Patterns: Broker Interactions for Intra- and Inter-enterprise

168 Broker Interactions for Intra- and Inter-enterprise

8.5.3 Stage 3: Extended enterprise

The last stage is to make the Wholesale services available to external Retail

systems.

Figure 8-12 Web Services Gateway implementation, stage 3

Stage 3 builds on stage 2 by externalizing the Wholesale services. The

considerations are primarily security concerns. The interaction between the

Retail, Wholesale, and Web Services Gateway remain the same as in stage 2.

8.6 Development guidelines

Normally, when implementing a Router solution, the interface of the service is

determined by an existing application (in ITSO Electronics, the Wholesale

department application). In other cases, you implement a Web service interface

that encapsulates one or more operations of an existing application.

Note: The addition of the filter means that the WebSphere Application Server

Enterprise edition is required.

SOAP/

HTTP

Web Services Gateway (Router)

External

Retail

UDDI Registry

Wholesale1

SOAP/

HTTP

Wholesale2

SOAP/

JMS

Filter Impl.

Enterprise Application

Firewall

Firewall

Firewall

Firewall

Chapter 8. Router solutions using Web Services Gateway 169

If you plan to implement a Router Pattern, all the service providers have to use

the same service interface (targetNamespace, operations, etc.) and the same

binding (RPC or Document, literal or encoded, etc.). If there is any difference

between the service interface of the different providers, you will have to

implement a request filter that transforms the incoming message to the service

provider format.

Before implementing the Router solution, confirm that both the client and Web

service applications are working properly. For example, try connecting them

directly, without going through the gateway.

8.6.1 Implementation process

The section outlines the procedures used to implement the solutions for the ITSO

Electronics scenario.

Here is a summary of the necessary steps:

1. Web-service-enable the target application. The solution assumes that the

Wholesale systems have implemented their delivery date applications using

an EJB which can easily be converted to a Web service.

2. Register the business and services in the UDDI registry. This step is the same

regardless of the stage you are implementing, however, in stage 1 and 2

(intra-enterprise) you might elect to use a private UDDI registry. In stage 3,

you might consider using a commercial UDDI registry.

Note: This process assumes the following conditions:

򐂰 An enterprise application called WSWholesale1EAR exists. It contains an

EJB module with an EJB called WSWholesale1EJB. The EJB is coded to

return a delivery date for a part number supplied by the client.

򐂰 A second enterprise application called WSWholesale2EAR also exists. It is

similar to the first Wholesale application.

This section will describe the process used to create Web services from the

two EJBs, register them to the UDDI Registry and the Web Services Gateway,

and create a client to access the newly created Web services.

This process also assumes that:

򐂰 A third enterprise application called WSRetailEAR has been created and

skeleton code has been added. The only thing missing is the code that

invokes the Web services through the Web Services Gateway.

170 Broker Interactions for Intra- and Inter-enterprise

3. Create and deploy the filter application (stages 2 and 3).

4. Create the Web Services Gateway services and export the WSDL.

5. Export the Web services definition from the Web Services Gateway.

6. Web service enable the source application using the WSDL exported from the

Web Services Gateway. The Retail system needs to have the proper

information to call the Web services.

7. Test the source and target applications in the WebSphere Studio test

environment.

8. Deploy the source and target applications in your WebSphere Application

Server runtime environment.

8.6.2 Web service enable the target application

Figure 8-13 shows the steps involved in creating the Web services enabled

target application using the stateless session bean from our sample code.

Figure 8-13 Web service development for target application

Let’s walk through the process shown in Figure 8-13 for our target application.

Application

Assembler

Deployer

Application

Component

Provider

develop package deploy

WebSphere

Studio

Web

JAR

WebSphere

Studio

WebSphere

Admin

Console

WebSphere

Admin

Command

Line Tool

WSDL2

Java

Command

Line Tool

Target

WSDL

WebSphere

Application

Server

Enterprise

Archive

Enterprise

Archive

Set of

Components

Deployment

Descriptors,

Proxy classes