The FT has a front page story today saying that Ulster Bank is absorbing the cost of negative interest rates (on money it has deposited at the ECB) because its systems can’t handle a minus sign. Doubtless whoever wrote the code, maybe in the 80s, never thought rates would fall below zero.

We had a similar problem at a bank in the 90s when our COBOL based general ledger couldn’t handle the number of zeros in the Turkish lita; we wrote to their central bank and PM to see if they wouldn’t mind looping a couple off so that we could continue to process transactions. History does not record the answer, but I suspect there came none.

Legacy systems were in the news in government IT this week as it was stated that there was no central register of such systems, that they are blocking data sharing and that there’s no plan to move off them. GDS, says Alison Pritchard, the interim leader, will be looking for money in the next spending review to deal with the problem.

This is, of course, an admirable aim. The trouble is, departments have been trying to deal with these systems for two decades – borders, immigration, farm payments, student loans, benefits, PAYE, customs etc all sit on systems coded in the 70s, 80s and early 90s. Legacy aka stuff that works. Just not the way we need it to work now.

Every department can point at one, and sometimes several, attempts to get off these systems … and yet the success rate is poor. Otherwise why would they still be around?

The agile world does not lend itself well to legacy replacement. Few businesses would accept the idea that their fully functional system would be replaced in a year or two with a less functional MVP. What would make the grade? How would everything else be handled? Could you run both in sync?

In the early 2000s a few of us tried to convince departments to adopt an “Egg” model and build a new business inside the existing business – one that was purely internet facing and that would have less capability than the existing systems but that would grow fast. Once someone (business or person) was inside the system, we would support them in that new system, whatever it took – but it would be a one way ticket. We would gradually migrate everyone into that system, adding functionality and moving ever more complicated customers as the capability grew.

It’s a challenging strategy. It would have been easier in the 2000s. Harder now. Much harder. But possible. With commitment. And a lot of planning.

Original source – In The Eye Of The Storm

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