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JAX-WS 2.0 defines a
Handler interface, with subinterfaces
LogicalHandler and
SOAPHandler. The
Handler interface contains
handleMessage(C context) and
handleFault(C context) methods, where
C extends
MessageContext. A property in the
MessageContext object is used to determine if the message is inbound or outbound.
SOAPHandler objects have access to the full soap message including headers. Logical handlers are independent of protocol and have access to the payload of the message.
The new handler types can now be written without casting the message context object that is passed to them. For instance:
public class MyLogicalHandler implements LogicalHandler<LogicalMessageContext> {
public boolean handleMessage(LogicalMessageContext messageContext) {
LogicalMessage msg = messageContext.getMessage();
return true;
}
// other methods
}
public class MySOAPHandler implements SOAPHandler<SOAPMessageContext> {
public boolean handleMessage(SOAPMessageContext messageContext) {
SOAPMessage msg = messageContext.getMessage();
return true;
}
// other methods
}
A
close(C context) method has been added that is called on the
handlers at the conclusion of a message exchange pattern. This allows handlers
to clean up any resources that were used for the processing of a request-only
or request/response exchange.
The
init() and
destroy() methods of the handler
lifecycle no longer exist. Instead, a method may be annotated with the
@PostConstruct annotation to be called after the handler is
created or the
@PreDestroy annotation to be called before the
handler is destroyed. Note that the annotated methods must return
void and take no arguments:
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
public class MyLogicalHandler implements LogicalHandler<LogicalMessageContext> {
@PostConstruct
public void methodA() { }
@PreDestroy
public void methodB() {}
// other methods
}
In the examples above, the
LogicalMessage object allows a
handler to get and set the message payload either as a JAXB object or as a
javax.xml.transform.Source. The
SOAPMessage object
allows access to headers and the SOAP body of the message.
Both context objects extend
MessageContext, which holds
properties that the handlers can use to communicate with each other. A standard
property
MessageContext.MESSAGE_OUTBOUND_PROPERTY holds a
Boolean that is used to determine the direction of a message.
For example, during a request, the property would be
Boolean.TRUE
when seen by a client handler and
Boolean.FALSE when seen by a
server handler.
The message context object can also hold properties set by the client or
provider. For instance, port proxy and dispatch objects both extend
BindingProvider. A message context object can be obtained from both
to represent the request or response context. Properties set in the request
context can be read by the handlers, and the handlers may set properties on the
message context objects passed to them. If these properties are set with the
scope
MessageContext.Scope.APPLICATION then they will be
available in the response context to the client. On the server end, a context
object is passed into the
invoke method of a
Provider.
Starting from a WSDL file, handler chain configuration is through WSDL customizations as defined by
JSR 109. A
<handler-chains> element is added to the customization file. The following is a simple handler chain with one handler (customization may be on server or client side):
<-- excerpt from customization file -->
<bindings xmlns="http://java.sun.com/xml/ns/jaxws">
<handler-chains xmlns="http://java.sun.com/xml/ns/javaee">
<handler-chain>
<handler>
<handler-class>fromwsdl.handler_simple.common.TestHandler</handler-class>
</handler>
</handler-chain>
</handler-chains>
</bindings>
Multiple
handler-chain elements may exist within the
handler-chains element. These may optionally use a service name,
port name, or protocol pattern in their description to apply some chains
to certain ports and protocols and not to others. For instance (note the
wildcard character used in the service name):
<-- excerpt -->
<handler-chains xmlns="http://java.sun.com/xml/ns/javaee">
<handler-chain>
<service-name-pattern xmlns:ns1="urn:namespace">ns1:My*Service</service-name-pattern>
<handler>...</handler>
</handler-chain>
<handler-chain>
<port-name-pattern xmlns:ns1="urn:namespace">ns1:HelloPort</port-name-pattern>
<handler>...</handler>
</handler-chain>
<handler-chain>
<protocol-bindings>##SOAP11_HTTP</protocol-bindings>
<handler>...</handler>
</handler-chain>
</handler-chains>
Handlers will appear in the final handler chain in the order that they are included in the customization file. However, logical handlers will be sorted out and called before protocol handlers during execution.
Starting from a Java class, annotations are used to describe the handler
chain as defined by
JSR 181.
The following example uses the
@HandlerChain annotation to refer
to a file describing the chain.
import javax.jws.HandlerChain;
import javax.jws.WebService;
@WebService
@HandlerChain( file="handlers.xml")
public class MyServiceImpl {
// implementation of class
}
An example
handlers.xml file is shown below. The schema is
the same that is used for the customization.
<?xml version="1.0" encoding="UTF-8"?>
<jws:handler-chains xmlns:jws="http://java.sun.com/xml/ns/javaee">
<jws:handler-chain>
<jws:handler>
<jws:handler-class>fromjava.handler_simple.common.TestHandler</jws:handler-class>
</jws:handler>
</jws:handler-chain>
</jws:handler-chains>
When packaging the service, the handlers.xml file must be in the classpath
within the WAR file, either directly under
WEB-INF/classes or
further down in the same package as the service class file.
On the server side, the handlers may be configured in the sun-jaxws.xml deployment descriptor as well. A handler chain specified here will override handlers in WSDL customizations or annotated classes. The schema for the handler section is the same as in the previous examples:
<endpoints ....>
<endpoint ....>
<handler-chains xmlns="http://java.sun.com/xml/ns/javaee">
<handler-chain>
....
</handler-chain>
</handler-chains>
</endpoint>
</endpoints>
Handler chains may be configured on the client side at runtime by setting a
chain directly on a
BindingProvider (e.g., a
Dispatch
object or a port proxy) or by using a
HandlerResolver. This
example shows how to add a handler chain to a port proxy:
// given proxy interface HelloPortType
HelloPortType myProxy = // create proxy
Binding binding = ((BindingProvider)myProxy).getBinding();
// can create new list or use existing one
List<Handler> handlerList = binding.getHandlerChain();
handlerList.add(new MyHandler());
binding.setHandlerChain(handlerList);
To configure the handlers that are added to newly created
Binding
objects, add a handler resolver to the service with
setHandlerResolver().
The new resolver will be used whenever a
BindingProvider is
created from the service. An example resolver is as follows:
/*
* Add handlers to the returned list based on the information
* in info.getBindingID(), getPortName(), and/or getServiceName().
*/
public class MyResolver implements HandlerResolver {
public List<Handler> getHandlerChain(PortInfo info) {
List<Handler> handlers = new ArrayList<Handler>();
// add handlers to list based on PortInfo information
return handlers;
}
}
A resolver that modifies the initially configured handler chains could
be written by calling
service.getHandlerResolver() and passing
the original resolver to a new one:
// original HandlerResolver passed in constructor or setter method
public List<Handler> getHandlerChain(PortInfo info) {
List<Handler> handlers = originalResolver.getHandlerChain(info);
// alter list based on PortInfo information
return handlers;
}
The
fromjavahandler and
fromwsdlhandler samples set a
SOAPHandler on the client and server. This handler simply outputs the contents of the SOAP message and can be used to see the requests and responses being passed back and forth. See the sample documentation for information on running the samples.