Currently I am dealing with a java software which is bad written. It has a lot of jsp files. These jsp files have mostly java codes inside and they even call database connection and do some transaction directly. This project also has data models, controllers, but I just doesn't understand why they put so many business logic inside jsp files. Anyone can give me a suggestion on how to improve its design? These project is huge and has no ejbs. It is basicly MVC models. Should I use Struts, or Spring, or anything to make it less bugs and improve performance? Thanks.