scheduler

1. periodic and at-time job scheduling for the user-defined jobs

2. mysql and sqlite persistence

3. socket server for the api interfaces

4. webpy server (will be decommission)

5. job tracter for the graphic view

Author: Zhihui Chen

References: https://github.com/dbader/schedule

https://github.com/mrhwick/schedule