see below ...
James Cook wrote:
> I hate when someone nitpicks a simple example that I post. I hope this isn't
> considered nitpicking.
I should have said its illustrative rather than prescriptive.
>
>
> Because memento and state are object references, setting memento = state,
> and state = memento for a rollback, won't accomplish what you intend.
> Instead, StateHolder could implement cloneable, and you could call the clone
> method to save and restore the object's member variables.
Right. Implement the clone method in the StateHolder set memento equal to that.
>
>
> Also, memento can be declared transient, and you wouldn't have to worry
> about *any* passivation of this variable.
Right. Passivation in a stateful session bean does not occur while the session
is in the Method Ready TX state (when its in the middle of a transaction.).
make memento transient.
So the code should look as follow (with corrections):
public class MySession implements javax.ejb.SessionBean,
javax.ejb.SessionSynchronization{
public StateHolder state;
public transient StateHolder memento;
public void afterBegin( ) {
memento = (StateHolder)state.clone( );
}
public void afterCompletion( boolean committed){
if( ! committed){
state = memento; // roll back state
}
}
...
}
public class StateHolder implements java.io.Serializable, Cloneable{
public int id;
public String name;
public Employee empBean;
public Object clone( ){
StateHolder sh = new StateHolder();
sh.id = id;
sh.name = name;
sh.empBean = emBean;
return sh;
}
}
>
>
> jim
>
> ----- Original Message -----
> From: Richard Monson-Haefel <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, November 09, 1999 8:15 AM
> Subject: Re: Stateful session bean state
>
> > No. This would be the case with an entity bean but not a stateful session
> > bean. You can, however, have the bean implement the
> SessionSynchronization
> > interface so that you are aware of the outcome of a transaction can use
> the
> > memento pattern to roll the bean's state back the way it was before the
> > transaction started.
> >
> > public class MySession implements javax.ejb.SessionBean,
> > javax.ejb.SessionSynchronization{
> > public StateHolder state;
> > public StateHolder memento;
> >
> > public void afterBegin( ) {
> > memento = state;
> > }
> > public void afterCompletion( boolean committed){
> > if( ! committed){
> > state = memento; // roll back state
> > }
> > memento = null; // less to passivate outside of a
> transaction
> > }
> > }
> >
> > public class StateHolder implements java.io.Serializable{
> > public int id;
> > public String name;
> > public Employee empBean;
> > }
> >
> > Note: The assumption here is that server is smart enough to preserving
> things
> > like a bean reference within the StateHolder.
> >
> > Richard
> >
> > --
> > Richard Monson-Haefel
> > EJB Expert for jGuru.com
> > ( http://www.jguru.com )
> >
> > Author of Enterprise JavaBeans
> > Published by O'Reilly & Associates
> > ( http://www.ejbnow.com )
> >
> >
> > "Kiely, Conor" wrote:
> >
> > > Question: Does the container have any responsibilities for managing the
> > > state
> > > of attributes in a stateful session bean where a transaction might roll
> > > back ?
> > >
> > > I'm not talking about serializing the state on passivation.
> > > I'm talking about attributes modified within (say) a TX_REQUIRED
> > > method, which rolls back after the attribute state has been updated.
> > >
> > > Can/should the container restore the pre-transaction attribute state ?
> > > I can't see mention of this (or maybe I'm not 'getting' it), but it
> > > would be 'nice'.
> > >
> > > Conor.
> > >
> > >
> ===========================================================================
> > > 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".
> >
>
> ===========================================================================
> 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".
--
Richard Monson-Haefel
EJB Expert for jGuru.com
( http://www.jguru.com )
Author of Enterprise JavaBeans
Published by O'Reilly & Associates
( http://www.ejbnow.com )
===========================================================================
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".
