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Launch URL with LTI 1.3

Question asked by Greg Werner on Oct 8, 2019
Latest reply on Oct 8, 2019 by Greg Werner

Overview

 

We are unable to execute an external tool launch with LTI 1.3 using the `external_tool/retrieve?url=...` pattern. All other features work with LTI 1.3, such as authentication, assignment selection, grade posting, etc.

 

Setup

 

We have a current LTI 1.1 integration which uses the link in the url query parameter to launch an external tool:

 

https://example.instructure.com/courses/<course_id>/external_tools/retrieve?assignment_id=<assignment_id>&url=https%3A%2F%2Fexample.com%2Fv1%2Ffoo%2Fprojects%123%2Fservers%456%2Fautograded%2Fbar123%2Ftest13%2Fassignment.txt

 

Where:

 

- example: name of our organization and sub-domain value

- course_id: canvas course id

- assignment_id: canvas assignment id

- url: we use the optional submission type and data extension (Score - Canvas LMS REST API Documentation) to set this url query parameter value

 

This link works correctly when installing the application with LTI 1.1 settings. However with the LTI 1.3 settings, the link does not work.

 

Result (Error)

 

"Couldn't find valid settings for this link"

 

Expected Result 

 

Launch external tool as it does with LTI 1.1.

 

Additional information

 

We have found that the url query parameter does not influence the error we get from Canvas. With LTI 1.3, we get "Couldn't find valid settings for this link". We use the submission type and data extension from the Score API to set the url value in the link above. We are using the JSON config documented here: LTI 1.3 Quick Start - Google Docs . Our API, as a provider, never receives a request when attempting to launch the external tool with the link. As mentioned in the overview, all other operations are working seamlessly, such as authentication, assignment link selection, grading, etc.

 

We would like to understand what the equivalent LTI 1.1 link (...external_tools/retrieve?url=...) is in LTI 1.3. So far, we see that External Tools - Canvas LMS REST API Documentation is a possibility but have not gotten that to work. 

 

Thanks!

Greg

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