[DISCUSS] IBM using LLMs to convert COBOL to Java

I have my doubts that this works well, every LLM we've seen that translates/writes code often makes mistakes and outputs garbage.

This sounds no different than the static analysis tools we’ve had for COBOL for some time now.

The problem isn’t a conversion of what may or may not be complex code, it’s taking the time to prove out a new solution.

I can take any old service program on one of our IBM i machines and convert it out to Java no problem. The issue arises if some other subsystem that relies on that gets stalled out because the activation group is transient and spin up of the JVM is the stalling part.

Now suddenly, I need named activation and that means I need to take lifetimes into account. Static values are now suddenly living between requests when procedures don’t initial them. And all of that is a great way to start leaking data all over the place. And when you suddenly start putting other people’s phone numbers on 15 year contracts that have serious legal ramifications, legal doesn’t tend to like that.

It isn’t just enough to convert COBOL 1:1 to Java. You have to have an understanding of what the program is trying to get done. And just looking at the code isn’t going to make that obvious. Another example, this module locks a data area down because we need this other module to hit an error condition. The restart condition for the module reloads it into a different mode that’s appropriate for the process which sends a message to the guest module to unlock the data area.

Yes, I shit you not. There is a program out there doing critical work where the expected execution path is to on purpose cause an error so that some part of code in the recovery gets ran. How many of you think an AI is going to pick up that context?

The tools back then were limited and so programmers did all kinds of hacky things to get particular things done. We’ve got tools now to fix that, just that so much has already been layered on top of the way things work right now. Pair with the whole, we cannot buy a second machine to build a new system and any new program must work 99.999% right out of the gate.

COBOL is just a language, it’s not the biggest problem. The biggest problem is the expectation. These systems run absolutely critical functions that just simply cannot fail. Trying to foray into Java or whatever language means we have to build a system that doesn’t have 45 years worth of testing that runs perfectly. It’s just not a realistic expectation.

Not a cobol professional but i know companies that have tried (and failed) to migrate from cobol to java because of the enormously high stakes involved (usually financial).

LLMs can speed up the process, but ultimately nobody is going to just say "yes, let's accept all suggested changes the LLM makes". The risk appetite of companies won't change because of LLMs.

That's alot of effort to go from one horrible programming language to another horrible programming language.

So the fintech companies who rely on that tested (though unliked) lump of iron from IBM running an OS, language, and architecture built to do fast, high-throughput transactional work should trust AI to turn it into Java code to run on hardware and infrastructure of their own choosing without having architected the whole migration from the ground up?

Don't get me wrong, I want to see the world move away from cobol and ancient big blue hardware, but there are safer ways to do this and the investment cost would likely be worth it.

Can you tell I work in fintech?

Converting ancient code to a more modern language seems like a great use for AI, in all honesty. Not a lot of COBOL devs out there but once it's Java the amount of coders available to fix/improve whatever ChatGPT spits out jumps exponentially!

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"all those COBOL developer jobs" nowadays probably fit in one bus. That's why every company that can afford it moves away from COBOL.

If even highly skilled humans couldn't do that, artificial pseudointelligence doesn't stand a chance in hell.

There's nothing of substance here. Just suits chasing buzzwords. Nothing will actually happen, just like nothing actually happened every other time some fancy new programming language or methodology came along and tried to replace COBOL, including Java.

according to a 2022 survey, there’s over 800 billion lines of COBOL in use on production systems, up from an estimated 220 billion in 2017

That doesn't sound right at all. How could the amount of COBOL code in use quadruple at a time when everyone is trying to phase it out?

What a terrible day to be literate

Oh FFS there is nothing magical about COBOL like its some kind of sword in the stone which only a chosen few can draw. COBOL is simple(-ish), COBOL is verbose. That's why there is so much of it.

The reason you don't see new developers flocking to these mythical high-paying COBOL jobs is its not about the language, but rather about maintaining these gianourmous, mission-critical applications that are basically black boxes due to the loss of institutional knowledge. Very high risk with almost no tangible, immediate reward--so don't touch it. Not something you can just throw a new developer at and hope for the best, the only person who knew this stuff was some guy named "John", and he retired 15 years ago! Etc, etc.

Also this is IBM were talking about, so purely buzzword-driven development. IBM isn't exactly known for pushing the envelope recently. Plus transpilers have existed as a concept since... Forever basically? Doubt anything more will come from this other than upselling existing IBM contracts who are already replacing COBOL.

ChatGPT did an amazing job converting my Neovim config from VimScript to Lua including explaining each part and how it was different. That was a very well scoped piece of code though. I'd be interested to see how an LLM goes on large projects as I imagine that would be a whole different level of complexity. You need to understand a lot more about the components and interactions and be very careful not to change behaviour. Security is another important thing that was already mentioned in this thread and the article itself.

I put my self as doubtful but really interested to see the results nonetheless. I've already been surprised a few times over by these things so who knows.

Why Java instead of C# or Go though?

Of all modern languages, why java? Which will likely soon become legacy for backend applications

Without a requirements doc stamped in metal you won’t get 1:1 feature replication

This was kind of a joke but it’s actually very real tbh, the problems that companies have with human devs trying to bring ancient systems into the modern world will all be replicated here. The PM won’t stop trying to add features just because the team doing it is using an LLM, and the team doing it won’t be the team that built it, so they won’t get all the nuances and intricacies right. So you get a strictly worse product, but it’s cheaper (maybe) so it has to balance out against the cost of the loss in quality

Im sorta excited for stuff like this to get going in terms of video games. There are some great games and it would be great if it was easier to pull it into a more modern engine or such.

This is the best summary I could come up with:

For large organizations, it tends to be a complex and costly proposition, given the small number of COBOL experts in the world.

When the Commonwealth Bank of Australia replaced its core COBOL platform in 2012, it took five years and cost over $700 million.

Running locally in an on-premises configuration or in the cloud as a managed service, Code Assistant is powered by a code-generating model, CodeNet, that can understand not only COBOL and Java but around 80 different programming languages.

A recent Stanford study finds that software engineers who use code-generating AI systems similar to it are more likely to cause vulnerabilities in the apps they develop.

“Like any AI system, there might be unique usage patterns of an enterprise’s COBOL application that Code Assistant for IBM Z may not have mastered yet,” Puri said.

IBM sees a future in broader code-generating AI tools, as well — intent on competing with apps like GitHub Copilot and Amazon CodeWhisperer.

The original article contains 734 words, the summary contains 159 words. Saved 78%. I'm a bot and I'm open source!

So a 'compiler' then? From a fairly straightforward easy to use COBOL to whatever. makes sense. can the new code work in the mainframe environment? or is that what this piracy is about?

har har har.

:D

Though previously all such cases used to happen gradually, giving most people enough time to adapt to the changes.

The Luddites would like to have a word with you.

Something I found is that LLM struggle with weirder cases, when it comes to code.

I once tried getting ChatGPT (though admittedly only 3.5) to generate code in understand SaHuTOrEPoL, which is one of the more esoteric languages I created, and it really struggled with it.

This might be a stupid question, but how is this different from cross compilers? Is it more natural and readable?

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Get your grandma to read that title and try to explain what any of it means.