Dynamic scheduler in Liferay - cron

Question

I need to execute a task periodically in Liferay, I find that you can create a class that implements MessageListener and in the receive method you can implement the action. Until here its fine, but after this to program the time you need to do it in liferay-portlet.xml, if the xml file is used I cannot edit the duration dynamically.
Is there any way I can create a task that can be programmed to dynamically get the values for scheduling duration from the DB?
I believe that with SchedulerEngineUtil I must to be able tho do this, but I don't know if it's the correct way or how do it?
Does anyone know how I can find any documentation and some example?
Thanks in advance

Answer 1

Exactly, to execute a task periodically you must implement MessageListener and do the following in your liferay-portlet.xml -
<scheduler-entry>
<scheduler-event-listener-class>com.#className</scheduler-event-listener-class>
<trigger>
<simple>
<simple-trigger-value>1</simple-trigger-value>
<time-unit>minute</time-unit>
</simple>
</trigger>
</scheduler-entry>
This will trigger the event listener class every 1 minute.So try fetching data from DB using Util method in here.
Let me know if that helped.

Answer 2

To add a dynamic scheduler you have to implement a MessageListener and register it using the SchedulerEngineHelperUtil:
String pId = "portlet id here"; // TODO put portlet ID here
Message msg = new Message();
msg.put(SchedulerEngine.PORTLET_ID, pId);
msg.put(SchedulerEngine.MESSAGE_LISTENER_CLASS_NAME, MyListener.class.getName());
Trigger listener = new IntervalTrigger(MyListener.class.getName(), MyListener.class.getName(), 50);
SchedulerEngineHelperUtil.schedule(
listener, StorageType.PERSISTED, "some description",
DestinationNames.SCHEDULER_DISPATCH, msg, 0);
You may also want to read my answer also covering a solution for creating a static scheduled-task.

Answer 3

The time is set in cronText, where 12 is minutes and 10 is hours. Currently this cronText makes it schedule every day at 10:12 am.
String portletId = "yourportlet_WAR_yourportlet";
String cronText = "0 12 10 1/1 * ? *";
Message message = new Message();
message.put(SchedulerEngine.MESSAGE_LISTENER_CLASS_NAME, YourListenerClass.class.getName());
message.put(SchedulerEngine.PORTLET_ID, portletId);
message.put("portletId", portletId);
SchedulerEngineHelperUtil.schedule(
new CronTrigger("jobName", "jobGroup", cronText),
StorageType.PERSISTED,
"Message Scheduler Description",
DestinationNames.SCHEDULER_DISPATCH,
message,
0);