Unauthorized Linked problems in MATLAB Grader activity on LMS Moodle

We have the following query regarding the MATLAB Grader integration with LMS Moodle 3.9:

When a Matlab Grader activity is created in a LMS course, it automatically links us to a Matlab Grader problem that we have not chosen ( stand-alone copy of the problem is added), instead of the user himself linking the activity to a problem (page that says “Add Problem” at the top). In previous tests this failure did not occur.

It should be noted that we are using the same LTI credentials on various Moodle platforms.

However, we note that these failures do occur randomly, both for users linked to your MathWorks account and those who are not linked.

Answer 1

[Cris LaPierre]

Your LMS knows what problem to load based on the LTI key and the resource_link_id the platform assigns to the LTI problem. When launching a problem, MATLAB Grader first looks to see if a problem on that key with that resource link id already exists. If it does, it loads the existing problem. If one does not, a blank problem is created.

According to the LTI implementation guide, the resource_link_id should be unique for every placement. I suspect the issue is that your LMS platform is reusing resource link id's, or your multiple platforms are creating the same resource link ids as each other. When this happens, the assigned id may be the same as a previously-created problem. When it is, Grader loads the existing problem rather than creating a blank problem.

If you need help determining if this is indeed what is happening, I suggest contacting technical support. However, to solve the issue if it is, you will need to work with your LMS administrator or IT support, as Moodle may not be creating the resource_link_ids as expected.

[Cris LaPierre]

Another possible solution may be to use a different credential in each Moodle instance. You should contact your MathWorks account representative to see if this may be a possibility.

[Administrador Configuración]

Thanks Cris

Do you know of any institution that uses Matlab Grader integration with different LMS Moodle using the same LTI credential? Could you tell us if they have the same problem?

Likewise, I share the route structure of the Moodle LMS with which we currently use the same LTI credential:

https://domain.pucp.edu.pe/cursos/

https://domain.pucp.edu.pe/programas/

https://domain-pucpvirtual.pucp.edu.pe/

[Cris LaPierre]

I don't know of any schools in particular that have encountered this issue, but I've encountered it using Moodle's demo site: https://sandbox.moodledemo.net/

Since the site resets every hour, the resource_link_ids it assigns are repeats of what I have used previously (1, 2, 3, etc). I therefore observe the same behavior - a problem appears as soon as I add a MATLAB Grader problem.

I would suggest contacting MathWorks technical support, as they may be able to help provide a workaround.