Schedule::Cron is a Perl module that provides a simple but complete cron-like scheduler. It can be used for periodically executing Perl subroutines. The philosophy behind Schedule::Cron is to call subroutines periodically from within one single Perl program instead of letting cron trigger several (possibly different) Perl scripts. Everything under one roof. Furthermore, Schedule::Cron provides a mechanism to create crontab entries dynamically, which isn't that easy with cron. It knows about all extensions (at least all extensions the author is aware of, i.e those of "Vixie" cron) for crontab entries like ranges including 'steps', specification of month and days of the week by name, or coexistence of lists and ranges in the same field. It even supports a bit more (like lists and ranges with symbolic names). It has existed since 1999 on CPAN and is successfully used in many projects.
TimeMachine Scheduler is a Java scheduler which can scale and run a high volume of jobs with many different types of schedules, such as repeating on a fixed interval or based on cron expressions. The scheduler can control the job executions with thread pools, and it can persist job data into different storage receptacles. Users may use the built-in schedule server with an easy-to-use configuration file, or developers may use it as a library to extend the scheduler and write custom jobs, schedules, or user services.