Patterns: Implementing Self-Service in an SOA Environment

292 Patterns: Implementing Self-Service in an SOA Environment

10.1 Architectural overview model

The architectural overview model, shown in Figure 10-1, illustrates how the

ITSOMart application was extended to communicate with enterprise systems

using Web services.

The highlighted portion of Figure 10-1 is the focus of this chapter. From the J2EE

architecture point of view, this is the part of the application server business logic

tier that retrieves some business data from one or more applications in the EIS

tier. Results are retrieved and processed and sent back to the presentation tier.

Figure 10-1 Architectural overview model: Web services

The components that participate in the Web Services Scenario are:

򐂰 CreditCheckProxy

This proxy is used by the Processor application to call the CreditCheck Web

service.

HTTP

Requests

Self Service

Application

Mail Sender

(MDB)

MailService

ESB

Processor

Mail Service Proxy

(JMS)

(MDB)

queue

JCA

Resource

Adapter

CRM (CICS)CRM Proxy

Web

service

queue

Processor.ear

CreditCheck

Proxy

CreditCheck

Web

service

HomeDelivery

Proxy

HomeDelivery

Web

service

BusinessDelivery

CreditCheck.ear

DeliverySystem.ear

Mediations

RoutingMediationsEJBEAR.ear

AggregatorEJBEAR.ear

Chapter 10. Web services scenario 293

򐂰 HomeDeliveryProxy

The Processor application uses this proxy to call the HomeDelivery Web

service. The ESB intercepts the request and routes it to the appropriate

services.

򐂰 Enterprise service bus (ESB)

The ESB is implemented using the service integration bus. The bus acts as

an intermediary for the Web service. Using an ESB insulates the application

from changes in the Web service location and provides the opportunity to

implement mediations or security measures in the future.

򐂰 CreditCheck

The CreditCheck Web service returns a credit rating for the customer.

򐂰 DeliverySystem

The DeliverySystem application has two Web services: HomeDelivery and

BusinessDelivery. These delivery systems create account numbers for the

new customer and return the information to the user.

This scenario illustrates the following three application patterns using Web

services technology:

򐂰 Directly Integrated Single Channel application pattern:

ITSOMart calls a Web service that returns a customer credit rating. The rating

is used to determine whether to allow the customer to open an account.

򐂰 Router application pattern

ITSOMart allows the user to select whether they want home delivery,

business delivery, or both. If home or business delivery is chosen the request

is routed to the appropriate service to assign an account number that is then

returned to the user. The routing is performed through the use of a mediation

in the ESB.

򐂰 Decomposition application pattern

If the user selects both home delivery and business delivery, the request for

an account number is sent to both services. The responses with the account

numbers are aggregated into a single response for the customer. The

decomposition of the message into multiple messages and the recomposition

into a single response are performed through the use of a mediation in the

ESB.