Sessions are used to maintain data across multiple page requests. The request object is passed on to a page only (unless forwarded by the page using RequestDispatcher forward() etc.)

If u have to choose between a request object and session for passing data it is always advisable to go for the request object. This is bcoz the scope is only for a page / request, hence will not load the memory. if put up in a session it'll stay there are keep on loading the memory every time u put in new data (unless u clear it...) this will make the application to be slow and bad performance...

depends on how much data is in the request object and how much data is in the session object. it also depends on the implementation which is specific to a web server.