Wednesday, 11 January 2012

WebLogic 11g Clustering: Communications In a Cluster


Overview


* Use IP multicast for backward compatibility.
* Use unicat for one-to-many communication.
* Use IP Sockets for peer-to-peer communication.

Peer-to-Peer Communication Using IP Sockets

* IP sockets provide a simple, high-performance mechanism for transferring messages and data between two applications.
* Clustered WebLogic Server instances use IP sockets for:
- Accessing non-clustered objects deployed to another clustered server instance on a different machine.
- Replicating HTTP session states and stateful session EJB states between a primary and secondary server instance.
- Accessing clustered objects that reside on a remote server instance (multi-tier cluster only)
* Two types of socket reader implementations:
- Native: use whenever possible for performance gains.
- Pure-Java: set reader threads to max open sockets.
* Potential socket usage:
- Normally two
- "Pinned" services require additional sockets.

Cluster-Wide JNDI Naming Service

* Similar to single server instance JNDI tree.
* In addition it stores services offered by clustered objects from other server instances in the cluster.
* Each server instance in a cluster creates and maintains a local copy of the logical cluster-wide JNDI tree.
* Deploy homogeneously to avoid cluster-level JNDI conflicts

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