Tuesday, 27 July 2010

Architecture in Agile

When a team first starts practicing agile a question that usually comes up fairly early is where architects fit in.  In a set of processes which usually considers ‘big-up-front requirements’ it’s nemesis, it can be a startling realisation that we (the engineering side) might have our own version of that.  Architecture tends to be associated with big-up-front specs and, if you’re not doing any of that big-up-front stuff, then where does the role of an architect fit in?

The first step towards finding your answer to that question is to understand what architecture actually is:

Architecture isn’t something separate and distinct from your projects that you can either choose to indulge in or choose to abstain from – architecture is simply the shape of what you produce.  Everything piece of software in the world has architecture, the only question is whether it was done by design or by accident.  The question is essentially whether you drive it explicitly and control your technical destiny or whether you leave it to chance and hope for the best.  Driving it would be the job of the architect.

To make a slightly controversial statement, architecture by itself has no value.  But architecture, as defined as ‘the correct technology platform meeting the current and future functional and non-functional needs of the business’ is worth everything that you can put into it.  I believe in architecture.

Architecture must be explicitly handled – lest it get away from you and leave you with unsustainable systems – but that’s not the same as saying that you must have an architect.  You simply need to have the responsibility for the shape of the system (the technical decisions) clearly understood.  Why not devolve the responsibility?  Something common to most agile approaches is the empowerment of the teams to self-organise and take control of the destiny of their own product.  Architecture is no different and, where you can identify neat boundaries between different products owned by different teams, this type of ‘product architecture’ works very well with minimal enterprise oversight.  Less distinct separation between systems generally = more enterprise oversight.

Somewhat counter to the freshman agilist’s intuition, you do need to make some up-front decisions in most projects.  Agile is about making sure you know enough about something to be effective by when you need to know it – it’s not about knowing nothing.  The trick to handling technical designs is knowing what those up-front decisions should be and what’s better handled as part of how the project evolves.  Unfortunately this judgement takes some experience to develop, but a good guideline is to stick to things which can’t be easily changed later – such as schemas, APIs, and namespace.

If you’re a formally nominated architect in an agile environment my advice is stick to patterns and delegate implementation decisions.  When you are dealing with a flow of work and you can’t initially nail down the complete set of requirements in buildable detail – the business case for agile – then you have to let your vision for the product, and the size and nature of the commercial opportunity it supports, help you pick out the right patterns.  Patterns are the best currency for an architect to deal in if he has a team of smart developers keen to take some ownership; the ‘here is a design doc, build this’ approach becomes a constraint rather than a support.

In more larger or more complex agile environments – with multiple development teams and multiple products – an architects role moves into governance; the design of common elements and the way in which products integrate and interact.  What we might call enterprise architecture I guess.  The goal here is to put together a framework which promotes self-contained and distinct products, giving each team their own jurisdiction while still ensuring smooth overall performance of the whole estate.  In my experience this maxes out the total delivery throughput of the whole organisation and gives the satisfaction of ownership to the doers.

If you’re new to architecture (giving or receiving!) and need to make sense of all this then I’d recommend joining IASA because a key part of our mission there is bringing clarity to what an architect really does for a team, a product, and a business.

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