Chapter 3 Service Endpoint Design

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The J2EE container extracts the method call invoked by the client along with

the parameters for the call, performs any XML to Java object mapping necessary,

and hands the method to the Web service interface implementation for further pro 

cessing. A similar set of steps happens when the service sends back its response.

Note:

 All the details between the method invocation and response just

described happen under the hood. The platform shields the developer from these

details. Instead, the developer deals only with typical Java programming language

semantics, such as Java method calls, Java types, and so forth.

3.3

Key Web Services Design Decisions 

Now that you understand what happens in a Web service interaction, let us look

further at the issues involved in the design and implementation of a Web service. We

first look at what goes into designing a Web service, examining the issues for which

decisions are required and, when possible, making recommendations. (Similarly,

Chapter 5 examines the issues to consider when designing a Web service client.)

Before doing so, it is worthwhile to repeat this point:

E

Web service technologies basically help you expose an interoperable interface 

for a new or an existing application. That is, you can add a Web service inter 

face to an existing application to make it interoperable with other applications, 

or you can develop a completely new application that is interoperable from its 

inception.

It is important to keep in mind that designing Web service capabilities for an

application is separate from designing the business logic of the application. In

fact, you design the business logic of an application without regard to whether the

application has a Web service interface. To put it another way, the application's

business logic design is the same regardless of whether or not the application has a

Web service interface. When you design a Web service interface for an applica 

tion, you must consider those issues that pertain specifically to interoperability

and Web services and not to the business logic and you make your design

decisions based on these issues.

When designing a Web service, consider the logic flow for typical Web ser 

vices and the issues they address. In general, a Web service: