RE: A design philosophy question

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I am  being neither flippant nor simplistic.  lets use your example:

"Let's for instance take an order line. Let's say that you want to have
order number, line number, item, quantity ordered, quantity shipped, unit
price and extended price. This information comes from various places. This
is presenation format, and I don't expect to write a different BL server for
each format."

You are quite right. This info comes from different places and all sorts of
factors in all variations from customer discount to delivery and
availability are involved.  Why do you say this is part of the presentation
process?  I do not see it that way at all.

This same string of data is needed for sales look ups, quoting, shipping,
order entry, and finally for billing.  So, why not write the program that
does all of that. Write it once. Bullet proof it.  Then your screen puts up
the fields (already defined in the data structure) and recovers the data and
sends it off to your bulllet-proofed program for verification anad
discounting, etc.  Notice all of the F-specs you DON'T write?  Notice the
total lack of concern about data security?  And notice that your green
screen needs almost no lines of code?  Even  your subfile has all of the
order line fields available, (even qty x price = extended is already done in
the BL layer).

Your decision becomes: do I add extended to total as we go, or do I read
through the subfile and total once, at the end?

I hope that my answer doesn't seem simplistic or silly.  I really do believe
our future lies in horizontal, not vertical modulaization.

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Booth Martin   http://www.MartinVT.com
Booth@MartinVT.com
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