Re: [GNAP] [Txauth] Revisiting the photo sharing example (a driving use case for the creation of OAuth)

I've often thought of front channel as an interaction visible to the user,
and back channel as being between two software systems, in this case, the
client and GS.

Consent from the user is the front channel, independent of how the user
gets to the GS, or if an app is part of the GS, or is the GS.
ᐧ

On Thu, Aug 13, 2020 at 8:34 AM Fabien Imbault <fabien.imbault@gmail.com>
wrote:

> Indeed.
>
> On Thu, Aug 13, 2020 at 5:33 PM Justin Richer <jricher@mit.edu> wrote:
>
>> A point I forgot to make below: the “front channel” isn’t going to exist
>> for a lot of systems anymore, where interaction happens through an app or
>> communication happens through some separate communication fabric. So there
>> are cases, just like in OAuth 2, where there’s only a “back channel” and
>> the other aspect of the AS never comes into play.
>>
>>  — Justin
>>
>> On Aug 13, 2020, at 11:17 AM, Fabien Imbault <fabien.imbault@gmail.com>
>> wrote:
>>
>> Without surprise, +1 to differentiate between the back-channel and the
>> front-channel.
>>
>> On Thu, Aug 13, 2020 at 5:15 PM Justin Richer <jricher@mit.edu> wrote:
>>
>>> Denis, I want to focus on one point here:
>>>
>>> In OAuth 2.0, the user consent is performed by the AS using an authorize
>>> endpoint where the user consent is solicited and captured.
>>>
>>> Since a user, with no prior experience, shall first connect to a RS to
>>> perform an operation, the user consent shall be performed by the RS,
>>> instead of the AS. This means that we should define a "consent"
>>> endpoint at the RS.
>>>
>>>
>>> One of my goals with XYZ’s design was to be able to separate the
>>> interaction with the user from the web-based flows for the delegation
>>> protocol, and that aspect is enshrined in the GNAP charter as well.
>>>
>>> It points to the reality that there are two different aspects of the
>>> traditional AS that we might need to talk about separately now. One deals
>>> with delegation, issuing tokens, returning data directly to the client (not
>>> through a separate API, since that’s the RS), and other back-channel stuff.
>>> The other aspect deals with interacting with the user and/or resource
>>> owner.
>>>
>>> We already saw bits of this in OAuth 2: the AS is defined by the pair of
>>> the token endpoint and authorization endpoint, each filling the respective
>>> roles above. What if we formally separate these? Strawman names:
>>>
>>>
>>> Delegation Server (DS) - handles the back-channel stuff
>>>
>>> Interaction Server (IS) - handles the front-channel stuff
>>>
>>>
>>>  — Justin
>>>
>>> --
>>> TXAuth mailing list
>>> TXAuth@ietf.org
>>> https://www.ietf.org/mailman/listinfo/txauth
>>>
>>
>>