CELTIC Python Bindings

This module contains a thin wrapper around the CELTIC service which allows for cross-platform LTI validation.

Dependencies

• requests

Tests

tox is used as a test runner for this library. It is configured to run tests for py27, py35 and py36.

pip install tox
tox

Usage

from celtic_lib import get_lti_validator, LTIValidatorException

LTI_LISTEN_LOCATION = "https://localhost:8000/lti"

def handle_request(request):
    """
        request contains some LTI payload you just received in your application    
    """

    app_key = "some_long_unique_string_unique_to_this_application"
    celtic_service_uri = "https://location_of_celtic_service.net/"

    lti_validator = get_lti_validator(celtic_service_uri, app_key)

    http_method = request.method # Will be "POST", since we are only listening on the POST endpoint
    try:
        status, result = lti_validator.validate_request(LTI_LISTEN_LOCATION, http_method, request.POST)
        return print("Request is valid and can be trusted")
    except LTIValidatorException as e:
        return print("Request failed:", e.message, "|", e.status_code)

# router is an imaginary application router.
#   For purposes of this is makes the handle_lti_request function handle all POST requests which are directed at LTI_LISTEN_LOCATION
router.on(LTI_LISTEN_LOCATION, "POST", handle_lti_request)

Architecture

This module is fairly straightforward, it forwards any LTI request to a secure endpoint which contains a record of the oauth_consumer_key and the secret_key. This remote endpoint then validates the request, and returns a simple response indicating its validity.

DataRequester This class exposes a post method which takes the CELTIC service endpoint, and the POST data to send it. It returns the CELTIC response wrapped in the following interface:

* status_code
* json()

The primary reason of this class is to allow users to swap out the default DataRequester for their own to provide better control over the application

LTIValidator A class which handles the plumbing of the LTI validation. It is given a CELTIC service URI, an app_key, and a DataRequester instance. The user then only needs to call the validate_request method with a forwarded LTI payload to determine the validity of it.

LTIValidatorException An exception thrown when the server returns a not-good error code about the LTI response. The exception exposes the following data:

* message - The error message the CELTIC server responded with
* status_code - The HTTP status code the CELTIC server responded with
* errors - The response body the CELTIC service responded with

Developing

To make improvements to this package, the following is required:

* A python environment
* [pandoc](https://pandoc.org/installing.html) is used to convert this README.md into `reStructuredText`
    1. First: pip install pypandoc
    2. Second: Download installer from pandoc website