Hi,
EJB 2.0 specifications has put the "support for component-level
inheritance" in appendix A "Features deferred to furture releases".
Without any guidelines regarding this in specification you can get a
workaround but it don't let others to use your parent beans to create
children easily.
regards
Ravi
On Wed, 31 Jan 2001, Shelly Aggrawal wrote:
> What about the ejbFindByPrimaryKey and ejbCreate method problems, if the
> ParentPk and the ChildPk are different.
>
> ----- Original Message -----
> From: Carlos Otero Barros <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Wednesday, January 31, 2001 1:59 PM
> Subject: Re: Inheritance : Once Again:
>
>
> Hi Shelly.
>
> I don�t see any problem inheriting the EJB class (the bean class). But
> iheriting HI or RI you could get the deploy tool in trouble. A very
> simple-minded deploy tool should expect the direct ancestor of a HI be the
> EJBHome interface an so the RI. I�m not sure this is going to work on every
> appserver, specially with J2EE Reference Implementation.
>
> ----- Original Message -----
> From: "Shelly Aggrawal" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Wednesday, January 31, 2001 8:30 AM
> Subject: Inheritance : Once Again:
>
>
> > Hi All,
> > I know that we have visited Inheritance a lot of times in this mailing
> > list.. but the following seems to be still unconfirmed:
> >
> > Suppose i have a parent entitybean, say ParentBean. The RI and Home I
> Parent
> > and ParentHome. the PK type is ParentPK...
> > I understand that the only way to inherit an entity bean is by inheriting
> > the interfaces and classes separately. So, i have a child which is
> >
> > public interface Child extends Parent{
> > pubic void AChildMethod();
> > }
> >
> > public class ChildBean extends ParentBean{}
> >
> > I do not see a problem with inheriting the remote interface and with the
> > corresponding methods in the bean class. But can I, and is it valid, to
> > inherit the home interface... considering the fact, that the ParentHome
> will
> > have a
> > public Parent findByPrimaryKey() while the child will need to have a
> > public Child findByPrimaryKey() ... this is neither overriding nor
> > overloading... and hence will give a compilation error. A no argument
> > create() will also give rise to the same problem. So I gather that the
> > child can inherit the remote interface but not the home interface.
> > So, Parent's home is something like this
> > public interface ParentHome extends javx.ejb.EJBHome{
> > public Parent findByPrimaryKey() ;
> > public Parent create();
> > }
> >
> > and the Child's home would be
> > public interface ChildHome extends javx.ejb.EJBHome{
> > public Child findByPrimaryKey() ;
> > public Child create();
> > }
> >
> > Now, what happens in the BeanClass... I derive the ChildBean from the
> > ParentBean
> > public class ParntBean implements javax.ejb.EntityBean{
> > public ParentPK ejbCreate(){
> > // return ParentPk
> > }
> > public ParentPK ejbFindByPrimaryKey(){
> > // return ParentPk
> > }
> >
> > }
> >
> > public class ChildBean extends ParentBean{
> > public ChildPK ejbCreate(){
> > // return ChildPk
> > }
> > public ChildPK ejbFindByPrimaryKey(){
> > // return ChildtPk
> > }
> > }
> > The compilation of ChildBean class will give errors. I may be able to
> bypass
> > this by declaring the ParentPK as the return type but in this case ejbc
> > will give errors......
> >
> > Is this a restriction with Entity beans.. or is there some way to achieve
> > inheritance.
> > Any inputs will be most helpful.
> >
> > And also should the ChildPk be derived from ParentPK as in
> > public class ChildPK extends ParentPK{
> > int childId;
> > }
> >
> > Thanks and Regards,
> > Shelly
> >
> >
> >
> >
> >
> >
> > About Inheritance in EJBs. I am presenting my views and doub
> >
> >
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> >
> >
>
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>
>
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