Patterns: Implementing Self-Service in an SOA Environment

302 Patterns: Implementing Self-Service in an SOA Environment

Message structure

This scenario uses two simple text messages (request and a response) that are

exchanged between the Web service requester and the Web service provider.

These text messages contain customer details (the request) and the resulting

credit rating (the response). This could be extended to use a more structured

message approach in the form of XML messages.

Mediation

In this scenario, there are multiple delivery systems that can be called depending

on the delivery type selected by the client. Mediation can be used to route the

requests to one or more of the systems and if necessary, manage multiple

responses.

10.4 Development guidelines for Web services

The development process for building a Web service is very similar to the

development process of any other software. There are four main phases in

developing a Web service: build, deploy, run, and manage.

1. The

build phase includes development and testing of the Web service

application, including the definition and functionality of the service.

2. The

deploy phase includes publication of the service definition, the WSDL

document, and deployment of the runtime code of the Web service.

3. The

run phase includes finding and invoking the Web service.

4. The

manage phase includes the management and administration of the Web

service. This includes performance measurement and maintenance of the

Web service.

Figure 10-8 depicts the complete development process. Using different problem

domains, the terms used within this picture would change; however, the general

view would not.

Chapter 10. Web services scenario 303

Figure 10-8 Web services development

The remainder of this section describes the four development phases in more

detail.

Build phase

The build phase, which includes testing and debugging, is the first phase in the

development process of a new Web service. Because Web services can be

written from scratch and use already existing applications, there are two possible

paths to be followed:

򐂰 The solid path

From the initial state, we build or already have Java code. Using this Java

code, we build the service definition (WSDL document) with the business

methods that we want to expose. After we have generated the WSDL

document, we assemble the Web service application. This approach is called

bottom-up development. This is the approach used for developing our

CreditCheck application. We first implement the CreditCheck application as a

single application, and then expose these methods for use with a Web

service.

򐂰 The dashed path

From the initial state, we build or already have a service definition, a WSDL

document. Using this WSDL document, we build or adapt the Java code to

implement that service. After we have implemented the code, we assemble

the Web service application. This approach is called top-down development.

Deploy phase

The second phase of a Web service development process is deployment. In this

phase, we deploy the Web service to an application server. Deploying a Web

Build Deploy

1

1

Service

definition

WSDL

Initial

Java

code

Web

service

build

Web

service

deploy

Service

registry

Run

Client

deploy run

find

invoke

publish

build

build

or have

build or

have

assemble

assemble

Manage

Web

service

run

Web

service

manage

WebSphere

manage