Chapter 10. Servlets

• Introduction to Servlets

• Servlet Life Cycle

• Request Handling

• Response Generation

• HTTP Request Handlers

• The RequestDispatcher Interface

• Modeling Servlets in UML

• Modeling Other Servlet Aspects

• Servlet Deployment and Web Archives

• Identifying Servlets in Enterprise Applications

• Summary

Process Check: In this chapter, we focus on design as we progress through the Rational Unified Process (RUP) analysis and design discipline. We also discuss some aspects of implementation in the context of the servlet technology.

Recall the control object TransferFunds from the discussion in Chapter 6. If you look closely at the final sequence diagram presented in Chapter 6, you'll notice two very distinct types of interactions performed by this class:

• Interactions with boundary objects to obtain information and perform some basic work

• Interactions with entity objects

Implementing a control class with a dual set of responsibilities and a large scope would make the control class less maintainable and less scalable. To make the control class more maintainable and scalable, it is preferable to partition the control class into two classes, one focused on the external interaction and the other responsible for carrying out the internal coordination and logic.

As it turns out, the externally focused part of TransferFunds evolves to a Java servlet. We introduce the servlet in the next section, and then discuss how you actually determine the responsibilities of the servlet in the context of the HomeDirect case study.