Chapter 17
Activities to Evaluate Design Options

In the evaluate mindset, we critically examine design decisions to determine how well they meet our needs. Our designs don’t need to be perfect, but they do need to be good enough. Our goal is to make sure the architecture satisfices, that it is satisfactory and sufficient. When we’ve found a satisficing solution, then we say it has good fit.

During an evaluation we’ll learn all the ways our architecture is not satisfactory or sufficient. We might learn we don’t understand some nuance about the problem. Or perhaps a design idea that seemed good will turn out to have unacceptable trade-offs, miss an important constraint, or introduce too much risk. These things are better to know early, before it becomes difficult to change a potentially costly decision.

After an evaluation we should have enough information to decide which design mindset to embrace next. We’ll always embrace the evaluate mindset during the check step in the do-make-check cycle, but evaluation can be the main attraction during the do step too.

Evaluation is a continuous activity. Waiting until the end of a design phase to do an evaluation is too late. We should evaluate our work every step of the way. Once we deem some part of the architecture to be good enough then that part of the system’s design is ready to be refined further by focusing on finer-grained details. Everything in the architecture need not be ready before starting to build something.

The activities in this chapter help teams look deeply at different facets of the architecture and glean information needed to take action. Use them when you need to check your understanding, choose a design option, or help you figure out what to do next.