Allowing access to iCases through LTI

This post follows on from my Early Thoughts on LTI.

We have now fully implemented LTI for our iCases system. This has many benefits, including:

  • We no longer have to maintain authentication/permissions information within iCases, this can instead be done by WebLearn (Sakai), the Univeristy’s VLE.
  • Previously, it was only possible to log in to iCases if you had an Oxford Single Sign On username, so non-Oxford users had to use a single ‘anonymous’ account. That meant all non-Oxford users could see each other’s attempts and answers, and it was very difficult for them to pause and resume an attempt, due to the difficulty of finding the previous attempt among a long list of anonymous attempts.
  • iCases can be integrated into WebLearn making it very easy to add an iCase to a course.
  • Other institutions with a VLE/LMS that conforms to the LTI standard can easily use our public iCases.

We have already successfully made an iCase available to both Oxford and non-Oxford users through WebLearn/LTI, and are beginning to roll out our remaining iCases using this method. This includes making a number of iCases available publicly – see https://learntech.medsci.ox.ac.uk/wordpress-blog/?p=295.

As it currently works, the following is the process for adding an LTI Tool Provider to a site in WebLearn (the LTI Tool Consumer):

  1. Add a Basic LTI Tool to the site
  2. An individual with “Instructor” privileges (in WebLearn this means someone with a maintain/contribute role) can set up the Basic LTI Tool to point to the Tool Provider. This requires, at the very least, setting the URL and entering a key and secret (held/provided by us) into WebLearn.
  3. The Instructor can also set some launch/display settings. These settings include whether to open the Tool Provider in a new window and whether to pass information about the user, e.g. name/email address, to it, both of which we do.
  4. When the LTI Tool is launched, it sends a signed LTI request to the Tool Provider (i.e. iCases)

Turning iCases into an LTI Tool Provider wasn’t totally easy, but wasn’t as difficult as I had expected, and was made much easier by using the IMS Global Bsaic LTI PHP class – http://ims-dev.googlecode.com/svn/trunk/basiclti/php-simple/ims-blti/. The way I have got the LTI launch to work, at the Tool Provider end is a follows:

  1. Check that we have received an LTI request – iCases is set up so that it can only be accessed through LTI, although it would be possible to allow other access routes.
  2. Get the oauth_consumer_key from the launch data, and use this to look up the corresponding secret in a table to keys/secrets in our database.
  3. Create a new BLTI object (using the IMS Global class) which does all of the “is this a valid LTI launch?”/OAuth stuff for you.
  4. If this is the first time iCases has been launched from this context (i.e. a site in WebLearn), add the context to the database.
  5. If this is the first time that this user (defined by their WebLearn unique ID) has accessed iCases, add the user to the database.
  6. If this is the first time iCases has been launched from this context and the user has an Instructor role, allow them to choose an iCase to associate with this LTI tool instance. If this is the first launch from this context, and the user is not an Instructor, send them to an access denied page.
  7. Any future launches from this context will now send users directly to the associated iCase.
  8. As well as being the only ones who can link a Basic LTI Tool instance to an iCase, Instructors also get extra privileges within iCases, e.g. they can mark student attempts.

And that’s it! We are very excited by the options LTI opens up for us, in particular the fact that it enables us to make WebLearn a single, consistent route to many tools, and that we no longer have to worry about maintaining user accounts/passwords within our tools (which has security benefits for users). It would be possible to make Tool Providers appear as though they are actually part of WebLearn, although we haven’t done this for iCases.

We are anticipating LTI-ing a number of other tools in the near future, including CSlide and a project/module option choosing system – watch this space!

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