RE: [Springframework-developer] EJBs and their Bean Factories

[Alef A. <al...@jt...>]

> As for passivation/activation, it's not an issue for
> stateless beans, as those are not legal states. 
Oops, you're right. It seems like I'm already forgetting some of that
horrible stuff I've been using for the last 3 years (of which I'm glad ;-).

By the way, I was looking for that really big warning you had put up in the
SingletonBeanFactoryLocator (wasn't it), but couldn't find it anymore. No
warnings anymore ;-)?

Alef



> For stateful beans, you
> will get an unload and reload on the passivation/activation, but this is
> not for real if there is already a shared instance, all that will be
> unloaded/reloaded is the reference to the shared context/beanfactory.
> 
> Regards,
> Colin
> 
> 
> Alef Arendsen wrote:
> 
> >>Looking at the code for the EJB base classes, unless I'm missing
> >>something obvious (not unheard of), it seems that by default a separate
> >>bean factory is created for each bean instance.
> >>
> >>
> >Well, to put it bluntly: you're not mistaken; it's the way it is.
> >
> >As far as I'm concerned, the issue basically is that without violated any
> >rules that apply to implementing EJBs, it's just not possible to get an
> >ApplicationContext shared across multiple multiple beans of different
> types,
> >not even across multiple instances of the same type.
> >
> >For one because resources instantiated as fields of EJBs should either be
> >serializable (which the ApplicationContext isn't, not even mentioning any
> >beans inside it), or transient (or closed and thrown away on
> passivation).
> >
> >Another solution would be (and I hate to say this, but this is what we're
> >currently using in one of our applications that is still based on EJBs
> but
> >in the process of being migrated to Spring) to bind the context in a JNDI
> >tree, but here, the Serializable argument also applies. So that (when
> >applying the rules really strict) is one to throw away as well.
> >
> >Of course when using certain EJB container, you won't have to worry about
> >serializable issues when not accessing the JNDI from outside the VM the
> >server is running in. Also, having the ApplicationContext defined as a
> >singleton or something (ughh!) wouldn't result in too many problems using
> a
> >simple EJB container, but I guess that's not really an option we (Spring)
> >are eager to offer. The same applies to providing an approach based on
> >static fields.
> >
> >Ohh, there is something like the BeanFactoryLocator, but this only reads
> in
> >BeanFactory I believe.
> >
> >Basically my approach is to avoid the use EJBs where possible and if
> needed,
> >implement an EJB using Spring's EJB layer and don't worry about one or
> two
> >applicationcontexts too much being created. I mean, afterall, one of the
> >reasons I choose Spring in the first place is to be able to get rid of
> EJBs.
> >(I won't start a rant here, that might just be personal ;-).
> >
> >I don't know if this satisfies or if somebody else has opinions?
> >
> >Alef
> >
> >
> >
> >
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