[Owncloud] Background Jobs

[Frank Karlitschek]

Hi Jakob,

sounds like the perfect solution. :-)
Thanks a lot!!

Frank


On 11.08.2012, at 16:07, 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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