[jboss-user] [EJB 3.0] New message: "Re: @Serivce : Singelton EJB and reetrant calls"

jaikiran pai do-not-reply at jboss.com
Tue Feb 2 03:05:06 EST 2010

User development,

A new message was posted in the thread "@Serivce : Singelton EJB and reetrant calls":


Author  : jaikiran pai
Profile : http://community.jboss.org/people/jaikiran

> dastraub wrote:
> got the answer from the jboss developers via irc, thanks !
For the record - Here's what was discussed over IRC:
(01:40:14 PM) danielst: @Service means, there is only one instance of this EJB, ok. EJB Spec. 4.7.11 says, the container must ensure that only one thread can be executing an ejb-instance (non reentrant instances). If I use an @Service, does the container serials the calls to this EJB ? Or throws an javax.ejb.ComcurrentAccessEcxeption ?
(01:46:39 PM) Jaikiran: danielst: @Service is not the EJB3.1 @Singleton
(01:46:48 PM) Jaikiran: @service was a jboss specific feature
(01:47:45 PM) danielst: yes, I know - It's a JBoss extension. But how does this handle parallel calls to this ejb if there is only one instance ?
(01:47:59 PM) wolfc: Jaikiran: in essence a service bean should behave very much like a singleton. Thread safety is one of the basics of EJB.
(01:48:07 PM) wolfc: I'm not sure whether we actually guard for it though. :-)
(01:48:25 PM) Jaikiran: wolfc: hehe, that's what i meant (i don't think we guard it) 
(01:50:48 PM) danielst: thanks for this hints ;-) - I don't use this by my self, I have to review some other sources and looking for arguments ...
(01:52:11 PM) Jaikiran: danielst: pretty soon we will be having @Singleton support, which will obviously be spec compliant
(01:54:22 PM) You are now known as Jaikiran|Lunch
(01:54:46 PM) danielst: @Singleton is EJB3.1, right ?
(01:55:11 PM) Jaikiran|Lunch: danielst: yes
(01:56:46 PM) danielst: yeah, I quickly read it now, there is also an @ConcurrencyManagement.
(01:57:23 PM) Jaikiran|Lunch: yes allowing for bean managed/ container managed concurrency
(02:01:23 PM) danielst: ok, as short summary : don't use the @Service because the behavior of concurrent calls is undefined ... and wait for ejb 3.1. Will the EJB 3.1 container works with an JBoss 4.2.3 (I guess not) ?
(02:02:31 PM) Jaikiran|Lunch: EJb3.1 will be targeted against AS-6.0.x versions
(02:02:57 PM) Jaikiran|Lunch: some of the initial features (like nointerface and deployment through .war) are available in the upcoming AS 6.0.0.M2
(02:03:11 PM) Jaikiran|Lunch: btw, 4.2.3 isn't fully EJB3 compliant
(02:04:22 PM) Jaikiran|Lunch: if you are interested in EJB3.1, here's its current state for 6.0.0.M2 http://community.jboss.org/wiki/EJB31inAS600M2


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