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Implement dynamic status Java servlets and JSP

I am developing a web server and My home page takes request from user and /process servlet processes the request by making calls to other classes and interacting with the database.
/process servlet executes a long running process ( needs to run a perl script using ProcessBuilder, takes 3 mins) and return back to results.jsp?ID=something page.
Now I am doing the following,
Taking request at home.jsp --> /process servlet --> results.jsp
I am not using process.waitFor(), so that my response goes quickly to results.jsp.
And in results.jsp, I am checking for the files (named with ID) to be generated by the perl script and waiting for them to be generated and in meanwhile, I am showing status by refreshing the page every 15 seconds. Whenever the files are generated I am processing them in results.jsp and storing them in the database for further use with the query parameter ID.
And whenever user visits for the seconds time, results.jsp should not process everything, it should just grab the output from the database we previously stored.
Now I am doing too many database operations on results.jsp, but i feel this is the only way I can show them the dynamic status without changing the URL on browser.
Can you please help me out with any other effective way of doing things?
results.jsp?ID=1 draft
database.getOutput(ID) --- to get output corresponding to ID
<% if(ID!= null && database.getOutput(ID) == null) // checking for the first time
{
checking for files on refresh
}
if(database.getOutput(ID) != null)
{
pull details from databse and show here
}

Sessions handling in Vaadin

I have a Vaadin application that starts with a user login, but the problem is with Vaadin is the session handling as I can open two sessions from 2 different browsers with the same login which should not be possible to do. But I did not find any documentation regarding that besides this topic but it's not working properly as the data are not saved in the hashmap correctly.Anyone got the same problem?

Vaadin 7 works by default so that it creates everytime a new UI instance when a new browser tab is opened (or the tab is refreshed). You should store information about current user to VaadinSession or standard HttpSession and check in UI.init() if the session contains user information.
To store information into VaadinSession one can say:
VaadinSession.getCurrent().setAttribute("currentUser", currentUser)
HttpSession can be accessed as follows in Vaadin:
VaadinSession.getCurrent().getSession()
Please note that VaadinSessions are stored into HttpSession and HttpSession can contain multiple VaadinSessions if multiple Vaadin servlets are deployed from the same war file, and the user uses those at the same time.

How to prevent concurrent logins?
I keep track of logins using a self-generated login-token. A random string between 32 and 128 bytes in length that gets stored in a cookie and a backend database, typically under a user's account.
If User (A) shares her login credentials with User (B) a new login-token is generated for the new login and stored in a cookie and updated in the backed database.
If User (A) (who might for example already be logged in) attempts to perform an action while User (B) has just logged-in, User (A)'s session will be destroyed and she'll be redirected to the login screen after a backend test confirmed her login-token isn't a match.
Think of Sessions and Logins as two different things. Sessions can be generated all day long, but login STATE should be stored in a central store.

You can save all logged users to static Set. Static variables are globally shared. On start app, check whether the collection is already login.

What is a good strategy to manage sessions for beta webapplication?

I am trying to create a webapplication using Spring. The webapplication is a beta/demo site, which is invitation only. So, I need to generate a link to the webapplication url, appending a unique id, which would be valid for 24 hours. User can use that link for 24 hours and make use of the (I kind of also have plans of restricting the user by ip)
To achieve such token generation and expiry, should I just rely on the container with session time out to do it? or does it make sense to create spring backed service layer with token creation and expiry services?
EDIT
Now that I have a bounty on this to draw more attention, I thought I will rephrase the question so that it makes more sense - what would be a good strategy to force users out of a web application after a certain period of time?

Relying on session timeout would not be sufficient solution .
I am not acquaint with Spring . I would put my generic solution as below for any web application having requirement as yours :
Invitation is assumed to include a link to the Web Application .
The link is assumed to include the unique id .
The Beta/Demo user table is assumed to have a beta-expiry ( datetime ) column to hold the expiry date and time .
When your web application is accessed using the link in the invitation , update the beta-expiry column for that unique_id considering 24 hrs from then .
When a Beta/Demo user attempts to sign in , check the beta-expiry column for that particular user and allow access if the expiry is not reached . Display appropriate message in case of expiry .
Whenever a signed in Beta/Demo user performs subsequent accesses to your web application , check the beta-expiry column for that particular user and allow access if the expiry is not reached . Display appropriate message in case of expiry .
If seems useful , display a countdown timer showing the left over time somewhere in the header area .
In case of extension of Beta usage for all or a portion of users , you could update the beta_expiry column appropriately .
Additionally you could also have an invitation-expiry column to hold invitation expiry considering a particular duration for eg. a 48 hrs from when the invitation was sent .
We use a little bit similar solution to sign out ( signed in ) users from our SaaS application after a particular duration of no access .

I think that you should rely more in the back-end rather than a session on a cookie, imagine the case that you set the cookie for 24 hours expiration but the client deletes the cookies from the browser, (depending on your logic) your link will generate a new session or the request will be blocked.
IMHO you can store a session cookie on the client but you need to have a second source of comparison in the server, maybe a database, no-sql document, a collection in cache, something that you can compare and check the latest access to the client.
just to put all together imagine the following use case:
the user get the invitation link and click on it
the system check if the first time they log into the system, and save that date as a "start date" and another one as "last access"
the system sets an authentication cookie with 24 hours expiration
the system track every post back/ ajax call to the server and update "last access" date
if user deletes the cookie the system check the "last access" and make a comparison with the current server date
if valid the system creates a new auth cookie with the remaining hours
if not valid the system sends a message to the user.
for the user the cookie will expire according to the time left (calculation between start date and last access)
I hope this helps.
regards

One strategy is to keep track of expiry date-time of all the users by storing the relevant data in DB and using a cache library (to reduce DB hits while checking for the expiry date). Here is a small example:
Create a DB table with columns to map user id to expiry date: id, unique_user_id, expiry_date_time. You need to create the unique user id in your code and save it in DB before sending the URL to the user with this id. You can keep null as the initial value for expiry_date_time. Create a class to represent this mapping in Java:
class UserIdWithExpiryDate{
private String userId;
private Date expiryDateTime;
...
}
Define a Service with a cacheable method that will return an instance of this for a given userId :
public interface CacheableService {
#Cacheable("expiryDates")
public UserIdWithExpiryDate getUserIdWithExpiryDate(String id);
public void updateUserIdWithExpiryDate(String userId);
}
import org.joda.time.DateTime;
#Service
public class CacheableServiceImpl implements CacheableService {
#Autowired
private YourDao dao;
#Override
public UserIdWithExpiryDate getUserIdWithExpiryDate(String id) {
return dao.getUserIdWithExpiryDate(id);
}
public void updateUserIdWithExpiryDate(String userId){
Date expiryDate = new Date(new DateTime().plusHours(24).getMillis());
dao.update(userId, expiryDate);
}
}
The result of getUserIdWithExpiryDate method is stored into the cache so on subsequent invocations (with the same argument), the value in the cache is returned without having to actually execute the method.
Next step is to check the user's expiry date while accessing the site. This can be done using OncePerRequestFilter:
#Component("timeoutFilter")
public class TimeoutFilter extends OncePerRequestFilter {
#Autowired
CacheableService cacheableService;
// Here you need to decide whether to proceed with the request or not
#Override
protected void doFilterInternal(HttpServletRequest request,
HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
filterChain.doFilter(request, response);
}
}
Steps that can be taken inside the doFilterInternal method to check the validity of the user:
Get the user Id from request
Execute: cacheableService.getUserIdWithExpiryDate(userId)
If step 2 returns null, there is no user present with this id. You should not proceed with the request.
If step 2 returns an instance of UserIdWithExpiryDate, check the value of "expiryDateTime"
If the value of "expiryDateTime" is null,it means user is accessing the site for the first time.Update "userExpiryDate":cacheableService.updateUserIdWithExpiryDate(userId) and proceed with the request.
If "expiryDateTime" is not null, compare this with current date_time. If expiryDateTime.isAfter(currentDateTime), proceed with the request.
For caching, you can use Spring Cache Abstraction with EHCACHE.

