20100723 (JAX-WS study)

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 an SEI.

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

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 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.
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 life cycle 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.

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);

JAXB supports the grouping of generated classes in Java packages. A package consists of the following:
A Java class name that is derived from the XML element name, or specified by a binding customization.
An ObjectFactory class, which is a factory that is used to return instances of a bound Java class.

When XML element information can not be inferred by the derived Java representation of the XML content, a JAXBElement object is provided. This object has methods for getting and setting the object name and object value

Custom JAXB binding declarations allow you to customize your generated JAXB classes beyond the XML-specific constraints in an XML schema to include Java-specific refinements, such as class and package name mappings.
JAXB provides two ways to customize an XML schema:
As inline annotations in a source XML schema
As declarations in an external binding customization file that is passed to the JAXB binding compiler

The JAXB annotations defined in the javax.xml.bind.annotations package can be used to customize Java program elements to XML schema mapping.