tool.md

LTI Service - Tool

How to use the bundle to make your application act as a tool in the context of LTI services.

Using the LTIServiceClient

In LTI services context, a tool, in order to call a service platform endpoint, need to be granted following the client_credentials grant type with assertion.

The client LtiServiceClient is available form your application container to make authenticated LTI service calls to a platform by following this standard.

To use it, you can inject anywhere you need the the LtiServiceClientInterface and you need to provide on which registered platform you want to make the call.

For example:

<?php

declare(strict_types=1);

namespace App\Action\Tool\Service;

use OAT\Library\Lti1p3Core\Registration\RegistrationRepositoryInterface;
use OAT\Library\Lti1p3Core\Service\Client\LtiServiceClientInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

class LtiServiceClientAction
{
    /** @var RegistrationRepositoryInterface */
    private $repository;

    /** @var LtiServiceClientInterface */
    private $client;
    
    public function __construct(RegistrationRepositoryInterface $repository, LtiServiceClientInterface $client)
    {
        $this->repository = $repository;
        $this->client = $client;
    }

    public function __invoke(Request $request): Response
    {
        $registration = $this->repository->find(...);
        
        $serviceResponse = $this->client->request(
            $registration,                    // Will ask the grant on the registration platform oauth2 endpoint, or form cache
            'GET',                            // Service call method
            'http://platform.com/service',    // Service call url
            ['some' => 'options'],            // Options
            ['scope1', 'scope2']              // Scopes
        );

        // Your logic based on the $serviceResponse ...
        
        return new Response(...);
    }
}

Notes: once the access token is fetched by the LtiServiceClient, it will cache it (into it's configured cache, for given TTL) to avoid asking every time the platform a new token.