Updating session attributes every fixed time interval. Java, Servlets, JSP

Question

I'd like to update user session attributes (for example, user's money amount) every 20 minutes. How can I achieve this? Any ideas?

A servlet will only execute when called by the browser/front-end/jsp thus you'll have to get your some javascript to call the servelt every 20 minutes... Or you can manipulate the session object using javascript — TungstenX, Dec 07 '14 at 16:26
@TungstenX there are many ways to manipulate session attributes other than by calling a servlet. A session is just an object, which can be manipulated at any point in Java code. And it is not possible to manipulate (or even access) the session object directly from Javascript code. — abl, Dec 07 '14 at 16:51
@abl Of course one can get hold of the session object in Javascript: <% HttpSession s = request.getSession(false); %> and you are correct, on the Java side one can get hold of the session object under certain conditions. — TungstenX, Dec 09 '14 at 15:35
@TungstenX I see no Javascript in your comment. That's a scriptlet. — abl, Dec 09 '14 at 18:40

score 2 · Answer 1 · edited May 23 '17 at 12:05

Your problem has two distinct parts:

For the first part, you just need to keep a collection of all current sessions that you can access from anywhere (i.e. without the need of having an HttpServletRequest). This is answered in this post: How do I get a list of all HttpSession objects in a web application?

For the second part, your best fit is probably a ScheduledExecutorService. See also: Running a Java Thread in intervals

score 0 · Answer 2 · answered Dec 07 '14 at 16:27

0

You can use Timer Service for this task.

If you use Spring you can try TaskExecutor

answered Dec 07 '14 at 16:27

How do you get hold of a specific session object in the timer task? – TungstenX Dec 09 '14 at 15:39
You can take put user's session to a timer task on the servlet side – Ruslan Ostafiichuk Dec 09 '14 at 21:36

2 Answers2