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Creating a Simple Web Service and Client with JAX-WS

This section shows how to build and deploy a simple web service and client. The source code for the service is in <INSTALL>/javaeetutorial5/examples/jaxws/helloservice/ and the client is in <INSTALL>/javaeetutorial5/examples/jaxws/simpleclient/.

Figure 15-1 illustrates how JAX-WS technology manages communication between a web service and client.

Figure 15-1 Communication Between a JAX-WS Web Service and a Client

The starting point for developing a JAX-WS web service is a Java class annotated with the javax.jws.WebService annotation. The WebService annotation defines the class as a web service endpoint.

A service endpoint interface or service endpoint implementation (SEI) is a Java interface or class, respectively, that declares the methods that a client can invoke on the service. An interface is not required when building a JAX-WS endpoint. The web service implementation class implicitly defines a SEI.

You may specify an explicit interface by adding the endpointInterface element to the WebService annotation in the implementation class. You must then provide a interface that defines the public methods made available in the endpoint implementation class.

You use the endpoint implementation class and the wsgen tool to generate the web service artifacts that connect a web service client to the JAX-WS runtime. For reference documentation on wsgen, see the Application Server man pages at http://docs.sun.com/.

Together, the wsgen tool and the Application Server provide the Application Server's implementation of JAX-WS.

These are the basic steps for creating the web service and client:

Code the implementation class.
Compile the implementation class.
Use wsgen to generate the artifacts required to deploy the service.
Package the files into a WAR file.
Deploy the WAR file. The web service artifacts (which are used to communicate with clients) are generated by the Application Server during deployment.
Code the client class.
Use wsimport to generate and compile the web service artifacts needed to connect to the service.
Compile the client class.
Run the client.

The sections that follow cover these steps in greater detail.

Requirements of a JAX-WS Endpoint

JAX-WS endpoints must follow these requirements:

The implementing class must be annotated with either the javax.jws.WebService or javax.jws.WebServiceProvider annotation.
The implementing class may explicitly reference an SEI through the endpointInterface element of the @WebService annotation, but is not required to do so. If no endpointInterface is not specified in @WebService, an SEI is implicitly defined for the implementing class.
The business methods of the implementing class must be public, and must not be declared static or final.
Business methods that are exposed to web service clients must be annotated with javax.jws.WebMethod.
Business methods that are exposed to web service clients must have JAXB-compatible parameters and return types. See Default Data Type Bindings (page 510).
The implementing class must not be declared final and must not be abstract.
The implementing class must have a default public constructor.
The implementing class must not define the finalize method.
The implementing class may use the javax.annotation.PostConstruct or javax.annotation.PreDestroy annotations on its methods for lifecycle event callbacks.

The @PostConstruct method is called by the container before the implementing class begins responding to web service clients.

The @PreDestroy method is called by the container before the endpoint is removed from operation.

Coding the Service Endpoint Implementation Class

In this example, the implementation class, Hello, is annotated as a web service endpoint using the @WebService annotation. Hello declares a single method named sayHello, annotated with the @WebMethod annotation. @WebMethod exposes the annotated method to web service clients. sayHello returns a greeting to the client, using the name passed to sayHello to compose the greeting. The implementation class also must define a default, public, no-argument constructor.

package helloservice.endpoint;

import javax.jws.WebService;

@WebService
public class Hello {
  private String message = new String("Hello, ");

  public void Hello() {}

  @WebMethod
  public String sayHello(String name) {
    return message + name + ".";
  }
} 

Building and Packaging the Service

To build and package helloservice, in a terminal window go to the <INSTALL>/javaeetutorial5/examples/jaxws/helloservice/ directory and type the following:

ant 

This command calls the default target, which builds and packages the application into an WAR file, helloservice.war, located in the dist directory.

Deploying the Service

You deploy the service using ant.

Upon deployment, the Application Server and the JAX-WS runtime generate any additional artifacts required for web service invocation, including the WSDL file.

Deploying the Service

To deploy the helloservice example, follow these steps:

In a terminal window, go to <INSTALL>/javaeetutorial5/examples/jaxws/helloservice/.
Make sure the Application Server is started.
Run ant deploy.

You can view the WSDL file of the deployed service by requesting the URL http://localhost:8080/helloservice/hello?WSDL in a web browser. Now you are ready to create a client that accesses this service.

Undeploying the Service

At this point in the tutorial, do not undeploy the service. When you are finished with this example, you can undeploy the service by typing this command:

ant undeploy 

The all Task

As a convenience, the all task will build, package, and deploy the application. To do this, enter the following command:

ant all 

Testing the Service Without a Client

The Application Server Admin Console allows you to test the methods of a web service endpoint. To test the sayHello method of HelloService, do the following:

Open the Admin Console by opening the following URL in a web browser:

  http://localhost:4848/

Enter the admin username and password to log in to the Admin Console.
Click Web Services in the left pane of the Admin Console.
Click Hello.
Click Test.
Under Methods, enter a name as the parameter to the sayHello method.
Click the sayHello button.

This will take you to the sayHello Method invocation page.

Under Method returned, you'll see the response from the endpoint.

A Simple JAX-WS Client

HelloClient is a stand-alone Java program that accesses the sayHello method of HelloService. It makes this call through a port, a local object that acts as a proxy for the remote service. The port is created at development time by the wsimport tool, which generates JAX-WS portable artifacts based on a WSDL file.

Coding the Client

When invoking the remote methods on the port, the client performs these steps:

Uses the javax.xml.ws.WebServiceRef annotation to declare a reference to a web service. WebServiceRef uses the wsdlLocation element to specify the URI of the deployed service's WSDL file.

@WebServiceRef(wsdlLocation="http://localhost:8080/
    helloservice/hello?wsdl")
static HelloService service;

Retrieves a proxy to the service, also known as a port, by invoking getHelloPort on the service.

Hello port = service.getHelloPort();

The port implements the SEI defined by the service.

Invokes the port's sayHello method, passing to the service a name.

String response = port.sayHello(name);

Here's the full source of HelloClient, located in the <INSTALL>/javaeetutorial5/examples/jaxws/simpleclient/src/java directory.

package simpleclient;

import javax.xml.ws.WebServiceRef;
import helloservice.endpoint.HelloService;
import helloservice.endpoint.Hello;

public class HelloClient {
  @WebServiceRef(wsdlLocation="http://localhost:8080/
      helloservice/hello?wsdl")
  static HelloService service;

  public static void main(String[] args) {
    try {
      HelloClient client = new HelloClient();
      client.doTest(args);
    } catch(Exception e) {
      e.printStackTrace();
    }
  }

  public void doTest(String[] args) {
    try {
      System.out.println("Retrieving the port from 
          the following service: " + service);
      Hello port = service.getHelloPort();
      System.out.println("Invoking the sayHello operation 
          on the port.");

      String name;
      if (args.length > 0) {
        name = args[0];
      } else {
        name = "No Name";
      }

      String response = port.sayHello(name);
      System.out.println(response);
    } catch(Exception e) {
      e.printStackTrace();
    }
  }
} 

Building and Running the Client

To build the client, you must first have deployed helloservice, as described in "Deploying the Service." Then navigate to <INSTALL>/examples/jaxws/simpleclient/ and do the following:

ant 

This command calls the default target, which builds and packages the application into a JAR file, simpleclient.jar, located in the dist directory.

The run the client, do the following:

ant run 

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