Hi Kevin.
Thanks for the detailed, well explained reply.
I thought IsA is initials for something like "Inehritance Structure
Architecture" or something like...
Well, the inheritance discussed is not a IsA...
I just have some entities with same attributes ... (and I am lazy...)
Cheers
Shahar
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Kevin P. Monaghan
Sent: Sunday, January 07, 2001 9:47 AM
To: jBoss
Subject: RE: [jBoss-User] Inheritance in CMP beans - followup
Hi Shahar:
The "Is-A" relationship is all about inheritance, also called a gen-spec
relationship or "generalization-specialization" relationship between
classes. If you are using inheritance correctly, a subclass (the
"specialization") "is a" kind of it's super class (the "generalization").
For example - and I really hate this example but anyone can understand it -
a CheckingAccount is a ("is-a") kind of Account, a SavingsAccount is a
("is-a") kind of account. So, in theory, this is a good candidacy for
inheritance. There is a "is-a" relationship between CheckingAccount and
Account as well as between SavingsAccount and Account.
WRT your comments about OO, real live code reuse (outside of within the
constructs of a framework or architecture-level / system-level components)
may occur but in very small amounts. You have to look at amounts of reuse in
different areas. For example, how much reuse do you get in the arena of
business objects? Maybe not too much. I have been developing OO apps for 10
years now and anything more than a trivial amount of code reuse at the
business object level is rare. Originally, OO was touted as being all about
code reuse, but in reality it is about complexity reduction, flexibility and
extensibility (at the least).
Good luck,
Kevin
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Shahar Solomianik
Sent: Sunday, January 07, 2001 1:57 AM
To: 'jBoss'
Subject: RE: [jBoss-User] Inheritance in CMP beans - followup
Hi all.
Sorry for not being here while you discuss this issue...
I DO want it just for code reuse, nothing else...
The ancestor remote interface will never be deployed as a remote interface,
it will only be derived from.
Could you please explain "inheritance in Java is about IsA behaviour not
code re-use" ? (what is IsA ?)
Object Oriented was originally thought of as a code reuse method, wasnt it ?
(I mean, components and stuff came later, didnt they ?)
Shahar
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Kenworthy, Edward
Sent: Friday, January 05, 2001 10:03 AM
To: 'jBoss'
Subject: RE: [jBoss-User] Inheritance in CMP beans - followup
Hi Shahar
Don't do it.
If you have remote interface A and create remote interface B by extending A
then you are saying "I can use an instance of B to substitue for an instance
A". THIS IS NOT TRUE !
EJB does not properly support inheriting of one bean from another. By which
I mean, you can do it, BUT it will not behave as it should. (eg IsA doesn't
work!).
If you don't care about this, ie you are using the inheritance for code
re-use then I would do it in a different way because otherwise you would
confuse people (inheritance in Java is about IsA behaviour not code re-use).
I would do it by factoring out a common base (which is NOT a remote
interface) which both A and B extend.
Edward
-----Original Message-----
From: Shahar [mailto:[EMAIL PROTECTED]]
Sent: 03 January 2001 17:12
To: [EMAIL PROTECTED]
Subject: [jBoss-User] Inheritance in CMP beans - followup
[Hi again]
off course, I also intend to extend the remote interface. Possible ?
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