I'm not sure, but is it a good idea to use read only entity beans for static
data? Shouldn't the session beans be used for this instead?
just a thought!
Anurag
>
>I should have mentioned that the server I am using is WebLogic that
>implements a custom READ-ONLY strategy for entity beans. READ-ONLY entity
>beans poll the database at a given time interval for updates. However, I
>only want one instance of the bean to exist per-server/per-cluster
>otherwise
>I will have many beans polling the database many times.
>
>Myles
>
>
> > -----Original Message-----
> > From: Jean-Baptiste Nizet [SMTP:[EMAIL PROTECTED]]
> > Sent: 05 December 2000 13:50
> > To: [EMAIL PROTECTED]
> > Subject: Re: Readonly Entity Bean Strategy
> >
> > David Sims wrote:
> >
> > > Myls Jeffery wrote:
> > > > We have a requirement for a number of static data types in our
> > project.
> > > > Each type of static data will be provided by a read-only entity
>bean.
> > I
> > > > want to ensure that only one instance of an entity bean is created
>so
> > that
> > > > we do not have multiple entity beans of the same type polling the
> > database
> > > > for the same data.
> > > >
> > > > To accomplish this, I was thinking of creating a PK class for each
> > entity
> > > > bean that no matter what ID you pass to it it will treat it as the
> > same.
> > > > Therefore the EJB server will not create a new instance of the
>entity
> > bean -
> > > > it will simply return the existing one.
> > >
> > > I've done this very thing in the past. Home.findByPrimaryKey() always
> > > ignored the PK that was passed in and instead "found" the same PK
>every
> > > time. You should be able to do the same thing with Home.create().
> > >
> > > In the situation I was in, we needed a "singleton", so this was the
> > > strategy we took. Worked out fine. It was a portable, EJB primary key
> > > generator that was part of the Enterprise Tool Kit.
> > >
> >
> > Maybe I miss something, but if you really implemented a singleton this
> > way, then I
> > won't ever buy your product :-(
> > First of all, EJBs are intended to be distributed. This means that if
>your
> > servers
> > are clustered, you can't have a real singleton (only a singleton per VM)
> > for all
> > your servers. The only way to have a real singleton is to break out of
>the
> > EJB
> > model and to implement, for example, a CORBA singleton.
> > Second, even if you use a single container, this container might
> > instantiate
> > several instances of the same entity bean (i.e. the same PK). In fact,
>all
> > the
> > servers I've used, except Weblogic, use one instance of the same Entity
> > Bean per
> > concurrent transaction.
> >
> > Do I miss something?
> >
> > JB.
> >
> > >
> > > That's not much information, but I hope it helps.
> > >
> > > cheers,
> > > david
> > >
> > > --
> > > David Sims [EMAIL PROTECTED]
> > > Sims Computing, Inc. www.simscomputing.com
> > >
> > >
> >
>==========================================================================
> > =
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>to
> > > [EMAIL PROTECTED] and include in the body of the message "help".
> >
> > --
> > Jean-Baptiste Nizet
> > [EMAIL PROTECTED]
> >
> > R&D Engineer, S1 Belgium
> > Kleine Kloosterstraat, 23
> > B-1932 Sint-Stevens Woluwe
> > +32 2 200 45 42
> >
> >
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>
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