I’m considering taking an old PHP4 web application and re-writing it using ASP.Net MVC4 in C#.
The old application was licensed under GPL2.
I’m unsure how this affects my new application, if at all. I obviously can’t directly copy any of the code from the old PHP application to my .Net application as the two languages are totally different.
Equally, the old application wasn’t even OO in nature, nor did it follow any kind of design pattern (i.e. MVC).
In essence, my new application will only be taking the “ideas & features” of the original application. Even the database schema will be significantly different.
Would I still have to GPL my new application or is it considered a new work where I choose a license myself?
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As the link in the comments shows, this is borderline acceptable. It can be made safe by a cleanroom approach: make a specification, listing every idea and feature that you will copy. Your new code will implement the specification, and therefore not be a copy of the old code.
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