JAX-WS is a high-level API that simplifies the development of SOAP-based web services. JAX-WS stands for Java API for XML Web Services. Developing a web service via JAX-WS consists of writing a class with public methods to be exposed as web services. The class needs to be decorated with the @WebService annotation. All public methods in the class are automatically exposed as web services. They can optionally be decorated with the @WebService annotation. The following example illustrates this process:

package net.ensode.glassfishbook; 
 
import javax.jws.WebMethod; 
import javax.jws.WebService; 
 
@WebService 
public class Calculator { 
 
    @WebMethod 
    public int add(int first, int second) { 
        return first + second; 
    } 
 
    @WebMethod 
    public int subtract(int first, int second) { 
        return first - second; 
    } 
} 

The preceding class exposes its two methods as web services. The add() method simply adds the two int primitives it receives as parameters and returns the result; the substract() method subtracts its two parameters and returns the result.

We indicate that the class implements a web service by decorating it with the @WebService annotation. Any methods that we would like to expose as web services can be decorated with the @WebMethod annotation, but this isn't necessary; all public methods are automatically exposed as web services. We can still use the @WebMethod annotation for clarity, but it isn't strictly necessary to deploy our web service; we simply need to package it in a WAR file as usual.

Web service clients need a WSDL (Web Services Definition Language) file in order to generate executable code that they can use to invoke the web service. WSDL files are typically placed in a web server and accessed by the client via its URL.

When deploying web services developed using JAX-WS, a WSDL is automatically generated for us. The exact URL for the generated WSDL varies depending on the Java EE 8 application server we are using. When using GlassFish, URLs for JAX-WS WSDLs follow the following format:

[http|https]://[server]:[port]/[context root]/[service name]?wsdl

In our example, the URL for our web service's WSDL (when deployed to GlassFish) would be http://localhost:8080/calculatorservice/CalculatorService?wsdl (assuming GlassFish is running on our local workstation, and GlassFish is listening for HTTP connections on its default 8080 port).