Patterns: Implementing Self-Service in an SOA Environment

296 Patterns: Implementing Self-Service in an SOA Environment

Figure 10-3 Component model diagram

A Web service call to HomeDelivery invokes the HomeDelivery inbound service

on the bus. The destination representation for the HomeDelivery service has a

mediation that looks at the request and makes a routing decision based on the

delivery service requested by the client. The request could be routed to the

HomeDelivery service, the BusinessDelivery service or both. If both services are

called, a second mediation intercepts the responses and combines them into one

response.

10.2.2 Object model

In this section we provide an object model for our Web services scenario.

Class diagram for CreditCheckClient

Figure 10-4 on page 297 shows a class diagram of the classes directly involved

with providing Web services for the CreditCheckClient application.

On the requester side, the ProcessorWebService bean from the ITSOMart

application requests the credit rating using the CCWSClientBean EJB.

CCWSClientBean is the Web services requester bean, serving as the interface

between the ITSOMart application and the CreditCheck Web service. As far as

the application knows, it is simply calling a local method called

returnSimpleQuote on this bean and expects a credit rating to be returned.

Self Service Application

Processor EJB Module

HomeDelivery

Client Proxy

DeliverySystem Application

Service Integration Bus

Web Service

Destination

HomeDelivery

Data Binding

HomeDeliveryBean

HomeDelivery EJB Module

BusinessDelivery

Data Binding

BusinessDeliveryBean

BusinessDelivery EJB Module

Router

Mediation

Aggregator

Mediation

Chapter 10. Web services scenario 297

On the provider side, a stateless session EJB called CreditCheck serves as the

Web services bean for the provider. In a real application, this bean would

probably act as a facade to the actual enterprise business objects. It knows

which enterprise objects to call in order to retrieve the information it needs to

create a response to the Web services request.

Figure 10-4 Class diagram of the CreditCheckClient application

Class diagram for ClientDelivery

Figure 10-4 on page 297 shows a class diagram of the classes directly involved

with providing Web services for the ClientDelivery application. The flow is

identical to that of the CreditCheckClient application.

<<

use

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<<use>>

<<

use

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<<

use

>>

EJSLocalStatelessCCWSClientHome_f09aa5f3

<<

Java Class

>>

c

EJSStatelessCCWSClientHomeBean_f09aa5f3

<<

Java Class

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c

EJSLocalStatelessCCWSClient_f09aa5f3

<<

Java Class

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c

CCWSClientLocalHome

<<

Java Interface

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I

CCWSClientBean

<<Java Class>>

c

CreditCheckProxy

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Java Class

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c

CreditCheckInboundServiceLocator

<<

Java Class

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c

CCWSClientLocal

<<

Java Interface

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I

CreditCheckInboundPortBindingStub

<<

Java Class

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c

CreditCheckInboundService

<<

Java Interface

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I

<<

Java Interface

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CreditCheck

I

<<

use

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<<

use

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<<

use

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<<

use

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<<

use

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use

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298 Patterns: Implementing Self-Service in an SOA Environment

Figure 10-5 Class diagram of the Web service requester and provider

Sequence diagram

Two Web service calls are performed in this part of the scenario. Both calls are

originated from the createCustomer() method in Processor.java. The first call is

issued to get a credit rating for the customer from the CreditCheck Web service.

The second call is to get an account number. The fact that the account number is

created by one of two account services depending on the type of delivery

account requested is transparent to the user and to the Processor application.

Routing to the proper account service is done in the ESB.

For simplicity we will treat each of these Web service invocations as separate

sequence diagrams. In reality, the Processor code performs several steps in

sequence to create a customer, the first is to get the credit rating, and the second

is to get the account number.

<<

use

>>

<<

use

>>

<<use>>

<<use>>

EJSLocalStatelessDeliveryWSClientHome_bc5368fa

<<

Java Class

>>

c

EJSStatelessDeliveryWSClientHomeBean_bc5368f

<<

Java Class

>>

c

EJSLocalStatelessDeliveryWSClient_bc5368f3

<<

Java Class

>>

c

DeliveryWSClientLocalHome

<<

Java Interface

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I

DeliveryWSClientBean

<<Java Class>>

c

HomeDeliveryProxy

<<Java Class>>

c

HomeDeliveryInboundServiceLocator

<<

Java Class

>>

c

DeliveryWSClientLocal

<<

Java Interface

>>

I

HomeDeliveryInboundPortBindingStub

<<Java Class>>

c

HomeDeliveryInboundService

<<Java Interface>>

I

<<

Java Interface

>>

HomeDelivery

I

<<

use

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<<use>>

<<

use

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<<

use

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<<

use

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<<use>>

<<

use

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Chapter 10. Web services scenario 299

Get credit rating

The sequence diagram in Figure 10-6 shows the interaction of classes and the

flow of control through the application as the credit rating for the customer is

obtained from the CreditCheck service.

Figure 10-6 Sequence diagram for the CreditCheck Web services requester and provider

1) The createCustomer() method in the Processor class is invoked.

1.1) createCustomer() invokes getCreditRating() method in the

ProcessorWebService class, passing the customer information

needed to obtain a credit rating.

1.1.1) getCreditRating() invokes the getCreditCheck() method to get the

creditCheck information of a particular customer.

1.1.1.1) getCreditCheck() does a JNDI lookup for the CCWSClient bean,

which acts as an interface to the Web service.

1.1.1.1.5) getCreditCheck() invokes the returnSimpleQuote() method of

CCWSClient bean, which in turn, invokes the returnSimpleQuote()

method of the proxy for the CreditCheck application. Control is then

passed to the CreditCheck application on the Web service provider.

The CreditCheck application returns the credit check reply message

back through the chain to CCWSClient bean.

1.1.1.1.7) The credit check rating gets passed back through the chain to the

requester side.

1: createCustomer

1.1: getCreditRating

1.1.1: getCreditCheck

1.1.1.1: <<create> InitialContext

1.1.1.1.1: lookup

<<return>>

1.1.1.1.2: lookup

1.1.1.1.3: create

<<return>>

1.1.1.1.5: getCreditCheck

<<return>>

1.1.1.1.4: create

1.1.1.1.6: returnSimpleQuote

<<return>>

1.1.1.1.7: returnSimpleQuote

<<return>>

1.1.1.1.8: getCreditRating

<<return>>

1.1.1.2: createCustomer

Processor:Processor

c

I

ccLocalHome:CCWSClientLocalHome

ProcessorWebService:ProcessorWebService

c

ic:InitialContext:

I

Property:CCWSClientLocal