TAO ltiDeliveryProvider extension

The LTI Delivery extension allows test-takers to take a delivery (delivered test) via LTI

The endpoint for this service to proctor a specific delivery is: https://YOUR_DOMAIN/ltiDeliveryProvider/DeliveryTool/launch?delivery=YOUR_DELIVERY_URI

https://YOUR_DOMAIN/ltiDeliveryProvider/DeliveryTool/{"delivery":"YOUR_URI"}(base64 encoded)

This link can retrieved using the LTI button in the deliveries section in the TAO admin user interface.

Alternatively a configurable link can be used by omitting the delivery parameter https://YOUR_DOMAIN/ltiDeliveryProvider/DeliveryTool/launch

In this scenario the instructor would need to call the LTI service first, and will be presented with a list of deliveries. Once he has chosen one of these deliveries it can no longer be changed. Test-takers subsequently clicking on the same link (as identified by Resource ID) will start the delivery chosen by the instructor.

The expected roles are:

Learner for people taking a test
Instructor for people configuring a link

Custom parameters:

max_attempts Overrides the number of executions allowed on the delivery. Expects a positive integer value or 0 for unlimited attempts. Attempts on LTI calls are calculated per resource_link_id instead of per delivery.

Return Values:

log message will contain the status of the delivery execution
- 100 for an active delivery
- 101 for a paused delivery
- 200 for a finished delivery
- 201 for a terminated delivery

Installation instructions

These instructions assume that you have already a TAO installation on your system. If you don't, go to package/tao and follow the installation instructions.

If you installed your TAO instance through package/tao, oat-sa/extension-tao-ltideliveryprovider is very likely already installed. You can verify this under Settings -> Extension manager, where it would appear on the left hand side as ltiDeliveryProvider. Alternatively you would find it in the code at /config/generis/installation.conf.php.

Note, that you have to be logged in as System Administrator to do this.

Add the extension to your TAO composer and to the autoloader:

composer require oat-sa/extension-tao-ltideliveryprovider

Install the extension on the CLI from the project root:

Linux:

sudo php tao/scripts/installExtension oat-sa/extension-tao-ltideliveryprovider

Windows:

php tao\scripts\installExtension oat-sa/extension-tao-ltideliveryprovider

As a system administrator you also install it through the TAO Extension Manager:

Settings (the gears on the right hand side of the menu) -> Extension manager
Select ltiDeliveryProvider on the right hand side, check the box and hit install

REST API

LTI delivery service REST API

Configuration options

Feature flags

FEATURE_FLAG_MAINTAIN_RESTARTED_DELIVERY_EXECUTION_STATE

A bool-typed environment variable, controlling whether a delivery execution state should be kept as is or reset each time it starts.

"false" – the state will be reset on each restart. Default behavior.
"true" – the state will be maintained upon a restart.

FEATURE_FLAG_AGS_SCORE_SENDING_RETRY

A bool-typed environment variable, controlling whether AGS score should be resent if it fails to be sent.

"false" – the application won't try to resend another request when it fails. Default behavior.
"true" – the application will try to resend requests until the number of max retries is reached.

LaunchQueue.conf.php

Configuration option `relaunchInterval`

Description: specifies time (in seconds) for a test taker to wait before the page is reloaded when waiting in LTI queue

Possible values:

Any numerical value (> 0)

Configuration option `relaunchIntervalDeviation`

Description: specifies time (in seconds) to pick a random amount of seconds between 0 and relaunchIntervalDeviation, then the random result is randomly added to or subtracted from relaunchInterval for each time the queue page is being reloaded. The goal of this option is to prevent knocking the backend simultaneously by multiple clients.

Possible values:

Any numerical value between 0 and relaunchInterval

LtiDeliveryExecution.conf.php

Configuration option `queue_persistence`

Description: a persistence that LTI delivery execution service should work based on. Should be a persistence name that's registered in generis/persistences.conf.php

Value example:

default
cache

LtiNavigation.conf.php

Configuration option `thankyouScreen`

Description: whether the 'thank you' screen should be shown once a test is passed through LTI. It only takes effect if the custom_skip_thankyou LTI parameter is omitted. Otherwise, it's only depends on the LTI parameter.

Possible values:

true
false

Configuration option `delivery_return_status`

Description: if enabled, the deliveryExecutionStatus return parameter will be included in a consumer return URL. This parameter will always be set to a delivery execution state label.

Possible values:

true: include the parameter in consumer return URLs
false: omit the parameter

Configuration option `message`

Description: a factory for producing LTI messages

Possible values:

an instance of any class that has the getLtiMessage method

Value example:

new oat\ltiDeliveryProvider\model\navigation\DefaultMessageFactory()

LtiResultIdStorage.conf.php

Configuration option `persistence`

Description: a persistence that LTI result aliases should be stored in. Should be a persistence name that's registered in generis/persistences.conf.php

Value example: