Article about unmaintainable software on bank mainframes

March 19, 2015 12:23 AM

Please help me locate an article I read online a couple of years ago. Essentially it went like this: the core software that banks use to run transactions is very old and hard to maintain, and they're terrified of breaking something by trying to integrate new features. Therefore, "instant" transactions via online banking aren't really instant: what actually happens is that there's an elaborate front-end emulating the functionality of the core system. Every night the front-end system delivers all the queued-up "faked" transactions to the core system, which actually processes them.

Further details:

1. The author was an IT professional with a long career in banking systems, and the article was presented as an "insider's view".

2. I don't remember when it was published. My googling attempts have turned up a lot of articles about "bank X moves to real-time transaction processing on its core system", suggesting that things have started to change since the article was written.

3. There was discussion of potential failure modes -- in particular, the possibility that even when the customer thinks a transaction has completed (because the front-end has processed it), it will fail some hours later on the core system.

posted by pont to Computers & Internet (4 answers total)

You're describing ACH, the automated clearing house system banks use. I don't know what article you read, but if you search for ACH you'll find any number of relevant pieces, like this one.
posted by Admiral Haddock at 2:42 AM on March 19, 2015

Obviously not the original article you're looking for, but this Planet Money podcast gives a good overview of the ACH.
posted by doctord at 9:59 AM on March 19, 2015

Pretty sure you're thinking of a comment someone made on the blue about ACH.
posted by pwnguin at 9:22 PM on March 19, 2015

Best answer: Found it. Frances Coppola, The legacy systems problem, 2013-03-08. This is the scenario I was recalling:

Just to give an example of what MIGHT happen, suppose that a customer deposits cash into their account. That cash shows up immediately in their balance in the customer-facing applications - online banking screens, telephone services, branch information points. And they can use it for payments. But the core system doesn't apply that cash to the balance, or the payments made using that cash, until the overnight process. If that process fails, or the customer application doesn't transfer the information correctly, the result could be an imbalance between what the customer thinks they have in their account and what the bank says they do.

posted by pont at 2:45 AM on March 22, 2015 [1 favorite]