JNDI clustering

Question

When I do a:
          Context context = new InitialContext();
          In a clustered environment, will that connect to the cluster JNDI or the
          localhost JNDI?
          We need to make sure whenever our stateless session beans get a handle
          to the context, it is the localhost JNDI, Is there a way to do this if
          the answer to the above question is the cluster?
          The problem we have is we are binding local objects into JNDI, each
          server in the cluster needs to get references to one of these objects
          (the stateless session bean needs to do a lookup and get a reference).
          So our code looks something like this:
          public class MyStatelessSessionBean implements SessionBean
          public void myRemoteCall(...) throws RemoteException
          Context context = new InitialContext();
          MyLocalObject object = (MyLocalObject)context.lookup("MyObject");
          We need to ensure that the MyLocalObject that is returned is one from
          the localhost, not one in the cluster.
          thanks,
          -chris
          

Answer 1

On the server if you do a Context ctx = new InitialContext() it will return you
          local initial context. So, your lookup will be local.
          Instead if you use a dns cluster name then the first server name that dns server
          returns will be used to connect and get an initial context if you are on a
          standalone client.
          Environment env = new Environment();
          env.setProviderUrl("t3://fooclust:7001");
          Context ctx = env.getInitialContext()
          When you do a lookup in the jndi tree, what you get back depends on the server
          configuration and doesn't depend on where you look if you are in a homogenous
          cluster.
          - Prasad
          Chris Humphrey wrote:
          > Thanks for the reply. We are currently using the Referenceable interface to
          > store and get objects from jndi, so the objects are not serializable.
          >
          > It sounds like I have a problem to fix here, let me recap to make sure I
          > understand. If the bean was accessed with a DNS cluster for the context, I
          > will get back a reference to the cluster, if the bean was accessed using
          > 'localhost' I will get back a reference to the jndi running locally.
          >
          > This was what I was afraid of. Is there a way to forceably get an initial
          > context to the localhost jndi?
          >
          > Thanks again for the reply.
          > -chris.
          >
          > Wei Guan wrote:
          >
          > > Comments inline
          > >
          > > --
          > > Hope it helps.
          > >
          > > Cheers - Wei
          > >
          > > "Chris Humphrey" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > When I do a:
          > > >
          > > > Context context = new InitialContext();
          > > >
          > > > In a clustered environment, will that connect to the cluster JNDI or the
          > > > localhost JNDI?
          > > In cluster, JNDI tree is "replicated JNDI tree". Every server in the
          > > cluseter has the same "replicated JNDI tree".
          > > " Context context = new InitialContext();" will give you reference to the
          > > JNDI tree in the same JVM as the caller's.
          > >
          > > >
          > > > We need to make sure whenever our stateless session beans get a handle
          > > > to the context, it is the localhost JNDI, Is there a way to do this if
          > > > the answer to the above question is the cluster?
          > > >
          > > > The problem we have is we are binding local objects into JNDI, each
          > > > server in the cluster needs to get references to one of these objects
          > > > (the stateless session bean needs to do a lookup and get a reference).
          > > >
          > > > So our code looks something like this:
          > > >
          > > > public class MyStatelessSessionBean implements SessionBean
          > > > {
          > > > public void myRemoteCall(...) throws RemoteException
          > > > {
          > > > Context context = new InitialContext();
          > > > MyLocalObject object = (MyLocalObject)context.lookup("MyObject");
          > > > }
          > > > }
          > > >
          > > > We need to ensure that the MyLocalObject that is returned is one from
          > > > the localhost, not one in the cluster.
          > > If your "MyObject" is a serializable object, serializable objects binding
          > > the JNDI tree will be replicated. That is, "MyObject" will have a copy on
          > > each server's JNDI tree. Since you get JNDI reference from localhost, your
          > > lookup("MyObject") will get the copy in the same JVM.
          > >
          > > >
          > > > thanks,
          > > > -chris
          > > >