[Year 12 SofDev] U3O2 module context diagram

[Selina Dennis]

Hi Mark,

 

My suggestion would be to not provide/require a context diagram here. As
you're not talking about a high level "view" of the entire system when
you're looking at a single function to calculate costs, a context diagram
wouldn't be the most appropriate diagram for students to
represent/interpret. Realistically you'd be talking about a DFD Level X
(where X would vary depending on the complexity of the entire system).
Thus, entities don't need to be shown, only the data flows entering and
exiting.

 

Hope that helps,

 

Selina Dennis

Strathmore Secondary College

 

From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Mark KELLY
Sent: Monday, 9 May 2011 3:12 PM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] U3O2 module context diagram

 

I'm tempted to use the simple version since dataflows between external
entities (EE) is verboten. 

The problem is that it implies that the customer directly provides data to
the module, whereas the website and system pass the data on before the
module becomes involved. The CD with the EE-to-EE flows would be more
informative and accurate, but it breaks our rules... 

It's a wrinkle I haven't faced before with context diagrams. 

On 9 May 2011 14:31, Esther Andrews <ANDREWS.Esther at bssc.edu.au> wrote:

Funny how the apparently simple can end up being complex.

Given your description I'd say the customer does not directly provide input
into the system so should not be on the Context diagram.

Esther

 

From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Mark KELLY
Sent: Monday, 9 May 2011 2:13 PM
To: Year 12 Software Development Teachers' Mailing List
Subject: [Year 12 SofDev] U3O2 module context diagram

 

Hi all. I',m adapting the detailed example of SD U3O2 from the study design
for my own U3O2; I'm fiddling at the edges and not changing the overall
shape of the example where the task is to create a specific module (cost
calculator) in a larger ordering/accounting system that takes order data
from a corporate website.



While getting into creating the SRS I thought the context diagram would be a
doddle.  One external entity, the customer.  The system in the circle  is
the cost calculator module.  One data flow from the customer with order
information. One data flow to the customer with the invoice. Done.

Then I realised that from the module's perspective the rest of the ordering
system might be seen as an external entity since the module has no control
over the system's operation but must exchange data with it.

Then I realised that the system also would see the corporate website as an
external entity for similar reasons. So the customer would interact with the
website which would interact with the system, which would interact with the
module that the students will be writing.

But if I showed the customer providing an order to the website, that would
be a data flow between external entities which we are not supposed to show
in a CD/DFD.

How would you guys interpret a situation like this?

-- 
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

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


_______________________________________________
http://www.edulists.com.au - FAQ, Subscribe, Unsubscribe
IT Software Development Mailing List kindly supported by
http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority
and
http://www.vcaa.vic.edu.au/vce/studies/infotech/softwaredevel3-4.html
http://www.vitta.org.au  - VITTA Victorian Information Technology Teachers
Association Inc




-- 
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

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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.edulists.com.au/pipermail/sofdev/attachments/20110509/23842bde/attachment.html