling Web services asynchronously. Both the callback model and the polling model are available on the Dispatch client and the Dynamic Proxy client.

An asynchronous invocation of a Web service sends a request to the service endpoint and then immediately returns control to the client program without waiting for the response to return from the service. JAX-WS asynchronous Web service clients consume Web services using either the callback approach or the polling approach. Using a polling model, a client can issue a request and receive a response object that is polled to determine if the server has responded. When the server responds, the actual response is retrieved. Using the callback model, the client provides a callback handler to accept and process the inbound response object. The handleResponse() method of the handler is called when the result is available. Both the polling and callback models enable the client to focus on continuing to process work without waiting for a response to return, while providing for a more dynamic and efficient model to invoke Web services.

Using the callback asynchronous invocation model
To implement an asynchronous invocation that uses the callback model, the client provides an AsynchHandler callback handler to accept and process the inbound response object. The client callback handler implements the javax.xml.ws.AsynchHandler interface, which contains the application code that is executed when an asynchronous response is received from the server. The javax.xml.ws.AsynchHandler interface contains the handleResponse(java.xml.ws.Response) method that is called after the run time has received and processed the asynchronous response from the server. The response is delivered to the callback handler in the form of a javax.xml.ws.Response object. The response object returns the response content when the get() method is called. Additionally, if an error was received, then an exception is returned to the client during that call. The response method is then invoked according to the threading model used by the executor method, java.util.concurrent.Executor on the client's java.xml.ws.Service instance that was used to create the Dynamic Proxy or Dispatch client instance. The executor is used to invoke any asynchronous callbacks registered by the application. Use the setExecutor and getExecutor methods to modify and retrieve the executor configured for your service.

Using the polling asynchronous invocation model
Using the polling model, a client can issue a request and receive a response object that can subsequently be polled to determine if the server has responded. When the server responds, the actual response can then be retrieved. The response object returns the response content when the get() method is called. The client receives an object of type javax.xml.ws.Response from the invokeAsync method. That Response object is used to monitor the status of the request to the server, determine when the operation has completed, and to retrieve the response results.

Using an asynchronous message exchange
By default, asynchronous client invocations do not have asynchronous behavior of the message exchange pattern on the wire. The programming model is asynchronous; however, the exchange of request or response messages with the server is not asynchronous. To use an asynchronous message exchange, the org.apache.axis2.jaxws.use.async.mep property must be set on the client request context with a boolean value of true. When this property is enabled, the messages exchanged between the client and server are different from messages exchanged synchronously. With an asynchronous exchange, the request and response messages have WS-Addressing headers added that provide additional routing information for the messages. Another major difference between asynchronous and synchronous message exchange is that the response is delivered to an asynchronous listener that then delivers that response back to the client. For asynchronous exchanges, there is no timeout that is sent to notify the client to stop listening for a response. To force the client to stop waiting for a response, issue a Response.cancel() method on the object returned from a polling invocation or a Future.cancel() method on the object returned from a callback invocation. The cancel response does not affect the server when processing a request.

The steps necessary to invoke a Web service asynchronously are:

Determine if you want to implement the callback method or the polling method for the client to asynchronously invoke the Web service.

(Optional) Configure the client request context. Add the

org.apache.axis2.jaxws.use.async.mep

property to the request context to enable asynchronous messaging for the Web services client. Using this property requires that the service endpoint supports WS-Addressing which is supported by default for the application server. The following example demonstrates how to set this property:

Map<String, Object> rc = ((BindingProvider) port).getRequestContext(); rc.put("org.apache.axis2.jaxws.use.async.mep", Boolean.TRUE);

To implement the asynchronous callback method, perform the following steps.

Find the asynchronous callback method on the SEI or javax.xml.ws.Dispatch interface. For an SEI, the method name ends in Async and has one more parameter than the synchronous method of type javax.xml.ws.AsyncHandler. The invokeAsync(Object, AsyncHandler) method is the one that is used on the Dispatch interface.

(Optional) Add the service.setExecutor methods to the client application. Adding the executor methods gives the client control of the scheduling methods for processing the response. You can also choose to use the java.current.Executors class factory to obtain packaged executors or implement your own executor class. See the JAX-WS specification for more information on using executor class methods with your client.

Implement the javax.xml.ws.AsynchHandler interface. The javax.xml.ws.AsynchHandler interface only has the handleResponse(javax.xml.ws.Response) method. The method must contain the logic for processing the response or possibly an exception. The method is called after the client run time has received and processed the asynchronous response from the server.

Invoke the asynchronous callback method with the parameter data and the callback handler.

The handleResponse(Response) method is invoked on the callback object when the response is available. The Response.get() method is called within this method to deliver the response.

