Architecture as Tradition in the Unselfconscious Process
I've also proposed that the unselfconscious design process, which is very similar to the emergent design concept held so dearly by many agilists, requires some degree of tradition, and therefore, an underlying architecture. I've also gone so far as to propose the idea that many agile projects begin with a "traditional" architecture in mind:
Now, although some people in the XP/agile camp might disagree, refactoring is a viable solution only when the desired rate of change is slow, and only when the gap to fill is small. In other words, only when the overall architecture (or plain structure) is not challenged: maybe it's dictated by the J2EE way of doing things, or by the Company One True Way of doing things, or by the Model View Controller police, and so on. Truth is, without an overall architecture resisting change, a neverending sequence of small-scale refactoring may even have a negative large-scale impact.
In the past few days, I've been reading "The Economics of Architecture-First," by Grady Booch, IEEE Software, Sept/Oct, 2007. Here is an interesting excerpt:
Now, strict agilists might counter that an architecture-first approach is undesirable because we should allow a system's architecture to emerge over time. On the one hand, they're absolutely correct: a system's architecture is simply the name we give to the artifact that results from the many local design decisions made over a software-intensive system's lifetime. On the other hand, they're wrong: agile projects often start out assuming a given platform and environmental context together with a set of proven design patterns for that domain, all of which represent architectural decisions in a very real sense.
I could almost call this synchronicity :-).
For more on emergent architecture (or structure), see my now-old post Infrastructure and Superstructure.