facade pattern maybe??
----- Original Message -----
From: "Victor Langelo" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, August 08, 2000 9:44 AM
Subject: Re: A design question...
> Tom,
>
> This is a basic problem with the current EJB spec. I don't know what the
future
> holds. For now we handle this with a combination of a mapping layer which
> supports polymorphism and using the often mentioned pattern (whose name I
> forgot) where entity beans are only accessed via a session bean. We then
hide
> the ugly details of which entity bean to use from the client in the
session bean
> code.
>
> Because the mapping layer supports polymorphism, we can access and edit
all
> specializations of person in a generic person bean. Granted, some of the
> specialization may not be supported in the interface. That turns out not
to me a
> major problem in the overall scheme.
>
> I also don't spend a lot of time trying to make every session bean
polymorphic.
> I make the domain objects polymorphic and make the beans polymorphic only
where
> it is called for by the user interface. Since we can use a person bean
when
> needing only general person data (name, birthdate, etc...) there is less
of a
> need for polymorphic beans than I orginally thought.
>
> --Victor Langelo
>
>
> Tom Lepski wrote:
>
> > Hi Kurt,
> > I understand your Collection analogy but I think this is really a
legitmate
> > demand. For eg. in a system there could be Persons, Managers and
Techleads.
> > Now, it is quite reasonable to retrieve all the Persons in one go and
then
> > depending on the person perform activities. So there have to be
different
> > entities because operations like manage() cannot be provided in Person
bean.
> >
> > But as I write this, I got another idea.
> > Support all the methods in Person (actually have just one kind of entity
> > bean which has superset of all the attributes) and also have a tag field
> > telling whether it is a Person or Manager etc. Now depending on this
tag,
> > call the appropriate methods. If you call manage() on a bean that has
the
> > tag value of Person, throw some runtime exception!
> >
> > Please give your comments on this. I am sure many of the projects
involving
> > EJBs must have ran into this kind of situation.
> >
> > Please help,
> > -Tom.
> >
>
>
===========================================================================
> To unsubscribe, send email to [EMAIL PROTECTED] and include in the
body
> of the message "signoff EJB-INTEREST". For general help, send email to
> [EMAIL PROTECTED] and include in the body of the message "help".
>
>
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff EJB-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