Tokens
For this marketing purposes we generate tokens upfront, store them in a database alongside all information like restrictions to certain user account, ip ranges (for certain mobile carriers), the date and time ranges of use and so on.
In case of one time codes we just mark it as being used in the database.
To generate those codes we use Random Numbers or encode some information and use (SHA-1 or better). Then we use bigInteger.toString(36) or a different scheme and group the first 16 letters to let it look like a license key.
If we express information with it like useraccount/name or carrier (mobile) or whatever we can even validate the token without a database.
Forcing User Out
Just check for the validity of the token the first time the user starts a session or logs in. Throughout the session you just check if the token has expired (store a value in the session if you have one, append it (encrypted) in the url or whatever or check against a database.
So on every request you just check if the user has permission to access your site otherwise you block the user with an error / info page.
You can also add a java script to each page. The script can determine whether the users permission to use your site has expired by:
Encrypt the relative time that the token is valid in a hidden div and calculate the absolute time using the users local time. Then compare the absolute expire time with the user time every now and than (lets say every 3 seconds) and you can yourself all those polling and pushing (comet, ajax, websockets) behaviour.
Once the java script program notice the token has become expired remove the content sections and replace it (or mark a hidden div as visible) with the info / error page content. This way every time the user revisits pages still stored in the browser history are destroyed also. (if this is a necessity for you).
Summary
Use random tokens and a database or encrypt information (like the day the token can be used) and SHA-1.
Check the tokens validity every time the user requests a page (store the timeframe in a session / url to save roundtrips to the database)
Provide a java script that destroys local pages in the history on revisit.

Here I can think of two use cases that I have seen.
1.) This kind of management is used in applications like online tests or email verifications, where user is provided a link with some token. This link and the token is valid for some fixed period of time and can be used only once. (Ex. online tests or password reset-emails)
2.) Another use case is to provide link with a token which are also valid for a fixed period of time, but in this case the link and the token can be used any number of time within the time period allowed (Ex. Online registration forms for test or some university enrollments).
So, definitely managing this using a session only will not be a good choice as the browsers can be cleared.
So you need to maintain the pair of the link and the token at the server (May be in a DB) with some other information like last accessed time, creation date and time, Valid upto .
To be more flexible validity time for link and the token can be set differently (eg. link can be used for a set of users, but the tokens are unique to a user).
So you can use this info on every user visit to check whether the link or token is still valid and what are their last accessed time. If it turn out to be expired then you can show the relevant error message.

What about "deleting the user's account" (depends on how you are building your logging system) after 24 hours.
Coupling this with checking user's account every time (s)he loads the page, will force him/her out at the first refreshing after the 24 hours threshold passses.

You can store the id with expiration time and when a request comes in with that id check if
it's still valid
and if you are trying to accomplish something like id is valid say 5 hrs after first request then store time when the first request is made and for each subsequent request check if it's still valid

GWT: Problem with application's architecture

I'm in little trouble with designing GWT application. I am trying to develope RIA app (with just one main widget, lets call it Main). First, user must be logged. Here's my way to do that, but it does have a problem, you'll see.
Show login components on root panel
If login was successfull (checks database), show Main widget
Widget is added to root panel
Everything works, but when you press Refresh it shows again login components ... It all happens in onModuleLoad method.
How should I redesign this logic? I'd like to let user logged (that means RootPanel will hold Main widget) for certain amount of time.

http://code.google.com/p/google-web-toolkit-incubator/wiki/LoginSecurityFAQ
How to remember logins
Our login
system so far misses a useful feature:
For now it requires users to log in
again every time.
We can use Cookies to allow the user's
web browser to 'remember' the login.
In GWT, to set the cookie (which you'd
do right after your GWT code receives
the response as we did in the previous
code fragment):
String sessionID = /*(Get sessionID from server's response to your login request.)*/;
final long DURATION = 1000 * 60 * 60 * 24 * 14; //duration remembering login. 2 weeks in this example.
Date expires = new Date(System.currentTimeMillis() + DURATION);
Cookies.setCookie("sid", sessionID, expires, null, "/", false);
Now you can run the following code
right after your !EntryPoint begins
execution:
String sessionID = Cookies.getCookie("sid");
if ( sessionID != null ) checkWithServerIfSessionIdIsStillLegal();
else displayLoginBox();
Remember - you must never rely on the sessionID
sent to your server in the cookie
header ; look only at the sessionID
that your GWT app sends explicitly in
the payload of messages to your
server.
I'm not sure what how your GWT app implemented communication with the login service, but if you want to see another example, I followed the example here:
http://code.google.com/webtoolkit/doc/latest/tutorial/appengine.html#user
While it uses the Google App Engine as the backend authentication service, I think it's generic enough to be adapted to any server that supports the GWT RPC server side and has authentication services.

You need some kind of server-side support to do it.
For example, when user logs in, mark it in the server-side session. In onModuleLoad(), call the server to check whether user is logged in before showing the login form.
Other problems related to pressing Refresh can be solved with history tokens.

