This figure demonstrates OC4J processes in their respective islands within the cluster. The OC4J islands, designated within the shaded area, crosses application server instances to endure that the OC4J processes exist on more than a single host to avoid the single point of failure. Within the OC4J home instance, the OC4J processes are grouped into two islands, default-island and second-island, to handle the load of state replication with the OC4J cluster.