Deep linking LTI External Tool

So my tool creates bits of user generated content, and it is very handy to be able to provide a url that links directly to one of those pieces of content. However I can't passes any arguments to the external tool definition that canvas uses to perform the basic lti launch

I want to be able to do something like this

https://canvas/courses/14/external_tools/25?link=/deep/content/link => https://my.tool.url/lti?link=/deep/content/link

I understand that canvas does not currently repackage GET params, from the launch link back into the basic_lti_launch, however I am looking for a solution that can achieve this same effect.

Is there any other way to accomplish this, where I can pass arbitrary url parameters thru to the external tool launch?

Clarification:

This needs to be a solution that doesn't require any admin rights, i.e. a student can generate the url for sharing etc..

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Accepted answers

peter3

Here is the workaround that I ultimately settled upon .. and it is working well.

I created a page inside my application that acts as a redirector (lets call it deeplink); the code flow works like this

/deeplink?redirect=/path/to/deep/content
the page body for deeplink takes the redirect param and puts it in a cookie and redirects to an LTI app installed inside canvas. i.e. forward to: https://canvas/courses/14/external_tools/25
Then that external tool forces an LTI Launch on my application /deeplink
now the page body checks and sees the existence of a redirect cookie and redirects the user to the appropriate page.

All comments

cesbrandt

I'm not an expert with the external tools (I hate them, actually), but I believe I've worked with them enough to be able to answer this (just take it with a grain of salt).

When you configure the "External App", you have to supply a Launch URL. You could add it directly to this. We have to do this for integration of Bookshelf Online and Chalk & Wire Learning Assessment. So, assuming "https://my.tool.url/lti" is your current Launch URL, simply add to the end of it that additional string you want to use. This would also help you to avoid in issues with regards to their new policy of allowing only one Launch URL per access path, assuming you need to load multiple links with a different additional field.

For multiple links off the same base Launch URL, you could alternatively leave the Launch URL as "https://my.tool.url/lti" and add the additional portion to wherever it is linked. This'll allow you to have the single "External App" while using different additional GET parameters. This is the solution we use for the two scenarios I mentioned, and it's worked fairly well, despite the subtle changes Instructure has made over the last year that seems to be targeted at ending use of multiple external tools from the same source.

unknown

Since apparently it's not possible to have Canvas do it for you, see if you can create a "sharable string". When a user decides to share something, instead of generating a deep link, create something like "aardvark316" or whatever (which is mapped to however you store the necessary state).

Another user can then type that code in to see (and hopefully bookmark somehow) the relevant content.

It is a bit of a kludge, but if you do your UX right, you might be alright.

To make it possible to actually make a deep link, I believe you might need to change the code around here to append any params to the URL. I don't know where that data would come from, since I'm not really familiar with Canvas' inner workings.

garth

@peter3 says:

"However you cannot generate a link to a backend lti tool, because you won't be passing thru the canvas SSO process and the backend LTI tool will have no context as to who you are."

If the student is creating content inside your environment, and if you have specific sharing rules, would it make sense to manage content, sharing and associated rules from within your environment?

Have you considered providing a "dashboard" view in your app, which would include a list of shared content from within your app?

In other words, allow the student to access your app as a dashboard instead of an assignment. From the dashboard you can display both a list of assignments, and display a list of content that has been shared with them. You also now have control over how content is shared, and you are leveraging authentication.

ebook vendors use a similar approach: one entry point allowing students to find reading material as well as assignments enabled by the instructor. You might also need to provide an instructor dashboard, allowing the creation of assignments from your environment.

This approach adheres to the SSO issue you mention, and requires no special privs in Canvas. It also allows you to implement any proprietary business logic necessary to meet your requirements.

Just trying to brainstorm.

peter3

Here is the workaround that I ultimately settled upon .. and it is working well.

I created a page inside my application that acts as a redirector (lets call it deeplink); the code flow works like this

/deeplink?redirect=/path/to/deep/content
the page body for deeplink takes the redirect param and puts it in a cookie and redirects to an LTI app installed inside canvas. i.e. forward to: https://canvas/courses/14/external_tools/25
Then that external tool forces an LTI Launch on my application /deeplink
now the page body checks and sees the existence of a redirect cookie and redirects the user to the appropriate page.

peter3

I agree it would, but if it did .. I wouldn't have had to ask the community for work arounds..

also it's not that complicated, and doesn't require ruby .. it's 10 lines of java code .. probably 6 in php.

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