SlideLTI

This Express web application enables LTI integration of a histology slide viewer in LMS like Moodle. It uses the Ltijs framework as well as OpenSeadragon. It is based on the Ltijs Demo Server.

The integration was tested on Moodle 4.1.

Requirements

• Node.js and npm: sudo apt install nodejs npm

• MySQL (or another database engine):

   sudo apt install mysql-server
   sudo mysql_secure_installation

Usage

• Download or clone this repository.

• Create an .env file and set the relevant variables, e.g.:

   TOOL_URL="http://localhost:3000"
   PORT="3000"
   DB_HOST="localhost"
   DB_PORT="8889"
   DB_NAME="slidelti"
   DB_USER="slidelti"
   DB_PASS="password"
   LTI_KEY="ltikey" # at least 16 characters long
   PRODUCTION=true

  Be sure to create the database and its user: mysql -u root -p

  In the MySQL console:

   CREATE DATABASE slidelti;
   CREATE USER 'slidelti'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
   GRANT ALL PRIVILEGES ON slidelti.* TO 'slidelti'@'localhost';
   FLUSH PRIVILEGES;

• Create a platforms.json file with the detail of your Moodle installation(s), e.g.:

   {
   	"platforms": [
   		{
   			"url": "https://your.moodle.edu/moodle",
   			"name": "<Name of your choice>",
   			"clientId": "<Provided by your Moodle installation>",
   			"authenticationEndpoint": "https://your.moodle.edu/moodle/mod/lti/auth.php",
   			"accesstokenEndpoint": "https://your.moodle.edu/moodle/mod/lti/token.php",
   			"authConfig": {
   				"method": "JWK_SET",
   				"key": "https://your.moodle.edu/moodle/mod/lti/certs.php"
   			}
   		}
   	]
   }

  You can get these values from the Tool configuration details on your Moodle installation (see below).

• Create a folder public/slides which contains the tile sources, e.g., in DZI (Deep Zoom Image) format. In our case, we had slides scanned in MIRAX (.mrxs) format, which we converted with vips dzsave (cf. libvips).

• Run npm install to install all dependencies.

• Run npm start to start the server

Moodle Integration

As an integration example, we take the popular Moodle LMS:

• In Site Administration > Plugins > Activity modules > External tool > Manage tools, click on configure a tool manually.
• Enter the following settings:
  • Tool name: SlideLTI (or any name of your choice)
  • Tool URL: The URL on which the tool is reachable (the same as in your .env file), with a trailing /
  • LTI version: LTI 1.3
  • Public key type: Keyset URL
  • Public keyset: The tool URL + /keys
  • Initiate login URL: The tool URL + /login
  • Redirection URI(s):
    • The tool URL + /
    • The tool URL + /slide
  • Supports Deep Linking (Content-Item Message): Enabled
  • Privacy: Set all settings to Never

After saving the tool, you can click on its View configuration details icon to see the endpoints necessary for the platforms.json file (see above).

For development purposes where the tool might be available through localhost, be sure to remove any cURL blocked hosts list and add cURL allowed ports list as necessary in Site Administration > General > Security > HTTP security.

You can now add this external tool to a course (Enable Edit mode, click on Add an activity or resource > External tool). In the activity settings, set the Preconfigured tool to the tool name configured before. Click on Select content to select a particular slide.

Deployment

In production, you would like to deploy this within a server like nginx:

• Install PM2, a daemon process manager for Node.JS: sudo npm install -g pm2

• Start the SlideLTI application: pm2 start index.js

• Install nginx: sudo apt install nginx

• Create a virtual host configuration: sudo nano /etc/nginx/sites-available/slidelti

  Add the following content:

   server {
   	listen 80;
   	server_name yourdomain.com;
  
   	location / {
   		proxy_pass http://localhost:3000;
   		proxy_http_version 1.1;
   		proxy_set_header Upgrade $http_upgrade;
   		proxy_set_header Connection 'upgrade';
   		proxy_set_header Host $host;
   		proxy_cache_bypass $http_upgrade;
   		add_header Access-Control-Allow-Origin https://your.moodle.edu always;
   		proxy_hide_header X-Frame-Options;
   		add_header Content-Security-Policy "frame-ancestors 'self' https://your.moodle.edu";
   		add_header "Cross-Origin-Resource-Policy" "cross-origin";
   		add_header "Cache-Control" "max-age=0, no-cache, no-store, must-revalidate";
   		add_header Pragma no-cache;
   	}
   }

  Adapt the TOOL_URL in your .env file according to your server domain.

• Create a symlink in /etc/nginx/sites-enabled: sudo ln -s /etc/nginx/sites-available/slidelti /etc/nginx/sites-enabled

• (Re-)start nginx: sudo service nginx restart