Be careful with this solution. It's not as easy as is said. I had a lot of problems with it. If you are going to do batch processing with EJB timers, you have to be very careful. EJB timer allows you to call EJB stateless and statefull session beans and they does not allow you to access files. Most of the time patch processing is dealing with files.
Another issue, if you are going to move big amounts of data between files or different databases you will have long transaction. All data in that transaction will be collected in memory and released only after completion. You have to know amount of data and how much memory will be consumed during this process.
After I had developed solution, I looked into Spring batch
http://static.springframework.org/spring-batch/ which can be better solution.
Development of batch processing tasks on glassfish was problematic and I got a lot of headache and sleepless nights, but at the end it works very well and I'm happy how stable and reliable it's.
Regards
Remis B
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