Re: [egov] Proposed Use Case template

[Rex Brooks <rexb@starbourne.com>]

Title: Re: [egov] Proposed Use Case template

Hi Folks,

I hesitated about responding to the initial suggestion because there is such a wide variance in the way use-cases are described in different contexts. (And I have been hesitating a long time before deciding to be more active in this TC, as a prospective member.)

I have seen more than three different kinds of use case descriptions in the TCs in which I have participated. These have included word processing documents, spreadsheets and Visio diagrams in addition to visual programming tools. Also, I was thrown by the combination of a specific kind of use-case diagram from UML combined with a set of textual elements that begin to describe some very context-dependent categories into which it is assumed specific use cases will fall. Unfortunately my own experience doesn't agree with this approach because it starts with a structure and in my experience processes don't occur that way even if a process seeks to create that kind of organized structure as an end result.

I am concerned that these high level overviews can't capture adequately how and where specific kinds of information is introduced into these processes. I am not suggesting that these methods be dropped, but set aside for the moment in favor of capturing "scenarios" drawn from actual experience with the specific kinds of processes to be modeled. In other words, I would rather see textual descriptions, for which a Word Template can be downloaded from the "Business Scenarios" document directory at

http://www.oasis-open.org/apps/org/workgroup/wsrp/documents.php

where I suggest just downloading the first one in order to see the template and an example of how it was used. While working on WSRP 1.0, we developed 10-12 of these "Scenarios" then narrowed down the field to a few that offered use-cases that appeared to capture the key ingredients we needed to address in the specification and worked from there down to specifics for the final. It was somewhat of a rigorous process and took more than 18 months, but it worked fairly well.

I would prefer to see, say three different kinds of environmental impact statements from different governments for different kinds of large scale projects in different environments, such as oil pipelines, timber processing plants and toxic waste treatment facilities, to chose just one area of governmental concerns, and see where such projects develop common features that can then be abstracted into the kinds of use-case models as I see being developed here.

If what is being proposed fits the actual scenarios, then we will know that we are grounded. Being grounded is more important, it seems to me, than creating structures at this point, although I am sure that a great deal of experience with "systems" has gone into this model, and it may well be accurate and useful, but I can't tell that in the abstract.

Please take no offense, Farrukh, I hope it proves out that your model is well drawn and fits many more instances than those I cite, but I have no background that enables me to reckon that.

However, you have certainly defined an extremely important consideration.

Ciao,

Rex

At 9:18 AM -0500 2/10/04, Farrukh Najmi wrote:

> Hi Tim,
>
> Thanks for these valuable suggestions Tim. Some questions and comments
> below...
>
> Tim Benson wrote:
> > A useful use case template. I have
> > several minor suggestions, which, if accepted in full, would add one
> > extra heading, merge four and make minor changes to three others:
> >
> > (a) Add a heading "Scope, Goal and Context". This might replace or
> > supplement the present "Description", as well as "Exceptions",
> > "Special Requirements" and "Assumptions" (all of which are
> > somewhat ambiguous terms, liable to be used in different ways by
> > different authors)
> I find Description as more general and descriptive than "Scope, Goal
> and Context". It is also more universally used in practice. What do
> others think?
> Exceptions are very distinct and important a section. It is to list
> what can be some out-of-the-ordinary paths or outcomes within the use
> case.
> For example a use case to register a new student in a course may have
> an identified exception that the student has not paid their fees and
> therefor will
> not be registered.
>
> I agree that "Special Requirements" and "Assumptions" are
> ambiguous. Maybe they can be combined into one title: "Special
> Requirements" and "Assumptions"?
> > (b) Suggest adding Cockburn's
> > classification of "High level", "User goal" and
> > "Sub-function" to categorise use cases into those which can be met
> > using more than one "user session", one "user session" or a
> > small part of a "user session" respectively.
> I am not clear on above suggestion. On a net search I found:
>
> http://www.dotnetcoders.com/web/learning/uml/diagrams/usecase.aspx
>
> But that does not explain what you meant. Can you post a link?
> > (c) Explicitly identify the primary actor
> > to whom the use case provides value, or initiates the use case -
> > perhaps add a phrase "(list primary actor first)".
> Excellent suggestion. Will add this phrase.
> > (d) Change "Pre-conditions" to
> > "Pre-conditions and Triggers" - it is often useful to identify a
> > specific trigger event especially in interoperability.
> Good suggestions. Will do.
> > (e) Change "Priority" to "Priority
> > and Frequency of Occurrence" - these are two different
> > dimensions.
> Priority is meant to be simple Low, Medium, Hi distinction. There are
> many factors that may decide on priority besides frequency of
> occurance.
> Do you think we should list "Frequency of Occurrence" as a
> separate title?
>
> I will send a revised template for use cases based on what we agree
> upon in the discussion on this thread later this week. Team please
> share your thoughts.
>
> --
> Regards,
> Farrukh
>
>
>
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-- 

Rex Brooks
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