RE: Event Handling

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Thanks to all for your help on this, it's been very interesting for me to
read.

The system needs to check arrivals in real time (give or take a second or
two), using a cron job every minute doesn't provide the real time checking I
would like.

However, when I then got to thinking about it, wouldn't this be an ideal
solution? I create a PHP script that loops for 60 seconds, checking the
database each second for new entries and processing them (meaning I get near
real time monitoring), and then have that PHP script called by a cron job
every minute.

The reason I think that could be a good solution for me, is that if the PHP
script crashed (for any reason), then at most it's 59 seconds before the
system kicks in again and begins processing all the queued arrivals. If I
coded a PHP script to loop infinitely processing things every second, it's
possible I wouldn't notice a crash for a considerable amount of time. The
proposed solution provides a good fail-safe, I think.

Does that solution seem sensible? Or overkill?

Thanks again for your help in this, it's quite novel for me.

-----Original Message-----
From: Ashley Sheridan [mailto:ash@xxxxxxxxxxxxxxxxxxxx] 
Sent: 15 March 2010 12:56
To: Midhun Girish
Cc: Jochem Maas; David Hutto; php-general@xxxxxxxxxxxxx; Alex Major
Subject: Re:  Event Handling

On Mon, 2010-03-15 at 18:28 +0530, Midhun Girish wrote:

> rene "a page with an ajax script that kicks off the
check-for-recent-events
> script on the server".. but that method is highly non reliable.... i dont
> think anyone will take that risk especially for an important web app....
> cron or any equivalent which runs on the server must be used instead of
> that..
> 
> 
> Midhun Girish
> Development Lead
> MobAlive Technologies
> 
> 
> 
> On Mon, Mar 15, 2010 at 6:08 PM, Jochem Maas <jochem@xxxxxxxxxxxxx> wrote:
> 
> > Op 3/15/10 12:00 PM, David Hutto schreef:
> > > On Mon, Mar 15, 2010 at 7:31 AM, Jochem Maas <jochem@xxxxxxxxxxxxx>
> > wrote:
> > >
> > >> Op 3/15/10 8:24 AM, Midhun Girish schreef:
> > >>> Hi ,
> > >>> Just as David Hutto has said,What you need is the cronjob... Make a
> > >> script
> > >>> say "check.php" which checks the db to see if any new entries are
> > made...
> > >>> and if yes send the mail ...
> > >>>
> > >>> now using the cronjob feature in linux os(which will be provided as
a
> > >>> service in your linux hosting cpanel), set a cronjob which calls the
"
> > >>> http://www.yoursite.com/check.php"; URL every minute.... now a
trigger
> > >> will
> > >>> be there every minute to the script and the emails will be send
> > >> irrespective
> > >>> of whether anyone is browsing the site or not.... hope it is
clear...
> > >>>
> > >>
> > >> use cron - yes
> > >> have cron call a web URL - no, instead just call the script via the
php
> > CLI
> > >> sapi,
> > >> e.g. a cmdline as follows in cron:
> > >>
> > >> /usr/env php /path/to/your/check.php &> /dev/null
> > >>
> > >
> > >
> > > I do believe removing the /dev/null will send error messages during
the
> > > building of the script, correct?
> > >
> >
> > the '&> /dev/null' redirects all output - I kind of make the assumption
> > that the
> > script would be logging stuff to a file or something when in production.
> >
> > so, yes, remove the redirection when your developing/testing the script.
> >
> >
> >


I agree. Even setting a cron on a local computer to call home to a
server script would be preferable to Ajax calls.

Thanks,
Ash
http://www.ashleysheridan.co.uk




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