Below are a number of resources that I found useful in implementing this:
- 1EdTech's unmaintained lti-1-3-php library gave some helpful information about endpoints.
- 1EdTech's unmaintained lti-1-3-php-example-tool gave some insight into the intended use of their library and further insights into the behavior of endpoints.
- Packback's lti-1-3-php-library is actual useful, maintained code on which this depends!
- Packback's wiki for that library was helpful in thinking through their implementation but is (as of this writing) lagging behind their actual implementation by a bit, I think.
- Instructure's LTI documentation was super helpful in figuring out both registration and launch issues.
- My own notes in this Packback issue regarding making a full implementation.
- Obviously the Slim Framework and their Slim-Skeleton were helpful starting points for the structure of the Slim app! I find it more useful to bring in the pieces of the skeleton as-needed, rather than starting with the app template.
- The LTI Debugger Chrome Extension which adds another tab to the Developer Console, which was about the only thing of value that I was able to pull from 1EdTech's LTI Bootcamp, which everyone else links to as a great resource. It may prove useful as I get more into the specifics of deep linking?