[Year 12 SofDev] Resource flows in a DFD

[Mark Kelly]

Hi Allan.  Yes, I realise DFDs have usually only shown data flows, as 
their name implies.  My concern was my research has found that physical 
resource flows (such as real books) have been included in context 
diagrams and DFDs.  That's the sticking point.

Allan Barnes wrote:
> My understanding from Uni days is that DFD's are diagrams of logical systems
> and represent flow of information. I don't quite follow what you mean when
> you say a resource flow, Mark, but the DFD can in my opinion show things
> such as book orders, for example, as this is a flow of information, however,
> it would not show that it is Michael who has ordered the books, or that he
> has ordered it over the phone, etc.
> 
> The physical design provides information about how the processing takes
> place. It may show who sends or receives the information, who manipulates
> the data, where it is manipulated, what happens to it, what structure it
> takes, whether the transaction occurs on the computer, the Internet, by
> telephone, by cash register or by a paper-based method. The physical design
> will also include details about the specifications of the hardware and
> software that is to be used in the information system. It uses diagrams such
> as hierarchy charts, structure charts and system flow charts to represent
> the information.
> 
> 
> 
>  
> 
> Kind regards
>  
> Allan Barnes, CEO
> Australian Institute of Education and Training
> P.O. Box 171
> Brunswick West 3055
> Ph: (03) 9387 2051
> FAX: (03) 9387 3470
> Mobile: 0409 428 221
>  
> -----Original Message-----
> From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
> On Behalf Of Kevin Feely
> Sent: Monday, 14 April 2008 4:49 PM
> To: Year 12 Software Development Teachers' Mailing List
> Subject: Re: [Year 12 SofDev] Resource flows in a DFD
> 
> Hi mark,
> In all of the exercises i have done with context diagrams (level 0) and 
> DFD's (mainly level 1 and only discussion about level 2) i have always 
> said only data (information) should be represented. That the DFD is not 
> concerned with the actual goods ordered or purchased for example, but 
> the information these transactions generate.
> I suppose this is because we are modeling information systems using the 
> DFD tool.
> I suppose it is possible to model physical systems with the DFD as well 
> ( obviously from your link!) but  iam not sure they should be intertwined.
> That is if a student represents a physical transaction on my information 
> DFD i would regard that as an error.
> regards
> Kev
> 
> Mark Kelly wrote:
>> I can't remember seeing a resource flow in an SD DFD, but apparently 
>> they exist (e.g. 
>> http://www.getahead-direct.com/gwba03-context-diagram.htm)
>>
>> Are they deliberately avoided in SD or are they not industry-standard?
>>
>> Cheers
>> Mark
>>
> 
> Important - This email and any attachments may be confidential. If received
> in error, please contact us and delete all copies. Before opening or using
> attachments check them for viruses and defects. Regardless of any loss,
> damage or consequence, whether caused by the negligence of the sender or
> not, resulting directly or indirectly from the use of any attached files our
> liability is limited to resupplying any affected attachments. Any
> representations or opinions expressed are those of the individual sender,
> and not necessarily those of the Department of Education and Early Childhood
> Development.
> _______________________________________________
> http://www.edulists.com.au
> IT Software Development Mailing List kindly supported by
> http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority
> and
> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html  - VITTA
> Victorian Information Technology Teachers Association Inc

-- 
Mark Kelly
Manager - Information Systems
McKinnon Secondary College
kel AT mckinnonsc.vic.edu.au
McKinnon Rd, McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085 Fax +613 9578 9253

Webmaster - http://www.mckinnonsc.vic.edu.au
IT Lecture notes: http://vceit.com
Moderator: IT Applications Mailing List

Only those who swim against the current know the current is there.