Interview question related to J2EE.. plz answer soon

When you design a web application from scratch, how do you decide what objects you need and what logic goes in which objects? Do you have a specific �layering� technique?

This is not a simple question that can be answered in a forum.
You need good desing knowledge or good web designers to start with. So, bottomline is you need resources that do great multi-layered system using object oriented and J2EE design patterns.
Then comes the picture of abstration, security, level of complexity of the perceived system(since this decides the resources and a decision to whether it needs to be a J2EE driven/ Servlet driven/ JSP driven system etc), then comes the choice of messaging technology choice(since this adds the true realtimeness of the system), legacy application integration issues and ofcourse the data modelling.
So as I said earlier yours is a 2 line question that demands a whole big picture.
Dan