I am relatively new to clustering so please do not send me to read
documentation. I have read all I could find.
I also read JBoss documentation on clustering but yet I do not entirely
understand. At the end of the message there is a quote from JBoss documentation
but I still need explanation in plain language. Can anyone please answer????
I think about implementing ServiceLocator that caches home interfaces in a
cluster. Yes, I know that it will be a one singleton per JVM. So I have 3
nodes, I will have 3 singletons. Is there a problem with that?
In a clustered environment (JBoss 4.0.5, a few nodes, sticky is off) are home
interfaces bound to a specific node in the cluster or not? In other words can
I or can I not...?
1. can I safely cache reference to a home interface (EJBHome) to a session bean
in a ServiceLocator ?
2. can I safely cache reference to a home interface to a entity bean in a
ServiceLocator ?
3. can I safely cache LOCAL home interface (EJBLocalHome) in a ServiceLocator ?
I use HA-JNDI (I think that I do since I put "localhost:1100" into
Context.PROVIDER_URL). This means I DO use HA-JNDI. Correct?
I create InitialContext as:
{
...........
Hashtable environment = new Hashtable();
environment.put(Context.INITIAL_CONTEXT_FACTORY,
"org.jnp.interfaces.NamingContextFactory");
environment.put(Context.URL_PKG_PREFIXES,
"org.jboss.naming:org.jnp.interfaces");
environment.put(Context.PROVIDER_URL, "localhost:1100");
return new InitialContext(environment);
..........
and I use True in META-INF\jboss.xml for all my beans
Below is a quote from section 1.2.1 How it works from "The JBoss 4 Application
Server Clustering Guide " On the server side, new InitialContext(), will be
bound to a local-only, non-cluster-wide JNDI Context (this is actually basic
JNDI). So, all EJB homes and such will not be bound to the cluster-wide JNDI
Context, but rather, each home will be bound into the local JNDI. When a remote
client does a lookup through HA-JNDI, HA-JNDI will delegate to the local JNDI
Context when it cannot find the object within the global cluster-wide Context.
The detailed lookup rule is as follows.
- If the binding is available in the cluster-wide JNDI tree and it returns it.
- If the binding is not in the cluster-wide tree, it delegates the lookup query
to the local JNDI service and returns the received answer if available.
- If not available, the HA-JNDI services asks all other nodes in the cluster if
their local JNDI service owns such a binding and returns the an answer from the
set it receives.
- If no local JNDI service owns such a binding, a NameNotFoundException is
finally raised."
Thanks to anyone who answers or just reads....
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