Just Rebuild It – Tales from the Trek – We Don’t Need Requirements

Technology Upgrades – Self Documenting (?)

I’ve been on several projects where the goal is to replace an existing, mature system with a brand new system in a new technology. This is generally a huge investment in time and money, fraught with risk, and results in almost the same functionality. Still, it can be necessary due to the old software being dependent on unsupported or non-secure technology and exponentially increasing maintenance costs. In a way, it’s like making the decision to replace an old car rather than repair it.

On nearly every project of this type that I have experienced, the project sponsors have insisted that we could cut out, or at least drastically reduce, business analysis. Their reasoning was that because the new system simply had to work exactly like the old system, the new system was already “fully documented” in the form of the old system.

There are a number of reasons why assuming that the old system “fully documents” the new system is a mistake. I’ll address one of them here.

Rebuilding Bugs and Poor Functionality

Often, software that’s running on outdated, unsupported technology has a lot of bugs and poor functionality that haven’t been addressed. Any changes to the system have become risky because the system is so fragile. If the only direction given to the development team is to rebuild the existing system as is with no additional analysis, the team will literally be building the same bugs and functionality into the new system. There’s no good way for the development team to know if something should be changed without at least some investment in business analysis.

The end result is that the users and project sponsors are even more frustrated with their investment in new software only to end up with the same problems. Even worse, sometimes, building the bugs into the new system costs more money. Imagine how much more it would cost to try to literally rebuild an old car exactly as it is rather than build a new car with the same basic functionality. It would take effort to make the brakes squeak just like the old car, have it shake at high speeds just like the old car, and randomly stall in the middle of intersections just like the old car.

The money spent rebuilding old bugs would be much better spent on some business analysis.

Feedback

What challenges have you had with generating requirements when replacing existing systems? What actions have you tried to address the challenges? I’d love to hear your stories from the trek.

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