[jboss-as7-dev] Getting on the same page with @Clustered @Singleton

[Andrig Miller]

The other complication, is that you may have a Singleton that has no state to replicate.  In that case, the single instance, with no replication makes sense.

Andy

----- Original Message -----
> From: "Radoslav Husar" <rhusar at redhat.com>
> To: jboss-as7-dev at lists.jboss.org, "David Lloyd" <dlloyd at redhat.com>, "Paul Ferraro" <pferraro at redhat.com>
> Sent: Wednesday, December 7, 2011 10:50:35 AM
> Subject: [jboss-as7-dev] Getting on the same page with @Clustered @Singleton
> 
> Hi guys,
> 
> I just want to sync up with everyone what's the plan on EE6's
> @Singleton
> running on multiple JVMs in 7.1*.
> 
> There is a common misconception that @Singleton is acting at cluster
> level. This is nay. The EE spec says:
> 
> A Singleton session bean is a session bean component that is
> instantiated once per application. In cases where the container is
> distributed over many virtual machines, each application will have
> one
> bean instance of the Singleton *for each JVM*.
> 
> 
> However the concept of @Clustered @Singleton where there is only 1
> failure-resistant bean instance within the cluster replicating state
> does make a lot of sense. Having to sync on the persistence level
> sounds
> dreadful. In one sense it is the successor of AS 5's singleton-ha
> which
> was deployment-level mechanism.
> 
> Is is possible to have this even though it is kind of violating the
> EE spec?
> 
> 
> David is requesting to fail the deployment of such:
> https://issues.jboss.org/browse/AS7-2887
> 
> Does it mean that we wont have it in 7.1? Maybe later?
> 
> 
> Cheers,
> Rado
> 
> 
> * EAP 6.0
> --
> Radoslav Husar
> 
> JBoss QE
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