The LTI® 1.3 Protocol
The learning tools interoperability (LTI®) protocol describes how any learning resource can communicate with a Learning management system (LMS) and exchange relevant information, seamlessly integrating them together to improve the educational process.
Possible interactions between Platforms and the Tools are described as Services. The LTI® 1.3 protocol officially describes 4 Services:
- Core (Launch)
- Deep Linking
- Names and Roles Provisioning (Memberships)
- Assignment and Grade
The Core Service (Launch) is the most basic interaction between a Platform and Tool. It describes the process through which a Tool can be launched from within a Platform, usually in the form of an embedded iframe, while receiving information about the launch context.
After a successful launch, a Tool should have access to an IdToken, a signed JWT containing the launch context and a variety of additional information.
Some of the relevant information that can be found in an IdToken:
- User Information
- User ID
- Role inside current Platform context (e.g. Instructor, Learner).
- Platform information
- Tool Information
- Context Information
- Course ID
- Activity ID
- Custom Parameters
A Custom Parameter is a key-value pair set at the moment of the creation of a Tool Link (e.g. Activity) inside a Platform. Tools offering multiple resources often use either Custom Parameters or Query Parameters to decide which resource to display after a successful launch.
More information about the LTI Launch and the IdToken can be found in the Official IMS LTI® Specification.
The Deep Linking Service can be used to create Tool Links inside a Platform.
The Deep Linking process consists of a Launch to the Tool’s deep linking endpoint where the user can select which resource(s) they want to link. The tool will then generate a signed JWT containing the selected resources and submit this message through a self-submitting form to the Platform.
Deep Linking resources are called “Content Items”, Tool Links are only one of the available types of Content Item:
- LTI® Resource Link (Tool Link).
- HTML Fragment
The LTI® protocol allows custom Content Item types to be created. Each Platform can choose any number of available types to support.
Tools will often assign Query Parameters to identify the selected resource in each Tool Link URL.
Names and Roles Provisioning¶
The Names and Roles Provisioning Service allows a Tool to retrieve a list of User memberships inside the current Platform context (usually the current Course). It is possible to filter the results with the following parameters:
- role - The User’s role within the context, e.g. Instructor, Learner.
- limit - The maximum number of results to be returned.
- rlid - Access Resource Link level memberships by passing the id for the current context's resource link.
Platforms can choose what User information they want to share with Tools, only two parameters are required to be present:
- user_id - The User’s ID inside the Platform.
- roles - The User’s roles within the current Platform context.
Assignment and Grade¶
The Assignment and Grade Service allows a Tool to retrieve and create scores and line items inside a Platform. These functionalities are separated into three subservices:
Line Item Service - Allows Tools to retrieve, create or delete line items in the current context’s grade book.
Score Publish Service - Allows Tools to publish scores to a specific line item in the current context’s grade book.
Result Service - Allows Tools to retrieve scores from lines items in the current context’s grade book.