keep track of a field in database

hi guys
i am working on my final year project.
in this i am making a reminder system for which i have to get input the time at which i must remind the user.now the problem is that how to know that now its the time to remind the user.
one of my approch is that i must implement a thread that interact with database and get the reminders to be remind in next 30 min.
how can i use this approach on jsp.
or can you suggest me any other approach ...
thank you in advance

Can't be done. When the time is up, how do you know where the user is surfing, or if he or she is even around their computer? They could be looking at Facebook, viewing videos, reading CodeRanch, or off bungeee jumping for all you know.

HTTP allows you to respond to requests made from the browser -- it's not a real-time protocol.

If, and only if, the user just happens to be on a page that you create, that page can poll with Ajax to see if it's time to make a notification. But only in that case.

thank you for reply
let me make it a bit easy .
i just want to send a mail and an sms to the user,as and when its the time of the reminding an sms and a mail is forwarded to him using mail and sms jars.
thank you

I have also used this timer in my project for sending sms & mail.
Study the:

java.util.Timer;
java.util.TimerTask;

That's different and has nothing to do with JSP. So I've moved this to a more appropriate location.

Hi,
I will suggest using Quartz scheduling for this. That will be better for your requirement.

help me out guys
i am unable to do it

You are going to have to ask a more specific question than that. What exactly are you having a problem with?

i am working on my final year project.
in this i am making a jsp based reminder system for which i have to get
input time at which i must remind the user by sending him a sms and e-mail.
i have taken time to remind by user and saved it into database.i have to interact with database and at that particular time i have to send an sms and email to user.
now the problem is that how to know that now its the time to send sms.
Thanks

i do not think it is possible. bit 1 idea is you create a J2se page and use timer class of java to check the time after every 50 seconds. You must have a computer running all the times that J2se page created. you can't ensure this on web platform as you must have to run a page everytime and sit it nearby.

this might also be possible with ajax asyou run the page and use ajax to send arequest after a particular time interval.

You are right Sunil Sunny. But, it will slow down the system.

Aniket S. Kulkarni wrote:You are right Sunil Sunny. But, it will slow down the system.

ya absolutely it will slow down the and also the size of database is always expected to increase once the site is published.

There are many ways to do this. Quartz is one popular framework which allows you to persist the schedule information and also triggers your persistent jobs. The Quartz site has useful tutorials too http://www.quartz-scheduler.org/documentation/quartz-2.1.x/tutorials/