Is it a bird Is it a building? No! It’s a bus!

02/04/2008 by Jon.

This post is part of a series based on the book Documenting Software Architectures: Views and Beyond.

One of the first sections (page xix) is about the picture on the front cover which shows a rather nice sketch of a birds wing. The section discusses the use of analogies and our usual staple of the “building” to help describe architecture. I am as guilty as anyone in using this as a way of explaining what I do. Yes, I do think about the structure of the system/building. No, I don’t worry too much about the colour of the screen background/carpet (apologies to any HCI specialists reading this, I do know that colour on a UI is important but hopefully you get my point).

The authors quite rightly point out that buildings are fundamentally static objects while systems and fundamentally dynamic. In fact most systems fail in their dynamic behaviour rather than their static structure. Hence the use of a birds wing which has a complex dynamic model is a far better analogy for architecture than the building. An excellent insight!

But somehow it wasn’t satisfying as an analogy. For the front cover of a book by architects, for architects, it works well. However when I tried to visualise myself standing in front of a group of business managers talking about bird wings it felt wrong. These people are fundamentally pragmatic and practical. If I start talking about hummingbirds I’m going to lose them. So what would be a good analogy?

Now I come from an engineering background so naturally started thinking about engines and alike. Again this failed the “audience empathy” test. Your average business person doesn’t care much for thermodynamics or metal fatigue. So I tried a little bigger. A car? Better on the empathy test but didn’t feel very business relevant. Then I struck on an idea. What about a bus? They are fundamentally about engineering which is good; we want to be based on good engineering practices. There are dynamic and static elements so it addresses the shortcomings of the building analogy. It has business users (the driver) as well as customers (the passengers). There are business owners (the fleet operator) and a support organisation (the maintenance team). Importantly it also meets the “audience empathy” test. We all know what a bus is, it is a common point of reference.

Now before we get too excited it is just an analogy. A useful way of getting understanding between different groups. This does not represent the birth of a new design method based on route planning and seat colours, but it might just help a little.

So I haven’t even reached the preface to the book and already the authors are making me think, even changing the tools of my job. While I will be using a different approach to theirs, this exercise has made me question what I do. I call that a good start, although at this rate it’s going to take me a long while to read this book!

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