If I may ask: how do you use AI for COBOL to Java migration when the bank forbids internet?
Good evening. I am sorry for my poor English. I am system engineer at an SIer in Osaka and our project is the migration of a regional bank system from COBOL to Java. About 1.8 million lines of COBOL, the oldest parts written in 1987. Many people on this site and in the news say "just use AI for legacy migration". I would like to try, but I have some conditions: The bank does not allow source code to leave the…
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Walt here, 30-odd years on mainframes. Honest answer: AI is useful for the part nobody wants to do, and useless for the part that matters. Useful: explaining a single paragraph of COBOL in plain language, drafting Java for a self-contained calculation, writing test cases from a copybook, summarising what a JCL job does. A local model can do that fine. I tried a small one on an air-gapped box last year. Not useful: knowing why the interest rounding on line 40,212 is different from the one on line 12,007. That is a business rule from 1994 that somebody's manager decided on a phone call. It is not in the comments and it is not in your Excel. The only way to find it is parallel runs: old system and new system on the same input, compare every output field, every night, for months. If you take one thing: build the comparison harness first. The AI can help you write it, ironically.- Kazuhiro, I did a smaller version of this in 2004, RPG to Java for an insurer. Walt is right. The code was the easy part; the undocumented behaviour the business depended on was the project. We found one batch job that existed only to correct the output of another batch job. Nobody alive knew why. Be patient, keep a list of every surprise, and never let anyone switch the old system off early. Cheers, G.