Hi,
Am 21.08.2012 18:02, schrieb Arthur Schiwon:
On 08/15/2012 01:56 AM, Alessandro Cosentino wrote:
@Jakob: maybe I am missing something here, but is there a way for
the
app developer to specify how often the job is executed?
I'd guess it is up to the (web)cron settings. As far as i can see
there are no parameters to pass, so (for now) you should take care
about it in your method.
apparently I forgot to answer the first mail. It is not possible to
pass a frequency to the job. This has several reasons: you don't know
when the (web-) cronjob will be executed and you don't know when the
next job will be executed when using the ajax.
Short: if your app needs a cooldown time you have to implement it
yourself ...
@Jakob: is it advisable to check if background jobs are enabled or
did you implement a fallback (e.g. checking after every call if there
is something to do?). Then it might make sense to provide an API
call.
If you rely on background jobs you should check if background jobs are
enabled (OCP\Config::getAppValue('core','backgroundjobs_mode', 'none')
!= 'none').
Take care,
Jakob
Cheers
Arthur
Thanks,
Alessandro
On Mon, Aug 13, 2012 at 9:50 AM, Klaas Freitag
<[email protected]> wrote:
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 <[email protected]>
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
<[email protected]>
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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