Web Technology: Theory and Practice

7

The Business Layer—EJB Fundamentals

Chapter Objectives:

• Introducing the concept of layering

• How EJB helps in layering applications

• Understanding the persistence framework

• Going through a few examples

So far, we have covered a facet of web applications development which included the simple or not too-complex sort of scenarios. However, enterprise applications are characterized by the presence of rich interfaces, large number of components, persistence mechanisms, need for fail-safe transactions mechanism, message queues, server/database clustering, and many such combinations.

At a high level, this calls for an engineering approach involving distributed systems and the need for a layered architecture. Development of complex enterprise ...