I decided to try Google App Engine for a personal project, that pulls yahoo weather at a regular time interval, but as I dived into Google App Engine then this simple thing can not be done in cron jobs, so I started to think about the solution, here is what I came up with, just the idea:

- Create a Cronjob class to handle the cronjob: this class will do the all the tasks that need to be done regularly
- Use javascript at client side to refresh the Cronjob page at a regular time interval.

I think the idea is simple, it does solve the problem but require you to have the page opened all the time. Some of you may have better idea?