To implement the polling method,

Find the asynchronous polling method on the SEI or javax.xml.ws.Dispatch interface. For an SEI, the method name ends in Async and has a return type of javax.xml.ws.Response. The invokeAsync(Object) method is used on the Dispatch interface.

Invoke the asynchronous polling method with the parameter data.

The client receives the object type, javax.xml.ws.Response, that is used to monitor the status of the request to the server. The isDone() method indicates whether the invocation has completed. When the isDone() method returns a value of true, call the get() method to retrieve the response object.

Use the cancel() method for the callback or polling method if the client needs to stop waiting for a response from the service. If the cancel() method is invoked by the client, the endpoint continues to process the request. However, the wait and response processing for the client is stopped.

When developing Dynamic Proxy clients, after you generate the portable client artifacts from a WSDL file using the wsimport command, the generated service endpoint interface (SEI) does not have asynchronous methods included in the interface. Use JAX-WS bindings to add the asynchronous callback or polling methods on the interface for the Dynamic Proxy client. To enable asynchronous mappings, you can add the jaxws:enableAsyncMapping binding declaration to the WSDL file. For more information on adding binding customizations to generate an asynchronous interface, see chapter 8 of the JAX-WS specification.

Note: When you run the wsimport tool and enable asynchronous invocation through the use of the JAX-WS enableAsyncMapping binding declaration, ensure that the corresponding response message your WSDL file does not contain parts. When a response message does not contain parts, the request acts as a two-way request, but the actual response that is sent back is empty. The wsimport tool does not correctly handle a void response. To avoid this scenario, you can remove the output message from the operation which makes your operation a one-way operation or you can add a <wsdl:part> to your message. For more information on the usage, syntax and parameters for the wsimport tool, see the wsimport command for JAX-WS applications documentation.

The following example illustrates a Web service interface with methods for asynchronous requests from the client.

@WebService public interface CreditRatingService { // Synchronous operation. Score getCreditScore(Customer customer); // Asynchronous operation with polling. Response<Score> getCreditScoreAsync(Customer customer); // Asynchronous operation with callback. Future<?> getQuoteAsync(Customer customer, AsyncHandler<Score> handler); }
Using the callback method The callback method requires a callback handler that is shown in the following example. When using the callback procedure, after a request is made, the callback handler is responsible for handling the response. The response value is a response or possibly an exception. The Future<?> method represents the result of an asynchronous computation and is checked to see if the computation is complete. When you want the application to find out if the request is completed, invoke the Future.isDone() method. Note that the Future.get() method does not provide a meaningful response and is not similar to the Response.get() method.

CreditRatingService svc = ...; Future<?> invocation = svc.getCreditScoreAsync(customerTom, new AsyncHandler<Score>() { public void handleResponse ( Response<Score> response) { score = response.get(); // process the request... } } );
Using the polling method The following example illustrates an asynchronous polling client:

CreditRatingService svc = ...; Response<Score> response = svc.getCreditScoreAsync(customerTom); while (!response.isDone()) { // Do something while we wait. } score = response.get();

Using handlers in JAX-WS Web services
As in the Java API for XML-based RPC (JAX-RPC) programming model, the JAX-WS programming model provides an application handler facility that enables you to manipulate a message on either an inbound or an outbound flow. You can add handlers into the JAX-WS runtime environment to perform additional processing of request and response messages. You can use handlers for a variety of purposes such as capturing and logging information and adding security or other information to a message. Because of the support for additional protocols beyond SOAP, JAX-WS provides two different classifications for handlers. One type of handler is a logical handler that is protocol independent and can obtain the message in the flow as an extensible markup language (XML) message. The logical handlers operate on message context properties and message payload. These handlers must implement the javax.xml.ws.handler.LogicalHandler interface. A logical handler receives a LogicalMessageContext object from which the handler can get the message information. Logical handlers can exist on both SOAP and XML/HTTP-based configurations.

The second type of handler is a protocol handler. The protocol handlers operate on message context properties and protocol-specific messages. Protocol handlers are limited to SOAP-based configurations and must implement the javax.xml.ws.handler.soap.SOAPHandler interface. Protocol handlers receive the message as a javax.xml.soap.SOAPMessage to read the message data.

The JAX-WS runtime makes no distinction between server-side and client-side handler classes. The runtime does not distinguish between inbound or outbound flow when a handleMessage(MessageContext) method or handleFault(MessageContext) method for a specific handler is invoked. You must configure the handlers for the server or client, and implement sufficient logic within these methods to detect the inbound or outbound direction of the current message.

