Is there any way to configure JNDI so the lookup first checks localhost and if it doesn't find matching name it performs automatic discovery of other jndi servers?
A:
My understanding of the documentation is that this is the default behavior when using clustering:
16.2.2. Client configuration
The JNDI client needs to be aware of the HA-JNDI cluster. You can pass a list of JNDI servers (i.e., the nodes in the HA-JNDI cluster) to the
java.naming.provider.urlJNDI setting in thejndi.propertiesfile. Each server node is identified by its IP address and the JNDI port number. The server nodes are separated by commas (see Section 16.2.3, “JBoss configuration” on how to configure the servers and ports).java.naming.provier.url=server1:1100,server2:1100,server3:1100,server4:1100When initialising, the JNP client code will try to get in touch with each server node from the list, one after the other, stopping as soon as one server has been reached. It will then download the HA-JNDI stub from this node.
Note - There is no load balancing behavior in the JNP client lookup process. It just goes through the provider list and use the first available server. The HA-JNDI provider list only needs to contain a subset of HA-JNDI nodes in the cluster.
The downloaded smart stub contains the logic to fail-over to another node if necessary and the updated list of currently running nodes. Furthermore, each time a JNDI invocation is made to the server, the list of targets in the stub interceptor is updated (only if the list has changed since the last call).
If the property string
java.naming.provider.urlis empty or if all servers it mentions are not reachable, the JNP client will try to discover a bootstrap HA-JNDI server through a multicast call on the network (auto-discovery). See Section 16.2.3, “JBoss configuration” on how to configure auto-discovery on the JNDI server nodes. Through auto-discovery, the client might be able to get a valid HA-JNDI server node without any configuration. Of course, for the auto-discovery to work, the client must reside in the same LAN as the server cluster (e.g., the web servlets using the EJB servers). The LAN or WAN must also be configured to propagate such multicast datagrams.
Pascal Thivent
2010-06-01 16:53:54
Maybe I wrote it not clearly enough. Lets say I am looking for an object registered in JNDI as "ObjectA". What I want to do is to first check localhost if "ObjectA" is registered there, and if not try to discover another JNDI server through multicast and check if ObjectA is there and if not throw NamingException (or whatever exception should be thrown).
Filip
2010-06-02 07:17:28
@Filip: Oh, I see now. Not sure if this can be done without coding this logic (seems to be a very special use case actually).
Pascal Thivent
2010-06-02 12:27:54