TimeMachine is an open source Java scheduler that can run high volume of jobs
with many different type of schedules. It supports repeating schedule on fixed
interval, CRON based expression, or even custom schedules. The scheduler can
manage job executions with thread pools, and it can persist job data into 
different storage. Users may run the scheduler as stand-alone server, or deploy
as web application. The scheduler engine is using a stack-based service 
container that is easy to configure and extend by developers.

Main Features:

* A stand-alone scheduler server with simple Properties configuration file.
* A web application (war) to run and manage the scheduler.
* Support job implementation in either Java or scripting languages.
* Support multiple thread pools for isolated jobs execution.
* Support in-memory or database data store.
* Support clustering - multiple schedulers nodes with single logical scheduler.
* Support job history recording.
* Built-in JobTask: LoggerJobTask, ScriptingJobTask and OsCommandJobTask.
* Built-in Schedule: RepeatSchedule, CronSchedule and DateListSchedule.
* Built-in Service: Crontab that's similar to Linux/Unix OS crontab service.
* Built-in Service: JobLoader to load schedules with simple properties file.

See documentations on