To use handlers with Web services client applications, you must add the @HandlerChain annotation to the service endpoint interface or the generated service class and provide the handler chain configuration file. The @HandlerChain annotation contains a file attribute that points to a handler chain configuration file that you create. For Web services client applications, you can also configure the handler chain programmatically using the Binding API. To modify the handlerchain class programmatically, use either the default implementation or a custom implementation of the HandlerResolver method.

To use handlers with your server application, you must set the @HandlerChain annotation on either the service endpoint interface or the endpoint implementation class, and provide the associated handler chain configuration file. Handlers for the server are only configured by setting the @HandlerChain annotation on the service endpoint implementation or the implementation class. The handler classes must be included in the deployed artifact.

For both server and client implementations of handlers using the @HandlerChain annotation, you must specify the location of the handler configuration as either a relative path from the annotated file or as an absolute URL. For example:

@HandlerChain(file="../../common/handlers/myhandlers.xml")
or

@HandlerChain(file="http://foo.com/myhandlers.xml")
For more information on the schema of the handler configuration file, see the JSR 181 specification.

For more information regarding JAX-WS handlers, see chapter 9 of the JAX-WS specification.

To create a JAX-WS handler:

Determine if you want to implement JAX-WS handlers on the service or the client.

Use the default implementation of a handler resolver. The runtime now uses the @HandlerChain annotation and the default implementation of HandlerResolver class to build the handler chain. You can obtain the existing handler chain from the Binding, add or remove handlers, and then return the modified handler chain to the Binding object.

To use a custom implementation of a handler resolver, set the custom HandlerResolver class on the Service instance. The runtime uses your custom implementation of the HandlerResolver class to build the handler chain, and the default runtime implementation is not used. In this scenario, the @HandlerChain annotation is not read when retrieving the handler chain from the binding after the custom HandlerResolver instance is registered on the Service instance. You can obtain the existing handler chain from the Binding, add or remove handlers, and then return the modified handler chain to the Binding object.

Configure the client handlers by setting the @HandlerChain annotation on the service instance or service endpoint interface, or you can modify the handler chain programmatically to control how the handler chain is built in the runtime. If you choose to modify the handler chain programmatically, then you must determine if you will use the default handler resolver or use a custom implementation of a handler resolver that is registered on the service instance. A service instance uses a handler resolver when creating binding providers. When the binding providers are created, the handler resolver that is registered with a service is used to create a handler chain and the handler chain is subsequently used to configure the binding provider.

Configure the server handlers by setting the @HandlerChain annotation on the service endpoint interface or implementation class. When the @HandlerChain annotation is configured on both the service endpoint interface and the implementation class, the implementation class takes priority.

Create the handler chain configuration XML file. You must create a handler chain configuration XML file for the @HandlerChain to reference.

Add the handler chain configuration XML file in the class path for the service endpoint interface when configuring the server or client handlers using the @HandlerChain annotation. You must also include the handler classes contained in the configuration XML file in your class path.

Write your handler implementation.

The following example illustrates the steps necessary to configure JAX-WS handlers on a service endpoint interface using the @HandlerChain annotation.

The @HandlerChain annotation has a file attribute that points to a handler chain configuration XML file that you create. The following file illustrates a typical handler configuration file. The protocol-bindings, port-name-pattern, and service-name-pattern elements are all filters that are used to restrict which services can apply the handlers.

<?xml version="1.0" encoding="UTF-8"?> <jws:handler-chains xmlns:jws="http://java.sun.com/xml/ns/javaee">  <jws:handler-chain name="MyHandlerChain"> <jws:protocol-bindings>##SOAP11_HTTP ##ANOTHER_BINDING</jws:protocol-bindings> <jws:port-name-pattern xmlns:ns1="http://handlersample.samples.apache.org/">ns1:MySampl*</jws:port-name-pattern> <jws:service-name-pattern xmlns:ns1="http://handlersample.samples.apache.org/">ns1:*</jws:service-name-pattern> <jws:handler> <jws:handler-class>org.apache.samples.handlersample.SampleLogicalHandler</jws:handler-class> </jws:handler> <jws:handler> <jws:handler-class>org.apache.samples.handlersample.SampleProtocolHandler2</jws:handler-class> </jws:handler> <jws:handler> <jws:handler-class>org.apache.samples.handlersample.SampleLogicalHandler</jws:handler-class> </jws:handler> <jws:handler> <jws:handler-class>org.apache.samples.handlersample.SampleProtocolHandler2</jws:handler-class> </jws:handler> </jws:handler-chain> </jws:handler-chains>
Make sure that you add the handler.xml file and the handler classes contained in the handler.xml file in your class path.

