[Year 12 SofDev] Use Case Questions

[Mark KELLY]

Hi Nick. Use cases are relatively new to SD so there's not really an
established understanding of our 'rules' for them, unlike (say) DFDs which
have been on the course and in exams for quite some time.

1. I would include printing the invoice as a system functional requirement.
After all, if the system does not generate the invoice, who does? If it
must be generated as part of the system's functionality, it should be in
the UCD.  Putting invoices into a tray, on the other hand, is not something
the software is expected to do - unless robots are part of the system.

2. How far you go separating use cases into separate <<includes >> is a
matter of judgement, I think. You have to use common sense to ask "Is this
functional requirement a significant discrete action or is it a trivial
part of a larger use case (e.g. "Print the heading on the invoice").
<<Extends>> are different because they are conditional, and if they are not
always carried out, they can't be lumped in with other activities that are
always carried out.

I give my kids latitude in their interpretation of how a UCD is built -
it's a bit of an art form, I think. As long as the functional requirements
are really CLEAR, I give my kids credit.  The main role of a UCD is to be
comprehensive and easy to understand.

At least that's what I reckon.

Regards
Mark

On 14 April 2012 22:53, Stebbing, Nicholas N <
stebbing.nicholas.n at edumail.vic.gov.au> wrote:

>  Hi all,****
>
> ** **
>
>                 I’ve spent much of today going through the archives of
> this list trying to glean as much info as I can about use case diagrams and
> Outcome 1 in general. I have to say this list is outstanding, the knowledge
> and resources shared is awesome.****
>
> ** **
>
>                 I am left with some questions about use case diagrams to
> help me assessing SAC 1…****
>
> ** **
>
> **1.       **Should things like “Printing invoice” and “Place printout in
> tray” be considered as use cases to go on a UCD?****
>
> (I’ve been telling my students no because they are not important functions
> of the system. They can be thought of as steps that are taken to complete
> the functions. Is this right? Could I be explaining it better?)****
>
> ** **
>
> **2.       **Many of my students have linked all of the different use
> cases up into a tangled web of includes and extends. At what point should
> they be separated?****
>
> (I’ve been thinking about this and have a couple of ideas. Firstly it
> seems that if an actor is associated with a use case then we can assume
> they are associated with any use cases that extend from or are included in
> it. So one point at which we need to separate cases is when one use case
> could be considered to extend from another but is performed by a different
> actor. For example if one person prepares an invoice but another person
> prints it they would have to be entirely separate use cases. Does this
> sound right?)****
>
> ** **
>
> Thanks in anticipation of any advice,****
>
> ** **
>
> Nick Stebbing****
>
> ICT Teacher****
>
> Bayside P-12 College****
>
> ** **
>
> ** **
>
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-- 
Mark Kelly
Manager of ICT, Reporting, IT Learning Area
McKinnon Secondary College
McKinnon Rd McKinnon 3204, Victoria, Australia
Direct line / Voicemail: +613 8520 9085, Fax +613 9578 9253
kel at mckinnonsc.vic.edu.au
VCE IT Lecture Notes: http://vceit.com
Moderator: IT Applications Edulist <http://www.edulists.com.au/>

--
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