Sharing sessions between a servlet and a JSP page is straight forward. JSP makes it a little easy by creating a session object and making it availabe already. In a servlet you would have to do it yourself. This is how:
//create a session if one is not created already now
HttpSession session = request.getSession(true);
//assign the session variable to a value.
session.putValue("variable","value");
in the jsp page this is how you get the session value:
<%
session.getValue("varible");
%>