Re: Persistence, EJBs and OO-Relational mapping

sriniv79_at_my-deja.com wrote:

> That might be the right thing to do. But I have seen pure relational
> data, such as Invoice and Line Items, being brought from the RDBMS and
> persisted in object wrappers!! Do you also agree that this is wrong?

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[snip]
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> I can only take the *own paradigm* with a pinch of salt. I would like
> my data obey the rules of relational arithmatic whichever paradigm is
> used to represent it.

Srinivan,

from the way you are choosing your arguments, I get the feeling that you are approaching the problem the wrong way around. "Relational arithmetic" is nothing natural. It was developed from bookkeeping data in spreadsheets. That is by no means a very effective look at business rules.

Reality consists of objects.
Even simple data can always be viewed as an object:

- data is generated by some method whatsoever
- rules can be applied for relationships between data objects
- something is done with the data to produce a result or output

This is why OO-languages add methods to objects. All the nice "features" of RDBMS can also be expressed in OO-methods. Within the near future we will see more object databases with method frameworks (like EJB), that add the same features (cascaded delete, "referential integrity", constraints, callbacks (triggers)) to their products.

Viewing data as objects makes life easier for the programmer. Storing object data to relational databases just does not work because paradigms do not match.

The OO-paradigm is by far more natural and easier to handle than relational set-arithmetic.
We will see a replacement in the next (x) years.

(working on x = 5)
(x = 20 is more realistic)

Regards,
Carl

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Carl Rosenberger
db4o - database for objects - http://www.db4o.com