how to debug JSP

Hi all!
How to debug JSP?

I want to start web server (sun one),
and when web browser sends request i want to see the java code
in debugger (like Eclipse) and execute line by line..

for ex. i have running server writen in c++
i can use gdb to "attach to the process", set breakpoint, ........
so how to attach Eclipce to JSP in the same way?