Overview

This chapter concludes the e-tailing case study discussed thus far in Chapters 14–19.

Now that I have discussed an entire set of individual patterns, it is time to step back to look at one of the biggest problems in software development: handling variation within the problem domain. Design patterns can help analysts identify and organize variations successfully.

In this chapter,

• I consider the problem of variation in the real world.

• I look at a portion of the e-tailing case study that represents significant problems of variation. In the process of solving this problem, I develop the Analysis Matrix, a simple variant on decision tables that I have found helpful to understand and coordinate variation in concepts. There is a parallel between this and the concepts of Christopher Alexander and Jim Coplien.

• I describe my use of the Analysis Matrix in the real world.