9. Improving design with patterns

Web applications are usually built ad hoc. This is hardly surprising, given the relative youth of the Web engineering discipline. Yet the key reason why Web components are not systematically reused is that current design approaches are not completely effective in helping the designer reason about the composition of existing structures. At the application (or conceptual) model level, a certain degree of reuse can be achieved. The reuse of navigation structures is much less advanced. In this paragraph, we argue in favor of a type of high-level reuse: the reuse of design experience.

Expert web application designers don't solve every problem from scratch. Most of the time, they reuse solutions they have used before. Yet critical design decisions made when defining the interaction style or navigation of an application are often hidden in the code or poorly documented....