The following example demonstrates a handler implementation:

package org.apache.samples.handlersample; import java.util.Set; import javax.xml.namespace.QName; import javax.xml.ws.handler.MessageContext; import javax.xml.ws.handler.soap.SOAPMessageContext; public class SampleProtocolHandler implements javax.xml.ws.handler.soap.SOAPHandler<SOAPMessageContext> { public void close(MessageContext messagecontext) { } public Set<QName> getHeaders() { return null; } public boolean handleFault(SOAPMessageContext messagecontext) { return true; } public boolean handleMessage(SOAPMessageContext messagecontext) { Boolean outbound = (Boolean) messagecontext.get(MessageContext.MESSAGE_OUTBOUND_PROPERTY); if (outbound) { // Include your steps for the outbound flow. } return true; } }

Enabling HTTP session management support for JAX-WS applications
You can use HTTP session management to maintain user state information on the server, while passing minimal information back to the user to track the session. You can implement HTTP session management on the application server using either session cookies or URL rewriting.

The interaction between the browser, application server, and application is transparent to the user and the application program. The application and the user are typically not aware of the session identifier provided by the server.

Session cookies
The HTTP maintain session feature uses a single cookie, JSESSIONID, and this cookie contains the session identifier. This cookie is used to associate the request with information stored on the server for that session. On subsequent requests from the JAX-WS application, the session ID is transmitted as part of the request header, which enables the application to associate each request for a given session ID with prior requests from that user. The JAX-WS client applications retrieve the session ID from the HTTP response headers and then use those IDs in subsequent requests by setting the session ID in the HTTP request headers.

URL rewriting
URL rewriting works like a redirected URL as it stores the session identifier in the URL. The session identifier is encoded as a parameter on any link or form that is submitted from a Web page. This encoded URL is used for subsequent requests to the same server.

To enable HTTP session management:

Configure the server to enable session tracking.

Enable session management on the client by setting the JAX-WS property, javax.xml.ws.session.maintain, to true on the BindingProvider.

Map<String, Object> rc = ((BindingProvider) port).getRequestContext(); ... ... rc.put(BindingProvider.SESSION_MAINTAIN_PROPERTY, Boolean.TRUE); ... ...

Enabling MTOM
JAX-WS supports the use of SOAP Message Transmission Optimized Mechanism (MTOM) for sending binary attachment data. By enabling MTOM, you can send and receive binary data optimally without incurring the cost of data encoding to ensure the data is included in the XML document.

JAX-WS applications can send binary data as base64 or hexBinary encoded data contained within the XML document. However, to take advantage of the optimizations provided by MTOM, enable MTOM to send binary base64 data as attachments contained outside the XML document. MTOM optimization is only available for the xs:base64Binary data type. The MTOM option is not enabled by default. JAX-WS applications require separate configuration of both the client and the server artifacts to enable MTOM support. For the server, MTOM can be enabled on a JAX-WS JavaBeans endpoint only and not on a provider-based endpoint.

To enable MTOM on an endpoint, use the @BindingType (javax.xml.ws.BindingType) annotation on a server endpoint implementation class to specify that the endpoint supports one of the MTOM binding types so that the response messages are MTOM-enabled. The javax.xml.ws.SOAPBinding class defines two different constants, SOAP11HTTP_MTOM_BINDING and SOAP12HTTP_MTOM_BINDING that you can use for the value of the @BindingType annotation. For example:

// for SOAP version 1.1 @BindingType(value = SOAPBinding.SOAP11HTTP_MTOM_BINDING) // for SOAP version 1.2 @BindingType(value = SOAPBinding.SOAP12HTTP_MTOM_BINDING)

Enable MTOM on the client by using the javax.xml.ws.soap.SOAPBinding client-side API. Enabling MTOM on the client optimizes the binary messages that are sent to the server.

Enable MTOM on a Dispatch client.

The following example uses SOAP version 1.1:

First method: Using SOAPBinding.setMTOMEnabled()

SOAPBinding binding = (SOAPBinding)dispatch.getBinding(); binding.setMTOMEnabled(true);

Second method: Using Service.addPort()

Service svc = Service.create(serviceName); svc.addPort(portName,SOAPBinding.SOAP11HTTP_MTOM_BINDING,endpointUrl);

Enable MTOM on a Dynamic Proxy client.

// Create a BindingProvider bp from a proxy port. Service svc = Service.create(serviceName); MtomSample proxy = svc.getPort(portName, MtomSample.class); BindingProvider bp = (BindingProvider) proxy; //Enable MTOM SOAPBinding binding = (SOAPBinding) bp.getBinding(); binding.setMTOMEnabled(true);

JAX-WS Guide

Table of Contents

Dispatch client

Dynamic Proxy client

Using the callback asynchronous invocation model

Using the polling asynchronous invocation model

Using an asynchronous message exchange

Session cookies

URL rewriting