Actually, sending  data to the servlet is the same as if you were going to post
form data. You need to make an HTTP
request to the servlet and then deal with the response which comes back. You
can either do a GET request where all of
the request data is in the URL, but there are URL length limitations. You could
also do a POST request and encode the
data in the HTTP request body. This is probably the most common method.

Here is one article on this issue:

http://www.j-nine.com/pubs/applet2servlet/