I was at a ThoughtWorks Geek Night presentation on the principles and techniques of evolutionary architecture given by Dr Rebecca Parsons, who works as ThoughtWorks CTO. She was giving a talk about evolutionary architecture and in fairness, everything she said was sensible. Technically I couldn't argue with any of it. Now, I have a lot of time for ThoughtWorks. Granted, they're not about to convert me to any sort of permanent role, but at the same time, the top level members (including Martin Fowler) do have what I consider to be one of the best stances on agile adoption, evolutionary systems and people driven approaches in the market. They're not perfect, but in a world where perfection is governed by how well the solution fits the problem, and that every problem is at least subtly different, I'm willing to live with that.
The one thing I did take issue with was her stance on the distinction between emergent architecture and evolutionary architecture. Dr Parsons regarded this distinction as being one of guidance. My viewpoint at the time was that everything is evolutionary and that there was no distinction. I still stand by this and the more I think about it, the more I think it's true. However, I'd redefine emergence as what happens as the result of these evolutionary processes where the guiding influence isn't immediately obvious.
So what are you whinging about now?
The problem I have with Dr Parson's definition is that there is nothing that we ever do in our professional (and personal) lives that isn't guided in any way. Even those people who love being spontaneous love it for a reason. Indeed, the whole premise of lean and agile is based on the principle of [quick] feedback, which allows us to experiment and change tack or resume course. Also, as humans in any field, we rarely do stuff for the heck of it. We choose particular tech for a reason, apply design patterns for a reason, write in imperative languages mostly for a reason and we do all of those things regardless of correctness and often of systematic optimality (i.e. we'd do this to make our lives easier, but potentially at the expense of systems as a whole).
She mentioned a term I've used for at least 4 years, and that's a 'fitness function'. For those who have a good grasp of genetics or evolutionary systems such as genetic algorithms (which used to be a favourite topic of mine at the turn of the millennium) or champion-challenger systems, this term isn't unfamiliar. It's a measure of distance of some actual operational result from the target or expected result. In the deterministic world of development, this may be percentage test coverage from the ideal test coverage for that project; in insurance risks it's the distribution of actual payout versus the expected payout and indeed in my previous post on evolutionary estimation, the R-squared was used to measure the distance between the distribution of done tasks and the normalised version of the same data.
What's the guidance?
Now, you can take guidance from any source and it doesn't have to be direct. Some people choose their favourite tech, some people choose familiar patterns and practises, some people prefer to pair-programme, some people prefer to make decisions at different points to others (the latest possible moment versus reversible decision) etc. Also, you can't always see what's guiding you, or know for sure what the 'guiding influence' wants. For example, Lean Start-up is an attempt to validate hypotheses about what the market wants (which is the guiding influence in that case) and the fitness functions are often ratios which divert the focus from vanity metrics (how many sales per 100 enquiries, how much it cost to sell this product - which are all standard accounting measure btw).
Additionally, emergent design often comes about through solving development detail problems through some mechanism of feedback, which again guides the development choices. For example, because it causes the developers a lot of pain or are guided by the needs of the client. Just as human being evolve their behaviour based on sensory stimulus (I won't put my finger in the fire again because it hurt), development 'pain points' guide the use of ,say, a DI framework, which the architect isn't always aware of. That 'guidance' Dr Parsons refers to can come from outside the immediate environment altogether.
For example, for my sins, I'm a systems architect. I'm a much better architect than I am a developer but I am often guided into development roles because of the lack of architecture consultancy jobs relative to software development contracts (the ratio as of 28/08/2013 is 79:48:1 for dev:SA:EA roles, which is a significant improvement over the 300:10:1 in 2011 - Note, these are contract only). It's a business decision at the end of the day (no work, no eat and I eat a lot). By that same token, I guide other decisions based upon my role as a consultant. For example, I derisk by having low outgoings, building financial buffers to smooth impacts, diversifying my income stream as much as possible etc. It also prevents me from being bored to easily and makes it easy for me to up and leave to another town when a role arises. All these non-work decisions are guided by factors from inside the work itself and there are factors which work the opposite way (for example, I am certainly not about to take on a permanent role as it is not something that suits my character and personality). Hence, a domain which is in a different spot in the 'system' [that is my life] has influences on those other facets.
In tech, this means the use of frameworks because they make life easier for the developer. There is a problem that needs a solution, the fitness function is how well the solution solves that particular problem over a period of time. For devs, that means it has to be shiny, has to garner positive results quickly, has to be 'fun' and has to allow devs to 'think' of the solution themselves (i.e. it can't be imposed dictatorially - this doesn't mean it can't be guided organically though). Systematic productivity improvements, which is often the domain of the architect and/or PMOs isn't high on most devs lists. You can see this by the way the vast majority of retrospectives are conducted.
In Summary: So no emergence?
Not exactly, rather that it isn't something that has an easily discernible influence from all perspectives. Taking a leaf out of chemistry and cosmology, we are all ultimately made up of atoms. Charge was the guiding influence that pushed protons together to make larger atom and eventually molecules. Those molecules eventually connected and made cellular structures, which then went on to form life as we know it (missing lots of steps and several hundred million years in the process). We don't see the atomic operations day-to-day but now we do know they are there and they are influenced by the environment they exist in and in turn, change the environment they exist in, which in turn changes them for the next generation. Up until these pioneers, we didn't know of DNA before Watson and Crick just as we didn't know for sure of the atomic level of matter until 19th century science validated the philosophical hypotheses of the ancient Greeks (darn long feedback loop if you ask me).
What worries me is that where the pattern isn't obvious, in general society this leads to conjectures, superstition and other perspectives (some of them untestable) because the individuals cannot tangibly see the guiding influence. So in an attempt to gain cognitive consonance from that dissonance, people come up with weird and wonderful explanations, most of which don't stand up to any form of feedback (or in some cases, are never scientifically tested). Science attempts to validate those hypotheses or conjectures and that's what makes it different. Over time, the science helped organically guide society into this emerged world (so far) where we have the medical advances we have or the computer systems we have. Not just that, but it is validated from many different angles, levels of abstraction, perspectives and details and none of them are wrong per se, they just use effective theories which may mean guiding influences for the existence of some phenomenon is missing (i.e. at a lower level of detail than is studied - Think neurological guiding influences on cognitive psychology).
The same is true of software systems and development teams. Without the scientific measurement step, and hence the guiding metrics/influence it's conjecture and nigh on pointless. Something may emerge, but it won't be guided by any factors of use to the client, may be guided by the developers alone, who are not always aligned with the client's needs, who remember, ultimately sets the fitness function and hence alignment the team should have.
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