Comment by PaulAJ
2 days ago
Anyone who doesn't understand what's so difficult should read this:
https://wiki.c2.com/?WhyIsPayrollHard
Its from a different domain, but it gives you a flavour of the headaches you encounter. These systems always look simple from the outside, but once you get inside you find endless reams of interrelated and arbitrary business rules that have accumulated. There is probably no complete specification (unless you count the accumulated legal, regulatory and procedural history of the DVLA), and the old code will have little or no accurate documentation (if you are lucky there will be comments).
Basically this. The people running the show would desperately like to make it simpler, but ultimately it’s left overly complicated due to priorities from past leadership well above our paygrade.
The right solution is always to just rip off the bandaid and do it again by hand in a new language or platform, and to eliminate useless complexity while doing so. Unfortunately no leader would ever do this because the Board and/or Shareholders would crucify them for not outsourcing it to McKinsey first and using the fancy-pants automation tool their report recommended.
There are a few shareholder-friendly patterns to get this done, but it is domain-specific. I’d say it’s more “rip off the bandaid slowly and carefully”.
Eg a common one is to wrap a new no-op new service around the old one, and gradually replace parts of the old one (the “strangler fig pattern”).
This is technically great, but it’s also financially great because you are don’t spending large sums on a big-bang rewrite. You’re spending relatively small sums on a “pay as you go” basis, something board members and shareholders do like.
But of course this depends on how your systems are set up.
Well, that, and any organization that has gotten themselves into this situation tend to have a very strong risk aversion principal. Which means they _can't_ approve something like this organisationally since there is simply too much risk embedded, and someone has to accept that.