Author: Yuzhuo Sun(ys684) This is the project file for CS5300 project 1a This project implements session management The operation is supported in http://localhost:8080/CS5300Project1/session URL URL mapping ---------------------------------------------------------- GET http://localhost:8080/CS5300Project1/session render a new session or refresh the current session POST http://localhost:8080/CS5300Project1/session replace button pressed: replace the message in current session POST http://localhost:8080/CS5300Project1/session logout button pressed: redirect to the logout page and terminate current session Implementation Structure -------------------------------------------------------------------------------------------------------------------- The project is implemented by two jsp file as follow: 1, index.jsp: mapped to /session url to render new session, refresh page, replace session message and do logout operation 2, logout.jsp: a logout page once a user is loggged out There are also two java files in the backend: 1, SessionServlet.java to manage the session, the class extends HttpServlet interface, thus implenments the doGet() and doPost() method. The doGet() method handles session initialization and session refresh; the doPost() method handles logout and replace message operation. This class also contains helper method in support of the doGet() and doPost() method described above. 2, Session.java, a java bean to construct a session. It wraps the following fields inside of this class: sessionID, versionNumber, message, expireTime and createTime. Cookie format -------------------------------------------------------------------------------------------------------------------- The cookie in this implementation use String "cs5300project1" as its key; the value consists a unique session ID generated from UUID and a version number seperated by "/". Session design -------------------------------------------------------------------------------------------------------------------- The session table is implemented using java.util.concurrent.ConcurrentHashMap with the key using sessionID and value using session object. The session object is contructed from Session.java class containing sessionID, versionNumber, message, expireTime and createTime. I generate a unique ID using UUID class everytime a new session needs to be rendered through genSession() method in SessionServelet.java class. After generate a new session, I add it into the session table. When each new request arrives, we check client cookie with corresponding cookie name, then retrieve existing session from the session, otherwise render a new session. Garbage collect timed-out session -------------------------------------------------------------------------------------------------------------------- I create a daemon thread in servlet class when servlet starts. It checks each session object from the session table in every 5 minutes, compare the expire time of each session object with current time. If it is before current time, it will be removed from the session table. Functionality of each source file -------------------------------------------------------------------------------------------------------------------- 1, index.jsp: implemented using http form, it will issue a http post to http://localhost:8080/CS5300Project1/session if the replace button or logout button is pressed. it contains a text field to receive user input as the new message if the replace button is pressed. It will issue a http get to http://localhost:8080/CS5300Project1/session if the refresh button is pressed. Also, this jsp file receives information from java servlet class and display them, including NetID(static), current session ID, version number of current session, time of last request, current cookie ID and session expire time. 2, logout.jsp: display a successful log out information once the user click the logout button in index.jsp page. 3,