[LON-CAPA-users] Disabling remote browser caching answers?

[Raymond Batchelor]

Hi Stuart,
 
To clarify.
The issue is/was this:

Students in a lab, use the same computers (sharing the same Windows account and FireFox browser) to submit answers to a few questions, before they leave.
We found that, unless we disabled history on those browsers, when students started to enter a numerical answer, the entire history of previous submissions by other students popped to view.  Kind of "gave the game away".  
We have disabled history in those browsers for which it was previously enabled, and thus resolved that particular localized issue.

Though, it would be nice to be able to selectively block history, for specific response fields (I suppose), in some instances.


Thanks,
Ray




----- Original Message -----
From: "Stuart Raeburn" <raeburn at msu.edu>
To: lon-capa-users at mail.lon-capa.org
Sent: Friday, 7 November, 2014 12:23:13
Subject: Re: [LON-CAPA-users] Disabling remote browser caching answers?

Hi Ray,

>   What, if any, is the best way for an author or course coordinator   
> to prevent students' browsers caching answers in a problem?

I doubt this is a caching issue.

When rendering a problem the response header sent to the browser by  
LON-CAPA includes:

Pragma: no-cache
Cache-Control: no-cache
Expires: <current date/time>

However, if the problem is being displayed after a student has made  
prior submissions, and the status is CAN_ANSWER then the most recent  
submission will be displayed in the textbox where the student enters  
an answer.

Some possibilities which could be implemented currently:

(a) Set the question type for the problem to "New Randomization Each N  
Tries (default N=1)"

or

(b) Add a javascript function to be called on page load to set the  
value attribute for all <input> form elements with name or id  
beginning with the string: HWVAL_ to ''.

Other possibilities, which would require modifications to LON-CAPA,  
would be to optionally exclude $oldresponse from the value attribute  
on the server side when the content is being rendered, and also to add  
a javascript function, as outlined in (b), to LON-CAPA itself, and  
then provide a parameter, settable by the CC, to determine whether to  
exclude $oldresponse and also run the javascript function on page load.


Stuart Raeburn
LON-CAPA Academic Consortium


Quoting Raymond Batchelor <batchelo at sfu.ca>:

> Hi All,
>   What, if any, is the best way for an author or course coordinator   
> to prevent students' browsers caching answers in a problem?
>
> --
> Ray
> _______________________________________________
> LON-CAPA-users mailing list
> LON-CAPA-users at mail.lon-capa.org
> http://mail.lon-capa.org/mailman/listinfo/lon-capa-users

_______________________________________________
LON-CAPA-users mailing list
LON-CAPA-users at mail.lon-capa.org
http://mail.lon-capa.org/mailman/listinfo/lon-capa-users

-- 
Raymond J. Batchelor, PhD.
Department of Chemistry
Simon Fraser University

Phone: 778-782-5635