On 28 Apr 2006, at 06:03, David Avendasora wrote:
I am using inheritance in the model as well as interfaces but the
problem isn't the inheritance! I'm having a hard time explaining
the structure of my application so I've done my first-ever UML
Class Diagram to try to explain it better. I've attached it -
hopefully it makes it.
I don't think I'm doing anything crazy. I think it is pretty
standard OO stuff (straight out of Head First Design Patterns). Can
anyone tell me a better structure?
Looks to my like a classic MRP model, a little over-refined. The
interfaces are an implementation details, and are really a red
herring. Choosing the database schema is as much to do with
performance as anything else. I think the first time I had to
implement one of these was pre-relational, and I was fortunate enough
to be able to use Total instead of IMS (extra detail added for the
veterans among us).
The design you displayed could be implemented in a zillion different
ways, and that's even ignoring the interfaces decisions. EOModeler
is going to want to have relationships defined using entities, rather
than interfaces, because EOF needs to be able to instantiate
instances of the related objects, which I think is fair enough.
In the absence of any information to the contrary, I'd probably use a
Part and a BoM table. I notice that the interfaces in some cases are
identical in the UML (which is an over-refinement hint). I'd
probably use a type field in Part to distinguish between your three
subparts, and make them separate entities. The BoM table doesn't
need to be separated. Relationships live in your Part entity/class,
and ignore the ones you don't want. Depending on your industry, it's
not unknown for "Intermediate" parts to suddenly become raw materials
or finished goods at times; this will also affect your design.
Paul
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