[Tutor] data flow
alan.gauld@bt.com
alan.gauld@bt.com
Wed, 7 Mar 2001 23:32:09 -0000
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What is a data flow model?
A model of how data flows thru a system.
In an order entry system order details will be captured from the customer
and stored in a data form. Later those details will be passed to various
order handling systems, stock control modules, billing and receipting
systems etc. Drawing the various processes and systems as bubbles and the
flow of data between them with arrows yieds a data flow model. (Actually
theres a bit more to it than that but thats the idea.)
You can then break down each top level process bubble and analyse how it
manipulates its top level data inputs to generate its top level data outputs
etc.
Data stores represent files and databases etc and provide a link to the
actual mdata definitions for a database etc. (Entity Relationships in
technical terms)
Check out any reasonable software engineering textbook for a more precise
description.
Data flows are very good at modelling typical business processes in a form
suitable for turning into software systems. They are less good for designing
the details of those systems. They are very poor at producing object
oriented designs, although various people have produced heuristics for so
doing...
HTH
Alan G.
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<BLOCKQUOTE
style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">
<DIV><FONT face=Arial size=2>What is a data flow model?</FONT></DIV>
<DIV> </DIV></BLOCKQUOTE>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>A
model of how data flows thru a system.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>In an
order entry system order details will be captured from the customer and stored
in a data form. Later those details will be passed to various order handling
systems, stock control modules, billing and receipting systems etc. Drawing the
various processes and systems as bubbles and the flow of data between them with
arrows yieds a data flow model. (Actually theres a bit more to it than that but
thats the idea.)</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>You
can then break down each top level process bubble and analyse how it
manipulates its top level data inputs to generate its top level data
outputs etc.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>Data
stores represent files and databases etc and provide a link to the actual mdata
definitions for a database etc. (Entity Relationships in technical
terms)</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>Check
out any reasonable software engineering textbook for a more precise
description.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>Data
flows are very good at modelling typical business processes in a form suitable
for turning into software systems. They are less good for designing the details
of those systems. They are very poor at producing object oriented designs,
although various people have produced heuristics for so
doing...</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001>HTH</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=970541923-07032001></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=970541923-07032001>Alan
G.</SPAN></FONT></DIV></BODY></HTML>
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