Hello,

I am looking for some ideas on a little project I am about to start. I want to create a monitoring service and looking for suggestions on the backend structure.

Lets say my service allows a member to enter a URL and the loaded page is checked for text, if the text is present the site is assumed to be 'up', if it doesn't the site is assumed to be 'down'.

Now lets say I have 100 members with 1 of these monitors each. What is the best way to call the script to check the service? At first I figured a cron job, but 100 cron jobs? What if I allow each member 5 monitors, thats 500 cron jobs, obviously you can see how that will get crazy and possibly unmanagable over time.

Then I thought maybe a cron job for each interval (monitors that check every 5min, 15min, 30min, 60min). So thats 4 cron jobs, maybe each could scan a database looking for members who have a 5min monitor and then runs the script.

It seems like there are alot of possibilities, so wondering if someone has some knowledge on this or how other services do it. Im trying to think in terms of ease of managment and server load.

Any ideas?

Thanks in advance!

You can do this with one cron job. Set up your script to check each site in a loop. Keep track of when each site was last checked and set up one cron to run the script in whatever interval you think appropriate. Assuming you are running this script on a shared host or otherwise don't want it to have to run through the entire database of sites to check in one go, all you have to do is record the start time and stop the loop once you exceed a certain amount of time.

Regardless, this probably won't work well if you do not have multiple servers available to do the monitoring. There will be a point where you will need more than the 5 minutes to monitor all the sites in your DB (every 5 minutes) - simply because some sites are slower than others.

Hello,

Thank you for the input!

Currently I am going to be running this off of 1 dedicated server. My plan would be to have the service free for users who do not mind longer intervals, and then eventually start a paid membership for those who want more monitors and shorter intervals. These folks would go on a separate server. Hopefully with a little time and patience I can start adding more servers which will pay for themselves.

More input is welcome. im just trying to consider all possibilities (good and bad) and try to build a strong foundation.