Re: [WWdevel] webwork page caching

[John J. <jj...@as...>]

Hi all,

I also use the back button frequently, so I kind of like things the way 
they are. 

For students who use the back button and then are mislead by what the 
page says (be it "you still have 10 minutes to finish" or "you have 2 
attempts left on this problem"), I think that those students don't 
deserve much sympathy since they did something to create the problem 
situation.  Moreover, understanding what has happened with web forms and 
the back button is no longer just for geeks.  With internet shopping, it 
is now more of a basic life skill.

That said, I would not be strongly opposed to adding no-cache, 
especially if it were just for students (I sense another addition to the 
permissions hash - which makes it easily reconfigured on a 
course-by-course basis).

John


P Gavin LaRose wrote:

> Hi Sam,
>
> The biggest reasons I was thinking this could be a problem were:
>  - On gateway tests I maintain a timer on the page indicating how much
>    time is left.  At the moment I'm doing this as a countdown from the
>    amount of time left when the page is first loaded---going back to this
>    page therefore results in the student thinking that s/he has more time
>    than is the case.  I can work around this if need be, but I think it's
>    really part and parcel of the second comment, viz.,
>
>  - In general, when going from page to page working a problem the 
> previous
>    page's information won't reflect the current state of a problem.  This
>    is particularly relevant when there are a fixed number of attempts 
> at a
>    problem, so that going 'back' makes it appear that one has more
>    attempts than is actually the case.
>
> I agree that being able to go back through the browser's history is 
> very useful, however.  One option would be to no-cache student pages, 
> or for students only.
>
> I'm not entirely familiar with where WeBWorK is using GET vs POST, so 
> I don't know where that becomes an issue.
>
> Gavin
>
> On Wed, 2 Nov 2005 at 23:35 Sam Hathaway wrote:
>
>> On Nov 2, 2005, at 11:34, P Gavin LaRose wrote:
>>
>>> Hi all,
>>>
>>> Watching some of our gateway testing, the following occurred to me: 
>>> it would be good to avoid students being able to use the browser's 
>>> "back" button to navigate.  And then I thought that this should be a 
>>> desirable state of affairs in general.  Because WeBWorK pages 
>>> contain state data, we don't really want people going back to 
>>> previous pages.  I use this occasionally when I'm working as a 
>>> course administrator, but on student pages I think it's something we 
>>> don't want happening.
>>>
>>> Would it make sense to add a 'no-cache' command to the header of all 
>>> WeBWorK pages, so that it would force the browser to go back to the 
>>> server to get each new page?
>>
>>
>> Is the problem just that there could be out-of-date information on 
>> cached pages? (Like the case where a user attempts a problem for the 
>> first time and then hits back to return to the problem list and it 
>> tells her that she hasn't attempted it?) Or are there more dangerous 
>> cases? (If there are those should be removed regardless of whether we 
>> add no-cache.)
>>
>> I actually like being able to quickly pop back to the previous page 
>> and then forward to the current one one without reloading.
>>
>> If we added no-cache we would also want to be more careful about when 
>> we use POST versus GET. Good browsers warn you when a POST request 
>> needs to be resubmitted (like in the case of no-cache) and this is 
>> annoying when the re-POST isn't actually dangerous.
>> -sam
>
>