So, what makes a good definition and what do we want a good definition of architecture to do for us?
A good definition:
Lets start by considering what it is we want architecture to do for us. While the definition itself should not be cast in these terms, the definition should be operationally useful in realizing those hopes. What do we want our kind of architecture to do for us? For the sake of simplicity Ill refer to our kind of architecture as IT architecture. In what follows, though I will try to make the case that our kind of architecture can and should be about much more than just IT.
One of the most powerful techniques architects use is modeling. A model is a simplified analogue of a system. The simplification makes it possible to consider the model and extrapolate its properties and behavior to the properties and behavior of the actual system. The art of modeling is leaving out the stuff that doesnt matter, so its absence wont affect the properties and behavior you are interested in. An analogy is a kind of model, so its not surprising that many IT architects use analogy as a way to try to understand their own discipline.
An obvious analogy come from the discipline that we borrowed the name frombuilding or civil architecture. (Its only recently that the word architecture had to be qualified to distinguish real architecture from upstart pretenders to the throne.) What does civil architecture do for its stakeholders, that IT architecture could also do for our stakeholders?
Many educated commentators have invoked the work of Vitruvius (Marcus Vitruvius Pollio, a Roman architect living in the first century B.C., author of De Architectura, The 10 Books on Architecture), specifically his three essential qualities of a building, as a basis for defining IT architecture:
I must admit that I have always been skeptical of this approach. Not to belittle Vitruviuss insight, but I have to ask what direct relevance it has to the idea of architecture as applied to complex information systems. How does Vitruvius two thousand year old conception of what makes a good building apply meaningfully to a discipline he could not have imagined?
That being said, theres no real news here; IT stakeholders clearly expect utility (i.e., business/IT alignment) and IT systems that wont fall down. Its not clear what beauty means when applied to IT systems, and more importantly what business value it might provide to stakeholders. And there are many other classical architects who have written about their discipline (e.g., Palladio). Why isnt their work considered as sound a foundation for IT architecture?
When I was an undergraduate at MIT, my Eastern Religions Professor Huston Smith taught that An analogy is like a bucket of water with a hole in ityou can only carry it so far. This lesson is particularly applicable to the temptation to analogize IT architecture and building architecture.