Re: [Taler] Withdrawal Flow (was: Taler Android UX)

[Florian Dold]

Hi Torsten,

Thanks, it's a great summary of what we've discussed so far.

I'm unsure about one aspect:  When you talk about the "select exchange"
screen, is this literally just the list of exchanges (and some button to
add a new one), or does it also contain some text like "Do you want to
withdraw 5 TESTKUDOS from bank.test.taler.net into your wallet?"?

This aspect of indicating to the user what's actually happening as a
resulting of scanning the QR code is IMHO currently missing.  It would
be confusing to be thrown into an exchange selection dialog without
further context!

The WebEx wallet always displays "do you want to withdraw ...", and
below that it displays the default exchange (and a button to change it),
if there is one.  If there is no default exchange, it'll show the
exchange selection dialog embedded into the same page, which is okay on
desktop browsers as there is enough screen space!

Another thing that's missing is the 2FA step that might happen after the
user confirms withdrawal in the wallet.  The final arrow is a bit
misleading, since the transaction doesn't happen immediately.  There are
three cases:

1. The bank transfer happens immediately, i.e. your bank chose to not
require 2FA for this transfer, maybe because it's under an amount
threshold, say <20 EUR per day.

2. The 2FA is "detached", i.e. you have to press "confirm" on a physical
Taler ATM, or a Taler cashier has to do a final "confirm" on their device.

3. The bank provides a confirmation_url, which allows you to navigate to
the Web page (or maybe even app!) where you can do the final 2FA step.
If you are using a desktop browser and a mobile wallet to withdraw, then
this confirmation_url is already displayed in your browser.  However, if
you accidentally close it, the wallet would have a way to re-navigate
you there.  For example by showing a dialog like:

   waiting for transaction confirmation
   [ click here to open your bank's confirmation page again ]

Note that the wallet is able to distinguish all three cases based on the
bank integration API's response.  Either the withdrawal operation is
already confirmed (case 1), it's not confirmed but the confirmation_url
is empty or not an http(s) URL (case 2) or the confirmation_url is an
http(s) url (case 3).

We could consider to include some explanation string (i18n-ized) for
case 2, which we can display in the wallet UI.  Something like "Waiting
for transaction confirmation (please confirm transaction on your
QuuxBank ATM terminal)".

The feature in the last paragraph is currently not (yet(?)) part of the
protocol, but the rest is, though very under-documented.

(Regarding Marcello's suggestion about the terminology, I actually
prefer the way you (Torsten) phrased it.)

- Florian

On 4/24/20 12:43 AM, Torsten Grote wrote:
> Dear all,
> 
> I have now summarized our discussion in an official design document that
> you can find here:
> 
>  https://docs.taler.net/design-documents/004-wallet-withdrawal-flow.html
> 
> It includes Belen's latest flow diagram. Although it does not look as
> nice, we can at least edit it in a textual graph language.
> 
> Please let me know if the document correctly reflects our discussion and
> if there's something else we should add.
> 
> Kind Regards,
> Torsten
>