Re: [jboss-as7-dev] Getting on the same page with @Clustered @Singleton
Here's a brief summary of what we've decided so far on this. We've
determined that a @Clustered @Singleton would, if implemented, act
similarly to a @Clustered @Stateful which only has one session.
When it comes down to spec, any kind of clustering is really non-spec
behavior. Having such features doesn't mean we aren't spec-conformant,
it just means we have additional functionality which goes beyond
specification.
Since we don't have @Clustered @Singleton today, this isn't considered a
high priority for the next release. But I suspect we could deliver this
for 7.2 if we wanted to.
On 12/07/2011 12:15 PM, Andrig Miller wrote:
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(a)redhat.com>
> To: jboss-as7-dev(a)lists.jboss.org, "David Lloyd"<dlloyd(a)redhat.com>,
"Paul Ferraro"<pferraro(a)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
> _______________________________________________
> jboss-as7-dev mailing list
> jboss-as7-dev(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/jboss-as7-dev
>
--
- DML