Wiki page detailing ATutor/Lightbox integration

Greg Gay at
Thu Feb 14 17:37:20 UTC 2008

Hi Joseph
We only present 10 images per screen, so there would be 10 updates going
on each time an image is moved. In most cases this won't be a problem,
for smaller installations, but on larger ones, with many people moving
images at the same time, potentially hundreds of calls to the database
and the webserver are being made. And, if there are 20 images per screen
etc., that number increases even more.

My preference would certainly be to eliminate the submit button. You're
right, some people may not even know they have to use the button,
particularly if you can't see it. For systems like Sakai, which caters
to bigger institutions, with higher end hardware and faster networks,
auto submit on move probably won't be a problem. But, ATutor also caters
to less "connected" clientele, who may be using lower end hardware, and
slower Internet connections, so we're going to default to the manual
save order method for now. They can always change that setting by
uncommenting a single line in the gallery code to change the setting to
save on move.  We'll probably end up making this a configurable option
at some point, unless we can cut back some on the hardware load and
network traffic.

Let me know if you do come up with a way to minmize the load.


Joseph Scheuhammer wrote:

> Hi Greg,
>> We also discovered by accident that the lightbox generates a submit
>> event when an image is moved,
> Part of the reason for doing this is to maintain state if the user
> leaves the page and later comes back.  A concrete case I can point to
> is Sakai's image gallery tool, where the user might switch galleries
> in the middle of rearranging thumbnails in one gallery.  When they
> switch back, they expect the last thumbnail order they saw to be
> maintained.  It's undesirable to force them to hit a submit button
> before switching out -- users will likely forget to do that (if they
> even know that they have to).
> The submit event is an ajax call and the result is ignored by the
> Lightbox JavaScript code.  If network traffic is a concern, then
> perhaps the information submitted could be minimized.  At the moment
> it submits a form with an input for every thumbnail in the box.  I'd
> have think about how that might be made smaller and still communicate
> enough information to tell the server how the order has changed.

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