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Functional decomposition is not used when applied to use case modeling.

This phrase is a copied one from a question paper.What is the meaning of that phrase.

This is not equal to the question What is Functional Decomposition?

Community
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dulaj sanjaya
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1 Answers1

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Use cases deal with synthesizing functions, not decomposing them. A technician decomposes a system to find the pieces it is built of. A business analyst tries to stack single parts of a system on piles so they are formed around a single goal. A use case describes a unique single piece of added value a systems gives to an actor. Indeed, functional decomposition is what most people try when describing use cases: finding bits and pieces. They all (like me) come from the programming guild where this is the daily job. But UC synthesis is working the exact opposite!

I recommend reading Bittner/Spence who explain this very complex approach in detail and very nicely.

qwerty_so
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  • Great answer! Most people do not know how harmful functional decomposition can be when developing use cases for the SUD(System Under Development), at the Software Design phase. Use Cases are a way of discovering requirements through a behavioural model of the SUD. – Soutzikevich May 09 '18 at 14:13
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    @P.Soutzikevich Yes, unfortunately. I guess it's due to the fact that the UML spec itself is very techie (for many reasons) and they do not transport the business aspect well. Also most UML users also have that tech background and are seduced to apply the decomposition pattern here as well. I can speak here for myself ;-) at least when starting 2 decades ago. – qwerty_so May 09 '18 at 15:32