ICEFaces Session Auto-Extension

I have an application in which users frequently leave the page running in their browser all day. The page has an intervalrendered that updates data every 30 seconds.
However, if the user doesn't interact with the page for a while, it still expires. I'd like it to auto-extend for as long as the browser is open and making the scheduled requests.
Is there a way to automatically extend the session everytime that the scheduled renderer is fired for one of these pages?

I don't really want to do Javascript hacks to click buttons when my code is already being called every 30 seconds by ICEFaces. The following hacked workaround for ICEFaces internal timer seems to work:
private void updateSessionExpiration () {
HttpSession sess = getSession();
if (sess != null) {
try {
Field fld = SessionDispatcher.class.getDeclaredField("SessionMonitors");
fld.setAccessible(true);
Map map = (Map)fld.get(null);
String sessID = sess.getId();
if (map.containsKey(sessID)) {
log.info("About to touch session...");
SessionDispatcher.Monitor mon =
(SessionDispatcher.Monitor)map.get(sessID);
mon.touchSession();
}
} catch (Exception e) {
log.error("Failed to touch session");
}
}
}
Also, with ICEFaces 1.8.2RC1 (and presumably eventually with the release version of ICEFaces 1.8.2 as well), there are two new workarounds available:
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpSession session = request.getSession();
if (session != null) {
SessionDispatcher.Monitor.lookupSessionMonitor(session).touchSession();
}
Or, put this in the web.xml to update on any hit to URLs within a specific pattern:
<filter>
<filter-name>Touch Session</filter-name>
<filter-class>com.icesoft.faces.webapp.http.servlet.TouchSessionFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Touch Session</filter-name>
<url-pattern>/seam/remoting/*</url-pattern>
</filter-mapping>

ICEfaces has an internal mechanism for keeping sessions alive (the mechanism is sometimes referred to as "heartbeating"). You may have a look at the belonging documentation and configure the mentioned parameters (especially heartbeatInterval and heartbeatTimeout) in your web.xml.

Iceface's Ajax bridge has callback APIs, for example Ice.onSessionExpired() which you may be able to use.
<body id="document:body">
<script type="text/javascript">
Ice.onSessionExpired('document:body', function() {
<!-- Do something here -->
});
</script>
See http://www.icefaces.org/docs/v1_8_0/htmlguide/devguide/references4.html#1094786 for more details.

If I have undestood what is your real purpose, then you need a sort of timer which automatically extends every user session client side, consequentely overriding the server side default page session expiration timing ( usually 30 minutes, only for detail because I understood that the script "renders" every 30 seconds if the user is active on the page ).
If so well, before JSF I always extended inactive user sessions via underground Javascript, so I'll use it also in your case. Pratically you can build a simple page listener in Javascript starting from:
window.setInterval( expression , msecIntervalTiming );
the "expression" can be a called function in which you invoke some dummy JSF needed to keep the session alive without reloading the current page visited by the user, in the past I used standard frame or iframe to make http calls, now with XHR / Ajax is more simple too.
Javascript example:
var timerID = null;
function simplePageListener() { // invoked by some user event denoting his absence status
// here goes all events and logic you need and know for firing the poller...
if (timerID == null) // avoid duplicates
timerID = window.setInterval( "window.startPoller()", msecIntervalTiming );
}
//...
function pollerStart() {
// make iframe or ajax/xhr requests
}
function pollerStop() {
// make action like page reloading or other needings
}
//...
function triggeredCleanTimer(timer) { // invoked by some user event denoting his active status
clearTimeout(timer); // it can be also the global variable "timerID"
timerID = null;
}
Substantially you use the "timerID" as a global reference to keep track of the listener status, so when you need to activate the "autoextension" you assign it a setInterval. Instead when the user come back to the page (triggered by some event you know), you clear the timeout stopping the listener polling. The above example obviously implies that the user, when comes back, must reload the page manually.
However in your specifical case, I'll avoid to interfere with javascript automatically generated by Icefaces framework. Even if, for ipothesys, you could simulate periodically some user events on invisible input elements (style set on "visibility: hidden", absolutely not on "display: none"), this causes the Icefaces event to not stop it and making itself work continuosly
Elements like <input type="button" name="invisivleButton" value="..." style="visibility: hidden, z-index: 0;" /> on which you can call periodically invoke the click event by
document.forms["YourDummyForm"]["invisivleButton"].click();
For the usage, see the old great JS docs of Devedge Online :-)
http://devedge-temp.mozilla.org/library/manuals/2000/javascript/1.3/reference/window.html#1203669