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Interaction between LTIGradeOnSubmit and LTI authentication (2.12)

Interaction between LTIGradeOnSubmit and LTI authentication (2.12)

by Karl-Dieter Crisman -
Number of replies: 0

Greetings. I was wondering whether in any version of the LTI authentication (and/or grade passback) there have been reports of the $LTIGradeOnSubmit variable causing trouble.

I was setting up our WW server to use LTI auth as we did last semester in the same course, using Canvas.  I did have to change the consumer secret as mentioned in some forum, and it turns out that the domain needs to have /webwork2 appended if you use homework (not course) passback mode, but those are all Canvas issues, not really WW ones.

Just after all testing with our Canvas admin, I set $LTIGradeOnSubmit = 1; just to see what would happen with our students, in the hopes passback would work this semester (we had a lot of trouble last time).  I assumed this would be harmless except regarding passback.  Cue getting many emails from students that the LTI authentication was not working.

In fact, it seems that only this one flag set in the course.conf file was enough for LTI auth to be completely skipped.  I could still log on myself with LDAP or "Basic", but there were none of the usual log messages about "tried LTI, then tried LDAP" for the student attempts - in fact, no log messages at all, just the login screen displayed.  Of course if students tried their LDAP auth then there were log messages, but they didn't know that wouldn't be possible (since the accounts didn't exist yet).

Is it possible there is some strange interaction between this flag and LTI authentication/creation? I looked reasonably diligently at all the old posts about LTI but did not find one - though I looked at them far too much last winter when we first set this up, so I admit to some fatigue at searching through WW posts.

If it matters, we're running 2.12 still (OPL is fully updated, though) due to legacy hardware we are reluctant to mess with.  That may mean we can't benefit from any known fixes in updates, but I thought I'd ask in case it was something else - or even something we could hotfix ourselves.  Thanks!