Chapter 19. Timer Service

Business systems frequently use scheduling systems to run programs at specified times. Scheduling systems typically run applications that generate reports, reformat data, or do audit work at night. In other cases, scheduling systems provide callback APIs that can alert subsystems of events such as due dates, deadlines, etc. Scheduling systems often run batch jobs (aka scheduled jobs), which perform routine work automatically at a prescribed time. Users in the Unix world frequently run scheduled jobs using cron, a simple but useful scheduling system that runs programs listed in a configuration file.

Regardless of the software, scheduling systems are used in many different scenarios: