[Year 12 SofDev] U3O2 module context diagram

[Mark KELLY]

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

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