@Clustered applied to @Stateless: needed or not?

[juanjobio]

Hi.

I can't find clear information about this topic. We are using EAP 6.2

As far as I know @Clustered in @Stateful enterprise bean allow session data to be replicate and inform the available nodes to the ejb client.

So, talking about @stateless:

- Is it needed to add @Clustered to @Stateless in a HA environment since they have no session data?

Extracted from (Clustering Changes in WildFly 8):

The @Clustered annotation currently has 2 orthogonal meanings:

1. If applied to a @Stateful EJB, then a specific cache will be used (as defined by the EJB subsystem)
2. If applied to a @Stateless or @Stateful EJB, remote EJB clients will have a dynamic view of the EJB's topology.

I thought that the dynamic view were informed always to the client regardless the annotation, but besides that in the client server accessing the ejb, the jboss-ejb-client.xml contains the reference to the  both servers that conform the cluster so the ejb client already knows the topology.

So my question is:

     Which are the differences between use @Clustered or not in a @Stateless enterprise bean in a clustered environment? Is it really necessary?

Thanks in advance

[wdfink]

Hello Juanjo,

if you not mark a @Stateless as @Clustered the features are not enabled, that mean

• if there is no other indicator for cluster the cluster modules (JGroups) are not started
• if you access from remote the ejb-client context did not know about the cluster,
  i.e. only the server(s) in your client.property (or code) are used, but if clustered the server send a cluster-view back and all other servers in the cluster are used as well
• the client continue with DeploymentNodeSelector instead of using the ClusterNodeSelector

All this features are not available if you use Local interfaces or access the server with the remote-naming (URL remote://) approach.