Please go through Calling a Report from within a JSP page Using Hyperlink and take a look at the sample code which will explain as to how one can invoke a report using JSP.
Yes,it is very much possible.I suggest that you go through scr8_urlcmds.pdf to find out how your string should look like ,incase you want to pass the Username and Passwords for your sub-report as well.
Pooja M.,
http://home.attbi.com/~pooja.mohan