Ok. Here's what they might refer to (each vendor might use the same terms to mean different things so *I'm really not sure*): Active replication: Every state change is actively replicated to the backup. Passive replication: State is stored periodically. Backup reads the log file upon failover to reconstruct the correct state.
Active Replication replicates components and services across all possible nodes in the cluster. This replication strategy was used in the initial release of JBoss 3.0. Passive Replication (also called Primary-Backup) chooses a primary node and a list of backup nodes for each component or service. The primary node processes all requests and sends updates to the backup nodes. This replication strategy is used by most commericial application servers including WebLogic. There are trade-offs to both approaches, however most scalable servers use a form of Passive Replication.
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