Foreword

The history of software engineering is, in effect, the history of abstraction. As complexity rises, we respond by raising the level of abstraction in our programming languages and in our methods. Thus, we have seen the move from C to Java, from structured methods to object-oriented design, and from classes to design patterns to architectural frameworks.

J2EE, the Java 2 Platform, Enterprise Edition, is such a framework. J2EE is a comprehensive platform for deploying complex systems. It raises the level of abstraction for the development team by offering a set of mechanisms (JSP, Enterprise JavaBeans, servlets) and services (JDBC, JNDI, JMS, and RMI to name a few), enabling the team to focus on its core business value instead of building infrastructure.

As good as J2EE is, however, there is a large semantic gap between what J2EE provides and what must be crafted for the business. Bridging that gap can only be achieved given a strong, foundational understanding of J2EE together with a sound architecture for the domain-specific system. The Unified Modeling Language (UML) comes into play here, for the UML is essentially the language of blueprints for software. Visualizing, specifying, constructing, and documenting the key elements of a system are essential as complexity rises, and this is the very reason for the UML's existence.

Khawar and Cary bring all of these elements together in this book to help you bridge that semantic gap. Not only do they cover all of the essential pieces of J2EE thus helping you build a foundational understanding, they also explain how best to use J2EE's mechanisms and services. This book will also guide you in applying the UML to model your systems built upon J2EE, thus enabling you to better reason about and communicate the analysis and design decisions your team must make in building quality software.

The authors have a deep understanding of J2EE and the UML and a strong sense of the best practices that can lead you to the effective use of both. Their experience in building production systems comes through in their writing, and especially in their comprehensive case study.

There is an essential complexity in building enterprise systems; this book will help you master much of that complexity.

—Grady Booch
Chief Scientist
Rational Software Corporation