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Re: [PHP-DB] How to drop a table when user leaves prematurely? From: -BD- (bd <email protected>)
Date: 07/16/01

Thanks, Christopher...

I feel better now knowing that I wasn't just missing something really
obvious.. on the other hand, I should have thought of the "stateless" aspect
myself....

I'll take the timestamp approach, and see what I can come up with...

BD

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----- Original Message -----
From: Christopher Ostmo <tech <email protected>>
To: BD <bd <email protected>>
Cc: <php-db <email protected>>
Sent: Monday, July 16, 2001 1:42 PM
Subject: Re: [PHP-DB] How to drop a table when user leaves prematurely?

> BD pressed the little lettered thingies in this order...
>
> > Ugh!
> >
> > I'm sure this is fairly simple, but I have yet to come up with a way to
do
> > it...
> >
> > In a nutshell, our application creates, uses and drops a table while the
> > user is working on the site. Unfortunately, because of "other
> > considerations", we can't use a defined temp table - it has to be
created
> > as a regular table. We have a routine in the app that will drop the
table
> > once the user is done with their work, but if they leave for some reason
> > before they're done, the table is left hanging out there. This wasn't a
> > problem at first, but we're building up quite a collection of useless
> > tables right now.
> >
> > Is there any way to drop the table automagically when the user leaves
> > prematurely, either by closing their browser or jumping to another site?
I
> > tried using register_shutdown_function(), but it didn't seem to have any
> > effect...
> >
> > I think, and I know I may be way off base, is that there are a lot of
pages
> > involved in this application, and I'm not sure how to tell the app that
the
> > user is just going from one page to the next or is actually going
> > bye-bye...
> >
>
> HTTP is stateless (there is no persistent connection between the server
> and browser), so there is no way for you to tell the difference on the
> server side whether the user has gone to get coffee, has closed his or
> her browser or has been abducted by aliens. You can do two things
> that are rather unreliable:
> 1) Have a "Log Out" button. This is unreliable because many (most?)
> people will simply not use it.
> 2) Use a javascript to detect when the user has gone away. This is
> unreliable because many people disable javascript or use non-compliant
> browsers.
>
> The only sure way to keep your temp tables at a minimum is to store a
> creation date or datetime field in the temp table and destroy the table
> when it has reached a reasonable age. I prefer to run perl scripts from
> cron to do this and typically choose 48 hours as the time at which I feel
> that it is safe to assume that the user has abandoned his or her data.
>
> Good luck...
>
> Christopher Ostmo
> a.k.a. tech <email protected>
> AppIdeas.com
> Innovative Application Ideas
> Meeting cutting edge dynamic
> web site needs since the
> dawn of Internet time (1995)
>
> Business Applications:
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>
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