Hi!

Here is my situation. Let's say someone ask me to develope an app just like
a commercial app that is currently in the market. I decide to write my
own code and all, but i might 'borrow' the structure and design of the
database, some interfaces and the basic idea about how this sytem works.
should i be worry about that? In case I should, will you explain me why?


Another issue is about frameworks, what is the procedure i should take
in order to develope an app with a free framework or with a commercial
one?
Another doubt is about using classs o programs that i've downloaded
from different websites, how can i use this classes with no probability
of problems? what if the classes have no referenceS about its creator?

TIA