Re: Use case driven work

Hi Frans,

My 2 cents in line below.

On 06/02/2015 12:34, Frans Knibbe | Geodan wrote:
> Hello all,
>
> It is great to see so many and diverse use cases being contributed. I do
> have some questions about how the use cases will be used...
>
> 1) The approach of gathering use cases, deriving requirements from that
> and then making something based on those requirements looks like the
> traditional waterfall method of system development. That method has some
> known problems. Most importantly, it makes it hard to deal with
> developments that somehow change the requirements. Will we rigidly hold
> on to the requirements once they have been defined? Or do we allow
> requirements to change even after the phase of collecting use cases?

That's a decision for the WG under the chairs' guidance but in terms of 
process, the Use Cases and Requirements doc can be updated at any time 
throughout the WG's life time, it doesn't have to be a one time thing.

>
> 2) At the moment, use cases come from WG members only. We are a diverse
> group, but I don't know if we are a good cross section of the people
> that will have to work with what we come up with. It would be a pity for
> real and important requirements to go unnoticed because of that. Would
> it be a good idea to ask for comments on the use cases from other,
> related communities, at some point before the requirements are defined?
> We could ask people to send comments to the public comment mailing list
> (public-sdw-comments@w3.org) for instance.

The WG *MUST* solicit comments from external stakeholders and *MUST* 
take note of what they say. That doesn't mean the WG has to agree with 
them but does have to respond to comments and the public comment list is 
there for that purpose. Those comments may themselves be a new use case 
or a modification of an existing one. The WG makes the decisions but the 
process ensures that those decisions are informed by the wider community.

>
> 3) It is my experience that in purely use case driven system design
> important requirements can be left out. That especially goes for
> requirements that do not directly come from user stories, but from
> common sense design principles. Principles like modularity, keeping
> things as simple as possible, separation of concerns. In my mind those
> things are very important. In case this kind of requirement does not
> follow from the use cases, do we still have room to add them or to keep
> them otherwise in mind?

Here are some examples of UCR docs:

LDP http://www.w3.org/TR/ldp-ucr/
Web Audio http://www.w3.org/TR/webaudio-usecases/
CSV http://www.w3.org/TR/csvw-ucr/
SKOS http://www.w3.org/TR/skos-ucr/

They all begin with an intro that sets out the general problem to be 
solved (one might think of that as a preçis of the charter). The intros 
also set the direction of the work to be undertaken and might identify 
the technologies to be used. That context can be used to guide the kind 
of requirements needed without necessarily ending up having to write a 
bunch of requirements that justify fundamentals such as the use of HTTP.

IMO the discipline of deriving requirements from use cases, preferably 
real world use cases with real data, is a good one. Ideally, the data 
associated with those use cases can then form the basis of a text suite 
that is published alongside each standard. Then the WG is confident that 
the new spec meets the requirements and developers can test their 
implementations against it.

Incidentally, Deirdre Lee, editor of the Data on the Web Best Practices 
WG's UCR, has gone as far as to create a little bit of RDF to describe 
which use cases link to which requirements - a process that certainly 
helped clarify my thinking when I've contributed to that doc. See
https://www.w3.org/2013/dwbp/wiki/images/2/2f/UCR.ttl
http://w3c.github.io/dwbp/usecasesv1.html

HTH

Phil.

>
> Regards,
> Frans
>
> ------------------------------------------------------------------------
> Frans Knibbe
> Geodan
> President Kennedylaan 1
> 1079 MB Amsterdam (NL)
>
> T +31 (0)20 - 5711 347
> E frans.knibbe@geodan.nl
> www.geodan.nl <http://www.geodan.nl> | disclaimer
> <http://www.geodan.nl/disclaimer>
> ------------------------------------------------------------------------
>

-- 


Phil Archer
W3C Data Activity Lead
http://www.w3.org/2013/data/

http://philarcher.org
+44 (0)7887 767755
@philarcher1

Received on Saturday, 7 February 2015 09:46:57 UTC