[Year 12 SofDev] DFDs

[Mark]

Thanks, Kevork. One learns something new every day!
I wouldn't introduce this complexity to our kids' DFDs and UCDs, however.

Cheers
Mark


On 25 February 2013 13:24, Kevork KROZIAN <kkrozian at ringwoodsc.vic.edu.au>wrote:

>  Hi James,
>
>
>
> I just opened *Use Cases Requirements in Context* by Daryl Kulak and
> Eamonn Guiney and p 39 states:
>
> “ It is often hard to decide which actors to show on a use case diagram.
> For example,, when a supplier provides an invoice to a company clerk and
> the clerk enters the invoice into the system, should the supplier be
> included in the diagram ? If the supplier is shown it is called a *
> secondary* actor. Our rule is that the supplier should be shown in the
> diagram if the supplier’s behaviour impacts the system in any way. For
> example, if a supplier sends a shipment late and that changes how the
> system reacts, then the supplier should be in the diagram.”
>
>
>
> In a restaurant a waiter can’t interact with the ordering system until the
> customer places the order. A delay does not change the response from the
> system.  The waiter would appear in the UCD but not the DFD which would
> show the customer – the supplier or source of the data or the order. I
> wouldn’t place the waiter in the DFD as they are not the source of the data.
>
>
>
> Perhaps you can offer details of your textbook if anyone wants to get a
> hold of it .
>
>
>
> Just my take on the discussion
>
>
>
> Kind Regards
>
>
>
> Kevork Krozian
>
> IT Pathways Manager
>
> Ringwood Trade Training Facility
>
> Tel: 0419 356 034
>
>
>
> *From:* sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au] *On Behalf Of *Vella, James
> *Sent:* Monday, 25 February 2013 10:56 AM
> *To:* sofdev at edulists.com.au
> *Subject:* Re: [Year 12 SofDev] DFDs
>
>
>
> Strictly speaking as someone who did DFDs at uni…
>
>
>
> As Mark has said, we sometimes think in a human sense however DFDs don’t
> allow us to see the interactions between two EEs.
>
>
>
> As Selina has said, the waiter is just the input method – so we can leave
> it out. I think our students sometimes find it hard at this stage where
> they have to decide what should and shouldn’t be included in our DFDs.
>
>
>
> In terms of the DFD, you could argue either way for one or the other….but
> NOT BOTH! J
>
>
>
> That being said, in the UCD you can list both as actors because they both
> have roles in the system.
>
>
>
> I have a whole text book on this stuff from my 2nd year at LaTrobe which
> I’m using with my kids at the moment…DFDs, UCDs, UML the whole kit and
> caboodle!
>
>
>
> Regards
>
>
>
> Mr James Vella
>
> MacKillop College
>
>
>
>  <snip>
>

Mark Kelly
mark at vceit.com
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