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Designing XML Based Applications

  Returned to a Web service client: if the application is accessing a Web service 

through JAX RPC. (See Chapter 5 for more details.)

  Through a JMS queue or topic (possibly attached to a message driven bean in 

the EJB tier) when implementing a business process workflow or implement 

ing an asynchronous Web service architecture. (See  Delegating Web Service 

Requests to Processing Layer  on page 92.) 

Note that a generic XML based application can additionally receive and

return XML documents through a servlet over plain HTTP.

Recall from Chapter 3 that a Web service application must explicitly handle

certain XML schemas schemas for SOAP parameters that are not bound to Java

objects and schemas of XML documents passed as attachments to SOAP mes 

sages. Since the JAX RPC runtime passes SOAP parameter values (those that are

not

 bound to Java objects) as 

SOAPElement

 document fragments, an application

can consume and process them as DOM trees and even programmatically bind

them to Java objects using XML data binding techniques such as JAXB. Docu 

ments might be passed as attachments to SOAP messages when they are very

large, legally binding, or the application processing requires the complete docu 

ment infoset. Documents sent as attachments may also conform to schemas

defined in languages not directly supported by the Web service endpoint. 

Code Example 4.2 and Code Example 4.3 illustrate sending and receiving

XML documents.

public class SupplierOrderSender {

private SupplierService_Stub supplierService;

public SupplierOrderSender(URL serviceEndPointURL) {

// Create a supplier Web service client stub

supplierService = ...

return;

}

// Submits a purchase order document to the supplier Web service

public String submitOrder(Source supplierOrder)

throws RemoteException, InvalidOrderException {

String trackingNumber

= supplierService.submitOrder(supplierOrder);

return trackingNumber;