3 Understanding Triggers

Scheduling configuration syntax

Currently plugin supports three types of triggers:

• simple — executes once per defined interval (ex. “every 10 seconds”);
• cron — executes job with cron expression (ex. “at 8:00am every Monday through Friday”);
• custom — your implementation of Trigger interface.

Multiple triggers per job are allowed.

class MyJob {
   static triggers = {
      simple name:'simpleTrigger', startDelay: 10000, repeatInterval: 30000, repeatCount: 10
      cron   name:'cronTrigger',   startDelay: 10000, cronExpression: '0/6 * 15 * * ?', timeZone: TimeZone.getTimeZone("GMT-8") //timeZone is optional
      custom name:'customTrigger', triggerClass: MyTriggerClass, myParam: myValue, myAnotherParam: myAnotherValue
   }
   void execute() {
      println "Job run!"
   }
}

With this configuration job will be executed 11 times with 30 seconds interval with first run in 10 seconds after scheduler startup (simple trigger), also it’ll be executed each 6 second during 15th hour (15:00:00, 15:00:06, 15:00:12, … — this configured by cron trigger) and also it’ll be executed each time your custom trigger will fire.

Three kinds of triggers are supported with the following parameters:

• simple:
• name — the name that identifies the trigger;
• startDelay — delay (in milliseconds) between scheduler startup and first job’s execution;
• repeatInterval — timeout (in milliseconds) between consecutive job’s executions;
• repeatCount — trigger will fire job execution (1 + repeatCount) times and stop after that (specify 0 here to have one-shot job or -1 to repeat job executions indefinitely);
• cron:
• name — the name that identifies the trigger;
• startDelay — delay (in milliseconds) between scheduler startup and first job’s execution;
• cronExpression — cron expression
• custom:
• triggerClass — your class which implements Trigger interface;

any params needed by your trigger.

It is also possible to adjust properties in a trigger Closure by the Grails configuration since the triggers block is given access to the grailsApplication object.

Dynamic Jobs Scheduling

Starting from 0.4.1 version you have the ability to schedule job executions dynamically.

These methods are available:

// creates cron trigger;
MyJob.schedule(String cronExpression, Map params?)
//  creates simple trigger: repeats job repeatCount+1 times with delay of repeatInterval milliseconds;
MyJob.schedule(Long repeatInterval, Integer repeatCount?, Map params?) )
// schedules one job execution to the specific date;
MyJob.schedule(Date scheduleDate, Map params?)
//schedules job's execution with a custom trigger;
MyJob.schedule(Trigger trigger)
// force immediate execution of the job.
MyJob.triggerNow(Map params?)
// Each method (except the one for custom trigger) takes optional 'params' argument.
// You can use it to pass some data to your job and then access it from the job:
class MyJob {
    void execute(context) {
        println context.mergedJobDataMap.foo
    }
}
// now in your controller (or service, or something else):
MyJob.triggerNow([foo:"It Works!"])