[Year 12 SofDev] DFD question

Mon Feb 25 11:10:41 EST 2013

I'm tending to agree with Selina on this one. The DFD would be not
dissimilar to the worked example in Adrian's book (pp 51-57). However, I
think I would definitely be including the waiter in the UCD as surely he is
an actor interacting with the use cases in the system.

signiture

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Michael Wooldridge

Information Technology Teacher

Mornington Secondary College

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From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Selina Dennis
Sent: Monday, 25 February 2013 10:31 AM
To: 'Year 12 Software Development Teachers' Mailing List'
Subject: Re: [Year 12 SofDev] DFD question

Hi Mark,

I'd disagree with your argument in regards to the Customer not playing a
role in interacting with the system. To me, the waiter is simply the input
method - much like a keyboard - and the information is coming from the
customer. So in a DFD/UCD scenario, I wouldn't include the waiter in the
process of ordering food - that would come from the customer. However, if
the waiter had some other interaction with the system, such as collecting
tips at the end of the day, then they would become more than simply the
input method, and thus would be shown.

Hope that makes sense! Just my take on it.

Selina Dennis

Strathmore Secondary College

From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Mark
Sent: Monday, 25 February 2013 10:06 AM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] DFD question

Hi all. It's an interesting situation.  This is my take on it.

We all probably start by seeing it from a human point of view: the customer
is dealing with the waiter, who deals with the system. So the customer is an
integral part of the transaction and therefore appear in a DFD or UCD...

But the waiter is not a part of the system: he/she interacts with it as an
external entity (EE).

So where does the customer fit in?  An EE to the EE waiter?  An EE once
removed? We don't do that in DFD or UCD.

>From the system's point of view, the waiter is an EE. The customer is a
fictional character that the system does not see, hear, or believe in. Only
the waiter exists to the system.  Everyone else is Santa Claus.

We could complicate it further and imagine that a child is giving her meal
choice to her mother who gives it to the waiter... should the child be in
the DFD/UCD now as an EE twice removed?

If a waiter were ordering his own lunch from the kitchen, would he be
represented again in the diagram - this time as a customerless EE?

As I read it, the customer is not directly interacting with the system; the
waiter is.  So the waiter appears as an EE.

So I would not include the customer at all in a DFD or UCD.

Anyone out there who did DFD/UCD at uni?

Cheers

Mark

On 25 February 2013 08:57, Kent Beveridge <kbeveridge at stbc.vic.edu.au>
wrote:

Data flow to my understanding here..

Waiter to Customer ....Request for order

Customer to Waiter ....Food/Beverage order

Waiter and Customer both 'entities' send data back to the central part of
the 'system' (restuarant system) via the waiter

Yep actors are waiter and customer.

I havent started UCD stuff with my guys just yet..focussing on DFD's ...ucd
next.

Kent Beveridge

ICT Coordinator & Maths Teacher

kbeveridge at stbc.vic.edu.au

  _____  

From: sofdev-bounces at edulists.com.au [sofdev-bounces at edulists.com.au] on
behalf of Mark [mark at vceit.com]
Sent: Saturday, 23 February 2013 7:15 AM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] DFD question

I had the same issue with the DFD and UCD for one of the programming
outcomes.  

The restaurant customer would be an obvious actor/external entity in a
system that takes meal orders.

However since the waiter is the one interacting with the system, and the
customer is interacting with the waiter, the customer does not appear at all
in the system representation.

Sometimes what seems logical is not as it first appears.

On 22 February 2013 13:14, Simone Tynan <Simone.Tynan at shcy.vic.edu.au>
wrote:

Hi all, 

I am having trouble with aspects of a DFD.

I have a DFD and context diagram in which shows a customer orders a service
and it is quoted and carried out.

Similar scenario, except the service is being carried out for a beneficiary.
(Think Ninja and assassins. ;-) )

The Customer is providing all details and payments. The beneficiary is not
actually adding to or receiving from the system (that I can see).

Are they still added as an external entity? Is there any connection between
them and the system?

Many thanks for any input/

Simone

************************************
Simone Tynan
eLearning Leader
LOTE Leader P-12
Simone.Tynan at shcy.vic.edu.au

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