(sorry my poor english, i'm a bit tired at the moment)
one way to do this is to submit a form with onChange()
..goes something like :
and this form looks something like:
<form name="formname" action="servlet/myservlet">
this is one way to send a request to servlet.
you can also send and request to servlet doing something like :
but both these ways are something we call by the name "bubblegum" ;)