[ovirt-devel] Certain questions about Quartz based scheduling in oVirt

[Sahina Bose]

On 11/26/2014 02:50 PM, Yaniv Dary wrote:
>
> ----- Original Message -----
>> From: "Yair Zaslavsky" <yzaslavs at redhat.com>
>> To: "Sahina Bose" <sabose at redhat.com>
>> Cc: devel at ovirt.org
>> Sent: Wednesday, November 26, 2014 7:32:32 AM
>> Subject: Re: [ovirt-devel] Certain questions about Quartz based scheduling in	oVirt
>>
>>
>>
>> ----- Original Message -----
>>> From: "Sahina Bose" <sabose at redhat.com>
>>> To: "Moti Asayag" <masayag at redhat.com>, "Shubhendu Tripathi"
>>> <shtripat at redhat.com>
>>> Cc: devel at ovirt.org
>>> Sent: Tuesday, November 25, 2014 1:13:06 PM
>>> Subject: Re: [ovirt-devel] Certain questions about Quartz based scheduling
>>> in	oVirt
>>>
>>>
>>> On 11/24/2014 06:27 PM, Moti Asayag wrote:
>>>> Hi Shubhendu,
>>>>
>>>> ----- Original Message -----
>>>>> From: "Shubhendu Tripathi" <shtripat at redhat.com>
>>>>> To: devel at ovirt.org
>>>>> Sent: Monday, November 24, 2014 8:58:34 AM
>>>>> Subject: [ovirt-devel] Certain questions about Quartz based scheduling
>>>>> in
>>>>> 	oVirt
>>>>>
>>>>> Hi All,
>>>>>
>>>>> We are in a requirement where we need to schedule jobs at certain time
>>>>> interval, hourly, daily, weekly and monthly (i.e. repetitive and cron
>>>>> kind of scheduling).
>>>>> I was trying to understand quartz based scheduling mechanism in oVirt to
>>>>> achieve the scenarios.
>>>>>
>>>>> Have some basic questions regarding the same -
>>>>> 1. Is there is mechanism to persist the scheduling data in oVirt ?
>>>> In ovirt we do not persist the jobs. The application reschedule the jobs
>>>> when it starts
>>>> and programmatically triggers jobs when required.
>>>>
>>>> On packaging/services/ovirt-engine/ovirt-engine.xml.in we specify the job
>>>> store configuration
>>>> as RAMJobStore, which is a volatile:
>>>>
>>>>       <property name="org.quartz.jobStore.class"
>>>>       value="org.quartz.simpl.RAMJobStore"/>
>>>>
>>>> You may select other implementation. See:
>>>> http://quartz-scheduler.org/api/2.2.0/org/quartz/spi/JobStore.html
>>> Would the correct approach then be to have multiple scheduler instances?
>> Please bare in mind that quartz has the ability to perform
>> Cron like scheduling (with cron expressions).
>>
>>
>> http://www.quartz-scheduler.org/documentation/quartz-1.x/tutorials/crontrigger
> +1
> I'm don't think creating a cron like ability in RHEV is needed this is why cron/quartz exists.
> Instances for users jobs should be added independently from RHEV.

Yes, we would use the quartz cron scheduling capabilities.

The point under discussion is the job persistence - to use Quartz's DB 
persistence feature, so that we do not have to implement the logic of 
instantiating these jobs on server restart

And if we need multiple scheduler instances - one that uses the volatile 
RAMJobStore, and another that uses the persistent database job store 
(JobStoreCMT)

thanks!
sahina

>
>>
>>
>>> 1. - that uses the in memory job store
>>>
>>> 2. that uses DB to persist the jobs.
>>>
>>> The second instance would be used to schedule and manage any dynamic
>>> jobs, for instance like the ones required for gluster volume snapshot
>>> scheduling
>>>
>>> Using a separate instance also would mean there's no change to existing
>>> jobs that are scheduled in Backend bean.
>>>
>>>
>>>>> 2. How to tackle edit and rescheduling of jobs ?
>>>>>
>>>> You can have a look at org.ovirt.engine.core.utils.timer.SchedulerUtil
>>>> interface in
>>>> the 'scheduler' project which provides that functionality, and the
>>>> related
>>>> classes.
>>>>
>>>> But if not special requirements, i guess the shipped quartz
>>>> implementation
>>>> should be
>>>> enough:
>>>>
>>>> http://quartz-scheduler.org/documentation/quartz-2.x/tutorials/tutorial-lesson-05
>>>>
>>>>> Kindly guide on how to achieve these.
>>>>>
>>>>> Thanks and Regards,
>>>>> Shubhendu
>>>>> _______________________________________________
>>>>> Devel mailing list
>>>>> Devel at ovirt.org
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>>>>>
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