One of the primary advatanges about 'components' is their lack of
inheritance.
Tough useful, inheritance provides some of these (and other) 'complex'
issues
on a long run (and a long run nowadays is 6 months ;-) I am happy using
interfaces
to model 'inheritance', but I'm not too confortable with code inheritance. I
prefer to
compose objects to reuse code.
In a tiered system firing upon a RDBMS (tough not the only 'use
case' of EJBs, by far
the most common), the point seems to vanish. You model (db) relations by
composing objects,
not inheriting code. Business Logic isn't the place where I would inherit
nothing but perhaps
the 'behavior contract'(the interface(s) ). It would be nice, tough, for
openness, that perhaps
some of these concepts would be explored further
My 2c,
Rifle
-----Original Message-----
From: Jose Gonzalez [mailto:[EMAIL PROTECTED]]
Sent: Monday, July 31, 2000 12:46 PM
To: [EMAIL PROTECTED]
Subject: Component inheritance in EJB2.0
Component inheritance was one of the things that I missed in EJB1.1.
After
taking a look at the public draft of EJB2.0, it seems they neither won't
include it in this specification release. I think this could be an
interesting thing to include, as there are a lot of discussions here about
how to emulate it, and inheritance has been one of the key concepts in OO
programming, that has led us to the component concept.
In the public draft there is a note about inheritance in D.3
Inheritance
(p.510) that says:
"The current EJB specification does not specify the concept of component
inheritance. There are complex
issues that would have to be addressed in order to define component
inheritance (for example, the
issue of how the primary key of the derived class relates to the primary key
of the parent class, and how
component inheritance affects the parent component's persistence)."
I'd like to hear your thoughts about these (so?) complex issues, and
about
the lack of component inheritance in EJB2.0.
Regards
Jose
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