LTI or REST?
We are often asked questions like, “When should I use LTI and when should I use REST?” “What is the difference?” “What can I do with REST that I can’t with LTI (or vise-versa)?” In this document we discuss the differences, the similarities, and how you can best design your integration with Learn using LTI, REST, or some combination of both.
LTI stands for Learning Tools Interoperability®. It is a standard developed and published by the IMS Global® Learning Consortium. You build your integration following the LTI and LTI Advantage standards. In LTI-speak, your integration is a “Tool” that integrates with a platform (LMS) like Learn. Learn has been certified to meet the LTI standards. If your Tool also follows the standards, you can ensure this by getting certified, then your Tool will work with Learn, and any platform that has been certified. This is a big differentiator between LTI and REST. A certified LTI Tool will work on multiple LMS Platforms. A platform’s REST APIs are always specific to the platform. But, at the end of the day LTI is a web-application, as is a REST API application. Your Tool, a web-application following the LTI standard, gets HTTPS requests from and makes HTTPS requests to the LMS.
REST stands for Representational State Transfer. It is a lightweight, flexible web service architecture that allows HTTP commands to be sent to Web Applications without unnecessary overhead. (REST documentation references HTTP, but to be secure everything with Learn is done over HTTPS.) Anthology has developed and published REST APIs for Learn.
When talking about LTI, we use terms like launch, platform, and tool. A Learn administrator can set up your tool in Learn, following documentation that you provide. Anthology provides documentation applicable to any LTI tool on help.blackboard.com. Rather than reference a link that may change your best bet for finding such documentation is to use your favorite internet search engine and look for “Learn LTI documentation.” I just did and the help page for our LTI documentation for admins was the top result! Once your LTI tool has been configured on a Learn system by the admin for that system, course instructors can then place links to your Tool in their courses. Search this site for LTI and you will find demonstrations and tutorials on LTI in Learn. The most common, and likley the best, way for and instructor to place content from your tool in their course is to use Deep-Linking 2.0. The point of this discussion is that once configured by the administrator, use of your tool and the content it provides looks like it is a part of Learn, including when the instructor is selecting content to be ‘placed’ in the course, and then when the student views and uses that content. And, using the LTI Advantage Names and Roles Provisioning Service (NPRS) and the Assignment and Grades Service (AGS), your tool can integrate closely with the course roster and the gradebook for the course. In summary, you can do a lot with LTI 1.3 & LTI Advantage, where the users of the LMS can use your web-application seamlessly from within the LMS and then with the aforementioned services even manipulate the course roster and gradebook. Get started with this documentation.
Given how much you can do with LTI, why REST APIs? Well, the LMS is also a web application and it can be represented by many different types of ‘objects’. Users, courses, enrollments, calendars, announcements, content items, assignments, quizes, etc. If you want a complete view of the representation of a user or course member in Learn, you need to use our REST APIs because LTI is written to apply to all platforms, while each platform has it’s own nuanced way of representing the different ‘objects’ in the system. For example a User in Learn has a uuuid identifier, an external ID, a datasource ID, a set of system role IDs, a URL for an avatar, etc. Some other LMS may or may not have these. LTI won’t give you everything about a User object in Learn, REST APIs will. LTI may give you a subset. Another thing is that LTI doesn’t cover things like creating a document in Learn, or pulling a list of all of the different types of content in a course, or creating, reading and deleting announcements. Here’s a short-list of ‘objects’ you can read and manipulate in Learn with our REST APIs: Announcements, Attendance/meetings, Calendar, content (in the LMS) & attached files, Assessments, Course Categories, Course Groups, Course Memberships (LTI does have Names & Roles, REST give more information about the membership object), Course Messages, Courses, Data Sources, Institutional Hierarchy Nodes, LTI Placements, Course Roles, Institution Roles, System Roles, User Sessions, Terms, Users. You can get started building your REST Application with this documentation.
REST AND LTI
Now things can get interesting. You might build a pure REST Application, but often the easiest way into your application is an LTI Launch from a course or system page on a Learn system. With the LTI launch, you get all of the information about the user and the context from where they came from in the Learn system. This is quite convenient for your user as they have a smooth path to using your application (Tool) from Learn. Next, as the user is already logged into Learn, you can behind-the-scenes get an authorization token for making REST API calls back to their Learn system, without having them log in again. (A REST application that doesn’t use an LTI launch from Learn will need to ask the user to log into the Learn system they are working with.) Now your LTI Tool/Appication has all of the LTI 1.3 functionality without having to make a bunch of REST API calls for that, and can also make REST API calls for any functionality not available via LTI.
|LTI||Learning Tools Interoperability®, a standard developed and published by the IMS Global® Learning Consortium.|
|REST||Representational State Transfer. A lightwweight, flexible web service architecture. (Vs older tech like SOAP,etc.)|
We will continue to add new examples, tutorials, and code samples, so make sure to check these links regularly.