How does application migration work?

Question

Software porting

Ever wondered how applications migrate from one language (platform) to another? Stupidly repeat the same code, but in a different language? Do they change the architecture, taking into account the jambs of the previous application? Etc.

Answer 1

We have one project being rewritten from java to C#. The code cannot be simply copied, it is rewritten from scratch, with minimal changes, according to the requirements of .NET. If there is a ready-made, well-described application architecture, then it will not take too long to rewrite it. Another thing is that the differences between the features of Java and C# are insignificant, almost all the features are present in .NET.

Answer 2

I am currently doing this as an architect in my office. The first time we tried about 3 years ago was to remake the GUI and write a layer that would translate the old business logic into the new API. Failed.
Now we are rewriting everything from scratch, new architecture, languages, everything is new, but until the new application receives all the functionality (3 years), customers will receive both.