[Novalug] Tools to map data flow

Peter Larsen plarsen@famlarsen.homelinux.com
Mon Nov 2 11:26:27 EST 2009


On Mon, 2009-11-02 at 05:30 -0800, Igor Birman wrote: 

> Back before the recent ice age, we used to use Data Flow Diagrams.
> Their purpose is to be very simple - they only have four symbols:
> process, input/output, file/database, flow.  They are easy to create
> and to share, and are designed to NOT describe anything about how or
> when things will be accomplished so that you can concentrate on just
> the data flows themselves.  They are easy to create in any software
> including open office draw, power point, visio, etc.


Ohhh we do use them today. But a bit more advanced and different
symbology. UML is a drawing standard that has the flow features as you
describe them, but it's much more extended now. Creating and planning
larger systems requires a way to symbolize your abstract thinking. If
you're a very very good programmer and all alone, you may not need to do
that as much. However, when you have 10s of programmers working on the
same models, features and approaches the models are essential for
coordination and planning.

You model your objects, data entities, your flow (programming, business)
and the interdependencies. The traditional data-flow also had
attachments to do this, but they were meant for very basic procedural
programming languages; not object-oriented programming languages. That's
why they're insufficient today.

I had a professor who put it this way: If you're a good cook you may
only need to be told to bake cookies and you have all the knowledge you
need. However, others may need the process broken down in step-by-step
guides. And the less we know the more detailed those steps have to be.
The same goes for software development.


> I am not really sure why people don't use them more?  Can anyone give
> me a reason not to use data flow diagrams?  I have a couple on my cube
> wall now and they are very helpful..


It's one of the things I miss in open-source projects. Why don't they
publish the object models?  Or the datamodel of the database when such a
thing is used? I think partly because the community isn't aware of a
standard for how to represent the UML and similar diagrams. But such
standards do exist (they're XML based). Eclipse does a good job of
trying to use these standard formats to render diagrams. And it also
helps you validating that your diagrams are complete and consistent.

Back before the ice-age, unless you had very very expensive Case tools,
your diagrams were just graphics. Once done, you transferred your
diagrammed reality to code manually. Today, when you do your diagrams
you're actually coding (at least in Java). It's a lot of time saved and
high QA as a result.

-- 

Best Regards
  Peter Larsen

Wise words of the day:
One doesn't have a sense of humor.  It has you.
		-- Larry Gelbart


> 
> Igor
> 
> 
> 
> ______________________________________________________________________
> 
> From: Rich Goodwin <Rich.Goodwin@cox.net>
> To: NOVALUG <NOVALUG@calypso.tux.org>
> Sent: Sun, November 1, 2009 4:33:48 PM
> Subject: [Novalug] Tools to map data flow
> 
> Since there are alot of smart folks out there doing different work, I
> thought someone may have an idea as to how to address an issue I have.
> I have an issue where I want to map out data as it flows from one
> system
> to another.  Since this is data modeling, I suspect there are several
> FOSS packages which may help/do this.  What is out there that folks
> use/like/detest?  
> 
> I would like to be able to track basic inputs and outputs (and more as
> possible) from systems.  This would be a manual process since I am
> referring to HR, payroll, accounting systems as "systems."  Some data
> may be stock but there has to be a means to enter custom or specific
> information.
> 
> This is a general request since I don't wish to unnecessarily bound or
> restrict the solution set. 
> 
> Thoughts?  Suggestions?  Is this a case for a UML system??
> 
> Rich
> 
> 
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