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• http://www.imsglobal.org/specs/ltiv1p1p1/implementation-guide
  • Terminology
    • Tool Consumer (TC) - LMS that's embedding the TP's resource 
    • Tool Provider (TP) - External system - could be another LMS - that is hosting the resource
    • Context - general term for course, project, group, etc.
      • urn:lti:context-type:ims/lis/CourseTemplate
      • urn:lti:context-type:ims/lis/CourseOffering
      • rn:lti:context-type:ims/lis/CourseSection
      • urn:lti:context-type:ims/lis/Group
    • resource_link_id - identifier of TC's resource
    • context_id - identifier of TP's context
  • Credentials
    1. TC-wide TP domain-specific credential
    2. TC-wide TP url-specific credential
    3. LTI-link-specific credential
  • IMS Learning Information Service can be used as a backend service to provide additional data between TC and TP.
    • TC sends LIS key to TP in launch sequence
  • Score routing
    • TC includes the service endpoint for the LIS Basic Outcomes Service and the lis_result_sourcedid to allow the TP to make service calls to set, read, and delete scores.
    • Server-to-server call - can by async and trusted.
  • Fields
    • Can add any extensions if prefixed with "ext_".
    • headers
      • lti_message_type=basic-lti-launch-request
      • lti_version=LTI-1p0
    • resource
      • resource_link_id: Must be unique per usage of the resource in the TC.
      • resource_link_title, [resource_link_description]
    • user
      • user_id - non-identifable, primary-key, not logical key
      • [user_image]
      • roles: list of LIS URNs for roles
      • lis_person_name_[given|family|full], lis_person_contact_email_primary
    • context
      • context_id, [context_type], context_title, context_label
    • presentation

      • launch_presentation_locale=en-US, launch_presentation_document_target=iframe|window

      • launch_presentation_css_url, launch_presentation_width, launch_presentation_height

      • launch_presentation_return_url: where to go after TP completes

    • tool consumer
      • tool_consumer_info_product_family_code=learn|desire2learn|sakai|eracer|olat|webct
      • tool_consumer_info_version
      • tool_consumer_instance_guid, tool_consumer_instance_name, [tool_consumer_instance_description], [tool_consumer_instance_url], tool_consumer_instance_contact_email
    • custom key-value pairs requested by TP as custom_keyname
    • security
    • LIS services for communicating "outcomes"
      • lis_result_sourcedid: unique value for the tuple (context_id, resource_link_id, user_id) to pass back scores to a grade book. Value may change between launches.
      • lis_outcome_service_url: URL for outcome service; shouldn't change between launches.
      • [lis_person_sourcedid], [lis_course_offering_sourcedid], [lis_course_section_sourcedid]
  • Basic Outcomes Service
    • XML
    • grade: 0.0 - 1.0

    • replaceResult (lis_result_sourcedid, score)

    • readResult (lis_result_sourcedid)
    • deleteResult (lis_result_sourcedid)

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opt One-time LTI configuration for this TP
    note right of TP
        Credentials shared out of band if TP has
            - domain-specific credentials or
            - url-specific credentials
    end note
    TP -> TC: (out-of-band) credentials: key and secret
end opt
loop LTI configuration for each LTI link
    TP -> TC: (out-of-band) launch URL, custom parameters to send with each launch
    opt Link-specific credentials, if needed
        note right of TP
            Credentials shared out of band if TP has
                - LTI-link specific credentials
        end note
        TP -> TC: (out-of-band) launch URL, credentials
    end opt
end loop

loop For each launch of the LTI link
    note left of TC
        context_id is identifier of TC's context.
        Context may be of type:
            1. Course template
            2. Course offering
            3. Course section
            4. Group
            5. None if TC launches link outside of a context 
    end note
    note left of TC
        resource_link_id: unique per TC's usage of the LTI link   
    end note
    note left of TC
        user_id: non-identifable, primary-key of the user
    end note
    opt If outcomes/scores are to be passed back to TC
        note left of TC
            lis_outcome_service_url: unique per TC's usage of the LTI link   
        end note
        note left of TC
            lis_result_sourcedid: unique for (context_id, resource_link_id, user_id)
        end note
    end opt
    TC -> TP: context_id, resource_link_id, user_id, [lis_outcome_service_url, lis_result_sourcedid]
end loop

opt If outcomes/scores are to be passed back to TC
    note right of TP
        LIS Basic Outcomes Service REST calls can be made aynschronously at any point.
    end note
    TP -> TC: replaceResult (lis_result_sourcedid, score)
    TP -> TC: readResult (lis_result_sourcedid)
    TP -> TC: deleteResult (lis_result_sourcedid)

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LTI v2 (2014)

• https://www.imsglobal.org/lti-v2-introduction
  • in addition to embedding tool, support for adaptive and general-purpose tools.
• https://www.imsglobal.org/specs/ltiv2p0/implementation-guide
• Introduces concept of "tool proxy".
• Allows REST calls between services.
• https://mfeldstein.com/ims-failed-lti-2-0/
  • IMS may be discouraging the use of LTI v2.

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