[Year 12 SofDev] Resource flows in a DFD

[Mark Kelly]

Hi Robert.  The question about resource flows became rather tangible in 
last year's SD paper (Section C, 1B) with the answer depending on the 
student recognising that a resource flow should NOT appear in a context 
diagram / DFD.

But, if 'real' DFDs _can_ show resource flows, the question would have 
been invalidated...

That's what concerns me.  We are marking things right or wrong according 
to a set of sometimes-arbitrary rules and definitions that sometimes 
only apply in our little world of VCE theory.  An outsider in The Real 
World could well argue that our answers are either moot or just plain 
wrong according to best practice.

Our definition of the SDLC, for example, is just one of many, yet we ask 
very specific questions about it that can rule all other SDLC variants 
incorrect.

I know the study design has to be specific, but it also needs to 
recognise the huge variations in accepted theory across the industry and 
can't afford to get too convinced that its - and only its definitions 
and formulations are gospel.

It's a tricky one.  I certainly wouldn't like to be writing the study 
design.  If I took my own argument to its logical conclusion, I'd end up 
spending 16 weeks covering all possible flavours of the SDLC, and the 
kids would be confused.

It's very comforting to be able to say "Kids, this is what you should 
assume the SDLC is..." and then lay it out neatly, but I keep reminding 
them that much of the theory we cover is just one interpretation of many 
varieties, and they might encounter alternative or contradictory 
versions in their travels.

Oh well, this is bordering on theology - and heresy :-)

Maybe that's why I sometimes I feel like Martin Luther nailing things to 
church doors  :-o

Timmer-Arends wrote:
> Mark and Adrian
> 
> Like you I've not heard of this so I  did a quick google on "context
> diagram"+resource flow"
> 
> Found quite a few references - they all seem to point to the idea of DFDs
> being expanded to include production and business modelling; for example:
> 
> Google books:
> "Process Oriented Analysis: Design and Optimization of Industrial 
> Production
> "
> By Urs B. Meyer, Simone
> E. Creux, Andrea K. Weber Marin
> 
> http://www.edrawsoft.com/Design-Data-Flow.php
> quote: "Data flow diagrams can be used to provide a clear representation of
> any business function..."
> 
> So I don't think SD has anything to worry about since it is looking only at
> information systems. And therefore we should only be looking at data flows.
> 
> I did find this PPT though, which doesn't do a bad job of DFDs (plus other
> business related stuff). It used Gane&Sarson conventions rather than
> DeMarco, but could be a good teacher resource if nothing else.
> www.computing.dcu.ie/~renaat/ca2/ca214/DataFlowModels.ppt
> 
> Regards
> Robert T-A
> 
> 
> ----- Original Message ----- From: "Mark Kelly" <kel at mckinnonsc.vic.edu.au>
> To: "Year 12 Software Development Teachers' Mailing List"
> <sofdev at edulists.com.au>
> Sent: Monday, April 14, 2008 1:12 PM
> Subject: [Year 12 SofDev] Resource flows in a DFD
> 
> 
>> 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
>>
>> -- 
>> 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.
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> 
> _______________________________________________
> http://www.edulists.com.au
> IT Software Development Mailing List kindly supported by
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> 
> 
> 

-- 
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.