I think we need Use Cases

I would like to suggest adding a discussion about the topic of Use Cases 
(not User Stories) to the agenda.

I believe a lot of the email threads in and outside of the WG are mixing 
up multiple use cases, and therefore we run into unnecessary 
controversies and misunderstandings. In reality we all agree on the 
requirements, but we need to spell out to which Use Case they apply.

Here is what I believe what is missing: we have User Stories and jump to 
Requirements from them. However, there are also Use Cases, which are 
generalizations of the User Stories, and which capture the essence of 
those into more abstract entities. As quoted in our current UCR document [1]

*Use Cases 
<https://w3c.github.io/data-shapes/data-shapes-ucr/#usecases>*are used 
to capture and model functional requirements. Use cases describe the 
system’s behavior under various conditions.

For shapes, such use cases could be:

1) Check constraints for a given resource
     a) against a given Shape (selected externally)
     b) based on Shapes derived from the resource

2) Check constraints for a given graph
     a) against an externally defined shape selection process
     b) based on the Shapes derived from the graph itself

The distinction between a) and b) is crucial. Both use cases are needed. 
There is another dimension:

C) When you are inside of a controlled environment / sub-community
O) When you are publishing a vocabulary to the open "Semantic Web"

The latter is the "default" intention that is encoded in a vocabulary 
when published, while the former allows anyone to re-purpose data, 
ignoring the default intention. I believe a lot of cross-purpose talk in 
this WG stems from this difference.

3) Use a Shape description to build an edit/search form
     a) with an RDF-based data model / API
     b) with something like plain JSON (e.g. using JSON-LD)

See also [2] on how to possibly implement the Use Cases 1 and 2 (there 
are of course other implementations possible).

Holger

[1] https://w3c.github.io/data-shapes/data-shapes-ucr/
[2] https://www.w3.org/2014/data-shapes/wiki/LDOM_Algorithm