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

[Paul Ferraro]

Rado,

We've decided to defer on supporting @Clustered @Singleton in 7.1.

As we also discussed, HA-singleton will still be supported in 7.1,
though it will only operate on MSC services.

Paul

On Wed, 2011-12-07 at 18:50 +0100, Radoslav Husar wrote:
> 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