Re: [use_cases] Web Payments Use Cases - Organized by Phases

> On 11 Mar 2015, at 13:06, Ian Jacobs <ij@w3.org> wrote:
> 
>> 
>> On Mar 11, 2015, at 4:47 AM, Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>> wrote:
>> 
>> 
>>> On 10 Mar 2015, at 19:36, Ian Jacobs <ij@w3.org <mailto:ij@w3.org>> wrote:
>>> 
>>> 
>>>> On Mar 10, 2015, at 12:34 PM, Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>> wrote:
>>> 
>>> However, it seems like you would like to include a note somewhere (e.g,. in a use case) about updating the vouchers. Where would you add it and what would you say?
>> 
>> The use cases I already submitted cover this to some extent,
>> but I think we need further uses cases to cover more of the details.  I will work on that.
> 
> +1. Could we chat about how to integrate them into:
> http://www.w3.org/2015/03/wpay-usecases.html <http://www.w3.org/2015/03/wpay-usecases.html>
> 
> (Either as micro-narratives or use cases)

Sure, let’s find a convenient time.

>  "Exceptions. This document does not explicitly address various exceptions that might happen such as transactions failing. The architecture will need to take these into account (e.g., if a Payer applies a coupon and the transaction fails, the Payer's coupon would be restored).”
> 
> Turning this into a general question:
> 
> * Should the use cases (but not the phase model at the higher level) call out exceptions that need to be addressed in the architecture?
>   Or should these first appear in the architecture?


Use cases are there to serve a purpose. That purpose is to provide a link between the user experience and the technical framework needed to support it. I personally find it valuable to have use cases that cover a broad range of scenarios and this helps to raise questions that the technical work needs to answer.   When it comes to writing software, handling the exceptions takes up most of the work. So having use cases that illustrate some fraction of the exceptions is helpful for grounding the technical discussion.

Writing the use cases is fairly easy. If writing up the flow model is complicating this, then just may be the flow model and the ramifications caused by exceptions should be described in a separate document together with the analysis of the functional requirements.

Best regards,
—
   Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>