Cluster-Related Configuration Options Follow Usage and Configuration Guidelines

11-4 Using Clusters for Oracle WebLogic Server

11.3.2.1 Cluster-Related Configuration Options

Table 11–2 lists key behaviors that you can configure for a cluster, and the associated method of configuration. Stateless Session Beans Scale better than stateful session beans which are instantiated on a per client basis, and can multiply and consume resources rapidly. When a home creates a stateless bean, it returns a replica-aware stub that can route to any server where the bean is deployed. Because a stateless bean holds no state on behalf of the client, the stub is free to route any call to any server that hosts the bean. Configure clusterable homes. See Table 11–2 . Configure Cluster Address. See Table 11–2 . Configure methods to be idempotence see Table 11–2 to support failover during method calls. Failover is default behavior if failure occurs between method calls.or if the method fails to connect to a server. The methods on stateless session bean homes are automatically set to be idempotent. It is not necessary to explicitly specify them as idempotent. Read-only Entity Beans Recommended whenever stale data is tolerable—suitable for product catalogs and the majority of content within many applications. Reads are performed against a local cache that is invalided on a timer basis. Read-only entities perform three to four times faster than transactional entities. Note: A client can successfully call setter methods on a read-only entity bean, however the data will never be moved into the persistent store. Configure clusterable homes. See Table 11–2 . Configure Cluster Address. See Table 11–2 . Methods are configured to be idempotent by default. Read-Write Entity Beans Best suited for shared persistent data that is not subject to heavy request and update.If the accessupdate load is high, consider session beans and JDBC. Recommended for applications that require high data consistency, for instance, customer account maintenance. All reads and writes are performed against the database. Use the isModified method to reduce writes. For read-mostly applications, characterized by frequent reads, and occasional updates for instance, a catalog—a combination of read-only and read-write beans that extend the read-only beans is suitable. The read-only bean provides fast, weakly consistent reads, while the read-write bean provides strongly consistent writes. Configure clusterable homes. See Table 11–2 . Configure methods to be idempotence see Table 11–2 to support failover during method calls. Failover is default behavior if failure occurs between method calls.or if the method fails to connect to a server. The methods on read-only entity beans are automatically set to be idempotent. Table 11–1 Cont. EJB Types and Guidelines Object Type Usage Configuration Clustering Best Practices 11-5

11.4 State Management in a Cluster