[Yr11 Information Technology] Data Flow Diagrams

[Mark Kelly]

Hi Litsa.

Yes, the lack of storage shapes definitely marks a CD.

I've seen the Context Diagram as a representation of the system as a 
single, featureless black box connected to its external entities. Hence 
the 'context'.

Once you open the black box and look inside, you start with DFDs.

Anyway, many sites say CD = DFD level zero.  There seem to be different 
opinions on the definitions...

Litsa Tzelepis wrote:
> hi mark,
> 
> i was going by the definitions in the book, but that's how i got taught 
> these diagrams at uni too - context diagrams are a representation of the 
> info. system without the inclusion of storage files, and the level 0 
> diagram is when the files are also drawn in and each process is 
> labelled, 1, 2, 3, etc. Level 1 diagrams are when the bubbles are broken 
> down further and labelled 1.1, 1.2, 1.3, etc. And so it goes..
> 
> sorry if i have confused anyone, litsa
> 
> 
> ----- Original Message ----- From: "Mark Kelly" <kel at mckinnonsc.vic.edu.au>
> To: "Year 11 Information Technology Teachers' Mailing List" 
> <yr11it at edulists.com.au>
> Sent: Thursday, September 04, 2008 12:20 PM
> Subject: Re: [Yr11 Information Technology] Data Flow Diagrams
> 
> 
>> I've always believed context diagrams WERE Level 0 DFDs...
>>
>> Googling seems to confirm it.
>>
>> Robert Minato wrote:
>>> Thanks for the reply Laurie and Litsa
>>>
>>> Don't have IT at work in our library but I like Litsa's idea of only 
>>> going to Level 0.
>>>
>>> Thanks for the suggestions
>>>
>>> Rob
>>>
>>> Robert Minato
>>> Technology Domain Leader
>>> Catholic College Wodonga
>>> 02 6043 5546
>>>
>>>
>>>
>>>
>>>
>>> On 03/09/2008, at 10:57 AM, Litsa Tzelepis wrote:
>>>
>>>> hello.
>>>> i also use potts, but i have the jacaranda text for the occassional 
>>>> backup.
>>>> if you have this text, try go to page 255 - 258. this should help.
>>>>  i teach context diagrams and then level 0 - i then discuss level 1, 
>>>> level 2, etc. but tell the students they only need to worry about 
>>>> the context diagram and level 0.
>>>>  hope this helps, litsa
>>>>
>>>>     ----- Original Message -----
>>>>     *From:* Robert Minato <mailto:rminato at ccw.vic.edu.au>
>>>>     *To:* Year 11 Information Technology Teachers' Mailing List
>>>>     <mailto:yr11it at edulists.com.au>
>>>>     *Sent:* Wednesday, September 03, 2008 7:57 AM
>>>>     *Subject:* [Yr11 Information Technology] Data Flow Diagrams
>>>>
>>>>     I'm preparing for DFDs, something I've not taught before. The
>>>>     Potts text give two pages of, too me, brief cover. When I look at
>>>>     the DFD examples on the VITTA support cd, I feel I'm way short of
>>>>     knowing much about them. Context/level 0 diagrams are fine, but
>>>>     going further seems to leave a lot of interpretation to the
>>>>     imagination. Given that my students aren't very worldly, I don't
>>>>     expect them to grasp the topic very easily.
>>>>
>>>>     How deep are we expected to cover DFDs? The study design
>>>>     lists: tools for representing data flows, including data fl ow 
>>>> diagrams.
>>>>
>>>>     Does anyone have any notes to better exp! lain level 1 and level 2?
>>>>
>>>>     Regards
>>>>
>>>>     Rob
>>>>
>>>>     Robert Minato
>>>>     Technology Domain Leader
>>>>     Catholic College Wodonga
>>>>     02 6043 5546
>>
>>
>> -- 
>> Mark Kelly
>> Manager - Information Systems
>> McKinnon Secondary College
>> McKinnon Rd McKinnon 3204, Victoria, Australia
>> Direct line / Voicemail: 8520 9085
>> School Phone +613 8520 9000
>> School Fax +613 95789253
>> kel AT mckinnonsc.vic.edu.au
>>
>> Webmaster - http://www.mckinnonsc.vic.edu.au
>> IT Lecture notes: http://vceit.com
>> Moderator: IT Applications Mailing List
>>
>> A conclusion is the place where you got sick of thinking.

> 


-- 
Mark Kelly
Manager - Information Systems
McKinnon Secondary College
McKinnon Rd McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085
School Phone +613 8520 9000
School Fax +613 95789253
kel AT mckinnonsc.vic.edu.au

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

A conclusion is the place where you got sick of thinking.