[jboss-user] [Clustering/JBoss] - Re: Does clustering require traffic over 1098 as well as 118

[bstansberry@jboss.com]

Thanks for asking; we resolved this on our support portal and I forgot to post the result here.

The issue is the RMI stub for the HA-JNDI service.  Clients that connect to HA-JNDI use RMI as the transport, so each server running HA-JNDI creates an RMI stub for use in communicating with that server.  When a client contacts the HA-JNDI service and downloads a proxy for that service, the proxy includes the RMI stubs for *all* the servers in the cluster.  The presence of these stubs is what allows the proxy to fail over from one server to another if needed.

So, say you have a 3 server cluster, A, B and C.  A client contacts C (e.g. at port 1100) and downloads an HA-JNDI proxy.  The proxy includes separate RMI stubs for A, B and C.

How does C have a stub for A and B?  When C joins the cluster, it fetches A and B's stubs, and sends its stub to A and B.

The traffic Anne was seeing was the normal traffic of an RMI stub communicating back to its origin server for the purpose of maintaining a "lease" on the RMI server object.  This "lease" is used by RMI's distributed garbage collection; without it the RMI server object could be gc'd.  By default, this communication happens when the stub is first deserialized, and every 5 minutes thereafter.  This communication is part of standard RMI stub behavior; it's not something JBoss wrote.

The communication occurred on 1098 because that's the RMI port they had configured for HA-JNDI.  By default in current versions of the AS, this port is 1101.

View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3966721#3966721

Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3966721