Mike MacDonagh's Blog

Somewhere in the overlap between software development, process improvement and psychology

What is enough agile architecure?

I wasn’t planning on writing a “how long is a piece of string?” post but it’s a question I often get, and something that I’ve played with a bit. The point of architecture is to address the aesthetics of a system, to consider its reusable bits or common forms, the overall shape and nature, the technology it’ll use, the distribution pattern and how it will meet its functional and non-functional requirements.

Of course in an agile, or indeed post-agile world, we don’t want to spend forever document and designing stuff in analysis paralysis. I’ve worked in projects where I had to draw every class in detail in a formal UML tool before I could go and code it. I’m pretty sure this halved my development speed without adding any real value. But I’ve also worked on projects where we’ve drawn some UML on a whiteboard while discussing what we were going to do and how we were going to do it – and that was really valuable.

This makes an architect’s job difficult. Of course, it’s always been hard:

The ideal architect should be a man of letters, a mathematician, familiar with historical studies, a diligent of philosophy, acquainted with music, not ignorant of medicine, learned in the responses of jurisconsults,  familiar with astronomy and astronomical calculations.

Vitruvius ~ 25 BCE

But as well as being a bit of a Renaissance man an architect also needs to know when enough is enough. I’ve found that I’ve done enough architecture with the team (not to the team) when we collectively feel like we understand the proposed solution, how it’s going to hang together, how it will address the risky bits and meet it’s requirements.
To do that, we tend to draw a few diagrams and write some words.

First, an architectural profile that gives us an idea of where the complexity is and therefore where the technical and quality risks are.

Second an overview sketch that shows the overall structure, maybe technology, target deployment platforms and major bits.

Third a set of lightweight mechanisms that cover the common ways of doing things or address particularly knotty problems and address some of those risks. These tend to describe the architecture (or mechanism flows) by example rather than aiming for total coverage.

I might add some other stuff to this if the project calls for it, like maybe a data model, a GUI mockup but generally that’s it 🙂

This post is an extract from the Agile Architecture content from Holistic Software Engineering


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