A session is represented using an instance of the
javax.servlet.http.HttpSession interface. A Tomcat session also implements the
org.apache.catalina.session.StandardSession class is the standard implementation of the
HttpSession interface within the Tomcat container.
Note the presence of the
StandardSessionFacade which implements the same pattern that we have seen countless times before, of narrowing its subject's API to prevent a servlet programmer from accessing Tomcat's internals. It wraps a
StandardSession instance and exposes the API defined by the
HttpSession interface. All calls to it are ...