I have a DBMS assignment to create an entire online bidding website that allows users to do many things like bidding on a timed auction, buy-it-now based on timed availability, and search among MANY more things. I’ve completed the website, with one minor exception: once a user wins a timed auction, that user must be notified that s/he is the winner and given 24hrs to checkout the item.
My early approaches consisted of simple PHP scripts that queried the DB when the user was on the page to see if the bid time ended and to see who the winner is, but there are two things wrong with that approach. 1. The user has to constantly refresh to find out if s/he won — if they’re on the page shopping. 2. If the user doesn’t log into the site for a month after the auction ended, s/he will not know for a month that s/he won the auction and therefore misses the 24 hr window to checkout.
I’ve been reading about cron jobs, but my concern is that, since they are scheduled jobs, there are no convenient times to schedule the jobs so that they get processed efficiently. What I mean is that I can’t continuously monitor and let every user who wins know instantly after the auction ends.
I also read on PHP exec( ), but I’m not sure that it’s the tool that I need to run this task because once exec( ) finishes, it doesn’t re-run.
So I guess, my question is if anyone has an idea of what I could implement to help me with this task.
You should use cron – have it run every minute or so to check the DB to see if some auction ended. The greater problem I think you’re construing is the notification to the user. If its the case they may not be on the site (or on some random page when they win) then don’t rely on notifying them via the website and certainly not from a PHP request they may or may not make to the site. Instead, consider having the PHP called by cron to check for winners send an email to them to notify them.
Think about Facebook (only because given the user base its the most universally experience example) – they provide a notification area if you’re on the site, but if you’re not on for a while, they send you an email letting you know something has happened. This is what you should do.