Kraken Cron

Kraken Cron provides job scheduling.

Requirements

• kraken api 1.0.0
• slf4j api 1.5.6
• hsqldb 1.8.0.7

Commands

• cron.usage

  kraken> cron.usage
  SYNTAX:
  * * * * * Runnable instance.name
  - - - - -
  | | | | |
  | | | | +----- day of week (0 - 6) (Sunday=0)
  | | | +------- month (1 - 12)
  | | +--------- day of month (1 - 31)
  | +----------- hour (0 - 23)
  +------------- min (0 - 59)
  
  EXAMPLES:
  Run once a year                       |   0 0 1 1 *
  Run once a week                       |   0 0 * * 0
  Run every five minute                 | */5 * * * *
  Run once a day from monday to friday  |   0 0 * * 1-5
  Run once a day on saturday and sunday |   0 0 * * 0,6
  

• cron.register [rule] [instance.name]

  kraken> cron.register * * * * * sample
  new schedule [1] registered.
  

  • Run 'sample' service instance (must be Runnable) every minutes.
• cron.unregister [schedule id]

  kraken> cron.unregister 1
  schedule unregistered.
  

  • Unregister schedule.
• cron.list
  • List all schedules.
• cron.queue
  • View current state of scheduling queue.
• cron.run [instance.name]
  • Run now
• cron.runnables
  • List all active Runnable instances.

Schedule Syntax

• The comma (',') operator specifies a list of values.
  • For example, "1,3,4,7,8" (space inside the list must not be used)
• The dash ('-') operator specifies a range of values.
  • For example, "1-6", which is equivalent to "1,2,3,4,5,6"
• The asterisk ('*') operator specifies all possible values for a field.
  • For example, an asterisk in the hour time field would be equivalent to 'every hour' .
• The slash ('/') operator (called "step"), which can be used to skip a given number of values.
  • For example, "*/3" in the hour time field is equivalent to "0,3,6,9,12,15,18,21".
•  http://en.wikipedia.org/wiki/Cron#crontab_syntax

How to create Runnable OSGi service instance?

• All iPOJO component instances have instance.name OSGi service property.
  • Create Runnable component using by ipojo.create command. (requires kraken ipojo bundle)
• Check if OSGi service is registered as you want.
  • Use osgi.services and osgi.properties [service.id] commands. (requires kraken core above 1.1.0)
  • instance.name property must be exist.

Cron API

How to build Schedule object?

• Run every minute.

  Schedule sample = new Schedule.Builder("sample").build();
  

• Run every day.

  Schedule sample = new Schedule.Builder("sample").buildDaily();
  

• Run every week.

  Schedule sample = new Schedule.Builder("sample").buildWeekly();
  

• Run every month.

  Schedule sample = new Schedule.Builder("sample").buildMonthly();
  

• Run every year.

  Schedule sample = new Schedule.Builder("sample").buildYearly();
  

• 0 0 1 1 3-6 sample

  Schedule sample = new Schedule.Builder("sample").build("0 0 1 1 3-6"); 
  

  • If you have specified any field using .set(CronField.Type, expression) before calling .build(expression), the former specification will be ignored.
• 0,3,5,9 4-10 */10 * 0 sample

  Schedule sample = new Schedule.Builder("sample")
                                .set(CronField.Type.DAY_OF_WEEK, "0")
                                .set(CronField.Type.DAY_OF_MONTH, "*/10")
                                .set(CronField.Type.HOUR, "4-10")
                                .set(CronField.Type.MINUTE,"0,3,5,9")
                                .build();
  

  • If there is no explicit specificaton of a field, default value will be *(wild).

How to get CronService reference?

• OSGi standard way

  ServiceReference ref = bundleContext.getServiceReference(CronService.class.getName());
  CronService cronService = (CronService) bundleContext.getService(ref);
  

• iPOJO way
  • use @Requires annotation or metadata.xml configuration.
  • iPOJO will inject CronService for you.

Schedule Registration

Schedule schedule = new Schedule.Builder("sample").build();
int id = cronService.registerSchedule(schedule);

Schedule Unregistration

cronService.unregisterSchedule(id);

Class Diagram

History

• 1.0.0 release: initial release (2009-10-19)