[Sigia-l] RE: Use cases and user centric design (was sitepath diagramming)

[Katherine Marshak]

Hi everyone. 
I've fallen behind on this interesting thread so please forgive me while
I respond to multiple posts. 

I strongly advocate developing a business process model or business
workflow model very early in a project. This model can often be sketched
on a white board in an hour (or you can devote lots of energy, depending
on the project). These models give the team has a common reference
point. It also reminds us that the application or site we're building is
a small part of users' lives. 

Several people (Doug Howell, Pradyot Rai, etc.) mentioned that they have
moved to diagrams to overcome problems associated with use cases. I've
seen some projects use this approach successfully when they keep the
notation simple (basic flow charting or UML activity diagrams without
lots of esoteric notation). If you use diagrams such as these, are you
still creating a use case model to show the overall scope? 

Several posts raised questions about the level of detail in use cases.
While there's no one answer that's right for every project, I think a
few rules of thumb can help.

-- Keep user interface information such as page names, link & button
names, tab order, widget selection out of the use case.

-- Specify the interaction between the actors and the system under
development. 

-- Specify the expected attributes/fields. Anne Hjortshoj said she uses
bullet lists of this info. This has been a very effective technique for
us, too. 

-- If you have business rules that apply to multiple use cases or
multiple projects, keep them in a business rule specification so the use
cases can all refer to a single (and hopefully correct) set.

-- Keep design decisions such as "The xyz field has a max length of 19
characters (alpha only)" out of the use cases. There are better places
to keep this info. 

Someone on this list also said that use cases don't ensure usability. I
agree. But let's say thanks to Ivar Jacobson because use cases are a
huge improvement over the system-centered way of stating requirements.
The fact that use cases can change "The system shall support..." into
"The <role name> <does something useful>" is wonderful! 

thanks,
Kathy Marshak, Senior Consultant
IconMedialab | www.iconmedialab.com