A more thorough search through the Maple TA Online Help has shed some more light on this question. Including the command randomize(): in Maple-based variable definitions sets the initial state of the random number generator using a number based on the system clock instead of the default seed in Maple.
By default, Maple TA is configured to log out the user after 30 minutes of inactivity. Browsing through and answering questions, clicking on "Verify" etc. will reset it back to 30 minutes. The pop-up appears after 25 minutes of inactivity, clicking on "extend session" during the next 5 minutes will reset it back to 30 minutes as well. If the user is too late and clicks "OK" past 30 minutes mark, Maple TA will redirect to the login page. If one single question takes more than 30 minutes to solve on paper and causes Maple TA log out in the mean time, I would strongly suggest to split it up into multiple parts (multiple questions or multiple verify sections within one single question). Not because of the logout issue, but because it will give you a better insight on the student's ability and provide you with more flexibility on partial grading.
Thanks for looking into this! Unfortunately we do not (yet) have a local server for MapleTA, but this security issue could be an argument for becoming self-hosted. One way around the concrete problem (without self-hosting, I think) is to embed the needed (if not all) *.mla procedures directly via manual copy-paste into the startup code from the worksheet that defines the *.mla file. But this, of course, is much more cumbersome than the wished-for simple one-line reference to the *.mla file itself.
Your answer, however, then also induces a similar question concerning the use of repository files inside MapleTA itself, as thoroughly explained in: [https://mapletacommunity.com/topic/64/how-to-create-and-use-a-maple-repository-in-maple-ta]. Admittedly, I did not check this out yet, but the question is, if this functionality also has been depreciated or blocked in the meantime?
Yes, of course, thank you very much! My mistake was to think, that everything could be 'driven' from the startup code. I see now that this is neither possible nor in fact necessary when using TA both to set up the variables for the MathApp and to give the precise and individual feedback.
Ok, thank you. The possibility of allowing the student to navigate through other sites or programs while doing the exam is in discussion since it can be considered not compliant with standards concerning safe exams procedures, but this option can be taken into account.
The way I would diagnose this is by editing the moodle code to print out the http packet that you get back from TA. It will be sending correctly from TA but I think at some point the packet is being changed on its way to moodle. The best way to check this is to print it out in the packet in the service.php file on the moodle server - this is the place the grade gets sent to - http://localhost:8888/moodle29/mod/lti/service.php. Of course this means you need access to a non-production version of moodle to test. Part of the problem is recreating this problem on a server where you have diagnostic control.
Yes, I'm using the 2016 version. It worked, thank you! I used $x*$response.provachain1.1.1 in the response area, where $x=4; was defined as the only line of the algorithm. Good to know also that it is wrong to consider the (addable by the user) field "id" from "Information Fields" as equivalent to the "id" appearing in the source, which is not the case.