Chapter 5 Client Design

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inate the need for the developer to use the JAX RPC APIs directly. By contrast,

the dynamic proxy and DII approaches both require the developer to use the JAX 

RPC APIs. 

5.3.1.1

Using Stub Communication

J2EE clients should use generated stubs to access services, especially for services

with fairly static interfaces. Stub communication easily allows Java access to a Web

service. This is the recommended approach for accessing services and their WSDL

files when they are unlikely to change over time. 

Figure 5.5 shows how a client application might access a Web service using a

stub generated by a tool prior to the client's deployment and compilation. The

WSDL file for the service served as input to the tool. The client side service end 

point interface, which implements the service endpoint interface on the client side

of the communication channel, provides the client view of the Web service.

The stub, which implements the client side service endpoint interface, acts as

a proxy to the Web service for the client; that is, the stub is the client's view of the

Web service. The tool that generates the stub class also generates all necessary

helper classes for accessing the service. These helper classes define the parame 

ters for calls to the service and the service's return values, ensuring that the

parameters and return values are all of the proper types expected by the JAX RPC

runtime. To generate these stub and helper classes, the tool relies on the WSDL

document as well as a JAX RPC mapping file. The mapping file supplies infor 

mation regarding the Java to XML bindings, such as the correct package name for

generated classes.

Client

WSDL

Tool

Service Endpoint 

Stub

JAX RPC

Interface

Mappings

JAX RPC Runtime

Web Service

Figure 5.5

Stub Communication Model