11.5 Summary

This chapter examined the recommended architectures for J2EE applications and covered designing an application for the J2EE platform. It described the Model-View-Controller architecture and showed how this architecture applies to enterprise applications. It also described the more commonly used J2EE design patterns, which are useful for designing components within an application.

The architecture of the sample application partitions its functionality into modules, assigns functionality to tiers, and decomposes the modules into specific objects to represent the behavior and data of the application. The principles guiding the architecture include reuse of software designs and code, separation of stable code from volatile code, object decomposition along skill lines, and ease of migration from a Web-centric to EJB-centric model.

The sample application adapts the MVC architecture to the domain of enterprise applications and shows how to apply J2EE design patterns to application components. It takes you through the design of the sample application, starting with formulating functional specifications and high-level considerations such as choosing application tiers and deciding between a local or distributed model. It shows you how to decompose an application into objects and design and implement these objects so that they are efficient, modular, and reusable.

The J2EE platform provides system services that simplify the work that application objects need to perform. The sample application uses the J2EE support for distributed transactions across multiple JDBC databases. In addition, it uses deployment and security capabilities of the J2EE platform to support customers with different profiles.