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

[Colin S. <col...@ex...>]

I think the warning should still be in BeanFactoryLocator, with 
references to it in the actual impl. classes...

Alef Arendsen wrote:

>>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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