When you go to an ATM machine and withdraw cash, chances are the bank uses a mainframe system that involves COBOL programs. The code looks like plain English and easy to learn.
There are 2 kinds of processes: batch or online. ATM or screen entry transactions use online single screen input output displays with embedded CICS or IMS data communication, while your business transaction gets updated real-time later on in the evening combining millions of transactions running batch jobs with embedded JCL (job control language) which eventually updates the databases with your transaction being finalized. The resulting batch output file will then get transmitted to the bank via an FTP process, usually the next day. That is why the money gets posted the next business day.
Databases are mostly DB2 now and some older IMS or ADABAS. It is hard to hack a mainframe system, even if you get hold of a TSO userid and password since that user's access is limited to their own system only. There is the application programmer access which is lower than a system programmer's access, with the exception of financial info. The access level is very compartmentalized, so you can only steal limited info. What is possible is when the database info goes to a web server and a hacker steals that via a secure FTP process.
I am a retired mainframe programmer, but today's world requires less coding and more bs meetings which go nowhere. The result is that a one line code change could take a month to implement, since it goes through a committee. With AI generated code, the future looks bleak for young programmers.
17 май 2024
