Legacy
Created on 2022-11-17 12:29
Published on 2022-11-19 19:56
The life that we are currently living is shaped in many ways by "legacy". In most cases, the word legacy carries positive connotations related to wealth, culture, and tradition. However, this is not the case with software. Here the word "legacy" has a lot of negative meanings associated with it. What is "legacy" in software? Why do we consider it bad?
Legacy software simply means that the code base is old, probably unmaintained, and hard to read. It says nothing about the value or the quality of the code, it just states that is old. Then why do we consider it bad? In the real world legacy is a source of wealth, something we grew upon. Probably the answer lies in our laziness. How many of us can fluently speak or write in Latin for example? Or classical Greek, old Norse, medieval French maybe? A few of us can, although is a pity, many fundamental works of mankind were written in those languages. Still, we do not read them in original, it is more convenient to read modern versions of those in a familiar language.
The same happens in software. Programmers are using contemporary languages and lost the ability to read older ones, so the code they stopped understanding became mysterious and potentially dangerous for them. As with classical languages, there is just of handful of people that have the patience to study and understand older code and those are the ones still able to explain the values that we, in our pride and ignorance, cannot see in the old code.
Many critical infrastructures and day-to-day codebases are "legacy", still, they work well, and they keep supporting our daily life. Banking still relies on Cobol and RPG, scientific computations still use Fortran, and operating systems still build on C.
I have to praise a relatively unknown "legacy" programming language and runtime: Concept. Concept is a 4GL (4th generation language) that started in Norway during the '80s. Googling it might yield 0 results, nevertheless, it delivers daily for a few million people. The language has all the features one would expect UI library, database connectivity, and it can run both server side and client side, it's kind of memory safe. The syntax seems a little dated but is still expressive enough to implement huge projects. As the community of Concept developers is not large it starts to lack new talent and also tooling. Despite this, there is still maintenance effort and is kept as much as possible in line with the latest industry trends: REST, JSON, MQs, 64bit code generation, containers, and such.
Understanding older languages is never easy. As I said before, due to our laziness we tend to ignore them and rewrite everything with no guarantee of a better job. Probably it is often a better idea to rewrite, but we first need to understand what we are replacing. We need tooling for understanding older code bases, especially when the original specifications of the software are lost. We need helper tools that guide us through the syntax and structure of the code and could provide handlers for the business logic already written in the old code bases enabling true reuse. Developing tooling that would transparently retarget old languages on new platforms will guarantee that the legacy received is still producing the expected results and we can build more interesting things in a more cooperative way. Rewriting software with feeble specifications or no specification at all, using the legacy system as a model but not fully grokking it, is in my opinion far more dangerous than keeping battle-tested code running.
