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Developing a service endpoint implementation for JAX-WS applications with annotations

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.

Before you begin

Set up a development environment for Web services and access an existing JavaBeans Web archive (WAR) file.

About this task

This task is a required step to develop a JAX-WS Web service from JavaBeans components.

JAX-WS technology enables the implementation of Web services based on both the standard JavaBeans service endpoint interface and a new Provider interface. 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.

Procedure

  1. 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.

  2. Annotate the service endpoints. 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.

Results

You have defined the service endpoint implementation that represents the Web services application. See JAX-WS annotations for additional information on supported JAX-WS annotations.

Example

Sample JavaBeans service endpoint implementation and interface

The following example illustrates a simple explicit JavaBeans service endpoint implementation and the associated service endpoint interface.
/** This is an excerpt from the service implementation file, EchoServicePortTypeImpl.java 
package com.ibm.was.wssample.echo;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;

@javax.jws.WebService(serviceName = "EchoService", endpointInterface = "com.ibm.was.wssample.echo.EchoServicePortType", targetNamespace="http://com/ibm/was/wssample/echo/", portName="EchoServicePort")
public class EchoServicePortTypeImpl implements EchoServicePortType {

                public EchoServicePortTypeImpl() {
                }

                public String invoke(String obj) {
                        String str;
                        ....
                        str = obj;
                        ....
                        
                        return str;

                }

}
/**  This is a sample EchoServicePortType.java service interface */

import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebResult;
import javax.jws.WebService;
import javax.xml.ws.*;


@WebService(name = "EchoServicePortType", targetNamespace = "http://com/ibm/was/wssample/echo/", wsdlLocation="WEB-INF/wsdl/Echo.wsdl")
public interface EchoServicePortType {


    /** ...the method process ...*/
        @WebMethod
    @WebResult(name = "response", targetNamespace = "http://com/ibm/was/wssample/echo/")
    @RequestWrapper(localName = "invoke", targetNamespace = "http://com/ibm/was/wssample/echo/", className = "com.ibm.was.wssample.echo.Invoke")
    @ResponseWrapper(localName = "echoStringResponse", targetNamespace = "http://com/ibm/was/wssample/echo/", className = "com.ibm.was.wssample.echo.EchoStringResponse")
    public String invoke(
        @WebParam(name = "arg0", targetNamespace = "http://com/ibm/was/wssample/echo/")
        String arg0);

}

Sample Provider endpoint implementation

The following example illustrates a simple Provider service endpoint interface for a Java class.
package jaxws.provider.source;

import javax.xml.ws.Provider;
import javax.xml.ws.WebServiceProvider;
import javax.xml.transform.Source;

@WebServiceProvider()
public class SourceProvider implements Provider<Source> {

    public Source invoke(Source data) {
        return data;
    }
}

In the example, the Provider implementation, the javax.xml.transform.Source type is specified in the generic <Source> method. The generic <Source> method specifies that both the input and output types are Source objects. An endpoint interface that implements the Provider interface must include a @WebServiceProvider annotation.

What to do next

Develop Java artifacts for JAX-WS applications from JavaBeans.



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Last updated: Nov 25, 2008 2:35:59 AM CST
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