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JAX RPC wrapper. If you choose to follow this path, ensure that the EIS vendor

provides a WS I Basic Profile compatible Web service. If the vendor does not,

consider writing an adapter layer yourself to handle any differences. This

approach may require upgrading your EIS system to a new software version, a

risk you may not want to take. In such cases, consider using the recommended

connectors and JAX RPC approach.

E

Consider using the built in Web services support provided by the EIS vendors 

to avoid writing additional interfaces.

6.3.2 Enterprise Beans and JMS Approach

You can use enterprise beans and JMS layers, separately or combined, to develop an

integration layer. With this approach, you use a J2EE application server to provide

an enterprise bean layer for synchronous interactions. For asynchronous interac 

tions, you place a message bus in the enterprise and require that applications use it.

The adventure builder enterprise uses this strategy for integrating applications

within one department. For example, a single department owns the order process 

ing module. Within that department, different groups handle various aspects of

order processing, such as credit card payments, supply chain interactions, cus 

tomer relations, and so on. In this workflow arrangement, interactions among

these departmental groups are handled in a loosely coupled, asynchronous manner

using JMS. When it needs to provide synchronous access, a group may use a

remote enterprise bean interface. (See Figure 8.3 on page 345.)

Using enterprise beans and JMS does not preclude the use of XML, which is

an additional benefit. For example, the adventure builder enterprise uses the same

invoice document listed in Code Example 6.1 when sending a JMS message

within its order processing center. The message driven bean that receives the JMS

message applies XML validation and translation logic just like any Web service

endpoint.

6.3.3 The Connector Approach

When using connectors, the new EAI application is programmed directly against an

interface provided by the EIS. For new applications that are also J2EE applications,

you use a connector to access the EIS. You can either buy an off the shelf connector

or write your own.