.. _juxl_hub_auth modifying_statements:

Modifying Statements
====================


.. image:: visualizations/responsibilities_2.jpg
   :width: 1000%
   :alt: Juxl-Hub-Responsibilites in a Sequence Diagram
   :align: center



The second task after at receiving a request is to modify the statements.

//TODO link why we need to modify statements


This step could contain multiple sub-steps.
There are many reasons why a statement should be modifyied and ways to modify a statements.
At this state there is only one modification taking place: Replacing the statement actor.


Replacing the Statement Actor
*****************************

A minimal could look like this:

.. code-block:: json

	{
	  "actor": {
	    "objectType": "Agent",
	    "account": {
	      "homePage": "https://not_my_jupyter.com/hub",
	      "name": "Not_John_Snow",
	    },
	    "name": "Not_John_Snow",
	  },
	  "verb": {
	    "id": "http://adlnet.gov/expapi/verbs/completed",
	  },
	  "object": {
	    "id": "http://example.com/activities/exercise-3",
	  }
	}


Jet, the actor could contain any value.
The user is able to replace any statement value.
A malicious user might replace their actor with another actor.

To ensure that users can only insert statements about themself, the actor value is replaced by a generated value.
Since Juxl-Hub-Auth has already authenticated the user using the token (see :ref:`juxl_hub_auth authenticating_jupyter_hub_user`), we can use the authenticated user as the actor.

Therefore, users can only insert statements about themself.






Anonymous Actor
***************

Juxl-Hub-Auth also supports anonymization.
Depending on the Configuration of Juxl, the actor might be one of the following:


A anonymous actor:

.. code-block:: json

	{
	  "objectType": "Agent",
	  "account": {
	    "homePage": "http://accounts.anonymous",
	    "name": "anonymous",
	  },
	  "name": "Anonymous",
	}


A pseudo-anonymous actor:

.. code-block:: json

	{
	  "objectType": "Agent",
	  "account": {
	    "name": "pseudo-anonymous-x34g3gpyb",
	    "homePage": "http://accounts.pseudo-anonymous",
	  },
	  "name": "pseudo-anonymous-x34g3gpyb",
	}

Or a JupyterHub actor:

.. code-block:: json

	{
	  "objectType": "Agent",
	  "account": {
	    "homePage": "https://jupyter.rwth-aachen.de/hub",
	    "name": "John_Snow",
	  },
	  "name": "John_Snow",
	}



Depending on the :code:`account.homPage` key, the following actions take place:

If :code:`account.homPage` equals :code:`http://accounts.anonymous`, or :code:`http://accounts.pseudo-anonymous` the actor is not replaced, because it is assumed, that the user wants to stay anonymous.
Otherwise, the :code:`actor` is replaced by the authenticated JupyterHub actor.

In more detail, the xAPI actor of the following JupyterHub at :code:`<jupyte_hub_url>` user: 

.. code-block:: json

   {
   "kind": "user",
   "name": "<name>",
   "admin": false,
   "groups": ["affiliation-member@rwth-aachen.de", "affiliation-student@rwth-aachen.de"],
   "server": null,
   "pending": null,
   "created": "2021-01-12T13:52:19.892397Z",
   "last_activity": "2021-07-21T16:36:40.422526Z",
   "servers": null
   }
   

is: 

.. code-block:: json

	{
	  "objectType": "Agent",
	  "account": {
	    "homePage": "<jupyte_hub_url>",
	    "name": "<name>",
	  },
	  "name": "<name>",
	}