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

[Radoslav Husar]

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