X : Any ideas about dealing with legacy?
Me : Do you mean legacy IT?
X : Yes.
Me : First, I prefer to call it toxic IT given it's not something you bring the kids to see, it accumulates and can damage the health of an organisation.
X : Any advice?
Me : Well ...
Me : To begin with, we need to understand what it is. Most legacy is custom built stuff that became a commodity long ago and most (not all) legacy has been created in the last 20 years ... some is older, way older ...
Me : ... the next thing we need to understand is the fear. Everyone knows where the legacy is, most people want to remove it but there is usually real fear because if we change something then other things will break ... we often don't know how it's connected in the org ...
Me : ... lastly, we're adding to the legacy today. Everything we custom build will add to the "legacy" pile over time unless we have a means of fixing this.
X : Is there a solution?
Me : Do you mean a magic piece of software? No. Instead there is a long slog but ...
Me : ... it's doable.
X : How?
Me : Do you use test driven development (TDD)?
X : No.
Me : From now on, every new project, every upgrade, every bug fix, every change throughout the organisation must start with TDD. No, excuses.
X : How will that fix it?
Me : Within a good few years, with hard work, you'll start to build enough of a test suite that you can look to change things with a bit more confidence. You might have to commission test building for some stuff because there will be gaps.
X : Few years??
Me : Give yourself 3 to 4 years depending upon the size of the estate. Remember most of this legacy has been built over 20 years and if you've not been using TDD then you've got a lot of basic ground to re-examine. Which is also why you don't add to the problem.
X : The business won't accept that?
Me : Does it want to be more efficient, more "innovative"?
X : Yes
Me : If it doesn't fix this problem, it'll find the opposite. I did say it was toxic. Past decisions borrowed from the future, you're just paying for it now ... the bill is due.
X : And once we have the testing?
Me : Then you can start to look to tidy up things. Maps will help (you should build those as well) and patterns like strangler. Small iterative steps but start by slowly building up those tests otherwise fear will always overwhelm you.
X : Should we outsource this?
Me : To a large management consultancy?
X : Yes.
Me : No ... well, not unless you want to be beholden to them forever. You need to take control of this part. The tests are your institutional knowledge. They are your orgs brain ...
Me : ... there are some tools / groups that can help you. Search on "explainable software" by @girba
X : Calling it toxic IT is rude.
Me : It has never complained before. When you're next with your server, give it a comforting hug and just say "that Simon is a bad man".
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