Special Edition Using Java™ 2 Enterprise Edition

Designing a Web-Based EJB Application

When you design a Web-based EJB application, it's often hard to figure out where to start. Do you start with the Web side or with the EJBs? Looking back at the typical three-tiered application model, your presentation layer depends on its interface to the business layer, and the business layer depends on the interface to the data layer. At some point, then, you need to define the data layer before the business layer, and the business layer before the presentation layer.

You typically find, however, that you jump from layer to layer initially, defining a little bit of each layer until you have a good idea of how your design will look. You then go into depth on each layer, starting with the data layer and working ...