During my ‘hexagonal architecture’ session at XPday Benelux, the discussion gave me some clues as to why I feel the “standard” layered architecture model is sub-optimal: I realised that I feel as if I’m looking at a picture of a pile of stuff from the side. Contrast this with a hexagonal model of the same system, in which I feel as though I’m looking down on the picture.
Why is this important? And what relationship does it have to being agile?
The answer, I believe, lies in Lakoff‘s theory that metaphor shapes much of our thinking. When I look at any architecture model I subconsciously impose a point of view on the picture, because my mind relates what I see now to previous experiences. A layered model “looks like” a pile of books or building bricks; a hexagonal model “looks like” an island on a map (another metaphor in itself!) or a table with chairs arranged around it. The choice of metaphor is made deep in my perceptual system, helping me to make sense of anything I see. And once the metaphor has been selected, my mind will then automatically supply it with a whole load of related beliefs, many learned as a baby. Among these are the effects of gravity and mass, together with related implications of downward dependency.
These associations cause me to believe that the things at the bottom of the pile are hard to move or change. Whereas in the hexagonal view I instinctively feel the system’s components are more loosely coupled – perhaps because they are associated only by proximity, and not by gravity.
So because of these deep-seated metaphorical associations, maybe we build less adaptable systems when we think of them in layers…?