Managing replication in your cluster

Replication is a service provided by WAS that transfers data, objects or events among application servers. Data replication can be used to make data for session managerm dynamic cache and stateful session beans available across many application servers in cluster

• Dynamic caching: Data replication service (DRS) is the internal WebSphere Application Server component that replicates data among application servers. There are several types of data replication, and WebSphere Portal can make use of data replication for dynamic caching and for memory-to-memory replication of session data. Enabling data replication for dynamic caching in a cluster environment is absolutely necessary to maintain data integrity between multiple WebSphere Portal nodes in the cluster. Replication also helps improve performance by generating data once and then replicating it to other servers in the cluster.


• Distributed sessions: WebSphere Portal can use the WebSphere Application Server capabilities to support HTTP session failover, which enables one node in a cluster to access information from the existing HTTP session in case of a failure in the cluster node originally handling that session. This capability is referred to as distributed sessions. WebSphere Application Server provides two techniques that can be used for distributed sessions, either of which can be used in a WebSphere Portal cluster. Distributed session support is not enabled by default, so you will have to determine whether to provide this capability in your cluster, and, if so, which of the two techniques you will use: memory-to-memory session replication and database session persistence.