I am using Jboss5.1.x, EJB3.0, Quartz 1.8
I have System which is being activated at specific time(surrounding that time).
The system should work once in a day.
I am setting value in a database which mention the activation time and every hour the system is pulling that value to check if the current time is matching the value (in case it is the system will activate itself).
This time has to be changeable in the future dynamiclly.
Now this technic gives me a headache, since I need to do some Math calculations (in case the current time has passed in couple of mins I still need to activate the system.
more over I need to take care for a case the system already activated so it wont be activated again in the same day (due to a time mistake caluclations.)
I could think about other technic which pulling the database once in couple of days to check if the activiation time has ever change(in this case I wont need to pull every hour, but in other case i am not sure Quartz can re-schedualre it's triggers while it's running)
any ideas? solutions?
Thanks,
ray.
You absolutely can reschedule triggers while Quartz is running (or add new triggers).
You can even do that from within the executing jobs if you like.
This a great example for my solution:
Dynamic time scheduling advice
Related
I can detect change clock time when app in foreground, background, or kill from Recent App by using android.intent.action.TIME_SET follow here.
However, if I Force Stop app in Setting->Apps I can not receive this broadcast anymore.
Currently, I want to detect user change clock time come back to my app after ForceStop so I do
long deltaTimeBeetweenCurrentTimeAndTimeSinceReboot = System.currentTimeMillis() - SystemClock.elapsedRealtime();
long oldDelta = mSharedPreference.getDeltaTimeBeetweenCurrentTimeAndTimeSinceReboot();
if(deltaTimeBeetweenCurrentTimeAndRebootTime - oldDelta > 5000){
// clock time change
}
Idea is I saved a delta between currently time (System.currentTimeMillis()) and time since reboot (SystemClock.elapsedRealtime()). Every time I open app, I will compare oldDelta and newDelta (except the first time install). It work well in case: User Fore Stop app->Change time->come back to app.
However, there is still have 1 case that is: User Fore Stop app -> Change the clock time -> Reboot device -> Open my app. At this time I can not use the above method to check the clock time have changed because after reboot the SystemClock.elapsedRealtime() will reset. How can I detect clock time have changed in that case?
Any help or suggestion would be great appreciate.
Few months ago I was in pretty the same situation. I didn't find any answer to directly solve the case, so I won't help you with it. But I can give you kind of advice:
Look at it with a different point of view.
What I did in my case, I answered myself to questions:
"Do I really want to know that user has changed the time - because I implicitly inform/present the fact to user?"
OR
"Do I want to know that user has changed the time - because I need it to invoke some actions or calculations in the application background?"
In my case I had NO-YES answers. So, for problematic case of Force-Stop + reboot I assumed that the time could had been changed and I reset my application's time configuration likewise the first app launch.
Let me know if it helps you anyway.
It would be hard to implement without external etalon (backend is the best option). You may save time a user force to stop the app and when the app alive again compare with some predefined delta (time window). If you get a "big" difference consider the user is cheating.
You may also play with timestamps of the filesystem to define some inconsistency.
I am using the Quartz Scheduler (version 1.8.3 due to project constraints) and I as assigned the task of creating an "MS Outlook-like" scheduler for Jobs specific to my project. Everything seems fine to work fine but I have a really huge problem with CronTriggers (this problem also exists in version 2.1 of Quartz):
I am using CronTriggers for recurrence patterns of DAILY, WEEKLY and MONTHLY. In addition to the recurrence pattern, I also provide an option for 'No. of occurrences'. This has become the bane of my life! CronTrigger does not provide an option for 'repeatCount' like SimpleTriggers do (bug: https://jira.terracotta.org/jira/browse/QTZ-242?page=com.atlassian.jira.plugin.system.issuetabpanels%3Achangehistory-tabpanel). Apparently this may be fixed in version 2.2 but I cannot wait that long nor do I believe my problem is unique!
A few options that I deemed worthy of investigation:
Calculate the 'EndTime' for the CronTrigger but using my own logic - this fails to cover all possible cases and is only approximate at best even for simple cases.
Use a TriggerListener or JobListener to keep track of no. of iterations of the job since I just need the job to stop after 'N' iterations and I have a 1:1 mapping from Job instance to Trigger. This does not seem very feasible and/or efficient by any stretch of the imagination.
Could any of you who have used CronTriggers with the option of 'No. of occurrences' please give some insights on how to solve this conundrum?
It seems that Quartz have implemented something that can help: TriggerUtils.computeEndTimeToAllowParticularNumberOfFirings.
