Agile software architecture documentation

Lightweight documentation that describes what you can't get from the code

"We value working software over comprehensive documentation" is what the manifesto for agile software development says. I know it's now a cliche, but the typical misinterpretation of these few words is "don't write documentation". Of course, that's not actually what the manifesto says and "no documentation" certainly wasn't the intent. To be honest, I think many software teams never produced or liked producing any documentation anyway, and they're now simply using the manifesto as a way to justify their approach. What's done is done, and we must move on.

One of the most common questions I get asked is how to produce "agile documentation", specifically with regards to documenting how a software system works. I've met many people who have tried the traditional "software architecture document" approach and struggled with it for a number of reasons, irrespective of whether the implementation was a Microsoft Word document or a wiki like Atlassian Confluence. My simple advice is to think of such documentation as being supplementary to the code, describing what you can't get from the code alone.

Readers of my Software Architecture for Developers ebook will know that I propose something akin to a travel guidebook. Imagine you arrive in a new city. Without any maps or a sense of direction, you'll end up just walking up and down every street trying to find something you recognise or something of interest. You can certainly have conversations with the people who you meet, but that will get tiring really quickly. If I was a new joiner on an existing software development team, what I'd personally like is something that I can sit down and read over a coffee, perhaps for an hour or so, that will give me a really good starting point to jump into and start exploring the code.

The software guidebook

Although the content of this document will vary from team to team (after all, that's the whole point of being agile), I propose the following section headings as a starting point.

  1. Context
  2. Functional Overview
  3. Quality Attributes
  4. Constraints
  5. Principles
  6. Software Architecture
  7. Code
  8. Data
  9. Infrastructure Architecture
  10. Deployment
  11. Development Environment
  12. Operation and Support
  13. Decision Log

The definitions of these sections are included in my ebook and they're now available to read for free on the Structurizr website (see the hyperlinks above). This is because the next big feature that I'm rolling out on Structurizr is the ability to add lightweight supplementary documentation into the existing software architecture model. The teams I work with seem to really like the guidebook approach, and some even restructure the content on their wiki to match the section headings above. Others don't have a wiki though, and are stuck using tools like Microsoft Word. There's nothing inherently wrong with using Microsoft Word, of course, in the same way that using Microsoft Visio to create software architecture diagrams is okay. But it's 2016 and we should be able to do better.

Documentation in Structurizr

The basic premise of the documentation support in Structurizr is to create one Markdown file per guidebook section and to link that with an appropriate element in the software architecture model, embedding software architecture diagrams where necessary. If you're interested to see what this looks like, I've pushed an initial release and there is some documentation for the and the Financial Risk System that I use in my workshops. The Java code and Markdown looks like this.

Even if you're not using Structurizr, I hope that this blog post and publishing the definitions of the sections I typically include in my software architecture documentation will help you create better documentation to complement your code. Remember, this is all about lightweight documentation that describes what you can't get from the code and only documenting something if it adds value.

About the author

Simon is an independent software development consultant specialising in software architecture and the author of Software Architecture for Developers. Simon lives in Jersey and regularly speaks to audiences around the world. You can find Simon on Twitter at @simonbrown and .

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