How can you use JAX-WS to handle SOAP web services?

1 What is JAX-WS?

JAX-WS stands for Java API for XML Web Services. It is a standard specification that defines how to use Java annotations and classes to create web service endpoints and clients. JAX-WS is based on the WS-I Basic Profile, which is a set of guidelines for interoperable web services. JAX-WS supports both document-style and RPC-style web services, as well as SOAP 1.1 and SOAP 1.2 versions.

3 How to publish a JAX-WS web service endpoint?

To publish a JAX-WS web service endpoint, you need to create an instance of the Endpoint class and invoke its publish method. The publish method takes two arguments: the address of the web service and the implementation object of the web service endpoint. For example, you can publish a web service endpoint using the following code:

import javax.xml.ws.Endpoint;
public class Publisher {
  public static void main(String[] args) {
    Endpoint.publish("https://localhost:8080/hello", new HelloService());
  }
}        

The above code publishes a web service endpoint named HelloService at the address https://localhost:8080/hello. You can then access the web service using a SOAP client or a web browser.

4 How to create a JAX-WS web service client?

To create a JAX-WS web service client, you need to generate the client stubs from the web service WSDL (Web Service Description Language) file. The WSDL file is an XML document that describes the web service interface, operations, and messages. You can use the wsimport tool that comes with the JDK to generate the client stubs. For example, you can use the following command to generate the client stubs from the WSDL file located at https://localhost:8080/hello?wsdl: wsimport -keep -s src https://localhost:8080/hello?wsdl The above command generates the Java source files and class files in the src folder. Then, you can use the generated classes to invoke the web service operations. For example, you can use the following code to create a web service client and call the sayHello method of the HelloService web service:

import hello.HelloService;
import hello.HelloServiceService;
public class Client {
  public static void main(String[] args) {
    HelloServiceService service = new HelloServiceService();
    HelloService port = service.getHelloServicePort();
    String response = port.sayHello("World");
    System.out.println(response);
  }
}        

The above code creates an instance of the HelloServiceService class, which is a factory for the web service proxy. Then, it obtains the web service port, which is an interface for the web service operations. Finally, it calls the sayHello method and prints the response.

5 What are the benefits of using JAX-WS?

Using JAX-WS has several benefits for web development, such as simplifying the creation and consumption of SOAP web services using Java annotations and classes. It also supports various web service features, like SOAP headers, attachments, handlers, and MTOM (Message Transmission Optimization Mechanism). Furthermore, it enables interoperability with other web service platforms and languages that follow the WS-I Basic Profile. Additionally, it provides tools and utilities for generating, testing, and deploying web service endpoints and clients.

6 What are the alternatives to JAX-WS?

JAX-WS is not the only Java API for web services; there are other alternatives, such as JAX-RS, an API for RESTful web services which utilizes annotations and classes to create web service resources and clients. Apache CXF is an open source framework that supports both SOAP and RESTful web services, providing features such as WS-Security and WS-Addressing. Apache Axis2 is another open source framework that supports SOAP web services, offering features such as WS-Discovery and WS-Trust. It also supports multiple transports, like HTTP, SMTP, TCP, and JMS.