I haven't tested it yet, but this is the code I have wrote for now:
CronTrigger trigger = newTrigger()
.withSchedule(cronSchedule(cronExpression))
.build();
Date endDate = TriggerUtils.computeEndTimeToAllowParticularNumberOfFirings((OperableTrigger) trigger,
new BaseCalendar(Calendar.getInstance().getTimeZone()), 10);
trigger = trigger.getTriggerBuilder().endAt(endDate).build();
If this won't work, then as said here and here, you can't set a repeat count, and you should use TriggerListener.
In any case, version 2.2 doesn't have this feature.
Update
I've tested it, and it works.
Wy dont't you instead use the Simple Trigger? You would have the additional taks of calculating the time interval at the time of scheduling the job, but that will be a one time activity.
I'm about to create a small application which will be responsible for sending out various reports to various users at various intevals. We might be talking about 50 or 100 different reports going to different people. Some reports needs to be generated every day, some every week, and some every month.
I've been using the Quartz library earlier to run tasks at regular intervals. However, in order to keep things simple I like the thought of having a single Quartz thread taking care of all reports. That is, the thread should loop through all reports, say every 15 minutes, and determine wether it is time for one or more to be generated and sent. It does not matter if a report is generated at 12:00 or 12:15.
I'm thinking about wether it would be possible, somehow, for each report to set up specific times such as "mon#12:00,wed#12:00" or "fri#09:30". Then, based on that, the thread would determine if it was time to send a report or not.
My question is; has anyone else done something like this and does any libraries exist which can make it easy to implement this task?
why not simply register a separate quartz task instance for each report and let Quartz handle all the scheduling for you? That is after all the point behind it.
you can create just single thread and it would ping a "job schedule data structure" at some time interval to see if it needs to run a report. If yes, it would run the report, otherwise, it would go for a short nap and ping again after specified sleep time.
It will cause problem if one job takes too much time to complete and you start accumulating jobs.
The job schedule data structure would keep its record sorted by time stamp.
I'm using a ScheduledExecutorService to provide an update to a database every hour with the scheduleAtFixedRate method. The problem is that it gradually gets later - in long service I've been logging it and it's about a second a day.
I made a small class just to examine this aspect - seems to work fine when nothing is happening on the PC ( running WinXP ) but if things are going on it rapidly gets later. 18:00:00.5 last night was its first log and this morning was 09:00:00.5 then 10:00:05.9, 11:00:26.8, 12:00:45.3, 13:01:07.8...
I can attach the code although my example isn't the smallest.
Anyone else experienced this? Any ideas why this isn't working properly?
I can think of lots of ways around it but I'd really like to know why it doesn't work as advertised!
Thanks, Mike
This is normal AFAIK. With scheduleAtFixedRate, If any execution of this task takes longer than its period, then subsequent executions may start late. That being said, I'd recommend scheduleWithFixedDelay. This will ensure that tasks are carried out at the specified delay interval.
I am building an app for which I need to set up cron jobs. What I want to do is to set the specific minutes in a hour where specific crons should run. For instance:
Task1 at 1st minute of the hour
Task2 on every second minute of the hour
Task3 every 2 minute only in the second half of the hour
Building this in the standard Unix cron format is reasonably straightforward, but could not figure out how to do it in the Google-App-Engine.
The documentation does not list any non-trivial examples. Any suggestions on how to do it? Examples would be excellent.
The documentation you linked to seems to indicate that it isn't possible to do what you want using only Cron for Java (unless they have an undocumented feature for it). In particular this doesn't appear to allow for multiple times.
time specifies the time of day, as HH:MM in 24 hour time.
The Python version says the exact same thing.
However, one solution (albeit somewhat more expensive in terms of CPU usage) would be to call a URL every minute, and from the handler for that URL, dispatch out to whatever other calls you need.
In other words, something like:
<?xml version="1.0" encoding="UTF-8"?>
<cronentries>
<cron>
<url>/run-scheduled-tasks</url>
<description>Run all scheduled tasks</description>
<schedule>every 1 minutes</schedule>
</cron>
</cronentries>
Then in run-scheduled-tasks, check a database for when each task last run, and if your complex condition for triggering them has occurred since then.
If the documentation is correct you can't get as granular as you are wanting. Doesn't look like they support picking a particular minute of the hour. Or a subset of an hour.
You might have to get creative. Why do you need such specific timing?
This may seem silly. Write three servlet. And schedule them from another UNIX machine on the other part of the world :D. Or even you can write a java app to do it. enjoy
Have a look at Quartz and see if that'll solve your problem.