Overview

This chapter continues the e-tailing case study discussed in Chapters 14–16.

In this chapter,

• I introduce the categorization scheme of patterns.

• I introduce the Observer pattern by discussing additional requirements for the case study.

• I apply the Observer pattern to the case study.

• I describe the Observer pattern.

• I describe the key features of the Observer pattern.

• I describe some of my experiences using the Observer pattern in practice.