[Year 12 SofDev] Oliver's Mexican Cantina

Fri Jul 29 14:40:04 EST 2011

Hi again Allan

The study design example was doing its best to curtail the scope of the
student's software: a wise and noble ambition.
I can appreciate why the example wanted to exclude the need for complex
wireless data transmission from the student's scope, but the unrealistic
repercussions in the CD/DFD (as you described) don't sit well either.

I don't know what the official definition of a data store is, or even if
there is one at all.
If a program writes data to a file, but never reads it back again, is it
still a data store?  After all, once it's written it's not really *in* the
system any more.
It's a handkerchief dropped by the roadside waiting for the other software
to come along and pick it up.
Most of the time our DFD data stores are read/write.
This rare exception in the Cantina example is unusual and (I find) hard to
handle using basic DFD/CD theory because it is so unusual.

Anyway, that's my 4 Mauritanian ouguiyas and 2 khoums' worth.

On 29 July 2011 09:58, Allan Barnes <abarnes at aiet.com.au> wrote:

>  Hi Mark****
>
> ** **
>
> I have to admit I didn’t spend a lot of time reading the case study in the
> study design, although I did find it a little confusing. I don’t quite
> understand the idea behind the kitchen system – if I was designing the info
> system (which clearly I’m not) the external entity at the end of the line
> would be the chef who stands there and yells out the orders  a la Gordon
> Ramsey but without the swearing, and the kitchen system would therefore just
> be the display mechanism for the order to be received, similar to a printer,
> for example. The transmitting software I also would not have considered as
> an entity either as it is just the method used to transfer the data from the
> waiter to the chef, and therefore is not part of the systems analysis model.
> ****
>
> ** **
>
> To me it is:****
>
> **
>     **** **
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>
> As pointed out, if it is a context diagram the data store is not shown, but
> if it is a DFD it is. I read the case study once and couldn’t see any
> reference to whether it needed to be a DFD or context diagram – it may have
> been in there and I missed it.****
>
> ** **
>
> The way I was taught at Uni was that the system analysis stage is not
> interested in how the information gets from point A to point B – that is the
> domain of the person designing the system, thus the hand-held PC, the
> transmitting software and the display are irrelevant to the analysis of the
> system. If Gordon says he wants his waiters to have hand held PC’s and the
> data to be transmitted somehow to somewhere and displayed on a screen then
> this is part of my design of the system but is not relevant to how the
> information is gathered and processed.****
>
> ** **
>
> I don’t know if systems analysis and design has changed since my uni days
> but we were always taught a very strict delineation between analysis and
> design and what was considered in each stage.****
>
> ** **
>
> ** **
>
> The Aussie dollar is doing well so I’m back on the Aussie (no disrespect to
> the PNG currency).****
>
> ** **
>
> ** **
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>
> Kind regards****
>
> ** **
>
> Allan Barnes, CEO****
>
> Australian Institute of Education and Training****
>
> P.O. Box 171****
>
> Brunswick West 3055****
>
> Melbourne, Victoria****
>
> Ph: (03) 9387 2051****
>
> FAX: (03) 9387 3470****
>
> Mobile: 0409 428 221****
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> *From:* sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au] *On Behalf Of *Mark KELLY
> *Sent:* Friday, 29 July 2011 9:32 AM
>
> *To:* Year 12 Software Development Teachers' Mailing List
> *Subject:* Re: [Year 12 SofDev] Oliver's Mexican Cantina****
>
>  ** **
>
> Hi Alan. The kitchen display, to my way of thinking, is not connected to
> the Cantina software at all (a conscious decision by the author to limit the
> scope of the mobile device's functional requirements.)
>
> Between the mobile software and the kitchen system (which is an external
> entity) lies the transmitting software (also an external entity), and you
> don't show communications between external entities.
>
> 2 pigs and 1 yam's worth (for our Papua New Guinean readers)
>
> Regards
> Mark****
>
> On 28 July 2011 14:03, Allan Barnes <abarnes at aiet.com.au> wrote:****
>
> Hi Mark****
>
>  ****
>
> To my thinking the second terminator is the kitchen display and not the
> software itself. This is because (IMHO) the software is the method of
> transmitting the text file containing the order whereas the kitchen display
> is if you like the end user. Happy to be shot down in flames though. My 1c
> worth.****
>
>  ****
>
>  ****
>
> *Error! Filename not specified.*****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
>
> Kind regards****
>
>  ****
>
> Allan Barnes, CEO****
>
> Australian Institute of Education and Training****
>
> P.O. Box 171****
>
> Brunswick West 3055****
>
> Melbourne, Victoria****
>
> Ph: (03) 9387 2051****
>
> FAX: (03) 9387 3470****
>
> Mobile: 0409 428 221****
>
>  ****
>
>  ****
>
>  ****
>
> *From:* sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au] *On Behalf Of *Mark KELLY
> *Sent:* Thursday, 28 July 2011 1:43 PM
> *To:* Year 12 Software Development Teachers' Mailing List
> *Subject:* [Year 12 SofDev] Oliver's Mexican Cantina****
>
>  ****
>
> Hi all. I'm playing with an SRS based on the Cantina (study design p.84).
>
> I've got to the context diagram, and I've attached a first draft.  I'm not
> 100% of a couple of things:
>
> 1. I have excluded the customers as an external entity since they don't
> interact with the system: the waiter does.
>
> 2. I included the transmission software as an external entity since it
> takes the text file from the ordering software.  But if the text file is
> saved should it then be considered outside of the system rather than an
> active data store within the system?  In that case, the transmission
> software should not be included at all.
>
> Any ideas?
>
> Cheers
> Mark
>
> --
> 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/>
>
> Want a good time? Call 0112358. Ask for Mr Fibonacci.****
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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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> Want a good time? Call 0112358. Ask for Mr Fibonacci.*
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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/>

Want a good time? Call 0112358. Ask for Mr Fibonacci.
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