[Owncloud] Background Jobs

Klaas Freitag freitag at owncloud.com
Mon Aug 13 13:50:54 UTC 2012 

On 13.08.2012 16:23, Jakob Sack wrote:
> Hi Klaas,
>
> maybe I chose the wrong words: To disable background jobs you do not
> have to edit the program code but you must set the appconfig value
> core:backgroundjobs_mode to "none".
Ah, ok, sorry...

IMO the important point is that an update does not kick out such things, 
but you probably have taken care :)

Thanks,

Klaas

>
> Am 13.08.2012 11:49, schrieb Klaas Freitag:
>> On 12.08.2012 11:29, Jakob Sack wrote:
>>> I removed the option from the UI. In the program code the option "none"
>>> is still usable.
>> Come on, isn't that the worst of all possible solutions? ;-)
>>
>> Changing the program code is not the best way to do app configuration
>> as the change will be gone with the next update. Why not put an value
>> in config.php if we do not want a GUI option?
>>
>> I think there should be an option to set up ownCloud completely stand
>> alone, without having the system seeking out for other web services.
>>
>> Or do I get something wrong?
>>
>> Thx,
>> Klaas
>>
>>>
>>> Am 11.08.2012 23:08, schrieb Jan-Christoph Borchardt:
>>>> Ah sorry, I phrased it wrong. I didn’t mean »just use AJAX all the
>>>> time and remove the option for cron jobs«, I meant »AJAX is always
>>>> available and has no negative effect, so let’s just not have an option
>>>> to deactivate background jobs«.
>>>> Of course if the server supports it, cron should be used.
>>>>
>>>>
>>>> TL;DR: Nice, let’s remove the option to deactivate background jobs.
>>>>
>>>>
>>>>
>>>> On Sat, Aug 11, 2012 at 2:03 PM, Jakob Sack <mail at jakobsack.de> wrote:
>>>>> Hi Jan,
>>>>>
>>>>> thank you for the praise.
>>>>> as far as I know there is no reason for completely disabling
>>>>> background
>>>>> jobs.
>>>>> I strongly disaggree with you regarding your second argument. Using
>>>>> AJAX
>>>>> always is a bad idea. Exactly spoken, there are at least two problems
>>>>> with
>>>>> the ajax solution: if you installed ownCloud on a shared web hosting
>>>>> service
>>>>> and use it alone or with your family chances are high that there are
>>>>> periods
>>>>> with no one being online. Then you could miss news that are meant
>>>>> to be
>>>>> fetched every now and then. In this case a webcron serice would be
>>>>> perfect.
>>>>> On the other hand a large setup with several hundred users - we both
>>>>> know
>>>>> that they exist - should not be bombed with another hundred requests
>>>>> every
>>>>> minute. In this case it's better to use the systems cron service
>>>>> which does
>>>>> not have the limitations apaches processes might have.
>>>>> regards,
>>>>>
>>>>> Jakob
>>>>>
>>>>> Am 11.08.2012 20:30, schrieb Jan-Christoph Borchardt:
>>>>>
>>>>>> Awesoooome! Does that mean that step-by-step, all the »refresh« and
>>>>>> »rescan« buttons can go away?
>>>>>>
>>>>>> Just one thing: You say »there are four options: using the systems
>>>>>> cron feature, using a webcron service, using AJAX or not using
>>>>>> background jobs at all.«
>>>>>> Why even have the possibility to deactivate it? It’s a great function
>>>>>> which improves the experience silently, as with doing away with the
>>>>>> need for refresh buttons. And since doing it via AJAX is a good
>>>>>> default there’s no reason to not just do it like that always – or is
>>>>>> there?
>>>>>>
>>>>>>
>>>>>> On Sat, Aug 11, 2012 at 7:07 AM, Jakob Sack <mail at jakobsack.de>
>>>>>> wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> yesterday I pushed the new Background Jobs system to ownCloud
>>>>>>> master. As
>>>>>>> you
>>>>>>> can guess from the name, this feature allows ownCloud to do certain
>>>>>>> tasks
>>>>>>> in
>>>>>>> the background without blocking the UI. It also makes it possible to
>>>>>>> execute
>>>>>>> some tasks without any need of user interaction, for example
>>>>>>> fetching
>>>>>>> news
>>>>>>> while the user is on holidays.
>>>>>>> From a users perspective there is not much to pay attention to,
>>>>>>> background
>>>>>>> jobs tries to get out of the way as much as possible. On the other
>>>>>>> hand,
>>>>>>> administrators can use the settings interface to set the way
>>>>>>> background
>>>>>>> jobs
>>>>>>> are executed. There are four options: using the systems cron
>>>>>>> feature,
>>>>>>> using
>>>>>>> a webcron service, using AJAX or not using background jobs at all.
>>>>>>> Using
>>>>>>> the
>>>>>>> systems cron feature is the preferred way. It allows regular
>>>>>>> executed
>>>>>>> jobs
>>>>>>> without the limitations the web server may have. The second
>>>>>>> recommended
>>>>>>> option is the webcron implementation. By registering your ownCloud
>>>>>>> cron.php
>>>>>>> address at a webcron service like [1] you ensure that background
>>>>>>> jobs
>>>>>>> will
>>>>>>> be executed regularly. Using AJAX is the default option, although
>>>>>>> the
>>>>>>> least
>>>>>>> reliable. Every time a  user visits the page a single background
>>>>>>> job gets
>>>>>>> executed. The disadvantage of this solution compared to the webcron
>>>>>>> service
>>>>>>> is that it requires regular visits of the page. The reason for
>>>>>>> making
>>>>>>> this
>>>>>>> option the default is that this solution simply does not require
>>>>>>> access
>>>>>>> to
>>>>>>> the system or registration on some third party service.
>>>>>>> When you are implementing background jobs in your app, please be
>>>>>>> aware of
>>>>>>> the difference between the AJAX/Webcron and the cron
>>>>>>> implementation! The
>>>>>>> AJAX/Webcron implementation gets started by
>>>>>>> your-favorite-web-server, so
>>>>>>> you
>>>>>>> might have some limitations on execution time or memory. These
>>>>>>> limitations
>>>>>>> do not affect the system cron implementation, which calls php
>>>>>>> from the
>>>>>>> command line. As a consequence, you should split large tasks when
>>>>>>> not
>>>>>>> using
>>>>>>> system cron. You can check whether the app has been started by
>>>>>>> systems
>>>>>>> cron
>>>>>>> by checking if OC::$CLI is set to true.
>>>>>>> If you want to  use background jobs in your app, you have to
>>>>>>> register
>>>>>>> them
>>>>>>> in appinfo/app.php by calling OCP\BackgroundJobs::addRegularTask(
>>>>>>> $class,
>>>>>>> $method ).
>>>>>>> The first app featuring a background job is the news app being
>>>>>>> implemented
>>>>>>> by Alessandro Cosentino (zimba12). If you want to use background
>>>>>>> jobs in
>>>>>>> your app, have a look at the apps:newsapp repository first! There
>>>>>>> you
>>>>>>> will
>>>>>>> not only find a working example, but also a strategy of how to deal
>>>>>>> with
>>>>>>> the
>>>>>>> different requirements of AJAX/Webcron and the system cron.
>>>>>>> Regards,
>>>>>>>
>>>>>>> Jakob
>>>>>>>
>>>>>>> 1: http://www.easycron.com/
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